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HATCHERY SIGNALS A P R A C T I C A L G U I D E T O I M P R O V I N G H AT C H I N G R E S U LT S

Credits Hatchery Signals

Illustrations Main illustrator: Studio Michels

Publisher Roodbont Publishers B.V.

Other illustrations: Emka (40), Jolanda Hiddink (7, 33, 49, 98, 130, 174), Gemma Stekelenburg (45, 95)

Authors Sander Lourens (Hatchability.com, main author), Jolanda Holleman (Windkracht 10), Ton van Schie

Photography Main photographer: Marcel Berendsen

Graphic design Studio Hiddink, Marleen Klein Brinke

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English translation/correction Sue op ‘t Veld (Vertaalbureau AgroLingua)

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Thanks to Jessica Alderman, Marijke Bosman, Teun van de Braak, Keith Bramwell, Kathy Broekmeulen, Wouter Bruins, Ann Espeel, Fam. C. de Haas, Donna Hill, Tiny Janssen, Evert Kampert, Sabrina van de Kraats, Gerd de Lange, Louis Lemmens, Gerrit van der Linde, Fam. W. van Maanen, Conny Maatjens, Ron Meijerhof, Fam. E. Meijerink, Roos Molenaar, Willem van den Oetelaar, Carolien Overeem, Carla van der Pol, Helmich van Rees, Inge van RoovertReijrink, Cibele Araujo Torres, Tarsicio Villalobos, Merel v.d. Werf, Marieke Wispels, Gert Zoet, Broederij Het Anker, Broederij van Hulst, Broederij Lagerweij, Broederij Probroed, Broederij Verbeek.

Special thanks to Marleen Boerjan

Other photographs: A.P. Incubators (108); AAT (123); Aviagen (47, 109); Bolidt (4, 67); Ceva (129, 122, 129, 176, 177); Depositphoto: Branex (8); Dreamstime: Boyana Boycheva (24); Dreamstime: Dmytro Varavin (22); Dreamstime: Elena268 (23); Dreamstime: Euroleadergroup (9); Dreamstime: Fedor Eremin (78); Dreamstime: Gena Wells (21); Dreamstime: Jochenschneider (22); Dreamstime: Mastroraf (102); Dreamstime: Meryll (22); Dreamstime: Noppon Kobpimai (77); Dreamstime: Thierry Vialard (132); Dreamstime: Thierry Vialard (23); Edward Mailyan (190); Emka (38, 40, 102, 110); Frank van Merle (162, 185); GD (168); Gea Hogeveen photography (97); Hatchtech (89, 111, 124, 144, 158, 182); Heering (80, 81, 82, 181, 185, 187); Helmich van Rees (50, 117, 129); Hendrix Genetics (11, 36, 46, 62, 69, 102, 111, 113, 116, 127, 129, 129, 130, 133, 134, 163, 164, 165, 166, 172, 173, 175, 185, 187, 188); Henk Rodenboog (46, 98, 190); Hubbard Breeders (90, 137, 163, 166); Innovatec (70, 126, 127, 131, 141, 176); InOvo (125); Janssen Animal Health (142); Jamesway Chick Master Incubator (4, 8, 16, 17, 36, 43); Jan Smit (18); Koos van Middelkoop (50, 166); Lohmann Breeders (129, 138, 149, 156, 167); Maureen Bain (57); One2Born (146); Pas Reform (20, 21, 77, 87, 95, 140, 143, 150, 151, 152, 153, 165, 170); Paul van der Ven (177); Petersime (38, 110); Raymond van Tilburg (183, 184, 185); Sander Lourens (31, 34, 43, 47, 55, 66, 70, 71, 74, 84, 85, 92, 99, 101, 103, 106, 108, 109, 127, 134, 136, 137, 139, 142, 149, 152, 156, 159, 179); Soos (125); Stijn Peters (80, 177, 185, 187); Tim Engelen (12, 47, 59, 78, 81, 177); UV Light Technology Limited (56); Tiny Janssen (157); Ton van Schie (109, 130, 146, 164); Vencomatic (145); Viscon (116, 117); Wikimedia Commons: Florida Memory (4); Wikimedia Commons: Jankaan (93); Zoetis (121).

Roodbont Publishers B.V. PO Box 4103 7200 BC Zutphen, the Netherlands T +31 575 54 56 88 E info@roodbont.com I www.roodbont.com

References The experience of many people combined with expert knowledge and scientific papers was used to develop this publication. For ease of reading, we decided not to mention all sources of graphs and tables in the book. A full list of references is available upon request.

For more information please check www.hatcherysignals.com ©

Hatchery Signals is part of the Poultry Signals series. No part of this publication may be reproduced and/or published in print, photocopy or any other means whatsoever without the prior written permission of the publishers. The authors and publisher have compiled the contents of this publication with great care and to the best of their knowledge. However, the authors and publisher shall accept no liability due to damage of any nature whatsoever arising from actions and/or decisions based on the information provided. The publisher has tried to trace the copyright holders of all image material. When a source has remained unmentioned, holders of rights may contact the publisher.

www.agrolingua.com

Contents

45 46 47 48 49 50 51 52 53 55 58 59 60 61

5. Biosecurity Process steps in the hatchery Biosecurity zones at the hatchery Routing at the hatchery Clean floors and walls Biosecurity measures Personnel and hygiene Cleaning Disinfection of the hatchery

62 63 64 65 67 68 69 73 75

94 95 96 97 97 98 99 100 100 101 102 103 104 105 106 107 108 109 110 111 112

139 140 141 142 143 145

10. Chick quality Signals from empty eggshells Pipping height and pipping line Infection pressure Meconium Chick temperature Chick yield Drying off or dehydrating? Residual yolk Absorption of residual yolk Chick weight and length The signals given by chick length Working at the take-off table Selection criteria Navel and cloaca Belly Feathering Legs Beak Serious abnormalities Scoring systems Abnormalities and their causes Downgraded chicks Sex determination Sexing and sex-linked genetic traits Vaccination at the hatchery

148 149 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 171 172 173 174 176

11. Chick transport and delivery Chick storage Preparation for chick transport Cargo area climate Ventilation during transport International transport Transport to and from airports Feed and water during long transport Chick delivery Hygiene during delivery On the poultry farm House conditions inspection First week mortality

178 179 180 181 182 183 184 185 186 187 188 189 190

Index

191

4. Egg handling and quality Embryonic development during egg formation Cooling to physiological zero Cooling at the breeder farm Grading and on-farm traying Hatching egg quality Unsuitable for hatching Size and uniformity Hairline cracks Dirty eggs How should you deal with floor eggs? Storage at the breeder farm Humidity during storage Store eggs pointed end down Track and trace

7. Setting Do not mix Origin Parent stock age Laying date Preparing the incubator Setting eggs Pre-warming (single-stage) Pre-warming (multi-stage) Climate conditions during setting Transition from warming to cooling Humidification during setting First few days: ventilation inlets closed Day 4 to 11: regulate based on RH Heat distribution in the incubator Egg turning during setting The importance of turning Monitor turning Monitoring setter conditions Constantly improved measurement Candling

Variation in the hatch moment Pull time Unhatched eggs/dead in shell Count and assess unhatched eggs Hatching systems and early feeding On-farm hatching

28 28 30 31 32 33 34 35 36 37 38 39 40 41 42 43

3. Principles of artificial incubation Broilers and laying hens Eggshell temperature is key Incubation temperature Temperature settings Heat production by the embryo Ventilation Carbon dioxide Relative humidity Weight loss and machine settings Measuring moisture loss Purpose of ventilation Water cooling Air velocity Multi-stage or single-stage Minor differences, major implications

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18 19 20 22 24 25 26 27

76 77 78 78 80 81 82 83 84 85 86 87 88 89 90 91 92 93

2. The incubation process The anatomy of the hatching egg Development of an embryo From natural brooding to artificial incubation The environment of the egg Heat and temperature Gas exchange of the embryo The importance of uniformity

6. Egg transport and storage Condensation point = dew point Transition moments Dry bulb and wet bulb thermometer Climate during transport Jolts and vibrations Egg transport and logistics Inspection of incoming eggs Storage at the hatchery Climate conditions during storage Storage duration Longer storage Turning during storage SPIDES Disinfecting eggs Dry (fumigation) and wet disinfection After disinfection Disinfectants for eggs

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4 5 6 7 8 9 10 11 13 15

1. Introduction Key link How the chain works Incubation is interaction Each incubator is different Hatchery management The role of the hatchery manager Information exchange The signals concept Critical batches, locations and moments

8. Transfer Which egg has a live embryo? Infertile eggs, bangers, late mortalities, and living embryos What do key indicators tell you? In-ovo vaccination The optimal timing Suitability of the egg Hygiene is extremely important In-ovo sexing Transfer Hygiene at transfer Breakout analysis on day 18 Eggs in a clean hatcher Hatcher baskets

114 115

9. Hatching Air temperature in the hatcher Humidity in the hatcher Position in the egg Internal pipping External pipping The hatch window

132 133 134 135 136 137 138

116 118 120 121 122 122 123 126 128 129 130 131

CHAPTER 1:

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Introduction

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Fertile hatching eggs are produced with great care on a breeder farm. At the hatchery, the development of the embryos must proceed successfully to ensure a good start to the chicks’ lives so

they subsequently achieve optimal growth, production and health. This book focuses on hatcheries for

chickens, both laying hens and broilers.

A hatchery in 1950.

A hatchery in 2020.

In the first half of the 20th century, hatcheries were small-scale operations and there was no clear separation between egg and meat production. Nowadays, both sectors are completely separate production chains, from pedigree breeding to processed end products. In most countries, hatcheries have grown in size and the implementation and use of automated processes has continued to increase. However, hatching essentially remains a natural process that has remained unchanged for millions of years. Despite all the automated process control, sound knowledge of the natural hatching process is vital to achieve good results from artificial incubation.

Ha tc he ry S i gnal s

Key link

Hatchery

Vertical integrations In many countries, hatcheries are part of a vertically integrated system for the production of meat or consumption eggs. This means that the different links in the chain are all part of a single integration. In the case of independently operating links in the chain, the individual interests of each link weigh heavily, sometimes at the expense of

the general interest. A bonus-malus system is often used to improve results. In general, vertical integration allows for more and stricter control measures if quality problems occur.

In practice, logistic considerations sometimes result in mixing eggs and/or chicks from different sources at the hatchery, but mixed flocks will always have a poorer performance. This practice also presents a biosecurity risk.

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Various breeder/parent stock farms supply hatching eggs to a single hatchery. This hatchery then supplies the hatched chicks to various broiler or rearing farms. Hatcheries serve as a key link in the production chain. Eggs provided by different suppliers arrive in the same place and are mixed in a hatchery. Day-old chicks are subsequently distributed to different farms. A hatchery therefore acts as a pivotal link for disease control as well. Hygiene/biosecurity is therefore crucial in every link of the production chain. The hatchery managers must agree with the breeder farms and production farms on which hygiene protocols are applied.

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Breeder farm sector

Hatchery

Production sites (broilers and layers) A hatchery really plays a pivotal role in the poultry sector and is therefore very important, but vulnerable at the same time. For this reason, optimal communication between the different links is vital.

1. Intro d u c t i o n

How the chain works There are many steps in the process from hatching egg to day-old chick. Each step in the process has its critical points of attention. Egg collection and grading

Climate controlled egg storage and sometimes disinfection at the breeder farm

Egg transport from the breeder farm to the hatchery

Egg quality inspection

Climate controlled egg storage at the hatchery

Disinfection of eggs and setter loading

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Transferring eggs from the setter tray to the hatcher baskets

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Hatcher

Candling on day 18

Chick selection, sexing, vaccinations, other treatments (i.e. beak) and counting

Chick storage in an air-conditioned room

Transport to the broiler or rearing farm

Arrival at the poultry farm

Ha tc he ry S i gnal s

Egg Quality

Incubation is interaction

People

Incubation is a process where egg quality, technology and people (hatchery personnel) have equal influence on hatchability and chick quality. If any of these elements performs less well than expected, the results will be immediately visible in both hatchability and chick quality.

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Multi-stage and single-stage Hatching systems can be either multi-stage or single-stage. In single-stage incubators, a single batch of fresh eggs is set for 18 days and machine settings are adapted to meet the changing embryonic requirements with age. In multi-stage incubators, eggs from different embryonic ages are mixed. Typically, in North and Latin America and developing countries more multi-stage incubators are used, whereas in Europe single-stage incubators are more common. In some cases, even eggs for layers are placed in the setter with eggs intended for the broiler industry. Obviously, that is a far from ideal method.

Technology

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It takes more to hatch an egg than just an incubator. You need good basic material in the shape of uniform, fertile hatching eggs. The characteristics of these eggs largely depend on the type of egg (for broilers or laying hens), but also on the genetic background (breeds and lines). In addition, incubation involves certain processes that must be performed properly by skilled staff. Even though machines have been perfected and automated over the years, the human element remains an important factor in this process. After all, it is people who are responsible for ensuring smoothly running processes, and they can also intervene if things turn out differently than planned. The conditions are different at each hatchery, so there is no one-size-fits-all incubator suitable for all circumstances. Each hatchery manager works with their own settings and determines their own goals. One possible goal could be, for example, a higher than 93% hatch of fertile and less than 1% chick mortality in the first week.

Fahrenheit or Celsius? Two temperature systems are used worldwide: Fahrenheit and Celsius. This usually depends on the country, with most countries using Celsius whereas Fahrenheit is mainly used in the USA. However, in hatcheries, the most commonly used unit of temperature is Fahrenheit. Therefore, this book sometimes uses both units.

°C = (°F – 32)/1.8 or vice versa °F = (°C × 1.8) + 32

Incubator or setter? The total incubation process of about 21 days is split into two main phases: setting for 18 days and hatching for 3 days. In a hatchery the terms setter and hatcher are used, but the term incubator is also used to indicate the room where the eggs are kept during the ﬁrst 18 days. In this book the terms setter and incubator are both used.

1. Intro d u c t i o n

For an easy conversion tool, scan this QR-code. All other measurements are stated in the metric system. • Distance: 1 m = 3.3 ft = 1.1 yards • Weight: 1 kg = 2.2 lbs, 1 g = 0.035 oz • Area: 1 m2 = 10.8 sqft • Ventilation: 1 m3/h = 0.59 cfm • Air velocity: 1 m/s = 3.3 fps

Each incubator is different

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Has a new machine arrived? Then you will have a lot of fine-tuning and experimentation to do. Getting the settings right takes a few incubation cycles. Always adjust one parameter of the incubation process at a time in small steps to monitor the effect. When a new incubator is installed and started up, a specialist from the incubator manufacturer is usually on hand to help.

Each incubator manufacturer has its own view on how to control and regulate the microclimate around each individual egg. And each incubator is different. For example, there are differences in relation to air direction and air velocity. The incubation program is specific to a machine in a particular hatchery and is not interchangeable for use with other machines in other hatcheries. The quality of the incubation process depends largely on the quality of the incubator. But always remember: ‘Success is the combination of a good incubator, good hatching eggs and a good team.’ Every hatchery manager can learn to work with any make/type of incubator - it just takes time, patience and trust in your experience and intuition. If you work with different makes of incubators, you will become familiar with the specific strengths and weaknesses of each incubator and adapt your incubation programs accordingly. One machine is maybe more suitable for eggs from young parent stock and another for older parent stock. The flow of air can vary in strength and direction due to the position of eggs and setter trays and therefore the heat and gas exchange too. The position of the air inlet/outlet and the cooling/heating elements and sprayers is also important. What is the cooling capacity? If you switch to using a different incubator, you also need to change the incubation program. But the goal is always the same: to hatch the highest possible percentage of good quality chicks, regardless of the type of incubator used.

Someone must be assigned responsibility for the results. For example, there should be clear guidelines in place about who is authorised to enter the initial settings for the incubation programs, or adjust temperature settings in certain situations.

Create logbook per incubator Make sure that a good (digital) log is kept with technical faults. You register repairs and all other technical interventions to the incubator. You can link this later to hatching results. Or see a link between certain repairs.

Tip!

You can assess the results of the different brands or types of incubators by placing trolleys with hatching eggs from the same source in different incubators simultaneously. Or by exchanging eggs or data with another hatchery. This will help you to evaluate and adjust machine settings.

It’s a good idea to rotate personnel so they work in each department. This helps them understand and appreciate how the procedures work in different departments. After all, everyone at the hatchery is a member of one team working to achieve the same results!

Ha tc he ry S i gnal s

Hatchery management

LOOK-THINK-ACT

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What is the similarity between incubating chicks and the smell of babies? The hatchery manager should be able to recognise good chick quality by the smell. The smell in the hatcher should resemble a baby with a mildly damp neck. A sulphur odour is abnormal and indicates rotting (H2S: rotten eggs).

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The larger the size of the hatchery, the more important it is to have well-trained personnel. In large operations it is easier to lose sight of the details. And in a good team, tasks can be backedup among team members. Incubation entails more than simply reading the manual supplied with the incubator and following the instructions. Proper training and keeping up to date on the latest insights and developments is essential. The hatchery manager’s experience is also an important factor. Creating the optimal conditions requires a lot of verifying the programs and adjusting the procedures. The hatchery manager must also continuously assess the interim and final results and adapt the process accordingly. In the end, the hatchery manager is responsible for the final results. A functional database supports the manager to analyse the hatching results. Needless to say, the data must be entered and analysed correctly! By looking closely at the results, you can recognise patterns after poor hatchabity: is this always the same incubator, the same breeder farm or is it a matter of ‘Monday Blues’ and is it related to a human factor? In addition, incubation is a complex logistics process that demands good planning and stock control. The hatchery manager and the planner should therefore coordinate daily.

Start at the end The incubation process at a hatchery starts with planning of which batches of hatching eggs are going to be incubated. This planning depends on the market demand for meat or eggs for consumption. So you actually start at the end of the chain. The planning is prepared by a logistics manager. The hatchery manager is responsible for the incubation process and discusses the planning with the various supervisors for the following aspects: 1. Egg storage and disinfection. 2. Pre-warming/filling the setters, start up and daily inspections of the process. 3. Egg transfer from the setters to the hatchers. 4. Pulling the chicks and preparing them for transport.

1. Intro d u c t i o n

There are usually two main managers at a hatchery: the hatchery manager for the incubation process and the logistics planning manager for planning/staff/ placing eggs in the setter, etc. Ideally, they can replace each other for a large part. Each hatchery also often has its own contracted veterinarian and quality assurance manager. The quality assurance manager monitors and measures egg quality and collects data on chick quality. The QA manager reports to the hatchery manager and often also to the logistics manager (especially regarding egg quality).

The role of the hatchery manager

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Hatchery managers must be able to recognise all the sounds they hear. Always listen at times when it is quiet in the hatchery (mornings and evenings). Chicks that produce a lot of noise, for example, are an indication that the incubator climate is not comfortable. Also pay attention for any abnormal ‘technical’ noises that could indicate problems with turning the eggs, a worn fan belt, ventilation problems, etc. It is harder to hear these sounds in a large hatchery because there will always be some kind of activity 24 hours a day.

The hatchery manager has no easy task: to take care of a large batch of thousands of eggs, with the individual egg in mind. The climate directly surrounding the egg (microclimate) determines the development of the embryo. At the same time, in a commercial incubator, the climate (temperature, humidity, O2/CO2) surrounding the individual eggs is an average result produced by the climate control system inside the incubator, including the air velocity and the number of fertile (heat-producing) eggs. The incubator climate is regulated by various settings in an incubation program (setpoints). Based on sensor measurements, the climate parameters are automatically and continuously monitored and adjusted, to keep these as close as possible to the setpoints. A skilled hatchery manager knows how to optimise and fine-tune these settings, as the settings are egg-specific but also specific to the type of incubator. This is done based on factors such as hatchability, chick quality, weight loss, technical results, results of break-out analyses and chick-yield. In other words, the incubator settings can often only be corrected afterwards for use with future batches of eggs. This enables you to estimate which settings can be expected to give the best results each time. Each hatchery manager has their own goals. The hatchery manager is at the steering wheel and has to guarantee a ‘steady speed’. This means he (or she, of course) sometimes has to push the throttle and at other moments push the brake.

A hatchery manager must continually evaluate two considerations when making decisions: which conditions does the embryo want and how can I create those conditions using all the technology at my disposal?

37.8°C/100°F

‘It’s not about how hard to push the throttle, but about how fast you drive!’

37.8°C/100°F

The eggshell temperature (EST) is the most important incubation parameter. Compare it to a car you want to drive at a constant speed. It’s easy on a flat road. But on an uphill slope, you have to keep the gas pedal pushed down to maintain your speed. In the final phase, you will have to considerably cool the incubator to prevent the eggshell temperature getting too high. The hatchery manager is behind the controls, to keep cooling and heat production in balance. 10

Ha tc he ry S i gnal s

Information exchange

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Digital systems have facilitated better and more efficient data exchange. Currrently, a relational database model that presents data in tables is usually used. This makes it easy to select the right data for each hatchery or house. However, if you fail to utilise and apply the collected data, you are simply wasting your time and drawing the wrong conclusions.

The exchange of information between the upstream (breeder) and downstream (broiler or rearing farmer) links relative to the hatchery will reveal the causes and consequences of problems and possible relationships. The breeder flock manager provides information about the parent stock and the hatching eggs supplied to the hatchery. The most important data supplied by the breeder farmer mainly concern the age of the parent stock, diseases, medication use, vaccinations and any decline in production. The hatchery supplies feedback to the breeder farmer on egg quality, fertility and hatchability. This starts with the initial inspection of eggs upon arrival at the hatchery for egg quality and care. The hatchery also passes on information to the broiler or rearing farm, so the characteristics of the day-old chicks can be taken into account in the flock management strategy. For example, if the hatching eggs were laid by young mother hens, the chicks will be smaller and more temperature sensitive. In this case, the broiler producer can set and maintain the house temperature at a higher value for longer. In turn, the broiler producer informs the hatchery about aspects relating to the first week of life in particular. Feedback that is especially important for the hatchery is the mortality rate and growth rate during the first seven days.

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Despite high levels of automation and digitisation, many hatcheries still keep paper records and charts. You are then more conscious of the data and the data remains in one place. Make sure that this data is entered into a practical database, so that you can learn from it later and it does not end up in a file in the filing cabinet.

parent stock age vaccinations diseases chick day of hatch vaccinations

parent stock age vaccinations diseases egg storage period

Parent stock

Hatchery hatch chick weight embryo mortality cracks

Poultry farm (layers/broilers) mortality in week 1 feed conversion growth in week 1

The hatchery also plays a key role in the flow of relevant information.

1. Intro d u c t i o n

Share information Sharing information can answer important questions in case of problems. For example, how long the hatching eggs were stored at the hatchery, which reduces the number of ‘fertile’ eggs, or including floor eggs in the setters, which reduces chick quality and increases mortality. Combining chicks from different origins in one batch is often detrimental to uniformity. Sharing this information is essential to benefit the entire production chain. The so-called chick passport lists relevant data on the background of the flock of day-old chicks. This passport can be sent to the broiler producer before the day-old chicks are delivered. This allows the broiler producer to make the right preparations in advance. The chick passport subsequently accompanies the flock to the poultry meat processor. In many cases, the transport vehicle driver measures and registers the temperature of the floor and the litter. He/she informs the hatchery manager about the results. Too cold means too high chick mortality during the first week that is not directly related to incubation problems. Incorrect care of the chicks when they arrive at the broiler farm will make any problems related to the incubation process worse. Registering the specifics when the chicks leave the hatchery allows possible causes of problems to be traced or eliminated.

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Make sure the breeder provides the hatchery manager with vaccination schedules, so that batches of eggs from parent stock with similar vaccination schedules (immunity status = maternal immunity) can be placed together in the setter tray. Also take parent stock age into account.

Variation in eggs is reﬂected in the offspring Influence of egg storage on broiler weight (1st week)

100 150 200 Broiler weight on day 7 (g)

Proportion of eggs (%)

short storage period long storage period

250

Chicks that lag behind in growth have a significant impact on the average performance of the entire flock. This often becomes visible after the first seven days (higher mortality/lower growth rates). Not only is the average final weight lower, there is often a wide variation in chick weights. In this case, 95% of the batch consists of chicks hatched from eggs with a short storage period (green line) and 5% from eggs with a long storage period (red line).

Influence of parent stock age on final broiler weight

parent stock 40 weeks parent stock 26 weeks

500

1,000 1,500 2,000 Broiler weight on day 40 (g)

2,500

80% of these chicks originate from parent stock aged 40 weeks (average 2,000 g, green), and 20% of the chicks from parent stock aged 26 weeks (average 1,700 g, red). The end result is a flock of broilers that weigh an average of 1,940 g on day 40. This difference might only seem marginal but it is a significant loss for the broiler producer...

Ha tc he ry S i gnal s

The signals concept positioned horizontally, placed in plastic hatching baskets earlier or later… Factors often affect both heat production and heat transfer. For example, the size of the egg not only affects heat production but also the air flow over the hatching eggs. This can cause the embryo temperature to increase excessively in specific places with low airflow. You can expect a good hatching result from a batch of eggs with good uniformity incubated under uniform conditions: high hatchability from the fertile eggs and uniform chick quality. If the results are different, the chicks, eggshells and break-out results may provide some clues to identify the causes.

Caring properly for the hatching eggs all starts with critical observation. Look consciously and observantly. It is impossible to look consciously if you are distracted by other tasks at the same time. Take the time to recognise signals. Always remember that you are not working with eggs for consumption, but with embryos and chicks which are living organisms. Carefully examine the uniformity of a batch of eggs as well as the uniformity of incubation conditions. For example: egg shape, colour, eggshell quality, eggshell temperatures, data loggers, empty shells and the chicks themselves. These observations can provide plenty of information about the incubation process. Each signal requires a different response. Always think first about how something could affect the heat production of the embryo, as this impacts directly on the embryo temperature. Is it a small or a large egg; is the eggshell thin or thick; is it a hatching egg for a broiler or a layer; has the egg been stored for a long or short period; has it been turned or not; was the hen that laid the egg young or old...? Many factors also directly influence how much heat is released from the eggs. Higher or lower ventilation, air humidity, high or low air velocity, whether the eggs are turned periodically or

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Different ways to observe There are many different ways to gather information about the incubation process. In the past, the senses of the hatchery manager played a vital role: the most important data was derived from looking, smelling, hearing and feeling as well as weighing and temperature measurements. Nowadays, this information is supplemented with data collected using sensors for sound, temperature, humidity and gas composition. However, the experience of the hatchery manager is an unmistakably important source of information.

Use all your senses listen

smell

look

taste sensation

feel

Use all your senses to recognise the signals.

LOOK-THINK-ACT The central theme in Hatchery Signals is the LOOK-THINK-ACT principle. Ask the following three questions very consciously about everything you see: 1. What am I seeing? (seeing, hearing, smelling, feeling but also measuring) 2. Why is this happening? What is the explanation? Is it related to the temperature of the eggs, embryos or chicks? 3. What should I do? You are frequently stimulated to think first using the look-think-act principle. Try to answer the question yourself before reading on.

LOOK-THINK-ACT

ec This chick is dehydrated. The hatching egg has suffered excessive moisture loss, maybe caused by hairline cracks? Check the egg quality at this breeder, how old is this flock? Perhaps the eggshells have become too thin and extra calcium and vitamin D is needed in the feed? Or was the egg incubated too warm?

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The chick on the right has red hocks after hatching. This condition occurs because the chicks have become overheated and were exhausted before they could pip and hatch from the egg. This makes leaving the shell a real struggle and can result in damage to the hocks and beaks. Check the eggshell temperatures during the last week in the setter and in the hatcher after the eggs have been transferred. If necessary, reduce the temperature by adjusting the setpoint or try to localise and reduce the number of hot spots. Some hatchery managers relate red hocks to excessive or limited weight loss. That is understandable when they observe that red hocks seem to disappear when additional spraying is used and humidity is increased. Or when extra ventilation is applied to decrease humidity and increase weight loss. Both actions, however, likely reduce eggshell temperatures and avoid overheating, so if you observe chicks with red hocks, always check eggshell temperatures ﬁrst!

What causes red hocks?

Structured observation

Structured observation means really taking the time to look for signals: 1. Look without being distracted by other tasks. 2. Regularly stop and stand still when the eggs arrive, at the egg storage facility, at the setter, the hatcher and the selection station. Stay focused and do not perform any other work at this time. 3. Look at the hatching eggs and the hatched chicks. Look at the overall picture and the individual eggs/chicks, but also listen to the sounds produced by the automatic equipment: do they sound normal or abnormal? 4. Make observations at the appropriate points in the cycle. 5. Identify critical moments, critical eggs, and critical locations. 6. Register what you observe and measure systematically and compare your ﬁndings with the standards. 7. Always look critically, the majority of mistakes can be traced to too much conﬁdence in the automatic systems. Regularly check that maintenance schedules and sensor calibration have been performed accurately. 8. Take your time to analyse the automatic equipment comments. Dare to ask questions!

You should also be able to distinguish between a normal and an abnormal smell. You can smell ‘bangers’ and chicks with E-coli immediately. Ha tc he ry S i gnal s

Critical batches, locations and moments Being aware of and focusing on risk situations in your management practices can help prevent many problems. This applies to certain critical batches, places or moments in the hatching process.

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Critical locations There are critical locations in each hatchery where there is a higher risk of potential problems. Points known to be critical should be inspected daily, such as day-old chicks that might be held in a place that is too cold: this causes mortality in the first week. Try to make an inventory of these locations and optimise the conditions. Eggs placed in the middle of paper egg flats/pulp trays in the centre of the trolley are another example of a critical location. These eggs will have difficulty cooling. Or what about a hygiene lock where people are sometimes very creative in by-passing the protocols (e.g. a director who is just giving visitors a quick look at the hatchery and forgets about all the hygiene regulations).

Critical batches: dirty eggs should not be put in the setter at all in order to avoid cross contamination. High mortality in the first week and other problems with the flock can be so serious that using these eggs is not worthwhile. If you decide to incubate them anyway, make sure dirty eggs and washed eggs (as shown here) are marked with a special label in the setter tray to flag up that these eggs need special treatment. Place these eggs at the bottom of the trolley.

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Critical batches It is always possible to identify critical, at-risk eggs in the batches of hatching eggs. For example, eggs from older breeder flocks. These eggs have a thinner eggshell and less weight uniformity. Or floor eggs that have been washed and still added to the batch in the setter. Think about any critical eggs that may be present in each batch delivered, which problems could occur and how to respond in a timely and correct way.

1. Intro d u c t i o n

A critical location: water accumulating on the floor of the setter is a breeding ground for bacteria. The machines must be completely dry before being refilled with eggs. Evaporating water uses so much energy that the hatching eggs at the bottom of the trolleys will be incubated at too low temperatures for too long. This will have a negative impact on uniformity and hatch window.

A power outage (power cut, voltage dip, emergency power test) can make the incubators suddenly jump to another phase of the program, restart or even jump to the pre-heat program. The same applies to the climate control systems (frequency controller failure). This is a critical moment. Modern hatchery equipment is less susceptible to this, but always check if unexpected situations occur.

Critical moments Every moment in the process involves certain risks relating to the hatching results and chick quality. The hatchery employees need high levels of knowledge and skills to ensure they are aware of these moments and know how to respond adequately. Any movement of the hatching eggs is a critical moment, as it causes vibration and temperature fluctuations

(condensation). Day 18 - when the eggs are transferred - is also a critical moment. Eggs can crack or break and cool considerably or overheat in a very short time. Chicks in the holding area is critical: they are likely to get overheated, but draughts and cold spots can lower the chicks’ temperature, all leading to higher mortality during transport and at the farm.

Moment

Quality risk

Egg laying at the breeder farm

•

• • • • • • • • •

Poor hatching egg quality (too round, too elongated, infertile, soiled, etc.) Eggs cooled down too slowly Inclusion of ﬂoor eggs Soiled laying nests Poorly connected egg belts Rough handling Insufﬁcient hygiene Poor health of parent stock Too old parent stock Damaged eggs

•

Eggs cooled down too quickly Poor climate (and no uniform climate conditions) Poor storage conditions Stored too long Insufﬁcient hygiene Damaged eggs Malfunctions Eggs stored in wrong position (point upwards Temperature ﬂuctuations (day/night, partly because doors open and close more often during the day) Incorrect disinfection

Transport

• • • • •

Poor climate conditions Jolting during transport Outside temperature inﬂuences Insufﬁcient hygiene Malfunctions

Storage at the hatchery

• • • • • • •

Insufficient coordination with breeder farmer Poor climate conditions Insufficient hygiene Stored too long Malfunctions Damaged eggs Temperature fluctuations (day/night, partly because doors open and close more often during the day)

Disinfecting hatching eggs

• • • •

Incorrect disinfectant concentration Gas vs fogging Temperature not optimal Fog not uniformly distributed (not all eggs disinfected uniformly) Air distribution/movement through egg mass Duration of disinfection Insufﬁcient ventilation to remove disinfectant residue

• • • • • • • • •

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Storage at the breeder farm

• • •

Ha tc he ry S i gnal s

Moment

Quality risk

Setter

• •

• • • • • • • •

Hatcher

•

Poor climate conditions (too cold/hot, too dry/ humid, not uniform, insufficient CO2/O2 exchange) Poor hatching Poor embryo uniformity (long hatch window) Insufficient hygiene Too long in the hatching baskets Feed and water: insufficient quality and availability Malfunctions

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• • • • • •

Rough handling Poor climate conditions Insufﬁcient hygiene Malfunctions Bangers Wet baskets (too high throughput: too short drying time) Insufﬁcient machine maintenance Process takes too long (uncontrolled egg temperature)

Candling on day 18 and transfer

• • • • •

• •

Condensation on too cold eggs Heating up not uniform and too long for some eggs (> 24 hours) Fumes from disinfectants Poor climate conditions (too cold/hot, too dry/ humid, not uniform, insufficient CO2/O2 exchange) Eggs turned badly or at insufficient intervals Insufficient machine maintenance Insufficient hygiene Bangers Malfunctions

• • • • • • •

Insufﬁciently skilled employees Incorrect climate Insufﬁcient hygiene Rough handling Poor quality chicks Order of pulling (washed eggs, suspect farms last) Maintenance of chick handling equipment (interruptions cause delay, which is bad for the chicks)

Packing, loading and transport

• • • • • • •

Unsuitable chick density Insufﬁcient hygiene Wait time No access to feed and water Duration of transport Poor climate conditions Malfunctions

Arrival at poultry farm

• • • • • • • •

No access to feed and water Unsuitable climate (especially floor temperature) Insufficient hygiene Insufficient knowledge poultry farmer Insufficient coordination with hatchery Malfunctions Rough handling Not evenly distributed in the house

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Sorting and selection

1. Intro d u c t i o n

CHAPTER 2:

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The incubation process

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You first need to understand how a single egg incubates and hatches before you can understand the incubation and hatching process at a hatchery. And even then, the step to using an incubator is a giant

one! That process is geared to the average egg and knowing that each batch contains a variation of

eggs that must be taken into consideration. The greatest challenge is incubating and hatching all the eggs in the most optimal conditions.

How is the embryo supplied with nutrients in the egg?

Period

Source for energy and development

Day 1 to 4

Carbohydrates from albumen and yolk as an energy source.

After day 4

Fats from the yolk (yolk is approx. 30% fat). Cholesterol and other components (fats) from the yolk create cell walls and nerves.

After day 12

Calcium from the shell for calcification of the bones. Protein for tissue formation is provided by the albumen. The energy needed is mainly provided by the yolk.

Weight changes in the egg during the incubation period

40 35 Weight proportion (%)

Unlike a mammal, the egg has to contain all the required nutrients from the moment of oviposition. The shell around the eggs allows the exchange of heat, gases and moisture. The gas exchange depends on external factors. During the incubation process, you will notice changes in the utilisation of nutrients and in the development of the different parts of the embryo.

albumen

30 25

embryo

yolk

20 sub-embryonic fluid

15 10

allantoic fluid

0 0

amniotic fluid

10 15 Incubation time (days)

Changes that occur in the mass of the embryo, yolk and the albumen (egg white), and in the volume of the fluid structures of the developing embryo. Ha tc he ry S i gnal s

The anatomy of the hatching egg Is the yolk sac the remnant of the yolk?

It is important to know how a fertile egg is composed to understand the incubation process and to be able to assess a hatching egg.

It is not the case that the original yolk is partly used for energy and development of the embryo and that the yolk sac remains as ‘leftover’ of these processes. During the incubation process the albumen and the original yolk become more fluid with embryonic membranes and fluid compartments developing. This starts at day 3 and is visible as a ‘blood ring’ until day 11-12 when the chorion-allantoic membrane covers the whole inner eggshell membrane. In the meantime there is a continuous exchange of fluids between the various compartments. Towards the end of incubation, water is extracted and the yolk sac becomes more viscous, but by that time its content has changed a lot. The fact that it has a similar colour and is in a similar position within the egg, does not automatically mean that it is the same thing!

Air cell. The space between the shell membrane and the egg membrane. Provides oxygen for the chick’s first breaths after internal pipping. Albumen (egg white). Protects the egg yolk (buffer and anti-bacterial effect) and provides additional nutrients to the embryo.

Latebra. The column of white yolk that connects the blastodisc to the centre of the yolk (pale in fertilised eggs on an MRI-image).

Eggshell membranes. Protect the embryo from losing too much moisture and prevent entry of pathogens.

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Eggshell. The outer protective layer of the egg. The shell regulates the exchange of heat, gases (CO2 and O2) and water vapour (H2O) through the pores.

Chalazae. These cords attach the yolk in the centre of the unincubated egg.

remnants of vitelline membrane

shell membranes

chorion Embryo. The first stage of development starts in the hen’s body when the egg is produced. sero-amniotic connection Amniotic fluid. Serves to cushion the embryo and prevents dehydration.

Avascular mesoderm Vascular mesoderm Ectoderm Endoderm

yolk sac membrane

albumen

Chorion (outer membrane). Regulates the exchange of gas and protects against harmful bacteria.

White yolk. Provides nutrients for the first development phase of the embryo and has a slightly different composition than the yellow yolk. Vitelline membrane. Functions as a barrier that allows for diffusion of water and selective nutrients between the albumen and the yolk.

Cuticle. A layer of protein is deposited on the shell just before laying. It protects the contents of the egg and the shell by closing the pores.

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Germinal disc. The area of the egg from which the embryo begins to develop in the hen’s body after fertilisation.

Yellow egg yolk. Acts as a source of nutrients for the embryo.

yolk Yolk sac. Supplies the embryo with nutrients.

extraembryonic coelom amnion embryo

allanto amnion

chorio allantois

Allantois. Helps with the exchange of gases at a later stage.

The various membranes and compartments in the egg containing an embryo after three days of incubation. There are many interconnections between the compartments that allow the exchange of fluids facilitated by egg turning.

2. Th e i n c u b a t i o n p ro c e s s

Development of an embryo and external characteristics have been formed. In the second phase, a period of growth follows. During the last 3-5 days of the incubation process, the body functions mature. These include the thermoregulation ability, the immune system, the digestive system and the metabolism. How the body functions when mature depends on the conditions of incubation. Under optimal incubation conditions, all these functions will be better developed.

In the right conditions, the individual embryo develops into a chick in 21 days. There are three development stages. The first week is the differentiation phase, which already starts in the hen’s body after fertilisation. The specific tissues are formed during this phase. At this moment, the embryos are very sensitive to temperature fluctuations, jolts/vibrations and disinfectants. This phase requires a uniform embryo temperature to ensure all the embryos hatch at the same time later on. At the end of this first phase (day 10/day 11) all the organs

Day 1

Day 2

The germinal disc grows in size and the light-coloured ring around the embryo (arrow) means that the extraembryonic membranes are developing. These membranes transport `water’ from the albumen to the yolk under the embryo (subembryonic space).

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co Day 7 Egg tooth and comb visible; legs move, ﬁngers and digits (toes) are recognisable but not yet separated.

The blood ring (area vasculosa) is complete, head turned to the right, heart beats.

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The embryo is partly lying on its left side. Head starts to move. The eye pigment becomes visible; formation of wings and legs is clearly recognisable.

Embryo takes on a C-shape, lying on its left side. The heart takes on ﬁnal form with chambers (ventricles and atria). The volume of the sub-embryonic liquid is almost maximum.

Day 4

Day 3

The ﬁrst blood islands are formed; the head and heart are recognisable. The embryo ‘ﬂoats’ on the sub-embryonic liquid. The extraembryonic membranes continue to develop.

Day 8 Calcium starts to be deposited in the bones. The amnion absorbs water, so the yolk sac becomes ﬁrmer. Three rows of tail feather buds are clearly recognisable.

Day 6 Beak becomes visible. The embryo is protected in the closed amnion. The tip of the egg contains a jelly-like mass: the residues of protein (albumen). Almost all the water is now stored in the sub-embryonic cavity. The yolk has disappeared. Day 9 The amnion absorbs more ﬂuid and increases in size. A chorioallantoic membrane covers 80% of the embryo and the yolk sac. The beak opening is visible. The maternal antibodies are mainly found in the yolk sac.

Ha tc he ry S i gnal s

Day 10

Day 11

Active, but aimless, movement of the embryo in the amnion that now has a maximum volume. The toes are completely separated.

Day 12

Leg scales appear, ﬁrst feathers visible.

Day 13

Day 14

Day 15

Embryo starts to extend the head towards the air cell. Residues of the protein containing a small number of maternal antibodies are mixed with the contents of the amnion.

Movement decreases.

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Head in the yolk sac. Heat production and oxygen consumption increase exponentially. The embryo moves for longer periods. Movement stimulates bone development.

Chorioallantoic membrane surrounds the inside of eggshell. Volume of the amniotic ﬂuid decreases. The legs are bent and albumen protein is absorbed in the yolk sac.

Day 17

Embryo’s head faces the air cell, the volume of the amnion decreases.

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Day 18 Head moves under right wing, beak towards air cell, legs over the head. Intestines move into the abdominal cavity.

The protein is completely absorbed by the embryo. The down is fully developed.

Day 16

The yolk sac is absorbed into the body cavity.

2. Th e i n c u b a t i o n p ro c e s s

Day 20 The yolk sac is fully retracted via the navel, the chick pierces the inner membrane and starts peeping.

Day 21 Chick breaks through the eggshell, respiratory gas exchange through the shell has stopped and the navel can close. Chick pushes itself free from the eggshell.

Source: PasReform

Day 19

From natural brooding to artificial incubation In natural conditions, a hen incubates five to ten eggs, but in a commercial hatchery we are talking about tens of thousands. The entire incubation process aims to mimic the natural process, but because of its scale, specific demands and requirements are involved. To understand artificial incubation, it helps to understand how eggs are incubated - or broodednaturally. Each incubator is unique, creates variation, and therefore has its own specific incubation

program. The average eggshell temperature and the variation in eggshell temperature are the most important factors (not the incubator set point temperature). The hatchery manager has to identify the specific characteristics of each batch of eggs and know the features of the incubator. The breeding organisation and the incubator manufacturer provide manuals that describe the most essential basic operations/settings for eggs and machines.

Natural

Incubator

Egg collection

The temperature of the egg storage room is low (15-18°C), but can sometimes be increased intentionally for a short period (SPIDES: Short Periods of Incubation During Egg Storage). This takes place in a special SPIDES room or incubator.

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The hen lays a clutch of about 10 eggs. The hen only starts brooding her eggs when she has laid enough. In the meanwhile, she regularly sits on the eggs to warm them up.

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Keeping the hatching eggs warm

The broody hen will not leave the nest for the ﬁrst six days. She sits nestling her chest onto the eggs. The body temperature of the hen is 41°C (106°F). The incubation temperature is slightly lower: 37.8°C (100°F).

The most important thing is keeping all the eggs warm at the same temperature. Ventilating with fresh air is reduced to an absolute minimum, to ensure the temperature of all the eggs is as uniform as possible.

Turning the eggs

The eggs never lay completely horizontal. They are tilted with the point downwards at an angle of at least 20°. As the air cell increases in size, the eggs naturally tilt during incubation with the larger rounded end facing upwards. This ensures the chick is positioned correctly near the air cell. 22

In trays, the eggs should be positioned with the point downwards during storage. In the setter, the eggs should tilt at 38-45°. The setter trays are turned every hour (so in total 76-90°).

Ha tc he ry S i gnal s

Natural

Incubator Turning the eggs

When incubating her eggs, the hen turns them several times a day. She also swaps the positions of the eggs around regularly so they all receive the same amount of heat.

Eggs are turned automatically with a turning device.

As the incubation process progresses, the hen regularly leaves the nest so the eggs cool and come into contact with fresh air. The hen sits less ﬁrmly on the eggs.

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Cooling the egg

Removing heat and gas exchange gain importance in the second part of the incubation process.

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The chicks hatch

After 21 days of incubation, the chick pierces the eggshell with its egg tooth. Because most of the calcium in the eggshell has been used to form bones and feathers, the eggshell is now soft enough to be broken.

In the hatcher, the chick emerges from the shell and rests after all its strenuous effort. In some hatchers, the chicks have immediate access to feed and/or water.

Post-hatch

The chicks sit under the hen’s wings and do not eat until all the eggs have hatched and the hen starts to walk around.

2. Th e i n c u b a t i o n p ro c e s s

If they are not too cold or too hot, chicks can stay in the hatcher for a while, or be transported, without feed and water. Energy is stored in body tissues. The yolk sac provides additional feed and moisture during the ﬁrst few days. 23

The environment of the egg

LOOK-THINK-ACT

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The four pillars of incubation

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People often think that a broody hen never leaves her nest. That is certainly true for the ﬁrst few days, but as the incubation process progresses, she will occasionally leave the nest to eat and drink. This allows fresh air to reach the eggs and moisture to evaporate. An incubator mimics this behaviour by the temperature settings in the program. In nature there is also a temperature gradient (the hen’s breast is warm and gets colder towards the ﬂoor). In an incubator the temperature is the same all around the egg.

A broody hen never leaves the nest?

1. Temperature: the embryo requires a constant temperature for its development. This means introducing heat at ﬁrst, then removing heat at a later stage.

In natural conditions, the hen provides an optimal incubation environment for embryonic development. During an artificial incubation process, an individual hatching egg has precisely the same needs. The most important factors are turning the eggs, and the ambient climate around them: temperature, CO2/O2 concentration, and (relative) humidity. These climate factors are closely interrelated, so making the right management decisions is important. The climate is continuously measured and adjusted. Each phase of incubation requires specific settings depending on the type of eggs. These settings may vary according to the type of incubator. The settings must factor in fertilisation and the number of live embryos. There are also other factors that can directly or indirectly influence the heat production of the embryos, such as the age of the embryos, egg weight, type, eggshell quality and the availability of oxygen. The embryo temperature is the result of the balance between heat production and heat loss. Heat loss mainly occurs because all eggs lose 0.6-0.7% of the initial weight of water per day through evaporation on the eggshell and the movement of air over the eggs. Preventing large fluctuations in the climate is essential. The embryos will develop optimally during the first 18-19 days with an embryo temperature of 37.8°C (100°F). After pipping, the embryo temperature may increase. The optimal embryo temperature on day 20-21 of the incubation process gradually increases to 39.0-39.5°C (102-103°F).

2. Turning: essential for the ﬁrst seven days. Turning the eggs stimulates embryonic growth and prevents the embryo from sticking to the inner shell membrane. embryo age egg and yolk weight type (layer/broiler) shell quality oxygen supply machine temperature

Factors that determine the heat production of embryos. 3. Relative humidity: moisture loss/weight loss of eggs. 24

4. Gas exchange/ventilation: supply of O2; removal of CO2/H2O and heat. Ha tc he ry S i gnal s

Heat and temperature under constant conditions, the embryo temperature will also increase. In order to avoid the increase in embryo temperature, the heat transfer from the egg to the air immediately surrounding the egg should increase as well.

Heat and temperature during the incubation process internal external plateau phase pipping pipping

350

104/40.0

300

103/39.4

250

102/38.9

200

150

heat loss by evaporation

50 0

101/38.3

heat production

100/37.8 embryo temperature machine temperature

8 10 12 14 Incubation time (days)

99/37.2

Temperature (°C/°F)

growth

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Heat production or loss (mW)

development

98/36.7

The development of heat production and temperature. As soon as the heat production of the embryo increases, the machine temperature can be decreased slightly to create a cooling effect.

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At first, the heat production of the embryo is still low, but it steadily increases. Heat and temperature are clearly different units! Hatchery managers balance the heat production with the heat loss to maintain a constant embryo temperature. They can do this by measuring the eggshell temperature (EST). At the start of the incubation process, the machine temperature should often be slightly higher than the desired eggshell temperature. This is because eggs lose water and the evaporation of water has the effect of slightly cooling the egg. On average, this effect does not exceed 0.2°C (0.4°F). As heat production increases, and consequently the eggshell temperature increases, the machine temperature is decreased to prevent an excessive increase in eggshell temperature. So, the eggshell temperature determines a good incubation result. The metabolism of the embryo is inhibited in the third phase of the incubation process by the limited O2 permeability of the eggshell. This is also called the plateau phase. An increase in the O2 concentration increases heat production further, and hence the absorption and utilisation of the yolk. If heat production increases

Embryo/chick temperature changes over time

The embryo develops optimally at an embryo temperature close to 37.8°C (100°F), with an acceptable margin of no more than 0.3°C (0.5°F) below and 0.3°C (0.5°F) above this value. Any values outside this margin will slow down the incubation process or damage the embryo. The larger and longer the deviating temperature occurs; the more damage. In the hatcher, heat production will increase more after pipping and the embryo temperature may increase further. An embryo temperature of 40.0°C (104°F) or higher is fatal, but if the chick has dried after hatching, 40.0°C (104°F) is optimal. Correctly setting the temperature in the period around hatching is especially complicated, because the hatcher contains unhatched eggs as well as newly hatched chicks.

100°F

37.8°C

2. Th e i n c u b a t i o n p ro c e s s

101°F

38.3°C

102°F

38.9°C

103°F

39.4°C

104°F

40°C

Gas exchange of the embryo facilitate this, an egg has about 10,000 pores, protected by the cuticle, a protective layer around the egg. This layer has no visible openings but gases can permeate through it. The cuticle is 0.010-0.005 mm thick. An egg that weighs 70 grams has the same number of pores as an egg weighing 60 grams, although the eggshell is thinner. The ratio between the content and the surface area of a large egg is relatively larger. For this reason, certainly with larger eggs, the gas exchange must not be restricted too much. This also means that a larger egg has more difficulty releasing heat, increasing the risk of overheating. On around day 11, calcium starts to be absorbed from the eggshell. The shell becomes thinner at this stage which improves the gas exchange.

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The exchange of gas takes place through the outer chorioallantoic membrane and the allantois. Oxygen (O2) supply is vital for the development of the chick, as is sufficient removal of carbon dioxide (CO2) and water (H2O). The exchange of gas with the outside world is similar to what happens in the placenta with the mother’s blood.

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An embryo in a hatching egg shares some similarities with a baby in the womb. Both need warmth and the exchange of gases. The main difference is that the egg already contains the nutrients for the embryo while a human embryo receives its nutrition via the placenta. An embryo needs sufficient oxygen (O2) for proper development. O2 is absorbed from the air through the pores in the eggshell. As the embryo continues to develop and becomes larger, it absorbs more and more O2 and produces waste products in the form of water (H2O), carbon dioxide (CO2) and heat. An egg should be porous enough to allow the chick to breathe, but at the same time large losses of moisture should be prevented. No bacteria should be able penetrate the egg either. To

Incubating too warm is like running a marathon During a marathon, rapidly available energy from carbohydrates is used first. The body then switches to burning fat. Burning fat requires a lot of oxygen. If you keep running too fast, your body will start to utilise proteins from the heart muscle and the immune system. If you maintain a calm pace, you won’t experience any problems. The link with embryonic development? A hatching egg has a carbohydrate supply for the first week. After this, the blood vessel system has developed sufficiently to be able to transport oxygen and therefore burn fat. As the temperature of the embryo increases, the metabolism increases and, with it, the oxygen demand. If insufficient oxygen is absorbed, the system switches to burning protein. In this way, (locally) incubating too hot affects the heart and the immune system. The availability of oxygen plays a key role. This is determined by the presence of oxygen in the air, but also by the eggshell quality and the breed of chick.

Carbohydrates

Fat

Carbohydrates

Fat

Carbohydrates

Fat

Protein (heart, immune system)

Ha tc he ry S i gnal s

Weight loss and uniformity Within a batch of eggs, large variations in egg size and weight loss during incubation can occur. On average, hatching eggs lose 10-12% of their initial weight during the first 18 days of the incubation process. The relative humidity significantly influences how much weight is lost. With high relative humidity (RH) the eggs lose less weight. The weight loss is higher with lower relative humidity. Problems are often only seen with individual eggs that have lost less than 5-6% weight or more than 16-17%. This effect varies according to the breed and is also influenced by the age of the parent stock. Uniformity in weight loss is higher at high relative humidity and gets poorer at low relative humidity.

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Weight loss and uniformity

15%

drowning

dehydration Chicks are small and have dehydrated legs that feel dry and hard

12%

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Optimal zone weight loss

Lots of chicks with bellies that are too large/full and feel puffy

Once you understand the incubation process of a single egg or a clutch of eggs, you still have to translate this knowledge to make it applicable in a hatchery with thousands of eggs. In addition to different origins of the hatching eggs, hatching egg treatment and hatching egg quality, each incubator also adds another layer of variance to the incubating conditions. So it is evident that not every individual egg will be incubated under the optimal conditions. The embryos have different needs, but a wide variation can also occur between different positions in the incubator, which is mainly due to how the temperature is distributed in an incubator. As soon as you incubate large numbers of eggs all together, the priority is uniformity. Each embryo must be incubated optimally. And because you cannot treat each egg individually but have to treat all the eggs as a batch (incubator), it is vital to get this batch off to the most uniform start possible, so it can be treated as uniformly as possible. The purpose of all the processes is to maintain the optimal conditions and minimise variations within a batch. Taking this approach will ultimately produce dayold chicks with high uniformity. If the day-old chicks show poor uniformity, the broiler producer or rearing farm will start the cycle with a less uniform flock and then supply less uniform animals to the abattoir or layer farmer. This applies to all the links further along in the chain, the higher the uniformity, the better they can start and complete their processes.

Proportion of eggs (%)

The importance of uniformity

2. Th e i n c u b a t i o n p ro c e s s

Weight loss at 18 days (% of egg weight) The average weight loss is a less critical factor if the weight loss of individual eggs is very uniform. In that case, fewer eggs will have lost too little or too much moisture, even if the average is a bit below the recommended value. The humidity during the incubation process will have less impact on the final result. However, when large variations between individual eggs occur, it is important to keep the average moisture loss within a narrow margin and closely monitor humidity levels during incubation, even if the average value seems OK (12%).

CHAPTER 3:

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Principles of artificial incubation

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For optimal incubation results, it is important to understand the processes that create the optimal conditions for the eggs and to minimise variation within a batch. Hatcheries generally specialise in

hatching either laying hen chicks or broiler chicks.

Slow-growing broilers The egg weight of slow-growing broiler breeds is often slightly lower compared to eggs of regular broilers from parent stock of the same age. Egg quality is generally better. A decrease in hatchability due to a long storage period is therefore less. The incubation program must be adapted. This means that eggs for slow-growing and regular broilers cannot be mixed in one batch in the same incubator. At the end of the incubation period, embryos of regular broiler breeds produce more heat. The total time incubation time is also a little shorter (by 4-6 hours shorter). Embryos for slow-growing broilers are less sensitive to incubation temperatures that are too high after day 10.

Broilers and laying hens The processes used to incubate hatching eggs for broilers and laying hens have significant differences. Eggs from broiler parent stock and laying hen parent stock can never be incubated at the same time in the same incubator, because both types of egg place completely different demands on the incubation program. Hatching eggs for layer hen production contain relatively less yolk. Consequently, there is less energy available to the embryo for growth and heat production. However, the optimal embryo temperature during incubation is identical for laying hen embryos and for broiler embryos (37.8°C/100°F). Hatching eggs for laying hen chicks should therefore be incubated at a higher machine temperature.

Ha tc he ry S i gnal s

Broiler hatchery

Scale of hatchery

Layer hen hatchery

Relatively small: fewer incubators, incubators are smaller. Often 200,000 to 400,000 female chicks a week.

Relatively large: more than 100 large incubators, 2 million day-old chicks a week. approx. 21 days.

approx. 21.5 days.

Broiler embryos produce more heat in the second half of the incubation process.

Higher incubation temperature, as these embryos produce less heat than broiler embryos.

Breeding program: relative humidity

Variations in eggshell quality and therefore moisture loss increase with older parent stock. The variation is greater than with laying hens.

The eggshell is ﬁrmer and thicker so less moisture is evaporated through the shell. The hatchery manager must assess the chicks well and reduce the relative humidity in the incubator if the chicks have a large yolk sac (thick belly).

Smaller and more uniform (which is an important selection criterion for table eggs).

Egg size and shape Larger and less uniform (with a relatively larger yolk).

Incubation time Incubation settings: temperature

Important for a uniform broiler ﬂock, but more difﬁcult to achieve.

It is easier to maintain uniform weight in the parent stock for more uniform egg weight.

Eggshell quality

This is a less important selection criterion and therefore thinner.

A thick eggshell is a selection criterion for table eggs. This sometimes makes it more difﬁcult to attain sufﬁcient weight loss (often chicks with thick bellies).

Sexing

Males and females are not sexed, although this differs per Males and females are sexed at the hatchery. The males country. If broiler chicks are to reach a slaughter weight of are culled. In-ovo sexing is now also used, to avoid the practice of culling day-old males. more than 2 kg, they are often sexed since hens deposit more abdominal fat as they become heavier. And males grow more efﬁciently.

Treatments

No treatments. Vaccinations.

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Uniformity

Occasional beak treatment. Vaccinations.

Difference in heat production between hatching eggs for laying hens and broilers

Differences between breeds Eggs from different breeds/brands have different quantities of yolk and eggshell properties. Two important, related eggshell properties are permeability (via membranes and pores) and heat transfer (ability to absorb/release heat). Permeability is important for gas exchange and evaporation and therefore heat loss. The hatchery manager must take these properties into account when incubating hatching eggs from different breeds. The breeding company will supply a guide for each breed detailing the speciﬁc properties so the incubation program can be set accordingly.

3. P r in c i p l e s o f a r t i f i c i al i n cu bati o n

Heat production (mW/egg)

180 broiler

160 140 120

layer

100 80 60 40 20 0

6 8 10 Incubation time (days)

The yolk/white ratio depends on the type of bird (broiler/laying hen), the age of the parent stock and the size of the egg in a batch of hatching eggs. The quantity of yolk in the egg largely determines how much heat is produced. This is why broiler embryos produce more heat than those of layer hens.

Eggshell temperature is key

LOOK-THINK-ACT

Which measurement is correct?

7 day weight (g)

Chick yield (%)

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Effect of egg shell temperature on hatching results

Measure the eggshell temperature at the equator of the egg and not at the top, otherwise you will measure the temperature near the air cell. Air has an insulating effect, so you could measure a different value than the actual embryo temperature. If you do this manually, don’t wait too long to measure: after opening the door, the eggshell temperature will drop.

Because it is difficult to measure the embryo temperature, the eggshell temperature (EST) is measured. The EST differs approx. 0.1-0.2°C (0.20.4°F) from the embryo temperature, depending on the stage of incubation. At the start of incubation, when the eggs must be warmed, the embryo temperature is lower than the eggshell temperature. In a further stage of embryonic development, the embryo produces more heat and the embryo temperature will be higher than the EST. The heat that the embryo produces has to be removed. The same applies to the relationship between the eggshell temperature and the temperature in the incubator. Many other influences play a role, such as air velocity and evaporative heat. The eggshell temperature is therefore not the same as the air temperature in the incubator! In practice, each hatchery uses its own program. The eggshell temperatures affect the body weight and feed conversion rate of the day-old chick posthatch. The temperature in the incubator is often already reduced a long time prior to transfer of the eggs, otherwise the chick embryos could overheat between day 14 and day 18. At the end of the incubation period, the embryo temperature can exceed 40°C (104°F). And, at some locations, the variation in embryo temperature can increase by more than 2-3°C (4-5°F), depending on the position in the incubator, especially in places with little air movement and close to the spray nozzles.

99°F 37.2°C

99.5°F 37.5°C

100°F 100.5°F 101°F 101.5°F 37.8°C 38.0°C 38.3°C 38.6°C

98.5°F 36.9°C

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7 day mortality (%)

Eggshell temperature

If the incubation temperatures are persistently too high or too low, there will be higher mortality in the first week and a lower chick weight after a week. The chick yield (chick weight/egg setting weight) is slightly higher at a lower incubation temperature, but within a week this positive effect has disappeared.

Which temperature measurement is corret? T=? T=? T=?

Heat production is highest towards the end of incubation. Any mistakes in temperature measurement must be avoided. After day 14, you should take a few temperature readings on each egg to avoid wrong measurements. Low temperatures may be caused by insufficient contact of the embryo with the eggshell; the highest reading is the correct value. The air cell is also getting larger and may have shifted a little to the left or right (incorrect turning angle?). 30

Maintain a constant embryo temperature of 37.8°C (100°F). Check the temperature using an infrared thermometer. Make sure the tip of the thermometer is flat against the equator of the egg.

Ha tc he ry S i gnal s

Embryo temperature during the incubation process (°F/°C)

Incubation temperature Based on average values, embryonic development is optimal during the first 18-19 days at an embryo temperature of 37.8°C (100°F). After internal, and then external, pipping, the temperature of the embryos may gradually increase from day 20 to 39°C (102°F). As a rule of thumb, aim for a range in which 95% of the eggs/day-old chicks are no more than 1% below or above the optimal value: 1% of 37.8°C rounds off to 0.4°C. More than 95% of the eggs should therefore be in the range between 37.4-38.2°C. Note: this applies to the Celsius scale. At Fahrenheit you can stick to: between 99.3 and 100.7°F.

Optimal

Max

99.3 / 37.4

100.0 / 37.8

100.8 / 38.2

After pipping, day 20

101.5 / 38.6

102.2 / 39.0

102.9 / 39.4

Dry chick

103.1 / 39.5

104.0 / 40.0

104.9 / 40.5

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Day 1-19

This thermal image shows that the eggs in the centre of the setter tray are much warmer than the eggs at the sides. During incubation, the aim is to create the most uniform possible temperature in the whole incubator. However, the temperature can vary between different parts of the incubator. This is caused by different air velocities and using humidification sprayers.

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Variation inside the incubator There are always some cold spots and hot spots in an incubator. Cold spots occur in places such as close to the floor, the walls, the point where fresh air reaches the eggs first and around the sprayer or humidifier. Cold spots at the start of the incubation process, and hot spots at the end of the incubation process are places where there is generally little airflow. Some brief variations are not usually an immediate cause for concern. In natural conditions, the hen also occasionally leaves the nest to eat or drink towards the end of the brooding process. Prolonged deviations from optimal conditions may negatively affect embryonic development (and uniformity). Ensure proper incubator maintenance to avoid structural deviations.

Min

During the maturation stage (approx. from day 16), the embryo can respond slightly to the ambient temperature. If the temperature is too low, the heart rate decreases so the metabolic heat produced by the embryo is not released through the eggshell, but stays ‘inside’ the egg, with the embryo. The opposite also occurs: the embryo responds to ‘feeling’ too hot by increasing its heart rate so that more blood flows along the eggshell. This releases heat to the environment around the egg and allows a higher intake of oxygen. 3. P r in c i p l e s o f a r t i f i c i al i n cu bati o n

The most important thing is to maintain a constant, uniform temperature for all the eggs, particularly at the start of incubation. The ventilation is reduced to an absolute minimum (air inlets closed) to ensure the most uniform possible temperature in all the eggs and prevent cold air flowing into the incubator. If the air used to ventilate can be properly conditioned (pre-heated) this is not such a problem.

Temperature settings

Adjust incubator temperature to suit eggshell temperature

The most important aspect of the incubating process is the correct incubator temperature setpoint. The heat produced by the embryo must be removed, especially in the second stage of incubation. Incubating is in fact more about cooling properly rather than heating. This especially applies to broiler embryos and slightly less to laying hen embryos. In some incubators, the average eggshell temperature after day 10 may be allowed to increase slightly to prevent too low temperatures in some of the hatching eggs, which will then hatch too late. After pipping, the eggshell temperature may increase further and reach up to 38.9°C (102°F) at hatching. The average dry chick temperature will then be 39-40°C (103-104°F). If the temperature is too low, the chicks often hatch a little later, but they are not likely to suffer any negative consequences. If the temperature is too high, the chicks will hatch, but their condition will be affected, so their subsequent performance is poorer. When you enter the temperature settings, follow the advice of the incubator manufacturer and breeding company. You can adjust the settings for the next batch based on the quality of the day-old chicks produced.

Correct average incubator temperature: 15% of eggs too cold

Machine temperature slightly higher: 5% of eggs incubated too hot

97°F 36.1°C

eggs too hot

98°F 99°F 100°F 101°F 36.7°C 37.2°C 37.8°C 38.3°C Eggshell temperature on day 18

102°F 38.9°C

103°F 39.4°C

Insight into variation A hatchery manager must properly understand the variations in eggshell temperature before making any adjustments to the incubator temperature! It is always about balancing the number of chicks that can be saved by making adjustments and potential losses due to mortality or poorer quality. Incubation is much more complex than simply entering the right settings in the machine display. It is primarily about steering and responding to embryonic development and knowing and satisfying its needs, as well insight into the effect of air flows in the incubator. Variations in the stages of development in a batch and differing incubation conditions also cause variations in day-old chick quality.

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Signals of different embryo temperatures

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Increasing the average eggshell temperature by 0.3°C to 38.1°C (0.6°F to 100.6°F) in the plateau phase ensures that more eggs are incubated within the optimal range if the EST is less uniform. This will, however, compromise the quality of some of the embryos who now incubate at a too high temperature. However, in view of the results as a whole, it may be a wise decision because eggs that are incubated too cold will not hatch in time. This leads to even higher losses. It is better to eliminate cold and hot spots altogether and ensure a uniform eggshell temperature in every part of the incubator.

eggs too cold

Proportion of eggs in incubator (%)

Higher machine temperature

Assessment

Result

98.0-99.5°F (36.7-37.5°C)

Too cold

Slow hatchability (too late), poor chick quality

99.5-100.5°F (37.5-38.1°C)

Optimal

Good hatchability, good chick quality

100.5-102.5°F (38.1-39.2°C)

Too hot

102.5-104.0°F (39.2-40.0°C)

Too hot

Embryo temp. (day 15/18)

Good hatchability, lower chick quality Poor hatchability, poor chick quality

There is a direct relationship between the embryo temperature on day 15-18 and the hatching results.

Effects of increasing incubation temperature on the results of broilers Egg shell temperature (°F/°C) Week 1

Week 2

Week 3

Yolkfree body mass

Heart weight (g)

Length (cm)

Hatchability (%)

Body weight at 7 days

Image fits

98/36.7

100/37.8

102/38.9

33.8

0.28

18.3

77.8

148

multi-stage

100/37.8

37.9

0.36

19.4

84.7

155

single-stage

The eggshell temperatures also have a longer-term effect on broilers. A stable eggshell temperature is vital. If the temperature is initially too low, and then becomes too high, all the characteristics above will be negatively affected. In a multi-stage incubator, the parameters are geared to the average egg. The temperature of eggs that have only been in the incubator for a week will be too low and the temperature of eggs that are already in week 3 of the incubation will be too high. Maintaining a stable eggshell temperature is much easier in a single-stage incubator. 32

Ha tc he ry S i gnal s

Heat production by the embryo

ventilation

Incubator

In addition to maintaining an eggshell temperature of around 37.8°C (100°F), variations in eggshell temperature should also be minimised. There are various factors that affect the heat production of the hatching eggs, which in combination with the factors that affect heat transfer, determine the embryo temperature. The air temperature in the incubator supports embryonic development as the embryo is unable to maintain its own temperature (i.e. dependent on the ambient temperature) until it can produce more heat itself. This means the air temperature must be set higher in relation to the embryo (heating stage) and then lower (cooling stage). The transition point from heating to cooling greatly depends on the heat transfer, and in particular on the velocity of the air flowing over the eggs.

incubator oxygen

determining factor influencing factor shell conductance

oxygen uptake

egg size

embryo metabolic heat production

evaporative cooling

embryo temperature

incubator humidity

egg water loss

embryo growth

airflow incubator temperature

Embryo temperature: balance between heat production and heat loss

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Heat exchange and gas exchange between the embryo and the surrounding environment in the incubator is a complex set of many interrelated factors.

Heat production of hatching eggs Heat production (mW/egg)

250 200

Heat production • Time/development • Physical factors • Biological factors • Environmental factors

150 100 50 0

6 8 10 12 14 16 18 20 Incubation time (days)

The age of the embryos has the greatest effect on heat production. On the 18th day of incubation, heat production is about 150 mW per embryo. A dried-up chick may already have heat production of 300 mW, and when it also starts to take feed, its metabolic heat production can double to 500-600 mW in a short time!

3. P r in c i p l e s o f a r t i f i c i al i n cu bati o n

Heat loss • Evaporation • Heat transfer - temperature difference - heat capacity - air velocity Factors that influence heat production. Heat loss and heat production must be in balance. In this case, adjusting the incubator temperature will allow the desired eggshell temperature to be reached.

Ventilation: interaction of gas exchange and temperature control

Beware of overheating

The heat production of an embryo increases as it grows. The embryo absorbs oxygen and, in addition to heat, releases carbon dioxide (CO2) and water (H2O) to the air. Fresh air must be supplied and used air must be extracted otherwise the embryo will suffocate. At the same time, fresh air introduced for ventilation should have the least possible direct impact on the embryo temperature and should not cause temperature fluctuations and variations in the incubator. At the start of the incubation process, the incubator is kept closed as much as possible (air inlet closed) to exclude cold air. A high relative humidity caused by the eggs losing moisture ensures the eggs heat up to incubation temperature uniformly. This requires an incubator with a high heating capacity, as an incubator loaded with 60,000 eggs of 60 grams has to heat up an egg mass of 3,600 kg. Eggs have the thermal properties of water, and just try heating up 3.6 cubic metres of water by a few degrees… If the eggs are heated too quickly (within 4-6 hours) to incubation temperature, there is a high risk they will start to sweat. In an incubator with a high heating capacity and high heat transfer, it is best to heat the eggs gradually, or increase the heat in small stages, up to incubation temperature in 20-24 hours. It will take at least the same amount of time in an incubator with a low heating capacity and low heat transfer, but in these conditions the embryos will start development with less uniformity. The optimal heating profile varies from one incubator to another (and per parent stock age), so always follow the manufacturer’s advice.

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Between day 16 and day 18, when the embryos produce a lot of heat, measure the EST to see if any dangerous hot spots are developing. Monitor the temperature of the eggs in the centre of the trays at various locations in the incubator. If the average eggshell exceeds 39.2°C (102.5°F), the hatchability and chick quality will suffer. This has consequences not only for the incubation result, but also for chick development and the mortality rate later at the broiler farm. The growth and feed conversion performance of these chicks will also be poorer.

If the ventilation rate is set high to remove heat and moisture there is a risk of larger differences in EST being created in the incubator. This may cause some eggs to be incubated too cold. Regulate this by not opening the air inlets too much (air circulation inside the incubator for more uniform heat distribution). Or pre-treat the incoming air.

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Not every infrared thermometer is the same. An IR thermometer that can measure this remotely (right) is useful, but not very accurate. An ear thermometer is better. Also make sure that it is acclimatised (e.g. put it in the incubator for a while), because if condensation forms on the thermometer itself, the measurement is incorrect. Advanced thermometers preheat automatically to prevent this. A digital screen does not automatically mean that the measurement is accurate!

Ha tc he ry S i gnal s

Setting to a maximum CO2 level Ventilation in the incubator is often set to prevent the CO2 concentration from exceeding 4,000 ppm. The purpose of ventilating is to maintain this maximum CO2 concentration. Depending on fertilisation and heat production (time, breed, egg size, eggshell quality, etc.) you can calculate the ventilation volume in m3/hour. To calculate this, you need to know the properties of the incoming air. These properties - especially the air temperature and RH - should not fluctuate too much. If there are large differences between the temperature and humidity of the outside air during the day and at night, it is very complicated to accurately set the required volume of ventilation air. When the incoming air has a temperature of 25-27°C and values of 300-500 ppm CO2 and 50-55% RH, the incubator can easily maintain the optimal climate conditions for the eggs.

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Increasing CO2 concentration and storage time

6,000

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fresh eggs

5,000 4,000 3,000

In a sealed, airtight incubator, the CO2 concentration in the air can rise to 5,000-6,000 ppm in just a few days because the eggs release CO2 to the surrounding environment. This also changes the pH of the albumen. Many hatchery managers see this as a positive effect, as a high CO2 concentration at the start of the incubation process triggers the embryos to produce more blood vessels. In fact, some hatchery managers inject CO2 to stimulate this effect. You can utilise the embryos’ ability to cope with high concentrations of CO2 by keeping the air inlets closed and applying a non-linear weight loss pattern. But, be aware that the eggs will lose less moisture during the first few days. This lower moisture loss has to be compensated for later in the incubation process. This will mean increasing the ventilating level later in the process. However, this is in line with the needs of the embryos in the second phase of the incubation process (high heat production). This strategy is not always risk-free, because additional (higher) ventilation can mean some of the eggs are incubated too cold. For this reason, it is very important to treat the incoming air. As a compromise, the air inlets are often opened after 3-4 days, which reduces the RH of the air. This also reduces the CO2 concentration so that less correction is necessary at the end of the incubation process.

CO2 concentration in incubator (ppm)

Carbon dioxide

eggs stored for a long time (> 10 days)

2,000 1,000 0 0

2 3 Incubation time (days)

Fresh eggs have a higher CO2 content in the egg white, so the CO2 in the incubator also increases quickly. With older eggs, part of the CO2 has already disappeared during storage, so the CO2 in the sealed incubator increases more slowly. The incubator has to be sealed airtight and kept that way, otherwise you will be unable to reach these high CO2 concentrations.

CO2 concentration In the air cell, the air is saturated with moisture and the CO2 increases. The CO2 concentration is always higher here than in the air in the incubator or directly surrounding the eggs. Broiler embryos can cope with 1.4% CO2 (14,000 ppm) in the first 10 days. It is therefore more important to use ventilation to control the relative humidity of the air rather than the CO2 concentration during the first few days. The focus of ventilation in the first days is therefore on removing moisture. In the first four days, an RH higher than 65% is not unusual if you keep the doors closed. When the CO2 concentration in the second part of the incubation process exceeds the desired value, ventilation is used to regulate the CO2.

3. P r in c i p l e s o f a r t i f i c i al i n cu bati o n

Relative humidity can retain. Different RH settings are applied in the different phases before, during and after the incubation process.

Relative humidity is expressed as a percentage of the maximum amount of moisture that can be retained by the air at a certain temperature. The lower the temperature, the less moisture the air

Program settings Egg storage When hatching eggs are being stored, the RH is maintained at 60-80% at 16-18°C. The eggs do not dry out and the embryos do not develop either because they stay below the physiological zero point (22-25°C). Due to the lower temperatures, humidifying the air in the storage room is often unnecessary.

60-80 %

Setting

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50-55 %

During the incubation process, the RH is set to approx. 50-55%, depending on the egg weight, eggshell quality, the incubator and the previous experiences of the hatchery manager. The temperature is around 37.8-38°C (=100-100.3°F). During incubation, the egg should lose sufficient moisture (0.6-0.7% per day with linear moisture loss). The humidity profile in single-stage systems often varies. Multi-stage systems often have a constant humidity profile.

75-80 %

Hatching As soon as the chicks start pipping the eggshell (during the last two days), the RH can rise to 75-80%. This makes it easier for the chicks to hatch and they lose less moisture, so that dehydration is prevented. This is (almost) a natural process, as the liquid components of the egg evaporate when the chicks pip the shell (humidity peak). Spraying to artiﬁcially increase the humidity often has a negative effect on chick temperature. The incubator has to heat up again to compensate for the cooling effect. At hatch, controlling ventilation based on the CO2 concentration (0.4-0.5%) is an effective way to maintain humidity. Best is to wait before increasing the ventilation rate until CO2 levels start decreasing naturally. That indicates that the end of the hatch curve is approaching. Increasing ventilation too soon may result in a dragging hatch caused by cold spots. If almost all the chicks hatch at once, you will see a good humidity peak that decreases again as the chicks dry, so you can leave the humidity setpoint unchanged. The chicks are ready to be pulled when the humidity reaches 50-60% again.

Chick holding

50-60 %

Just before the chicks are pulled, the humidity is lowered again to 50-55% so the chicks dry well and do not become too cold. The humidiﬁers are usually not active when the chicks hatch. Too much ventilation when chicks are hatching is not advised: damp chicks are more sensitive to the ‘wind chill’ effect this causes. However, some hatchery managers set a humidity setpoint that is constantly between 55 and 60% after the eggs have been transferred to the hatcher. After hatching and processing, chicks can be stored in a chick holding room. In a correctly functioning chick holding room, chicks are kept at the right chick temperature. Remember that overheating chicks occurs more often and easier than undercooling chicks. Overheating causes more damage too.

Ha tc he ry S i gnal s

Weight loss and machine settings

Average weight loss, cumulative (%)

RH profiles of linear and non-linear weight loss including a fine tuning program 12

Setpoint RH

70 60

linear fine tuning

50 40

non-linear

30 0 2 4 6 8 10 12 14 16 18 Incubation time (days)

linear

8 6 4

fine tuning

non-linear

0 0 2 4 6 8 10 12 14 16 18 Incubation time (days)

The amount of moisture in the ambient air of the egg in the incubator determines the pattern of weight loss. Assess chick quality and the hatchability rate in combination with weight loss. Based on this, you can make minor adjustments using the ventilation and/or relative humidity setpoint. The various stategies have an effect on the weight loss over time.

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Opening the door disrupts the climate The RH in the incubator is approx. 55% and the machine temperature is 38°C for the first days. Assume the air outside the incubator has a temperature of 20°C with an RH of 55%. If you open the door, 50% of the air is replaced. This causes the temperature in the incubator to drop to 29°C and the RH rises to 62%. You close the door and the temperature has to increase again. As a result, the RH drops to 37% very quickly. These are immense climate fluctuations! So, it is essential to avoid opening the door of the incubator in the first few days. Pay attention to doors that do not close or seal properly! The climate fluctuations this causes will reduce the uniformity and increase the spread in the hatch window. During the first few days, the embryos are particularly sensitive to temperature fluctuations, and less to variations in humidity. But opening the door will disrupt the uniform embryo temperature, especially if sprayers are then activated to restore the RH.

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The egg must evaporate and lose moisture (= weight) in the setter. An average egg loses about 10-12% moisture in the first 18 days of the incubation process. For an egg that weighs 60 g this translates to a total 6-7 g weight loss, or 0.6-0.7% per day with a linear moisture loss profile (constant conditions of 37.8°C/100°F machine temperature and 55% RH). You can also opt for a non-linear moisture loss profile. If the air inlets are kept closed for the first few days, you must then use more ventilation to remove the moisture and lower the RH later in the process. Ventilation also removes CO2. The risk of a too extreme/excessive non-linear moisture profile is that the embryo will dehydrate during the final days (day 17/18) of the setting phase. There is also a risk of introducing too much cold air which will create cold spots. If too much moisture is extracted by excessive ventilation, humidification is often required from day 12 to prevent dehydration. However, the general advice is: no humidifiers in the setter! Bacteria can only multiply with water. Removing moisture through ventilation to manage how much moisture is lost is necessary for: • Optimal (natural) weight loss of the egg. • Optimal mineral balance in the embryonic parts. • Optimal chick quality. There are apps that can calculate the water content of the air based on temperature and relative humidity. You can also use the Mollier diagram to calculate this.

Outside

CALCULATION EXAMPLE Required ventilation to remove moisture A batch of 57,600 eggs loses a total of 0.8 to 1.0 litres of moisture per hour. Depending on the properties of the inlet air and exhaust air, you can calculate the required ventilation volume per hour. Inlet air of 25°C with 50% RH contains 11.5 g/m3 of moisture. Exhaust air of 37°C and 55% RH contains 24.1 g/m3 moisture. The difference is 12.6 g water (moisture). To remove 0.8-1.0 kg, ventilation (VH2O) of 63-79 m3/h (800/12.6 to 1,000/12.6) is required.

3. P r in c i p l e s o f a r t i f i c i al i n cu bati o n

1. Incubator closed.

2. Incubator opened.

3. Incubator closed again.

Measuring moisture loss

Day 14 Day 18

The size of the air cell allows you to assess the optimal RH each day. Determine the size of the air cell in a number of eggs, or the weight loss. In practice, a hatchery usually uses the weight loss of an entire setter tray for this purpose.

Day 7

The average moisture loss does not say much about eggshell quality. Measuring the average moisture loss (per setter tray) is purely an indication. The variation in moisture loss among the eggs is much more important. This value gives a precise indication of whether you need to and can increase or decrease the humidity during the incubation process to obtain better results. You can fine-tune the process by maintaining higher relative humidity during the first days of incubation. This enables you to improve the temperature uniformity as the heat exchange process is better; moisture transports heat. However, you should reduce the RH setpoint during the last days of setting and monitor chick quality (avoid dehydrated day-old chicks).

Optimal weight loss and age of parent stock Desired weight loss

25-40 weeks

10-11%

40-50 weeks

11-12%

50-60 weeks

12-13%

The desired weight loss depends on the breed and on the age of the parent stock.

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Age of parent stock

Automatic weighing systems can weigh trays (left) and trolleys (right) in the incubator to calculate an average egg weight. This gives an impression of the average weight loss of the eggs. But there can still be wide variations between eggs in a setter tray or on a trolley.

One way of checking variations in moisture loss is to individually number all the eggs from a few setter trays (e.g. 4-6) and weigh them to an accuracy of 0.1 gram on day 0 (at set) and day 18 (transfer). In the hatcher basket, the cause of why some eggs failed to hatch can be traced to too much or too little moisture loss. This will give you an impression of variations in weight loss per batch, and in which range of moisture loss there is good hatchability.

Ha tc he ry S i gnal s

Purpose of ventilation At the start of the incubation process, ventilation is determined by the relative humidity. When more CO2 is produced, ventilation is determined by the CO2 concentration. Moisture production does not depend on the fertility, but the CO2 production of course does. You can calculate the ventilation requirement based on the number of eggs, egg weight and heat production.

Oxygen Oxygen consumption varies according to the type of bird. You cannot incubate broilers and layers together and expect to create the ideal conditions for both types. Broilers eggs require higher levels of ventilation. They contain larger embryos that need more oxygen. They also pip the eggshell earlier than layers. Differences also occur between breeds: for example, Ross can utilise more oxygen than Cobb and Hubbard. Consequently, these embryos also cope better with temperature increases. Ventilation requirement for moisture and carbon dioxide

Required ventilation to maintain CO2 levels A setter contains 57,600 fertile eggs that each produce 18.5 ml CO2 per hour at day 18. The incoming air contains 400 ppm CO2 (0.4 l/m3) and the exhaust air is set at max. 4,000 ppm CO2 (4.0 l/m3). So per cubic metre 4.0 - 0.4 = 3.6 l is exhausted. In one hour 57,600 * 18.5 = 1,066 l of CO2 has to be removed. Therefore a capacity of 1,066/3.6 = 296 m3/h is required.

3. P r in c i p l e s o f a r t i f i c i al i n cu bati o n

ventilation requirement for CO2 (VCO2)

250

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ventilation requirement for H2O (VH2O)

Incubation time (days)

CALCULATION EXAMPLE

500

Here, until day 11, ventilation is based on RH, then based on CO2. To maintain a constant RH after day 11, you need to add extra moisture to the air (using sprayers or water rollers). However, this often has a side effect of creating cold spots near the humidifiers. It is better to treat the incoming air, so you don’t have to intervene with humidification in the incubator.

Heat production and CO2 production of broiler embryos

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Too much moisture removal To maintain relative humidity at a constant level, you should realise that this moisture comes partly from the hatching eggs and partly from artificial humidification. In the previous example, with exhaust air at 37°C and 55% RH and inlet air of 25°C and 55% RH ventilation of 80 m3/h was required to remove sufficient moisture. But to remove the CO2, the ventilation on day 18 is set to 305 m3/h. This will remove too much moisture (for a linear moisture profile). The difference in absolute moisture content between the incoming and exhaust air is 12.6 g/m3. So you are removing 305-80 = 222 * 12.6 = 2.8 litres of moisture per hour too much that you will then have to add to maintain a constant RH (and therefore removal of moisture). Another option is to use a non-linear weight loss program and reduce the relative humidity in the second phase of setting, without using a sprayer. This will benefit the uniformity of the eggshell temperatures! Do not let the RH become too low. This can negatively affect uniformity or hatchability in incubators with an insufficient cooling capacity.

Ventilation (m 3/hour)

CALCULATION EXAMPLE

Heat production (mW/60g egg)

CO2 production (ml/hour)

0.0

0.2

0.4

0.7

0.9

1.2

1.5

1.9

2.5

3.9

5.4

8.0

11.7

113

13.9

132

16.3

140

17.3

145

17.9

150

18.5

Day

When the heat production and therefore the CO2 production are known, you can calculate the ventilation requirements based on the CO2 levels. Multiply these values by the number of fertile eggs in the incubator and apply a correction factor for egg weight or differences between breeds (broiler eggs +10%). 39

Water cooling

LOOK-THINK-ACT

What causes this deposit?

Front coil Back coil

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If condensation forms on cooling tubes, dust and down will also accumulate on the wet surface (especially when air velocity is high). This will considerably reduce the cooling capacity. Over time, a hard layer will form on the tubes.

Ventilation based on the RH or CO2 does not remove sufficient heat from the incubator, so additional cooling is required. This is usually done in the incubator by a water cooling system. Cold water flows in copper pipes into the incubator and is heated by the heat produced by the embryos (and ventilator motor). The amount of water flowing through the copper tubes and the temperature difference between the water entering and exiting the incubator determines the cooling capacity. The cooling capacity can be adapted by installing more copper tubes, or by using larger tubes to allow a higher flow rate of water per minute. There are various other cooling methods in addition to the coil system shown here.

To prevent condensation on cooling tubes, it is better to use water with a higher temperature: when incoming water is warmer than 27°C (81°F), no condensation will form on the tubes. To achieve a sufficient cooling capacity, larger tubes can be used to allow a higher flow rate of water.

With climate conditions in the incubator of 37°C (99°F) and 55% RH, condensation can form quickly on the cooling tubes. This can cause problems, particularly in the hatcher.

Two cooling coils are installed, one behind the other and two next to each other. The water flows in the opposite direction through each coil. This avoids a lower cooling effect on one side of the incubator caused by water that has already slightly heated. Ha tc he ry S i gnal s

Air velocity

Air velocity and required incubator temperature setting Eggshell temp. - Incubator temp. (°C)

The eggshell temperature depends on the air velocity. Uniform eggshell temperatures are vital to a good incubation process, which is why uniform air velocity is important in all parts of the incubator. With low heat production, the heat transfer is not all that important. However, the older the embryos become, the more heat needs to be removed and this is when the air velocity starts to become more important.

Low fan speed at the start

Air velocity 0.0 m/s

2.5 2.0 1.5 1.0

0.1 m/s

0.5

0.5 m/s

0.0

2.0 m/s

-0.5

Incubation time (days)

You can save energy (and money) at the start of incubation by setting a low fan speed. The fan can run at a low RPM, without compromising on quality and hatchability percentage. This is possible up to about day 11, because the heat production of the embryo will increase rapidly at this stage.

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To ensure sufficient cooling effect, the difference between the incubator temperature and eggshell temperature with no air movement must be greater than at higher air velocities.

Did you know?

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Hatching eggs produced at a high altitude can be easily hatched in a hatchery at sea level. But the other way around is more difficult. This is because the eggshell properties change based on where the eggs were produced. Eggshells of eggs produced at a high altitude have fewer pores, as this prevents them dehydrating in these conditions. At high altitudes - from about 1,500 metres - the inspired oxygen pressure decreases. The heat transfer is also lower because there are fewer water molecules in the air. In an environment with less oxygen, higher eggshell temperatures will have a more detrimental effect on the embryos. This explains why achieving the correct, uniform eggshell temperature is even more important at high altitudes. The incubation process needs to slow down a bit to allow sufficient gas exchange. Incubating is impossible at altitudes above 2,000 metres. If you want to incubate eggs at high altitudes, the relative humidity has to be increased and oxygen must be added artificially (oxygen concentrator). However, this is rarely economically advantageous.

Point of attention CO2 sensor calibrated for altitude, or setpoint should be adjusted as the CO2 sensor is calibrated for sea level.

1. Egg produced at high altitude Good hatchability Because of reduced effective pore area, humidity in hatcher may have to be reduced to achieve sufﬁcient moisture loss.

2. Egg produced at same altitude as hatchery In general good hatchability Relative humidity may be kept standard as a higher rate of diffusion is compensated by the lower effective pore area. 3. Egg produced at sea level Reduction of hatchability Eggs with relatively large pore area, with drier air at higher altitude, moisture loss is too high.

3. P r in c i p l e s o f a r t i f i c i al i n cu bati o n

Hatchery at altitude (1,000-2,000 m)

Ideal situation: warm eggs heat cold eggs

16-18

13-15

10-12

7-9

4-6

Multi-stage or single-stage

1-3

In multi-stage systems, the setter trays are divided over the height and width of the machine in a fixed pattern (protocol of incubator manufacturer). In a full incubator, the embryos are nine days old on average. The eggs already in the incubator heat the new eggs. The setpoint of the incubator temperature is a constant value.

There are two, basic methods of incubation: multistage and single-stage. Technological developments, such as automation and climate control have driven upscaling of hatcheries. This prompted a transition from multi-stage incubation to single-stage incubation, which is now the standard practice. In a multi-stage setter, fresh eggs are set at different times, usually at three-day intervals, and fixed climate settings are used. Because the embryos are at different development stages, average settings are assumed. Eggs in a more advanced stage of development heat up newly set eggs and, the other way around, the developed eggs are cooled by the newly set eggs. The advantage of this system is optimal flexibility, but there are never optimal conditions for all the different ages of embryos. There is also a higher risk of contamination, because new eggs are loaded into the setter each time. This carries the risk of cross-contamination between batches. It is also difficult to clean the incubator because it is not emptied each time. But a multi-stage incubator still has to be cleaned and disinfected - preferably every six weeks. In the meantime, noticeable soiling should be removed each time new eggs are set. In a multi-stage hatchery, the eggs are pre-warmed in the setter room (25-27°C/77-81°F) for at least 12 hours. Better controlled pre-warming in the setter is an advantage with single-stage. With a single-stage system, all the eggs are loaded in the setter at the same time and the climate settings are adjusted during the process, based on the development stage of the embryo. This results in better quality day-old chicks. To maintain the embryo temperature at 37.8° (100°F), the set temperature must be slightly higher to start with and slightly lower later on, once the embryos start to produce heat themselves. An advantage of a single-stage system is greater hygiene as the incubator can be properly cleaned and disinfected when it is empty. A disadvantage is that it requires more heating, cooling and ventilation. But the results are better with single-stage, even during the later stages of the chicks’ lives.

13-15

10-12

7-9

4-6

16-18

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In practice: formation of hot spots and cold spots

1-3

In practice, the air does not flow in a uniform pattern through the trolleys. The tilted trays slow the airflow, resulting in less optimal transport of heat. Hot spots form at the top in heat producing trolleys and cold spots at the bottom of trolleys with fresh eggs.

Solution: position some trays horizontally

16-18

13-15

10-12

7-9

4-6

1-3

The solution can be to position trays of eggs at a further stage of development horizontally. This will obstruct the airflow less.

Ha tc he ry S i gnal s

Singlestage

Multistage

Single-stage benefit

Hatchability

87%

84%

Hatch of fertile

94%

91%

1st grade chicks

86%

83%

0.80%

0.95%

0.15%

Liveability

96%

94%

Average chick weight

45 g

44 g

Average broiler weight

2,750 g

2,700 g

50 g

Average daily gain

60 g/day

59 g/day

1 g/day

7-day mortality

Advantages and disadvantages of incubation systems Multi-stage

Single-stage

+ Setpoint for incubator temperature, humidity and ventilation are set to a constant value. + In the early stages, the eggs with young embryos are warmed by the older eggs. These eggs contain an embryo at a more advanced development stage that produces heat itself.

+ Climate can be adapted well to suit the embryos. + More constant embryo temperature. + Before set, the setter can be cleaned and disinfected (all-in all-out).

- More fluctuations in embryo temperature. - The machine is never empty; it must be specifically emptied for cleaning every six weeks. - Risk of cross contamination between batches.

- Requires more cooling, heating and ventilation.

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Single-stage systems are preferred worldwide, because the advantages of multi-stage are outweighed by the disadvantages. Seemingly minor differences can have major implications on the results of the entire production chain. For example, just a few points difference in the feed conversion rate per chick will make a significant difference for a broiler producer. If the feed conversion rate improves by five points (1.55 instead of 1.60) for a 2 kg broiler, this converts to a difference in feed intake of 100 grams. Translated to a 60,000-egg incubator, with 90% hatchability and 18.5 hatching cycles per year, that adds up to 100 tons of feed! At a feed price of € 300 per ton, this is € 30,000 per incubator. And for that sum you can buy a new machine with an ROI of less than a year.

Examples of differences between incubation systems

Minor differences, major implications

The central aisle in this large multi-stage setter allows easy access to the trolleys. It is filled with six sets of 15,552 eggs, in total 93,312 eggs.

Small hatcheries often start with a multi-stage system. This incubator is loaded at the front and emptied at the back. The setter trolleys are therefore always moving to the back. It is not empty every three weeks, and available for cleaning, so you have to plan cleaning very consciously and first empty the setter completely.

3. P r in c i p l e s o f a r t i f i c i al i n cu bati o n

A colour code indicates the various age groups in a multi-stage machine. In this small hatchery, the trays are coded alternately using black, red, green. This is a way of trying to achieve the most uniform temperature distribution possible.

CHAPTER 4:

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Egg handling and quality

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On a breeder farm, the parent stock (females and males) produce as many good quality, fertile hatching eggs as possible. Once an egg has been laid, there is nothing you can do to improve its

you already have.

quality - you can only make it worse - so monitor all the processes very closely to retain the quality

Embryonic development starts immediately after fertilisation in the hen, and only stops when the temperature has decreased sufficiently (to below physiological zero): • Embryonic development before laying. This depends on the genetically determined growth rate, body temperature and the time spent in the oviduct. • Embryonic development between oviposition and storage. This depends on embryonic growth and how quickly the egg cools, which in turn is influenced by the type of laying nest, ambient temperature and egg collection frequency.

There are three important periods the hatching eggs undergo before being set in the incubator: 1. The period in the hen’s body during egg formation (ovulation, fertilisation, egg formation): 0-24 hours. 2. The period in the house: (laying and egg collection): 24-32 hours. 3. The storage period (at the farm, during transport and at the hatchery): at least two days up to a maximum of 14 days.

Ha tc he ry S i gnal s

Dev elo pm en ti n

Blastoderm

Embryonic development during egg formation

Egg

uc id ov

Area opaca

Area pellucida

Hours after 24 fertilisation Laying

Days after laying

Posterior marginal zone (PMZ) Gastrulation

Hensen’s node

Chick

Primitive streak

Stage 4

Stage 14 (22 somites)

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Stage 32

Organogenesis

Embryonic development already starts before the egg is laid. After laying, the egg can be taken to a dormant state. Once development continues beyond stage 14, the incubation process must not be stopped and the incubator is not opened until all the organs have been formed (around day 5). The stages shown are part of the Hamburger-Hamilton classification which runs from 1 to 46 (= day-old chick).

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Physiological zero In the freshly laid egg, the young embryo continues to develop as the egg cools to below a temperature range of 22-25°C. The embryo then enters an inactive stage of ‘arrested development’. At this point, embryonic development can be slowed and eventually arrested without affecting the vitality of the embryo. In hatchery terms, this is referred to as the physiological zero. Under the right conditions, the eggs can now be stored well, without too many consequences for hatchability and chick quality. As soon as the temperature rises above 25-27°C, the development that has to be continued starts, but development is not optimal at this temperature. Development is only optimal when the correct incubation temperature (eggshell temperature 37.8°C) is reached. If the time that some of the embryos are within the non-optimal temperature range of 25-37°C is too short (< 4-6 hours) or too long (> 24 hours), there is a risk of embryonic mortality. If a SPIDES technique is applied, the temperature is increased in a short period up to the incubation temperature before being decreased again, which stops embryonic development (see page 89).

Cleavage

Fifteen minutes after the egg yolk with the egg cell has been released (ovulation), the egg cell is fertilised in the oviduct. Embryonic development starts from the moment of fertilisation, so while the egg is still being formed in the hen’s body. The first cell divisions occur and the egg white (albumen) and water are added. Finally, eggshell membranes are formed around the albumen covering the yolk. The ‘egg’ now slides into the shell gland where calcite crystals are deposited on the eggshell membranes to form the eggshell in about 20 hours. The first cellular differentiation takes place while the shell is being formed, so that, after the egg has been laid, the future head and tail have already been programmed for their eventual function. The abdomen and back are also differentiated while the shell is being formed. So at the moment the fertile egg is laid, the germinal disc has already been developing for 24 hours.

4. E gg h a n d l i n g a n d q u al i ty

Did you know? On very rare occasions, the embryo splits and creates twins. This division can be caused by vibrations and mechanical shocks. These embryos may hatch but are not viable. Double yolked eggs (fraternal twins) often die around day 10/11.

Eggshell temperature and embryo temperature Because we can measure the eggshell temperature directly but not the embryo temperature, we assume there is no great difference between the two. But, particularly with large temperature variations, these temperatures are not the same, because the embryo is in the centre of the egg surrounded by an insulating layer of ﬂuid. So during cooling for storage, the embryo temperature will be warmer than the egg shell temperature for some time. Later, during warming up for incubation, this is exactly the other way around.

Cooling to physiological zero

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Ensure that eggs in the laying nest or on the egg collection belt are cooled uniformly and optimally. The content of the egg must be cooled from body temperature (41°C) to below 22-25°C as soon as possible (within 4-6 hours). Collect the eggs at least 2-3 times daily and more often is better, as cooling is a slower process at house temperature than in a temperature-controlled egg storage area. Temperature fluctuations, or eggs subjected to too high temperatures for a prolonged period, may increase the likelihood of early embryonic mortality. Avoid irregular cooling patterns on the egg collection belt, e.g. caused by cold air flows (draught). An evenly distributed flow of air over the eggs will ensure the eggs cool down uniformly. To be on the safe side, 21°C is usually the guideline for the maximum temperature. In some countries, however, the eggs are placed in a cold store immediately. These eggs can cool down too quickly. Embryos that have cooled too quickly are not yet in the right condition to withstand handling and transport. This will be reflected in disappointing hatching results. Sometimes early mortality that is unrecognised as such will occur. In this case the eggs appear to be infertile (actual fertilisation is often almost 100%). Increased embryonic mortality before the blood ring stage has been reached is usually attributable to poor hatching egg management at the breeder farm. A major contributing factor here is a failure to control the temperature of the eggs.

Early mortality can be identified by discolouration (lighter yellow) on the yolk (= area opaca). A visible start of sub-embryonic fluid formation is also often seen: a light-yellow watery fluid typical of development on day 3. These eggs are often classed as infertile, while in reality the embryos were damaged before the egg reached the incubator. On top, infertile eggs and, below, cases of early embryonic mortality (break out on day 6).

Temperature development of the egg after laying Eggshell temperature

laying

incubation cooling

physiological zero transport of eggs

storage at the farm

pre-warming

storage at the hatchery

Time after laying The egg is laid warm and incubated warm. In the time between laying and pre-warming, the temperature should remain below the physiological zero with as few fluctuations as possible.

It is difficult to cool eggs in nests with litter. Collect these hatching eggs more frequently.

Ha tc he ry S i gnal s

Cooling at the breeder farm

LOOK-THINK-ACT

The process of cooling towards the physiological zero already starts at the breeder farm. So, in effect, the success of the incubation process has already been determined partially at this point.

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Packing If the eggs are packed directly into setter trays, select and process the eggs immediately after collection. If they are packed in boxes, make sure the eggs have cooled to storage temperature first. Otherwise, they will cool too slowly and embryonic development will continue but at the wrong pace.

Tray type affects cooling The type of tray the eggs are supplied on affects the temperature and variations in embryonic development. Eggs cool best on plastic trays or setter trays as these allow the air to circulate more freely between them. Eggs in the centre of paper egg flats/pulp trays and in the middle of a stack of six egg flats cool down slower because the paper has an insulating effect and obstructs the movement of air.

This thermal image shows recently collected, warm eggs placed underneath eggs that have already been collected. This is an incorrect loading method. Because heat rises, the heat of the eggs placed lower down heats the eggs above. Load the trolley starting from the bottom to ensure cooler eggs stay cool.

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Has this trolley been loaded correctly?

Cooling is a very slow process in warm conditions. In warm climate zones or during periods of hot summer weather, the eggs should be collected more frequently and taken to a cool storage area promptly to stop the cell division process.

4. E gg h a n d l i n g a n d q u al i ty

Eggs on paper egg flats cool slower than eggs on plastic trays. Paper trays are often used for export purposes due to their light weight, low price and because they are single-use. It is important that the eggs have cooled sufficiently before they are stacked on paper egg flats.

Grading and on-farm traying that plastic trays are thoroughly cleaned, disinfected and completely dry before each use. When the eggs are intended for export, they are often placed on paper egg flats after they have completely cooled to 18°C and packed in cardboard boxes. Hatching eggs are generally collected from the breeder farm 2-3x a week. On arrival at the hatchery, the eggs are then stored for a few days before being loaded into the incubators.

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Eggs can be graded at the breeder farm or at the hatchery. The purpose of grading is to ensure that only grade A hatching eggs are set. This is checked by random sampling at most hatcheries. The hatching eggs are stored at the breeding farm after laying until they can be placed in the incubator at the hatchery. The eggs have often already been placed in plastic setter trays (on-farm traying). This reduces handling later on at the hatchery. However, ensure

Each farm has its own reasons that determine the frequency of daily egg collection. One reason not to collect too frequently is when there are not enough eggs on the belt. The natural tendency is to set the collection belt to top speed, which can cause jolts, uneven transfer points and can cause hairline cracks. This has a negative effect on egg quality.

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On-farm traying: the eggs are placed directly in plastic trays at the breeder farm. If eggs are supplied on paper egg flats, they must be transferred to the setter trays later. This is an extra handling that takes time and money, and there is a risk of breakage.

An initial selection generally takes place at the breeder farm. The eggs are graded based on shape, size, extent of dirt, damage and possibly weighed and categorised into the required weight classes.

Keep the egg collection and storage room clean and tidy. Apply a good pest control protocol and leave the equipment to dry for a few days after cleaning.

Ha tc he ry S i gnal s

Hatching egg quality

Embryo The egg must contain a good quality embryo that is ring-shaped and 4-5 mm in diameter (doughnut shape).

The quality of the fertile hatching eggs largely determines the hatching results. A number of quality criteria determine what a good hatching egg is: shape, weight, shell, yolk, embryo and hygiene.

Eggshell The shell must not be cracked, ridged or dirty. These eggs lose too much weight and dry out or break during transfer. The shell must be sufficiently thick, perfectly shaped, clean, smooth and undamaged. Avoid scraping or sanding the eggshell surface to remove dirt. This will only make the problem worse.

Yolk The yolk should have a uniform colour. In addition, the yolk should also contain sufficient nutrients, vitamins and antibodies (through vaccinations, immunity and parent stock health status). Air cell The air cell must be stable and located at the blunt end of the egg.

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Shape A good hatching egg is round with a length-width ratio based on the Phi ratio (golden ratio) of 1:1.309 (shape index 100 * width/length = 0.76). A distinct point is especially important for correct placement in the setter trays. Wrong point setting leads to up to 30% lower hatchability and very weak chicks compared to those from correctly positioned eggs. The embryos do not survive in-ovo vaccination. The shape depends on breed, climate conditions and age of the parents (young parent stock around 74%, older parent stock often a bit rounder: 76%). Look at the information from the breeding organisation.

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Weight The optimal weight of a hatching egg is 50-70 grams, depending on the breed and parent stock age. Older hens lay heavier eggs which are more difficult to hatch.

Geometry of the egg

= 2Φ 2+√2 Φ = 1+√2

Φ3

Φ Φ

Double-yolk eggs will not hatch. Remove them. This is what an egg with a double yolk looks like under a candling lamp. Two dark spots are visible. These are the two yolks.

Example of type, parent stock age and hatchability Type of bird 1 +

=Φ

2Φ 2+√2

2Φ

The shape index is the width divided by the length of an egg. 99% of eggs have a shape index between 0.69 and 0.85. A low shape index signifies an elongated egg, a high shape index is a rounder egg. In the picture the mathematical calculation is based on the golden ratio (Phi = Φ = (1+√5)/2 = 1.618). The shape index will then be 2Φ/Φ3.

4. E gg h a n d l i n g a n d q u al i ty

Parent stock age

Hatchability set eggs

Average egg weight

Broiler young

24 weeks

70%

51 g

Broiler peak

34 weeks

90%

61 g

Broiler old

60 weeks

70%

70 g

Laying hens young

24 weeks

90%

54 g

Laying hens peak

26-80 weeks

95%

62 g

60 weeks

93%

65 g

Laying hens old

Eggs from broiler parent stock have much greater variation in hatchability during production than those from laying hen parent stock.

Unsuitable for hatching Unsuitable eggs should be removed immediately during the grading process at the breeder farm. The longer an unsuitable egg is kept in the system, the more unnecessary costs are involved.

Inspecting the eggs on arrival is very important. Also from a biosecurity perspective.

Blood stained.

Cracked.

Dirty floor egg.

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The following eggs are unsuitable as hatching eggs

Abnormal shell.

Elongated.

Toe punch.

Double-yolk.

Too small.

Damaged point.

Ha tc he ry S i gnal s

Size and uniformity

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Screening based on size. If the size of the hatching eggs is not uniform, the spread in the hatch window will very wide. This can be reduced by grading based on weight and by sufficient pre-warming, the so-called ‘pre-warming phase’ (= 5-6 hours pre-warming at 25 or 27°C before the incubation program starts).

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The hatching eggs must be as uniform as possible to ensure the eggs are incubated as uniformly as possible and to avoid large variations in the weight of the day-old chicks. Each type of egg has its own specific incubation conditions, which can even differ according to the breed. The incubation conditions must therefore be adapted according to the type of egg/the quality (and take into account the type of incubator). Embryos in large hatching eggs will produce more heat and have more difficulties dissipating heat, and therefore need more cooling. Embryos in small hatching eggs will produce less heat and need less cooling. The optimal temperature for embryonic development is identical for all embryos. It is 37.8 C whether the eggs are small or large. If the hatchery manager is not satisfied with the uniformity of the hatching eggs, he/she should inform the breeder farmer. In this case, there is usually something wrong with the uniformity (weight) of the parent flock. Eggs laid by very young flocks are often less uniform, and uniformity also often declines as the parent flock ages!

Egg weight is a good predictor of the day-old chick weight. The chick weight at hatch can be calculated based on 2/3rds of the egg weight. An egg of 60 grams will hatch on average a day-old chick weighing 40 grams. However, chick weight is NOT a measure of day-old chick quality. The amount of remaining yolk is an indication (or the chick’s body weight without residual yolk, i.e., the yolk-free body weight or YFBW).

45 grams

Large and small eggs being separated during selection at the breeding farm.

50 grams

60 grams

A rule of thumb: A 50-gram egg can just about be encircled by the thumb and index finger. Check this yourself, because each hand is different.

4. E gg h a n d l i n g a n d q u al i ty

Hairline cracks

LOOK-THINK-ACT

Chick mortality

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50.5% 56.4%

45.0 g

43.5 g

Chick weight

Hairline cracked eggs

74.4% 80.9%

Hatchability • Eggs set • Fertile eggs

Good quality eggs

Poorer results for all aspects Characteristic

7.5%

13.4%

17.0%

Embryonic mortality • Early • Mid • Late • Cull

7.9% 0.0% 4.6% 5.3%

13.9% 2.9% 15.5% 6.2%

Contaminated or broken

1.2%

5.2%

Egg weight loss in setter

Hatching eggs with hairline cracks have a poorer performance for all aspects above. This applies to results at hatch, and to the performance of the chicks later as broilers (higher mortality, lower chick weight).

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The eggs are visually checked for cracks. Only the outer shell is damaged, but the shell membranes are usually intact. You can recognise hairline cracks by a faint grey line on the eggshell surface.

What do you see here?

Hairline cracks are barely visible, thin cracks in the eggshell, which are caused by rough handling (transport, mechanical shocks, rough handling by staff). The eggshell is often of inferior quality to start with, and the impact of vibrations or other mechanical shocks can cause ruptures and cracks. This can soil the suction cups on the candlingtransfer system and make other eggs dirty, or interfere with the working of the suction cups. Setting eggs with hairline cracks reduces hatchability and chick quality, as the damaged eggs dehydrate more easily and there is a higher risk of infection. Eggs with hairline cracks can cause as many problems as eggs with more serious shell damage. The hatchability of these eggs is at least 25% lower than intact eggs. There is also a greater risk of contamination because pathogens penetrate the shell. As a result, mortality up to two weeks of age is four times higher among chicks hatched from eggs with hairline cracks than those from intact ones. In most hatcheries, random sampling of eggs (450 to 600 eggs) for hairline cracks is done using a company-specific protocol. The results are communicated to the breeder.

Candle the egg to make identifying hairline cracks easier.

Ha tc he ry S i gnal s

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The quality of a hatching egg laid in a dirty nest is automatically lower than an egg laid in a clean nest. Replace or regularly clean the nest pads. As soon as you notice the first signs of ‘bangers’ in eggs from a parent flock, inform the breeder farm. Higher chick mortality can also be directly linked to poor hygiene status and quality of the laying nests.

When a hatching egg is laid it is warm. The cuticle is still soft and can be permeated by bacteria. The egg then cools slowly, but the cuticle hardens within a minute. The most critical period for a hatching egg is therefore the first minute after laying. An egg laid on the floor or in a dirty laying nest can never be made ‘clean’. The dirt on an egg is full of bacteria and moulds. These bacteria can permeate the eggshell. The presence of bacteria inside an egg will cause spoilage more quickly, cause the death of the embryo and if pressure is produced by gas inside the egg, it may even explode - a ‘banger’. Floor eggs are unsuitable as hatching eggs! Up to as much as 1,000 times more bacteria can be found on the surface of floor eggs than on eggs laid in nests. Preferably, avoid setting floor eggs, and never place dirty eggs among clean ones. If a hatchery decides to incubate floor eggs, take additional measures to prevent cross contamination and separate the lower quality day-old chicks. Dirty eggs are usually placed on the lowest setter trays so if they explode in the incubator, the clean ones underneath are not contaminated. It makes no sense to incubate floor eggs separately and then mix the day-old chicks. These inferior chicks will never perform well and they will infect the rest of the flock! Each hatchery/integration has its own protocol for supplying floor eggs separately. A hatchery that disposes of these poor-quality chicks or raises them in a special unit avoids passing the problem on to the other links in the production chain. This has benefits for the performance and profitability of the entire chain!

Dirty eggs

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Egg bacterial load Extent of dirt

Bacterial load (# bacteria per mm2)

Fresh egg

300

Clean egg

3,000

Floor egg

25,000

Dirty egg

400,000

The bacterial load increases rapidly with the degree of soiling of the eggshell.

The limits regarding the degree of soiling What is the limit of the degree of soiling? Which eggs can you set or not? Yes

4. E gg h a n d l i n g a n d q u al i ty

Uncertain

LOOK-THINK-ACT

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Why are there empty spaces in this trolley?

About 2% of eggs supplied to the hatchery are used in the liquid egg market (e.g. shampoo). These are usually floor eggs. In integrated production systems, it is worthwhile refusing floor eggs. This boosts the profitability of the remaining eggs and day-old chicks. Medication administered to these chicks is often reduced by at least 50%.

Floor eggs are high-risk. About 1-2% of production are floor eggs. This figure can be as high as 10%. Anything above 2% is unacceptable. The percentage of floor eggs depends on good flock management, the parent stock age, and the flock itself.

Offspring mortality day 1-14 (%)

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The risk eggs are labelled and placed in the lower trays of the incubator. In this case they have been washed. There is a good reason to identify these eggs as a risk. They could potentially explode. Placing these eggs in the lower part of the trolley reduces the risk of contaminating the others. But there is still a serious risk of cross-contamination. So avoid this practice! Always hatch risk eggs separately from good quality ones and segregate the hatched chicks as much as possible. But best of all - don’t hatch these eggs in the ﬁrst place!

Effect of dirty eggs on early offspring mortality floor eggs

4 3

dirty nest eggs

2 1

clean nest eggs

Dirty eggs have a proven effect on the performance of offspring. This effect is seen in hatchability, but also in first week mortality and the general quality of the broilers.

In practice, floor eggs are supplied separately by the breeder farm. A label on the setter trays indicates the floor eggs. The chicks that hatch from these eggs are often included in the usual process, but this practice should be avoided.

Ha tc he ry S i gnal s

How should you deal with floor eggs?

Use a Rodac plate to identify which bacteria are present ON the surface of the egg. But this will not give any information about the bacteria already IN the egg.

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By definition, floor eggs are not good quality hatching eggs! Washing these eggs is inadvisable. By this stage the bacteria are often already in the egg. It makes no sense to wash the eggs. Whether or not floor eggs are washed varies from country to country. In some countries, all the floor eggs are disposed of as the quality is poor – particularly with older eggs. A batch with 2% of washed floor eggs may result in all the broilers requiring treatment with antibiotics later at the broiler farm. The best strategy is to dispose of dirty eggs to prevent poor quality day-old chicks entering the production chain. Some hatcheries prefer dirty eggs to be supplied unwashed. This avoids any mistakes, and the hatchery can decide whether to wash the eggs or not, and whether they are worth setting. Be aware that farmers may hide floor eggs between good quality eggs if the floor eggs are not paid for!

Floor eggs produce poorer quality day-old chicks. Preferably incubate these eggs separately. Each hatchery should also have a separate holding area for lower quality chicks. Segregating these chicks prevents diseases entering the production chain and benefits the performance of the entire chain. Broiler producers are often prepared to pay more for good quality chicks.

4. E gg h a n d l i n g a n d q u al i ty

You can remove mild soiling with your hands. Carefully remove traces of faecal material with a paper towel. Take care to avoid contaminating the clean parts of the egg with the towel. However, this has absolutely no effect on the hatching results.

Do not scrape or scour dirty eggs. Some of the dust this creates will accumulate in the pores and block them. This reduces the gas exchange. Scouring also damages the protective cuticle, and more bacteria can penetrate the egg which increases the risk of infection. Throw that egg away!

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Make sure the right temperature is used for washing water and do not confuse Fahrenheit and Celsius. A temperature of 100°F (37.8ºC) is too low for effective washing water, but 100°C is boiling hot. This will boil the egg and destroy the embryo.

Washing at the breeder farm If you do decide to wash the eggs anyway, do it properly and use clean water. Collect dirty eggs several times a day and wash them immediately. Note the number of dirty eggs. Never place dirty or washed eggs among clean ones. Always incubate and hatch these eggs separately. It is best to do this in separate setters so that chicks from dirty eggs do not infect good quality day-old chicks hatched from clean ones. However, chicks from dirty eggs are often mixed with a batch of day-old chicks from clean ones. This increases the risk of mortality as chicks from dirty eggs may carry harmful bacteria. Never wash clean eggs! Washing a clean egg also removes the protective cuticle. A washed egg can never be a grade A hatching egg.

An egg washer on a parent stock farm. The eggs seem nice and clean after washing, but need to be treated in the hatchery as dirty eggs, since dirt and contamination will still be present in the pores.

Conditions that apply to washing • • •

•

• • • • •

Use softened tap water for washing. Use fresh water after each batch of 150 eggs. Do not reuse the water! The temperature of the water should be approximately 42 to 45°C to prevent surface bacteria being pulled through the pores as the egg cools. Do not use warmer water, as this may kill the embryo. Do not wash the egg for longer than 3-4 minutes. Do not rub the surface of the eggs with a cloth. This will simply spread any bacteria and increase the risk of contamination entering the egg through the pores. Add the cleaning agent to the washing water in a concentration of 0.5 to 1% (5 to 10 grams/litre of water). Rinse the eggs after washing using sterile water at a slightly higher temperature than the washing water. Dry the eggs in a room with a temperature of 22°C. This room must be clean and dust-free. Do not stack the trays of washed eggs. This will prevent them drying properly. It is important to realise that washed hatching eggs always have an inherently higher risk of lower quality day-old chicks. Always store washed eggs separately from unwashed ones.

Washing might make a floor egg appear clean. And they might even be delivered at the hatchery as ‘clean eggs’. If in doubt, UV light will quickly reveal if an eggshell has been washed or wiped.

Ha tc he ry S i gnal s

Disinfection at the breeder farm Disinfection usually takes place at the hatchery. If disinfection is done at the breeder farm, it must be coordinated properly with the hatchery. The hatchery should instruct the farm about the egg disinfection protocol. Also provide instructions about how to wash the eggs at the breeder farm. Otherwise the different farms will follow their own protocols, which are not all the same. This will have a negative impact on uniform egg quality - and consequently on the quality of the day-old chicks. It is often better to disinfect the eggs effectively once at the hatchery than to have a situation where various breeder farms all disinfect their eggs in different ways.

Disinfection at the breeder farm

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If the eggs are disinfected at the breeder farm, preferably disinfect the eggs in a separate room with enough capacity to hold one day’s production. Then place the eggs in the storage room. Do not disinfect eggs in the storage room: most disinfectants are aggressive and can damage the copper cooling coils or other metals. It is not good practice to expose the embryo several times to disinfectants. So disinfect in moderation and most important of all - disinfect correctly. Some hatcheries only want clean eggs that are all disinfected at the hatchery. This avoids using different washing techniques and the quality of the eggs is more uniform.

The egg cuticle is a waxy layer that prevents bacteria from entering the egg. You can clearly see its effect if the cuticle is washed off. The cuticle is intact in the image on the left: a droplet of water rests on the egg. The cuticle has been washed off the egg in the image on the right: the water flows from the egg and penetrates through the pores. The eggshell also feels rough. Unwashed eggs with an intact cuticle feel smooth.

A special dye that can be used to make the cuticle visible, when absorbed by the waxy layer. The intensity of the colour indicates the cuticle thickness: the darker the colour, the thicker the cuticle.

4. E gg h a n d l i n g a n d q u al i ty

Recommended climate conditions during egg storage Storage duration

Temperature (°C/°F)

Relative humidity* (%)

Egg orientation

0-3 days

18-21 / 64.5-70.0

75-85

Blunt end up

4-7 days

15-17 / 59.0-62.5

75-85

Blunt end up

8-10 days

12-14 / 53.5-57.0

80-85

Blunt end up

More than 10 days

12-14 / 53.5-57.0

80-85

Pointed end up or alternatively turning the eggs every 24 hours

Storage at the breeder farm

*The recommended relative humidity range for eggs stored on paper egg flats is 50-75%; the risk of dehydration is much less on paper trays. Avoid floppy trays caused by too high relative humidity.

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Adapt the storage temperature in line with the storage duration. Maintain a temperature that is as constant as possible. When eggs are stored at the breeder farm, the storage temperature must be 2°C higher than the storage temperature at the hatchery to prevent condensation. Condensation occurs when relatively cold eggs are exposed to a higher temperature. Cold air can hold less moisture. This moisture will condense on the eggshell surface. Stacks with wet paper egg flats may break or collapse.

For the best results, hatching eggs must be set in the incubator within three to seven days after laying. In the time between laying and the start of incubation, hatching eggs must be stored in optimal climatic conditions with the correct temperature and humidity settings to maintain the quality. It is important to minimise any fluctuations in the day/night temperatures during storage. Eggs are usually stored at a constant temperature of 18°C. If the eggs are stored for a slightly longer duration, 15°C is also acceptable. The actual date of laying is very important for the hatchery. If the eggs have been stored for a long time at the breeder farm, there will automatically be wide variation in laying dates in a batch. How you deal with this is an important part of hatchery planning. The challenge the hatchery faces is having sufficient numbers of eggs to make up one batch of day-old chicks that can be set up as a full flock in a house.

Prevent direct sunlight shining on the stored eggs.

Short periods of incubation during egg storage Brieﬂy warming up hatching eggs for laying hens and broilers to an incubation temperature (37.8°C/100°F eggshell temperature for 3-6 hours) before storage has a positive effect on embryo viability (SPIDES). Applying this technique allows the embryo to grow through several stages of development, which enhances its ability to survive a longer period of storage (14 days). But positive effects have also been observed in shorter storage periods. The positive effects are lower early mortality, and more ‘fertile’ eggs (i.e. lower early mortality in fertile eggs). Chicks from eggs that have been held in long-term storage but pre-warmed brieﬂy, also perform equally as well as chicks hatched from eggs stored for a short duration. Heating the eggs for a longer exposure time (9 hours) has a less positive effect on hatchability. In this situation, the embryos have continued development for too long, or the contents of the egg have changed to such an extent that embryo development must continue.

The storage room must have smooth floors and ceilings so it is easy to clean. Clean, disinfect and dry the storage room at least once a week and run regular tests to detect the presence of bacteria. Ha tc he ry S i gnal s

Humidity during storage

LOOK-THINK-ACT

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Maintaining 75% (±5%) relative humidity in the storage room is sometimes suggested as a way of avoiding excessive moisture loss in the eggs. But remember that condensation can easily form on the fresh eggs (sweating). It is a good idea to calculate the dew point, at which condensation can occur. You need to know the temperature and humidity of the air and use an internet calculation tool (available on www. hatchability.com). Too much moisture loss only occurs when eggs are stored for an extremely long period. During the incubation process, the embryos appear to be able to compensate for this moisture loss during storage. Using humidifiers in storage rooms is not recommended due to the risk of the eggs becoming wet. This creates a favourable climate for bacterial and fungal development. Make sure a cooling fan is not pointed directly at the eggs. The eggs will then not be uniform in temperature. This causes major changes in embryonic development, resulting in a wider hatch window at the end. So ensure indirect ventilation and regularly check the temperature distribution in the storage room.

There is a lot of trafﬁc through this door in the storage room. It is opened and closed frequently. This creates an uneven temperature in the storage room and warm, moist outside air can ﬂow into it. Prevent staff from entering the storage room too often, and provide a lock. And install a door closer to ensure the door always closes tightly. Also pay close attention to where you place the sensor and the air conditioning units with respect to the door.

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Why is this a problem?

Incubator on the breeder farm? It is smart to set up a small incubator on a breeder farm. For example, you can place 30 eggs from different parts of the poultry house (using cracked eggs is ﬁne). After three periods of 24 hours you will have a good idea of the average fertility of a house. The farm manager is also armed with good arguments for ‘defending’ himself or herself in the event of deviating results. Good communication between the breeder and the hatchery will lead to a higher efﬁciency of hatching eggs. A trial incubation is often done at 25% production, and at 50% production. This will provide a good prediction of the fertilisation rates and the expected hatching results

4. E gg h a n d l i n g a n d q u al i ty

Store eggs pointed end down

Effect of egg positioning on hatching results Hatching results

Point down

Point up

Hatchability (% of transferred eggs)

Cull (%)

1.7

4.0

Grade-A chicks (%)

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An experiment into the effects of setting eggs small end up on hatchability and post-hatching performance indicated clear differences (Bauer et al, 1990).

If the egg is placed upside down, the embryo will also be in the wrong position. It will not be able to pierce the air cell at hatch.

Eggs are incubated with the pointed (small) end down. This automatically positions the air cell at the top. So the eggs must also be oriented with the pointed end down when they are loaded in setter trays on-farm or transferred from other trays to setter trays. If they are placed on a grading belt again and reoriented before being loaded in the setter tray, this is slightly less relevant. It is best to always store eggs with the pointed end down. The chalazae at the pointed end are stronger than on the blunt end so the yolk is held in place more securely. And, in view of in-ovo vaccinations, an egg has to be stored and incubated with the point down.

If eggs are transferred directly from paper egg flats to setter trays using suction cups, the orientation of the eggs is very important.

It is difficult to see which is the small or large end in round eggs. The shape of an egg is partly genetically determined. If you candle the eggs in the meantime (no later than day 12-13), you can clearly see the air cell. If you turn around the eggs that were incorrectly oriented, they will still hatch. But it is too late to correct the orientation after 14-15 days. 60

At egg collection, a mechanism that orients the eggs helps position them correctly. The rollers ensure the egg rolls towards the pointed end. An upright then orients the egg with the point facing backwards.

The eggs are delivered with the large end pointing upwards. Any eggs not placed point down on the tray are immediately noticeable. Incorrectly oriented eggs reduce hatchability by 20-50% and produce poorer quality chicks (higher mortality, less grade A).

Ha tc he ry S i gnal s

Track and trace The entire production chain of the day-old chicks must be traceable. For the purpose of track and trace, many countries require hatching eggs to be stamped with a code.

Type of egg

Washed eggs in the lower trays of the trolley have been coded individually.

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The laying date must be clearly indicated per egg tray, as eggs are not generally collected for transport daily.

Farm (and poultry house)

Type of egg

Farm (and poultry house)

Country of origin

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Country of origin

Each hatching egg is stamped with a code stating at least the country of origin, the producer code and a hatching egg code.

Export eggs also state the date of laying.

4. E gg h a n d l i n g a n d q u al i ty

This code also indicates that the egg has been washed.

CHAPTER 5:

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Biosecurity

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At the hatchery, the process from hatching egg to day-old chick is optimally facilitated. It is mainly a logistic operation that is determined by the planned time for chick delivery to the rearing or broiler

farm. The date of delivery is the starting point to move back in time and define the best planning

schedule. The hatchery aims for optimal efficiency in all the process steps, with a high level of attention on biosecurity.

Pests are a hygiene hazard in a hatchery. Provide good pest control (mice) at the hatchery.

A hatchery has many contact moments with the breeder farms, and subsequently with the rearing and broiler farms. These multiple contacts also mean a risk of infections. And the hatchery plays a key role in terms of biosecurity. You prevent infections by sufficient attention to hygiene. Good hygiene is vital to reduce: • Early embryo mortalities (clear eggs). • Unhatched eggs. • Second-grade chicks. • Chick mortality later at the poultry farm. • Diseases at the poultry farm. • Bacteria that are a risk for humans (Salmonella, Campylobacter).

Ha tc he ry S i gnal s

Process steps in the hatchery

8. Hatcher room/hatchers 9. Chick room (counting, grading, sexing, vaccinating, packing) 10. Chick holding area 11. Day-old chick dispatch 12. Clean setter trays/trolley storage 13. Cleaning and disinfection

14. Clean hatcher basket storage 15. Waste disposal 16. Vaccine storage 17. Laboratory 18. Clean chick box storage 19. Cleaning and disinfection of hatcher baskets and chick boxes, setter trays and trolleys

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Incoming eggs Egg receiving area Disinfection lock Transfer to setter trays Storage Setter room/setters Candling and transfer

1. 2. 3. 4. 5. 6. 7.

In the majority of cases, eggs are disinfected before incubation. Eggs can be disinfected at three points: immediately after collection and cooling (at the breeder farm), on arrival at the hatchery or just before the eggs are placed in the incubator - i.e., after storage. The timing of disinfection mainly depends on how the eggs are delivered. If they are supplied on plastic setter trays they can be disinfected at once. If the eggs are supplied on paper egg flats or in boxes, they must be transferred to setter trays first. Disinfectant cannot reach the eggs properly on paper egg flats. The disinfectant may be absorbed by the paper and hazardous fumes can be released afterwards. If the breeder farm and the hatchery are closely linked - as is the case with an integration - the eggs are often delivered already in setter trays. But if hatching eggs are traded on the free market, they are often delivered on paper egg flats as returning the setter trays involves more complex logistics. Delivery in setter trays is becoming increasingly common, so the eggs can be disinfected immediately on arrival. These eggs are also stored for a while. There might even be a storage room for eggs before and after disinfection. If the eggs are disinfected early in the process, there is a risk of reinfection. If the eggs are disinfected several times in a short period, this has a negative effect on hatchability. Sometimes eggs are disinfected just before incubation. Formalin gases might be released in the setter, especially when ventilation is closed. This will kill a certain percentage of embryos.

Hatchery layout

When to disinfect?

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The different areas in the hatchery design directly reflect the steps in the incubation process. This design is also determined by biosecurity considerations. Biosecurity at a hatchery is vital to prevent pathogens, e.g., Avian Influenza and Salmonella from entering, multiplying or spreading. Hygiene is especially important because: • Eggs that carry pathogens arrive from many different farms. • The climate conditions are ideal for pathogens to thrive and multiply: heat, moisture, nutrients (spoiled egg contents). • Many opportunities for pathogen survival (in the pores of the eggshell, in faecal residues on the eggshell, in or on the chicks, in ventilation ducts, and in other places that are difficult to clean). • There are many routes for transmission and spread of pathogens (air, feathers, personnel, and materials). • The chicks are then dispatched to various farms (laying hen/broiler, etc.).

20. Technical facilities 21. Ofﬁces 22. Canteen 23. Toilets 24. Changing room and showers male personnel 25. Changing room and showers female personnel

8 16

17 9

13 24

23 21

20 19

1 The design of the hatchery represents the steps in the entire process from arrival to dispatch. Using compartmentalised zones is not only practical logistically, but also, and primarily, essential for strict hygiene and biosecurity. 5. B io s e c u r i t y

Biosecurity zones at the hatchery

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The biosecurity zones are visible in all installations, for example segregated drainage and air circulation. At a hatchery, different air pressures are set for each zone. Large filter units that treat the incoming air can often be seen on one side of a hatchery, and exhaust air outlets on the other.

A hatchery is divided into biosecurity zones. These separate zones apply to human contacts, but also to materials that have to stay in a certain zone, and separate ventilation and drainage systems. The ideal design includes five, defined biosecurity zones. 1. Egg receiving and storage zone 2. Setter zone 3. Candling and transfer zone 4. Hatching zone 5. Chick processing and dispatch It is sensible to separate the candling and transfer zones, as this is a relatively ‘dirty’ zone, certainly if the batch contains bangers. However, you will have to keep returning to the setter room to collect new trolleys... The number of zones can also be reduced to three main zones, particularly in smaller hatcheries. 1. Egg receiving and storage 2. Setter zone 3. Chick zone (hatching, sexing, treatments and grading)

Pathogens can enter a hatchery via many different routes. These vectors include: eggs, personnel, materials, visitors, rodents and outside air. Egg receiving and storage zone

Setter zone

Candling and transfer zone

Hatching zone

Chick zone

The biosecurity zones are separated with regard to movement of personnel, ventilation and drainage systems. 64

Ha tc he ry S i gnal s

Routing at the hatchery Good hatchery design takes into account a clean zone (inside the hatchery) and a dirty zone (outside the hatchery). The borders between the clean and dirty zone are at the egg reception and chick dispatch. The use of separate truck bays for egg delivery and chick dispatch helps to prevent cross contamination. If eggs are disinfected immediately on arrival, the storage room is considered to be a clean zone. If eggs are stored first and only disinfected just before setting, the storage room is considered to be a dirty zone.

Setter trays

Hatcher baskets

Chick boxes

Farm materials

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Biosecurity zones imply using strict routes and separations to prevent contamination and transmission between the various zones. The movement of material and people between zones should be limited. Transitions between zones have to be obvious: hygiene locks and/or doors form a barrier to prevent too much easy traffic of personnel between zones. The group that poses the greatest risk is the technical service team. Their work involves all parts of the hatchery where troubleshooting or maintenance is required. And it is tempting to just walk from one area to the other without respecting the hygiene rules.

Materials must be cleaned and disinfected in the zone where they are used. This means that a hatchery has numerous cleaning and disinfection areas.

The personnel must also follow their own route. This illustration clearly shows that the changing rooms and canteen are risk areas, because they are places used by all the personnel. It also clearly shows how the technical personnel (black) move through the entire hatchery. 5. B io s e c u r i t y

Preferably use separate canteens. In this example, each group uses a different colour chair. Technical personnel have black chairs. They are seated closest to the entrance so they do not contaminate the entire room if their clothing is dirty. But this situation is not optimal.

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Different coloured clothing is used for each zone. For example, the technical personnel wear black overalls and black footwear. Make sure that technical personnel can change their footwear as they move from the hatching rooms to the transfer/setter rooms. Or even better: a different technical team for each biosecurity zone.

Each team has their own locker in the canteen to store their belongings. This also aims to minimise cross contamination.

Place a door that can be locked between different zones, to prevent people moving between them. A floor plan is also displayed on the door showing the layout of the zones.

The eggs here are being transferred from paper egg flats to setter trays manually. The clutter here presents a biosecurity risk. Don’t re-use paper egg flats!

The disinfection lock between the egg storage room and the setter room is also the point that separates clean and dirty routes. In other words, the entire area where eggs are handled (grading, placing on setter trays and preparing trolleys for the setter) is the dirty zone! Personnel must not walk to the setter rooms without showering first.

Ha tc he ry S i gnal s

Floor quality The floor in a hatchery is subjected to intensive use every day, as well as regular and thorough cleaning. Make sure the floors have a sufficient load bearing capacity per square centimetre to withstand heavy use by pallet trucks and heavy equipment. As many movements take place in and outside, the floor must provide enough grip, including when wet. It must also be durable enough to last for 20 to 30 years. To guarantee the safety of personnel, the floor must provide a certain level of slip resistance while still being smooth enough to allow thorough cleaning. The solution is a non-slip coating that prevents the risk of slipping without making cleaning difficult. It is also important to choose the right type of footwear to suit the floor surface. You can also apply an anti-microbial coating that kills bacteria on contact.

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Clean, and keep it clean Floors must be easy to clean and maintain. The surface of floors, walls and ceilings should be smooth and watertight. Cracks and holes are an ideal environment for bacteria. Light colours are the best background to show up dirt. Completely seamless, pore-free floors are recommended, as less dirt accumulates on this type of flooring and it is easy to clean. The setters are cleaned meticulously every 18 days, after transfer, while the hatchers and chick rooms are cleaned thoroughly every 3-4 days. The floor must therefore be resist-

ant to the most commonly used cleaning agents. Drainage systems are absolutely necessary, but they also encourage bacteria. Drains must therefore blend seamlessly into the flooring.

The floor is one of the most contaminated parts of a hatchery. The floor acts as a breeding ground for a multitude of bacteria. The different zones in a hatchery all involve different demands on flooring. The clean zones are used to store disinfected eggs and include the setter rooms. The dirty zones are egg reception areas, chick storage rooms, and the places where items such as the hatcher baskets are cleaned.

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Clean floors and walls

Drain at the centre of the corridor in the incubation room. This allows cleaning water from all sides to be drained. A drain located in a corner presents the risk of dirt accumulating and poor drainage.

Floors must be able to withstand cleaning with a strong jet of water, as well as aggressive cleaning and disinfection agents.

A smooth floor must be easy to clean, but at the same time have enough slip resistance.

Seamless wall-to-floor transitions prevent dirt from accumulating in gaps. This particularly applies to corners.

5. B io s e c u r i t y

Measures and work protocols Location

Biosecurity measures Measures

Incoming eggs

• •

Clean and disinfect this room weekly. Prevent air from condensing and forming moisture on the eggs (mould). This happens when cold eggs are placed in a warm, moist environment.

Egg storage room

•

Hygiene lock to prevent contamination entering any further into the hatchery. Closed to prevent air ﬂowing from this room into the hatchery. Store ﬂoor eggs and clean eggs separately. Store items not needed in this room separately.

Setter room

• • • •

• Transfer and candling room

•

• Hatcher room

•

• • Chick room

• • • •

The infection pressure is very low here. Ventilate with positive pressure ventilation. Bangers are the highest risk of contamination. Do not incubate ﬂoor eggs. Floor eggs are responsible for most cases of exploding eggs (bangers). Setter- and hatcher rooms have separate air circulation systems.

•

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•

The lock has two airtight, closed doors at each end. The airﬂow is directed from the setter room to the egg receiving room (using pressure differences). Ensure all doors are tightly closed, only open when necessary. Never use the disinfection lock as a corridor for personnel. Indicate clearly from outside that disinfection is in progress so the door is never opened by mistake during the process.

•

Many fragile eggs break at this point. Therefore, process eggs from old parent stock or problem ﬂocks last. The air pressure here is lower than in the setter room.

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Egg disinfection lock

• •

At hatch, infected eggs can release pathogens that can contaminate or infect the entire batch of chicks. Install a good air exhaust system that also removes fluff or down floating in the air. Fluff contains a lot of bacteria. Ventilate with under-pressure to prevent pathogens spreading to the rest of the hatchery. Clean and disinfect the fluff tunnel as well.

•

Hatcheries use the following measures to minimise and prevent contamination and infections: • Different air pressures are used in the various rooms to prevent air flowing from dirty to clean zones. • Each incubator is connected to a separate air inlet and outlet. This prevents exhaust air from coming into contact with the incoming air from the same or another incubator. • Rooms in the dirty zone are thoroughly cleaned, disinfected and dried after each use. • Personnel always follow a fixed route when entering the building. There should be no back flow of eggs and chicks, or clothing and footwear worn by personnel to previous steps in the incubation process. • Separate clothing and footwear are worn in the setter and hatcher rooms. • Before anyone enters the hatchery, they must take a shower and change their clothing. Don’t forget the shoes (disinfect company footwear well)! • Visitors must not have been in contact with poultry within 72 hours before the visit.

A lot of dust is released when the chicks are pulled. Eggshells and unhatched eggs are also a source of contamination. Install a separate air exhaust system. Clean, disinfect, and dry the hatcher baskets after each use.

Take samples from the air ducts regularly. Bacteria and moulds can accumulate here. The spores will be transported by the airflow and contaminate the hatching eggs.

Ha tc he ry S i gnal s

te ec pr ot Clear instruction that wearing overshoes outdoors is obligatory. Make sure overshoes are available at the exit.

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The hatchery is designed to prevent introduction and spread of infections, but personnel can make or break effective biosecurity. Make sure that every employee is fully aware of the importance of good hygiene. Train personnel so they are motivated to observe hygiene protocols and measures precisely. If everyone is aware of the importance of biosecurity, motivation is key to observing the regulations. Consider ways of making the causes and consequences of certain actions very clear to all personnel. The clearer and simpler the protocol, the more effective it is. An employee often spends half the day on production tasks and spends the other half cleaning and disinfecting. Many hatcheries have separate tool kits for ‘clean’ and ‘dirty’ zones containing the basic tools for that zone. This avoids tools being carried to all parts of the hatchery. External technical personnel must obviously follow the hygiene protocol before entering the hatchery. Regularly check that disinfection mats are still saturated with disinfectant. Occasional visitors are another risk factor. For example, a business contact who is visiting the director and wants to see the hatchery. Everyone must comply with the hygiene protocol.

Personnel and hygiene

Regularly check that soap and sanitisers are available throughout the day, and that they are used. Clear instructions are displayed here near the soap and disinfectant dispensers. The taps have extended handles that allow operation with the elbow.

5. B io s e c u r i t y

When chemicals are used (cleaning/disinfecting agents), always follow the applicable protocols including wearing PPE such as protective clothing, gloves and masks. Do not make any concessions! Disinfectants that do not require PPE to be worn are often more expensive. These products often make disinfection more complicated.

washing drying

cleaning footwear

disinfection

You can install one-way gates at crucial locations with sanitisers for hands and footwear, which must be used before the gate will open.

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Do all the personnel wash their hair each time they enter another hygiene zone? Shower for at least 5 minutes. In addition to washing dirt from your hair, you rinse away loose hairs and - equally importantly - you remove the dirt under your fingernails at the same time! How can you make this easier for staff with long hair?

gate opens only after disinfection

Attention! Personnel who work with the chicks must never just walk into the setter room. Fluff and down is a major vector of infection!

Make sure that staff do not wear jewellery at work. Personal belongings can be safely stored in lockers.

Barrier shower

Outside

Inside hatchery

Conventional shower

Outside

Inside hatchery

A barrier shower is the best solution. A conventional shower has two risks: people can walk past the shower and the entrance is a point where clean and dirty routes cross!

Ha tc he ry S i gnal s

LOOK-THINK-ACT

Which regulations apply for technical personnel? Do the technical personnel have access to all parts of the hatchery? Are there any protocols for the routes they take? Do protocols apply to taking showers and changing into different clothing? Are there separate tool kits for each zone? If no regulations apply, there is a high risk that: 1. Technical personnel carry pathogens to various parts of the hatchery. 2. External technical personnel bring pathogens into the hatchery.

What are these overshoes for?

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A truck driver is a risk for biosecurity. So at the loading dock (on the right in the photo) and the door where the driver enters, there must also be a disinfection bath and shoes for temporary use. Only allow a driver into the hatchery when this is absolutely necessary.

How creative are the personnel at your hatchery in bypassing hygiene measures? Is everyone aware of the importance of extreme hygiene? Here the gate on the right prevents employees from avoiding the disinfection unit.

Egg reception and storage

Incubation area

Candling and transfer

Make sure you provide all the resources necessary for optimal hygiene and personal safety in the right place.

Hatching area

Chick handling and dispatch

Clean

Dirty

Ensure visitors always follow the same route: from clean (disinfected eggs) to dirty (chicks). Visitors who supply goods (drivers) must not be allowed to pass the point where the eggs are disinfected.

5. B io s e c u r i t y

Correct

Incorrect Hair net

No hair hanging loose

Hearing protection

No moustache or beard (or covered with a net)

Face mask

No jewellery

Showered

Do not eat/ drink at work

No watch

Clean workwear

No loose clothing

Gloves

Phone not put away properly

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Not ill

Boots

A repaired floor. Cracks and holes in the floor are an ideal environment for bacteria and moulds to thrive. Repair any damage immediately. 72

No dirty clothes

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Washed and disinfected hands

No footwear that has been worn outside the hatchery

A tile floor is a hard-wearing surface, but the grouting between the tiles is difficult to clean. A cast concrete floor is preferable.

Ha tc he ry S i gnal s

Cleaning Cleaning and disinfection protocol Sweep and vacuum areas ﬁrst. Soak the surfaces with a foam cleaner. Allow the room and materials to dry. Rinse with water. Allow the room and materials to dry again. Disinfect.

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1. 2. 3. 4. 5. 6.

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The climate at a hatchery is an ideal breeding ground for pathogens. Good hygiene is vital! Clear cleaning and disinfection protocols must be established and observed in all parts of the hatchery. If disinfected eggs are placed in an unhygienic environment, disinfecting them was pointless. First make sure that dust and dirt are removed. Organic matter such as egg shells, fluff and blood inactivate disinfectants. Remove this first! Disinfection is mentioned a lot, but cleaning agents are responsible for the biggest reduction in germs. An effective cleaning agent can reduce > 95% of the harmful pathogens. It ensures that all fat, protein and dust are removed properly. These substances contain the most bacteria, as they are a source of nutrients and a protective layer for pathogens (biofilm). Pathogens can grow and develop without restriction, especially in the favourable environment at the hatchery. High cleaning efficiency and a good contact time with the surface are essential for the efficacy of cleaning agents. The result is an interaction between the two properties. A very powerful cleaning agent that does not adhere to the smooth surfaces (coating, plastic, stainless steel), will not reach the necessary contact time. And the maximum effect of cleaning will not be achieved. Alternating between alkaline (removes grease and fat) and acid (removes protein and minerals) cleaning agents should be part of the cleaning protocol. Always read the insert of cleaning agents and disinfectants carefully and follow the instructions. Ask your chemical supplier for advice. And know what to do if you spill chemicals on the floor or your skin.

A foam cleaner removes biofilms and mineral deposits. Using a high-pressure spray has the risk of spreading pathogens. 5. B io s e c u r i t y

There are four basic elements of cleaning that are key to its success. Mechanical action (brush, high pressure), product (soap, water), temperature (better cleaning at a higher temperature), time (the longer, the better).

Clean per room and not per cabinet. Because no matter what, the cleaning process will influence the relative humidity and temperature in the cabinets that are still filled with eggs. This depends on whether the ventilation is arranged per room or per incubator. 73

The frequency of cleaning in the hatchery Area

Frequency

Egg receiving/handling room

Once every week

Egg storage

Once every week

Setter room/hallways

Once every week

Setters

After each incubation cycle

Egg transfer room

After each use

Hatchers

After each use

Chick handling rooms

After each hatch

Chick despatch room

After each use

Racks, trays, baskets, boxes

After each use

Egg and chick trucks

After each egg/chick delivery

Develop clear cleaning and disinfection protocols for the hatchery. This includes a good schedule of activities and not just a correct execution.

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A dedicated cleaning trolley keeps all the necessary materials together, so you never forget anything. The simpler the process, the higher the motivation to perform it properly. Make sure all the cleaning materials are readily available. Two taps on the wall: one for water and one for air (for foaming).

Installing a pipe system to dispense disinfectant where it is needed can be effective. Clearly indicate that this is not drinking water! Use of plastic pipes avoids corrosion; copper pipes may corrode.

Did you know?

Protect the vulnerable sensors during cleaning and disinfection, but do not forget to remove the protective cover after cleaning/disinfecting before reloading the machine!

Regularly alternate between using cleaning and disinfecting agents with different pH values. For example, use alkaline cleaners for three weeks, followed by acid cleaners for one week. This prevents moulds and bacteria from becoming resistant.

Ha tc he ry S i gnal s

Disinfection of the hatchery

LOOK-THINK-ACT

What causes these brown streaks?

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Choose a disinfectant that does not have a corrosive effect on equipment and tools: chlorine in disinfectant corrodes stainless steel. The wheels on the trolleys can easily corrode, and therefore function poorly.

Effectivity of disinfectants The effect of a disinfectant depends on: • contact time with the surface • temperature • concentration • acidity • nature of the soiling • sensitivity of the dirt to the disinfectant. Always follow the supplier’s instructions.

• •

•

Make sure that chemicals have not expired, because then they will no longer be effective. Check the concentrations used in the different machines and cleaners. Increase your hygiene by walking through the hatchery regularly looking for ways to improve cleaning procedures. Sample for bacteria and Aspergillus and monitor this closely.

•

Caution!

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Destroying bacteria such as E. Coli, Pseudomonas and Staphylococcus, but also the Aspergillus mould is extremely important in hatcheries. All these pathogens have negative effects on hatchability, first-week mortality and chick quality. The presence of moulds is always a major challenge at a hatchery because the hatchery environment and climate are ideal: high relative humidity, high temperatures and organic matter (eggs, cardboard materials, etc.). In addition to the active ingredient, the method of application also determines how effectively the pathogens are destroyed. An active ingredient or combination of ingredients may be highly effective against the target pathogens, but if they are not applied properly, you will never achieve the desired results. When disinfecting rooms or surfaces: the more liquid used, the better the contact with the surfaces. So, it is not the concentration (mix according to the instructions), but the total approach that matters. For the best results and efficacy, alternate between disinfectants. Each product has its own mode of action. Changing the products you use means you can attack pathogens in multiple ways.

Properties of disinfectants Product

Mycoplasma

Gram +

Gram -

Pseudomo- Enveloped nadaceae viruses

Naked Bacterial viruses spores

Coccidia

Moulds

Hypochlorus

Formaldehyde

Glutaraldehyde

Hydrogen peroxide

Acid (peracetic acid)

+/-

Phenols (cresols)

Quaternairy Ammonium Compounds

+/-

Sodium hydroxide

+/-

Ammonia

++ = perfect effectiveness + good effectiveness +/– mild effectiveness – ineffective

Formalin disinfection is easy to use, and formaldehyde (gas) reaches all target areas. However, a respirator must be worn as formaldehyde is classified as a carcinogen. 5. B io s e c u r i t y

The effectiveness of different disinfectants varies widely, so make a conscious choice. In practice, an arsenal of different disinfectants is used to disinfect eggs and rooms. Whether certain disinfectants are approved for use varies greatly from country to country and per region. 75

CHAPTER 6:

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Egg transport and storage

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Hatching eggs are transported all over the world. During this process, hatching eggs are sometimes repacked several times. This causes undesirable movements and fluctuations in the climate conditions.

hatching eggs.

Temperature fluctuations, condensation, jolts and vibrations significantly reduce the quality of

This chick has an extra leg. This may have been caused by jolts and vibrations (e.g. a faulty automatic turner). This is a particular risk during the embryonic cell differentiation stage: from the moment the fertilised egg is in the hen’s body until the first few days in the incubator.

When a hen lays a hatching egg, it already contains a tiny embryo, consisting of around 40,000 cells. The first stages of organ development have already taken place: the embryo is in a dormant state. During storage, the goal is to maintain the resting phase of the embryo. Avoid temperature fluctuations during storage. After storage, the embryo temperature is brought back above physiological zero to the incubation temperature. This is a temperature range in which the embryo is warmed up gradually in 6-24 hours. Completing this process any faster or slower is not advisable, as it causes too much disruption to embryonic development. Uniform temperature increases for all eggs is more important by that time.

Ha tc he ry S i gnal s

Condensation point = dew point Condensation point The condensation points of eggs (sweating) at certain levels of relative humidity (RH) outside the storage room. Example 1: in a setter room of 25°C with 50% RH, eggs will ‘sweat’ when they are taken from a storage room where the temperature is set below 14°C. Example 2: eggs with a temperature of 27°C set in a warm incubator at 38°C and with 55% RH will stay just below the condensation point. This is why it is important to allow the eggs to acclimatise properly before setting them in the incubator. The setter room is usually a little colder than 27°C.

80% 2

30%

55%

10 0

25 30 Air temperature (°C)

Relative humidity (%)

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Dew point temperature (°C)

Dew point determination based on temperature and humidity values

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The moment that condensation occurs depends on the temperatures inside and outside the storage room combined with the relative humidity. It is a natural phenomenon that cold air can hold less moisture (water vapour) than warm air. When warm, moist air cools down it reaches a certain temperature referred to as the condensation point or dew point. At that moment the water vapour in the air condenses to form liquid droplets (dew). The highest risk of condensation (sweating) occurs when eggs are moved from the colder storage room/trailer to the relatively warmer environment of the receiving area at the hatchery. Unloading the eggs from a plane onto a loading platform at a ‘hot and humid’ airport is also a critical moment. The air that comes into contact with the eggshell cools quickly. The moisture in this air condenses on it as soon as the condensation point is reached. Condensation on the eggshell creates favourable conditions for bacteria and moulds to multiply and carries the risk of the egg contents being contaminated by pathogen absorption through the pores in the shell. You can calculate the condensation point based on the temperature and relative humidity values. The Mollier diagram is a commonly used tool, but there are also many handy calculation apps available.

Condensation, or sweating, on the eggshell surface. Cooled eggs will sweat if they suddenly come into contact with warm, moist air.

6. E gg t r a n sp o r t a n d s to rag e

You will see condensation form if a glass of cold drink poured straight from the fridge is placed in warmer surroundings. This is exactly what happens with hatching eggs too.

Temperature

laying

setting

laying

setting

laying

setting

Transition moments

transport transport

ᅚ

transport

Storage temperature

Changing egg temperature profile from laying to setting. Ensure the egg storage climate conditions (temp. + RH) at the breeding farm, during transport and at the hatchery are coordinated as well as possible. All temperature transitions must be gradual. The transition from cold to warm conditions in particular is associated with a risk of condensation. The U-shape is preferable: stable. The V-shape is not a serious issue provided the duration of transport is short. The W-shape must be avoided, as this has the highest risk of condensation.

There are many moments when hatching eggs are exposed to different temperatures and humidity levels. All of these are critical times for condensation formation. The following transitions involve risks for the eggs: 1. Laying nest –> Storage at the breeder farm 2. Storage at the breeder farm –> trailer for transport 3. Trailer –> egg receiving room 4. Egg receiving room –> storage at hatchery 5. Storage at hatchery –> pre-warming 6. Pre-warming –> set

Dry bulb and wet bulb thermometer

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You can accurately determine the humidity using two thermometers. One thermometer - the dry bulb - is suspended in the air. The bulb of the second thermometer - the wet bulb- is covered by a wick that is suspended in a container that holds water. The wet bulb thermometer always indicates a lower temperature than the dry bulb thermometer, because water continuously evaporates from the wick. Moisture that evaporates removes heat from the thermometer. The lower the RH, the faster evaporation is and the lower the wet bulb temperature (and therefore the greater the difference with the temperature indicated by the dry bulb thermometer). Combining the dry bulb and wet bulb temperature readings gives the state of the humid air (i.e. the relative humidity). A conversion table is supplied with each wet bulb thermometer.

A dry bulb and wet bulb thermometer to determine the RH. Essential for accurate measurement: refill the water container daily as the wick around the bulb must be kept moist. Prevent algae from forming in the water container.

A digital hygrometer can work very well too. However, a detailed reading does not necessarily mean it is a reliable one. Calibrate measuring sensors and equipment regularly!

Ha tc he ry S i gnal s

How to use the table 1. Read out the dry bulb temperature (first column). 2. Deduct the wet bulb temperature and look this figure up in the first row. 3. Read out the relative humidity value in the table.

Examples The dry bulb thermometer reads 24°C and the wet bulb temperature shows 18°C (6°C difference). This results in an RH value of 55%. The same applies to the Fahrenheit table. The dry bulb thermometer reads 72°F and the wet bulb temperature shows 60°F (12°F difference). This results in an RH value of 49%.

Relative humidity indicated by wet bulb and dry bulb thermometers (Celsius) Difference between wet bulb and dry bulb temperature (°C) 5 22% 29% 35% 39% 44% 47% 51% 54% 56% 58% 60% 62% 64% 65% 67% 68% 69% 70% 71% 71% 72% 73%

6 8% 16% 6 3 23% 28% 8 33% 3 8 38% 42% 2 45% 5 8 48% 51% 1 53% 3 55% 55 57% 59% 61% 62% 63% 64% 65% 66% 67% 68%

3% 11% 18% 24% 29% 33% 37% 41% 44% 47% 49% 51% 53% 55% 56% 58% 59% 60% 62% 63% 64%

7% 14% 20% 25% 29% 33% 37% 40% 43% 45% 47% 49% 51% 53% 54% 56% 57% 58% 59%

4% 11% 17% 22% 26% 30% 34% 37% 39% 42% 44% 46% 48% 50% 51% 52% 54% 55%

3% 9% 14% 19% 24% 27% 31% 34% 37% 39% 41% 43% 45% 47% 48% 49% 51%

0% 6% 11% 16% 20% 23% 26% 29% 32% 34% 36% 38% 40% 42% 43%

5% 9% 14% 17% 20% 23% 26% 28% 30% 32% 34% 36%

4% 8% 12% 15% 18% 21% 23% 26% 28% 29%

0% 4% 8% 11% 14% 17% 19% 21% 23%

1% 5% 8% 11% 13% 16% 18%

4 37% 42% 47% 51% 54% 57% 60% 62% 64% 66% 68% 69% 71% 72% 73% 74% 75% 75% 76% 77% 77% 78%

3 52% 56% 60% 63% 65% 67% 69% 71% 73% 74% 75% 76% 77% 78% 79% 80% 81% 81% 82% 82% 83% 83%

2 68% 70% 73% 75% 76% 78% 79% 80% 82% 82% 83% 84% 85% 85% 86% 86% 87% 87% 88% 88% 88% 89%

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1 84% 85% 86% 87% 88% 89% 89% 90% 91% 91% 92% 92% 92% 93% 93% 93% 93% 94% 94% 94% 94% 94%

0 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+

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Dry bulb temp (°C) 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44

Relative humidity indicated by wet bulb and dry bulb thermometers (Fahrenheit)

0 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+ 99%+

2 82% 84% 85% 86% 87% 88% 89% 90% 90% 91% 91% 91% 92% 92% 92% 93% 93% 93% 93% 94%

6. E gg t r a n sp o r t a n d s to rag e

Difference between wet bulb and dry bulb temperature (°F)

Dry bulb temp (°F) 36 40 44 48 52 56 60 64 68 72 76 80 84 88 92 96 100 104 108 112

4 65% 68% 71% 73% 75% 77% 78% 79% 81% 82% 83% 83% 84% 85% 85% 86% 86% 87% 87% 87%

6 48% 52% 56% 60% 63% 66% 68% 70% 71% 73% 74% 75% 77% 77% 78% 79% 80% 80% 81% 81%

8 31% 37% 43% 47% 51% 55% 58% 60% 63% 65% 66% 68% 69% 71% 72% 73% 74% 74% 75% 76%

10 15% 23% 30% 35% 40% 45% 48% 51% 54% 57% 59% 61% 62% 64% 65% 67% 68% 69% 70% 70%

1 12

9% 17% 7 24% 4 30% 0 35% 5 39% 9 43% 3 46 46% 49% 52% 54% 56% 58% 59% 61% 62% 63% 64% 65%

5% 12% 19% 25% 30% 35% 38% 42% 45% 47% 50% 52% 53% 55% 57% 58% 59% 60%

2% 9% 16% 22% 27% 31% 35% 38% 41% 43% 46% 48% 50% 51% 53% 54% 56%

7% 13% 19% 24% 28% 32% 35% 38% 40% 43% 45% 46% 48% 50% 51%

5% 11% 17% 21% 25% 29% 32% 35% 37% 40% 42% 44% 45% 47%

3% 9% 14% 18% 22% 25% 28% 30% 33% 35% 37% 39%

3% 8% 12% 16% 19% 22% 25% 27% 29% 31%

3% 7% 11% 14% 17% 20% 22% 24%

3% 7% 0% 10% 4% 13% 7% 16% 10% 18% 12%

Climate during transport

Trolley covers

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Nowadays, most trailers that transport eggs are accurately temperature and humidity controlled so the eggs can be transported under the optimal conditions. In that case, sunshine is not a problem. And when the trailer is moving, there is no immediate risk of overheating as the movement creates a cooling breeze. If there is no climate control in the trailer, the temperature of the hatching eggs may increase. If the temperature rises above 25°C, the contents of the egg (egg white, yolk and embryo) will also slowly warm. This can cause higher early embryonic mortality during the ﬁrst days of the incubation process.

This trailer is held up in congestion in sunny weather. Is this a problem?

The climate conditions during transport should replicate the climate in the storage room as closely as possible. Load the trolleys into the trailer one at a time. So do not place all the trolleys of eggs outside and then start loading the trailer. In other words, avoid exposing the eggs to sunlight, rain or freezing cold air. Make sure the loading bay is as close as possible to the doors of the storage room. Transport over short distances is not always done in climate-controlled vehicles. Ideally, the temperature inside the trailer should equal the temperature in the storage room at the breeder farm. Loading more eggs collected from other breeding farms is inadvisable as there is always a temperature difference. This practice can cause condensation with the inherent risk of contamination.

LOOK-THINK-ACT

You can use trolley covers to protect the eggs from outside temperature inﬂuences during loading and unloading. This prevents condensation. Be careful when using these covers in sunny weather, they can also cause very rapid warming! Do not use trolley covers in hot, sunny weather. Condensation can also form on the outside of the covers, especially when they are cold because the trolleys were already covered the evening before. And the combination of a cold cover around warm eggs produces condensation on the inside of the covers.

The conditions during transport can be monitored using climate data loggers in the trailer. If the climate conditions during transport have not been properly controlled, hatchability will be affected. It is important that the hatchery manager can review the climate data immediately when the eggs arrive so any interventions can be anticipated.

Transporting eggs and day-old chicks? Sometimes the same trailer is used to transport eggs and day-old chicks. This is not necessarily a problem providing two conditions are met: 1. Always clean, disinfect and dry the trailer properly before use! 2. Check the climate settings with the driver: chicks need a higher temperature setting (25-28°C) during transport than eggs (18-20°C).

A certified company should regularly inspect and calibrate the measuring sensors in the trailer. Ha tc he ry S i gnal s

Jolts and vibrations Rough handling and excessive jolts and vibrations in the period from fertilisation to the first days of the incubation process can disrupt embryonic development. The embryo may die or show abnormal development. Congenital malformations are generally seen at the extremities of the embryo. This can present as an extra leg or an opening in the skull (exposed brains). This is a particular risk with eggs from an old parent stock (> 45 weeks).

A simple solution has been used here to prevent movement and jolting. A number of paper trays have been clamped between the pallets of eggs to minimise movement during transport.

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Take extreme care to limit jolts and vibrations as much as possible when transporting eggs at the breeder farm and also at the hatchery. An electric pallet truck can help.

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These inflatable bumpers are deflated before the trailer is loaded. After loading, the bumpers inflate and create a soft cushion that securely holds the trolleys in place.

Remember that a trailer moves in various directions during transport. From front to back, left to right and up and down.

Always move the trolleys of eggs gently and calmly. Ensure smooth transitions between surfaces to avoid jolts and vibrations.

6. E gg t r a n sp o r t a n d s to rag e

Egg transport and logistics Did you know?

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There can be a wide variation of laying dates in a batch of eggs. This depends on how frequently eggs are collected for transport from the breeder farm. Eggs must be marked with the actual date of lay. At the hatchery, however, an average age of the eggs is often entered in the system. This means that neither of the groups of shortest and longest stored eggs will be optimally incubated. And the greater the differences, the less optimal the conditions will be for all the eggs. Preferably collect eggs from the breeder farm at least twice a week. In large integrations, eggs are supplied to the hatchery every day.

At the breeder farm, the hatching eggs are placed in paper egg flats, plastic or setter trays. The type of tray or box used for transport depends on what the hatchery wants. When eggs are collected from the farm, one-to-one planning is the best way to avoid cross-contamination. It is best not to collect eggs from various poultry farms in one trip. All material, including the trailer, that returns to the breeder farm from the hatchery must be cleaned, disinfected and dried at the hatchery. Provide clear instructions about the correct cleaning and disinfection protocols and ensure the driver has all the necessary equipment. Also consider providing registration forms. And monitor the results using swabs.

Egg storage after arrival at the hatchery. The number code indicates the batch. This makes it easier for personnel to locate and take the right batch to the incubator.

Transferring eggs from paper egg flats to setter trays.

Eggs are often transported to the hatchery already on setter trays in either transport- or setter trolleys. These eggs do not need to be transferred to setter trays.

Ha tc he ry S i gnal s

Inspection of incoming eggs ter tray of 150 eggs. The eggs are often weighed individually to assess the uniformity of a batch. The breeder is given feedback on the number of dirty or damaged eggs, hairline cracks or abnormalities. Misshapen or cracked eggs are diverted to the processing industry (liquid egg market). The assessment also considers the general presentation of the eggs: feathers, dust rings, labelling, and legibility of stamps. Floor eggs and washed eggs (if supplied) must be clearly marked. The quality assurance manager or person in charge of egg storage performs the incoming-egg inspection and informs the hatchery manager about the findings.

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When the eggs arrive, the entire batch from each breeder farm is assessed for uniformity, colour, size and shape. At the incoming-egg inspection, the quality assurance manager breaks a sample of 30 eggs from each batch. The quality manager assesses the condition of the eggs for: • breaking strength • hairline cracks • dirt and soiling • fertility • abnormalities in the albumen and yolk (e.g. blood in the yolk or albumen) In addition, a more extensive quality inspection is performed at different flock ages (e.g. 30, 40 and 50 weeks). This inspection assesses an entire set-

Eggs are removed from a tray and weighed individually for an impression of weight uniformity.

Measuring the breaking strength is an indicator of eggshell quality.

Candling the eggs with a candling lamp is part of the incoming inspection. This reveals the size of the air cell (an indication of eggshell quality and the duration of storage) and any hairline cracks.

6. E gg t r a n sp o r t a n d s to rag e

Storage at the hatchery times. In principle, the incubation process is only started once the sale of the day-old chicks has been finalised, or in the case of laying hens the number of rearing hens required is known. The eggs must be stored under optimal conditions in the meantime. In most egg storage rooms at a hatchery, the temperature is constantly maintained at 17-18°C, although it is better to adapt the temperature to suit the intended storage duration.

More than one storage room? Sometimes a hatchery has two egg storage rooms with different storage conditions and durations. The temperature settings should be adapted to suit the oldest eggs, as the youngest eggs will also hatch if stored at a colder temperature. Older eggs are often stored too warm. It is best to maintain a storage temperature of 15°C. Be aware of condensation forming when the eggs are moved to the setter room! It will also take longer for the eggs to reach the required incubation temperature. Prewarming to 25-26°C before setting is even more important for these eggs.

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Before the eggs can be set, they should be left at rest for at least 8 hours. The rest period is particularly important at a hatchery that processes eggs for layers. During this rest period, CO2 is released from the eggs and the albumen pH rises. After this period of rest, the albumen has become slightly thinner. This makes it easier for nutrients and waste to be transported between the embryo and its immediate environment. This creates the right basic conditions for the incubation process. Aim to set the eggs in the incubator within 7 days of laying. However, this is not always a feasible target, if, for example, you want to fill one section in the hatchery with eggs from a particular flock, or because you work in a (large) parent stock hatchery. The number of chicks ordered is not always the same each day, and it can be low at certain

Ensure uniform temperature distribution through good airflow during storage. So do not store eggs on the floor, very close to the wall, packed too close together or immediately under a flow of cold air. However, as long as the eggs are not producing heat, the effect of air velocity is not very important. It is important to watch out for condensation droplets on the eggs caused by temperature differences.

The eggs are grouped according to breeder farm and the date of laying. The laying date is stated on the pallet or trolley. The laying date is not the same as the date of arrival at the hatchery. The delivery can often include eggs aged from 1-3 days (depending on the collection frequency at the breeder farm).

Align storage conditions Try and align the storage temperature at the hatchery as closely as possible with the storage temperature at the breeder farm to avoid temperature fluctuations. Aim to maintain the most uniform and constant climate conditions possible in the storage room.

Do not rely blindly on the climate settings and the temperature and humidity indicated by the climate computer. Measure the climatic conditions in the storage room(s) regularly and at different positions. You can put this simple meter in various locations to get a good idea of storage conditions throughout.

Ha tc he ry S i gnal s

Climate conditions during storage During storage, temperature is the critical parameter. Theoretically, the relative humidity should be between 75-80% to prevent the eggs from drying out. This is not always the case in practice, and the optimal relative humidity during storage is around 65%. This is because the storage temperature is not high. Normally, a hatching egg loses a little more than 0.1% of its weight each day during the storage period, depending on the storage temperature. This appears to be compensated for by a

slightly lower moisture loss during the incubation process. When humidifying the air, keep the spray nozzles of the humidifier clean so they distribute a fine mist instead of large droplets. Prevent lime deposits and algae/moulds blocking the nozzles. Large droplets will wet the eggs creating an ideal environment for the growth of moulds and bacteria. Water reservoirs can also encourage bacterial growth. Clean the storage container at least once a week.

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Air cell The hatchery manager and quality assurance manager know from experience what the ideal air cell size should be when the eggs arrive at their hatchery. How much water evaporates from the egg is determined by the climatic conditions and the eggshell quality. The latter depends on the breed, nutrition, parent stock age and environmental conditions in the poultry houses. The size of the air cell is a good indicator of the right levels of relative humidity. Its size is determined by how long the egg is stored and the climate during storage (relative humidity and temperature). If the RH is below optimal, the air cell will be too large.

You can see a min-max. thermometer on the wall and a clipboard to note down the tempertaure fluctuations. There is also a separate min-max. thermometer for measurements in other places.

A humidifier in the storage room (yellow).

6. E gg t r a n sp o r t a n d s to rag e

The eggs may be delivered in different ways, but they are stored in the same room. Take this into account when setting the temperature, humidity and air distribution levels for the storage room climate.

Hatchability fertile eggs (%)

100

Influence of parent flock age and storage duration on hatchability

The longer the eggs are stored, the longer the incubation time and the lower the hatchability. At least, this is the case if the air temperature in the incubator is not adapted, as eggs stored for a longer period produce less heat. The duration of storage also affects chick weight because the eggs hatch later, and this has an impact on chick quality. So adapt and set the incubation conditions and timing in alignment with the storage duration.

prime (35-50 weeks)

old (> 50 weeks)

Storage duration

young (< 35 weeks)

7 14 Egg storage duration (days)

Eggs from older flocks maintain their hatch potential for less time during storage than eggs from young hens. The fertilisation rate is also lower.

hatchability (%)

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Hatchability (%)

70 60

albumen height (mm)

4 6 8 Egg storage duration (days)

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Albumen height / pH

100 pH

Changes in the egg during storage 10 9

A long storage period has a negative effect on hatchability, the albumen pH and the albumen height. But eggs stored for a short period (1-2 days) have better hatchability than eggs that are set immediately. Especially in eggs from young flocks where egg quality is still high. Degradation of the albumen in fresh eggs is necessary for good gas exchange during incubation. Exposure to ammonia gas can facilitate albumen degradation and, in this case, improve hatchability of short stored eggs from young parents.

Storage duration and optimal storage conditions Storage duration

Storage temperature

Relative humidity

1-3 days

20-23°C

68-73°F

65%

4-7 days

15-18°C

59-64°F

65%

7-10 days

12-15°C

54-59°F

75%

12°C

54°F

75%

Longer than 10 days

The impact of storage Storage impacts on hatching eggs in the following ways: • Each day longer than 7 days in storage, converts to 1 hour extra of incubation time. Eggs stored for a longer period (> 7 days) and fresh eggs must therefore be set at the hatchery at different times. • After 5 days of storage, the hatchability of broiler chicks declines by 0.5 to 1% for each extra day of storage. • When eggs are stored for more than 12 days, the chick quality will be lower at hatch. The effect of hatching egg storage duration on broiler growth can be as much as 200 grams at the age of slaughter. Influence of parent stock Egg size increases as the age of the parent flock advances, while eggshell strength declines. The poorer eggshell quality affects the internal egg quality during storage and incubation. On the other hand, this thinner eggshell could facilitate higher gas exchange. Heavier eggs take longer to incubate in this case (1 hour extra per 5 grams). There is generally a positive correlation between egg production and the hatching result. Lower hatchability is particularly likely if the egg production rate decreases faster than usual.

The storage duration determines the storage temperature. The longer the eggs have to be stored, the cooler the storage temperature. The higher RH during storage is also important as it prevents the eggs from drying out. Most hatcheries have just one storage room. As most of the eggs are stored for between 4 and 7 days, its temperature is set to 16-18°C.

Ha tc he ry S i gnal s

Point up or down? If stored for longer, eggs should be stored with the point upwards. The yolk has a tendency to float and rise inside the egg with the germinal disc pointing upwards. As the egg ages, the chalazae can no longer hold the yolk in position. If this germinal disc comes into contact with the air cell, it will be in direct contact with the outside air, stick to the membrane, and dry out. In the setter, the point should be oriented downwards again!

LOOK-THINK-ACT

What is an effect of a long storage duration? The longer eggs are stored, the longer the incubation period. Eggs stored for a short time have a strong, healthy embryo after 60 hours of incubation (right). An egg stored for 14 days has a weak embryo (left). This leads to higher early embryonic mortality.

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The optimal time to set eggs is between days 4 and 7 after laying. At this time, the condition of the hatching eggs allows oxygen to reach the embryo easily. However, planning considerations may mean that setting older eggs is unavoidable. If eggs need to be stored for longer, take the following measures: • Lower temperature (up to day 10, 12-15°C, longer than 10 days, 12°C). • Turn the eggs at least twice a day. Eggs that have been stored for two weeks longer must be incubated at a higher temperature. Embryos that have been stored for a longer period grow more slowly and therefore produce less heat. There will also be higher embryonic mortality and the eggs on the setter tray will be positioned between eggs that no longer produce any heat. The planned storage duration determines the optimal profile of the incubation temperature from moment of lay until the eggs are set. If the eggs are stored for 5-10 days, the storage temperature should be lower than with a storage duration of 3-4 days. As a practical physiological zero, 22-25°C is usually maintained, although embryonic development will only start up again from 27°C. But changes in the egg content will still occur at below 27°C. The colder the eggs are stored, the less the change in egg contents.

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Longer storage

If you intend to store eggs for a long time, the best (but unpractical) way to store them is with the pointed end upwards. The thick albumen gradually gets thinner during storage and the chalazae are no longer able to hold the yolk in position. The yolk will rise and come into contact with the air cell with the germinal disc always facing upwards. Direct contact with the inner shell membrane at the location of the air cell is not good for the embryo.

6. E gg t r a n sp o r t a n d s to rag e

Nature

Starting position

Turning during storage

Turned

If the eggs are only stored for a few days, turning is not really necessary. Eggs stored for more than 7 days should be turned preferably every hour during storage, but rotated at least several times (2-4 times) a day through an angle of 90° (tilting from -45° to + 45°). On the trolley, this must be at least 35°. The main reason for turning eggs during storage is to prevent the membranes adhering to the inner shell membrane and the yolk from floating against the air cell. During incubation, turning is important for normal embryonic development (distribution of fluids inside the egg). If the eggs are going to be stored for longer, an egg temperature treatment (SPIDES) will also be necessary.

Final position

Starting position

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Incubator

Turned

Final position

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Turning ensures that the yolk is always positioned with the germinal disc facing upwards. During natural incubation, the hen moves the eggs so they roll and tilt. In an incubator this is done by mechanically adjusting the angle.

The eggs are turned regularly during storage. The turning angle is normally between 35–45° relative to the position of a horizontal tray.

The trolleys in the storage room are coupled to an automatic turner.

Ha tc he ry S i gnal s

SPIDES

Effect of SPIDES on hatching results +3.5% +14.3%

{

Hatch of all eggs set (%)

+2.5%

{

100

{

80 70 60 50

98.5%

86.7%

89.2%

83.5%

87.0%

62.6%

76.9%

Fresh eggs

Stored 7 days

Stored 7 days SPIDES

Stored 14 days

Stored 14 days SPIDES

Stored 21 days

Stored 21 days SPIDES

40 30 20 10 0

The effect of SPIDES on hatchability of eggs stored for 7, 14 or 21 days This graph shows that the hatchability of eggs treated with SPIDES during storage is higher than the untreated eggs.

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Effect SPIDES-duration on hatchability

100 95 90

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% chicks from fertile eggs

If hatching eggs have to be stored for longer than 7 days, the eggs can be warmed to incubation temperature briefly and under controlled conditions. Hatching eggs vary in their developmental stage and this technique evens out the differences. This process is called heat treatment or SPIDES (Short Periods of Incubation During Egg Storage). The eggs are sometimes even heat treated several times, for example at hatcheries that produce layers or parent stock. In natural conditions, the hen lays an egg every day until her clutch is complete. Each time she sits on the nest and lays an egg, the older eggs in the nest will be warmed. So by regularly sitting on the nest she incubates the eggs for short periods. After laying, she leaves the nest until she is ready to lay the next egg. A fertilised embryo normally consists of about 40,000 cells. This number decreases the longer the egg is stored because the viability of the cells is reduced, and they even start to die. The SPIDES technique activates the cells and the number of viable cells increases again. This creates strong embryos that will still be able to achieve good hatchability, including better chick quality, even after a prolonged storage period. In a setter, the eggs are heated for a short period (3-4 hours) to a minimum of 32°C and a maximum of 38°C (90-100°F). As soon as they reach a temperature of 32°C, the eggs can be cooled back down and stored again. The eggs must not be heated for longer than 4 hours, otherwise the embryos will develop too far which leads to higher embryonic mortality. If multiple SPIDES treatment is given, do not heat the eggs to above 32°C for any longer than a cumulative time of 12 hours. In practice, this means heating for no more than 3 times for 4 hours at 4–5-day intervals. Some hatcheries have a separate incubator that allows a controlled SPIDES treatment according to a fixed program. Other hatcheries use the standard incubators, but use a special program. This technique is usually applied when the eggs arrive at the hatchery, because the schedule has already been finalised and, accordingly, how long the batch of eggs will have to be stored. Some incubator manufacturers include an option for SPIDES in the incubation program settings. 6. E gg t r a n sp o r t a n d s to rag e

85 80 75 70

control

3 hours

6 hours

1 week

9 hours

control

3 hours

6 hours

9 hours

2 weeks

A heating time of 3-4 hours is considered optimal. With a storage period of 1 week you can notice a peak at around 3 hours. However, with longer storage, a slightly longer SPIDES duration is optimal. Therefore, there is no fixed, optimal duration of SPIDES treatment.

This is microscope image of a young embryo. Above cell development stage 14 (Hamburger-Hamiltonclassification); the incubation process must continue otherwise the embryos will die.

Disinfecting eggs

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The climate in an incubator is an ideal environment for bacteria and moulds. Nutrients, moisture and warmth are all available.

All eggs are disinfected at the hatchery to destroy any pathogens possibly carried from the breeder farm, and to ensure low infection pressure on the embryos. Disinfection is a precautionary measure that ensures a uniform infection pressure for all eggs at the start of the process. Hatching eggs are usually disinfected in a separate room or dedicated disinfection lock after arrival and inspection at the hatchery. The clean eggs are then placed in the storage room (often done when eggs are supplied in setter trays). Or the hatching eggs are disinfected after storage and before setting (often done when eggs are supplied in paper egg flats). Gases used to disinfect – or fumigate – the eggs penetrate deep into the pores. Disinfectants not applied as a gas, but sprayed or misted onto the eggs, remain active on the surface of the eggshell and are therefore rarely as effective. Some disinfectants have a less direct, but residual effect that lasts several days longer than formalin. Taking samples from the eggshell and using agar culture plates to evaluate the efficiency of disinfection is not worthwhile. It is better to place the whole egg in a plastic bag containing a microbial growth media. This will give a better impression of the bacterial load on the eggshell. You can then sample the growth medium and dispose of the egg. The inside of the eggshell can also be sampled to determine how much bacteria has penetrated the eggshell.

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In practice, a hatchery always disinfects the eggs, regardless of whether they were already treated at the breeder farm. The advantage of disinfection at the hatchery is that a standard protocol is followed. This ensures the consistency and quality of the disinfection procedure. If the eggs are disinfected at the breeder farm, the hatchery must always be informed about the method and type of disinfectant used.

Disinfection reduces bangers. But it can never repair poor egg quality. Bangers are wasted eggs anyway, but they contaminate the eggs around them too when they explode. And these eggs will infect any newly hatched chicks if they happen to explode in the incubator. 90

Ha tc he ry S i gnal s

Dry (fumigation) and wet disinfection

LOOK-THINK-ACT

Eggs can be disinfected using dry methods such as gas. Fumigation with gas is the preferred method because gas penetrates deeper into the pores and does not form droplets. A very fine mist or fog is another common method of disinfection. This is a wet disinfection technique. Avoid droplets forming. It is important to avoid any movement or flow of air, as this can cause droplets to form in the mist. Wet disinfection using a mist can also be done in combination with evaporation (with low heating) to prevent droplet formation.

What are the risks of wet disinfection?

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The risk of wet disinfection is that the product can wet the egg. This occurs when the droplets are too large and deposit on the surface of the eggs. The egg then cools quickly and sucks the disinfectant through the pores. Use the correct nozzles and correct pressure and regularly check that nozzles are adjusted correctly. Apply a fixed disinfection program, adjusted to suit the installation (including ventilation) and use sufficient disinfection fluid.

A simple method of dry formalin disinfection, where formalin crystals are heated in a pan. 7 g/m3 is sufficient for effective disinfection. Formalin added to potassium permanganate is also used. Wet disinfection using mist.

The spray nozzles should create a very fine mist. Large droplets that wet the eggs will block the pores on the eggshell.

6. E gg t r a n sp o r t a n d s to rag e

Fumigation (dry disinfection) installation.

After disinfection

Fan to disperse mist

Spraying nozzle

Vertical ventilator to support air circulation

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The layout of a disinfection room. The spray nozzles are installed in the ceiling. There is a fan next to the nozzles, which disperses the disinfectant mist. After disinfection and neutralisation the fan ventilates the room to remove residual vapours.

The eggs must dry thoroughly after disinfection. Drying is usually an automatic phase of a disinfection program that includes a ventilation phase. But in fact, drying should not be necessary, because eggs getting wet should always be prevented, even during disinfection. Formalin vapour can be neutralised with NH3 so it is not toxic for humans. However, the use of formalin is prohibited in many countries. Or it is not listed with a registration number so it cannot be included in the quality assurance procedures. Use a Rodac plate to check the effectiveness of disinfection. Check the undersides of the eggs and spots where the egg touches the setter tray in particular. The setter tray should have been disinfected beforehand. Check according to a protocol; not by random sampling. Do not leave the eggs in the disinfection room for too long after disinfection. If the disinfection program includes sufficient ventilation/air exhaust, a short period in the disinfection room is not an immediate problem. However, the eggs should be taken to the storage room as soon as possible, so that they are in the correct climate conditions! And in a clean zone of the hatchery to prevent recontamination. Be careful when disinfecting moist eggs (from the cool storage): residues settle in the pores of the egg shell. These residues can be released again when the incubator warms up. If you keep the incubator closed for the first few days, the disinfectant (such as formalin) is released again, which can cause up to 10% fewer chicks. A solution might be to include a few phases of extra ventilation in the first days of the incubation process.

Young embryos are very sensitive to disinfectants, especially formalin. Always ventilate the room thoroughly after disinfection And use ‘chick and human friendly’ disinfectants. BioClean is applied here.

After wet disinfection, always perform a visual inspection of the eggs to check whether the mist or fluid has reached all the eggs. You should see a fine film on the surface of the eggs.

Ha tc he ry S i gnal s

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The material inside the disinfection lock and the incubator must be resistant to (aggressive) disinfectants. Iron, copper, zinc and aluminium are unsuitable. These materials quickly oxidise, like this handle on the disinfection room door.

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When disinfecting hatching eggs, the amount of fluid (in the form of gas/mist) is important. It must be suitable for hatching eggs and not have an adverse effect on the cuticle. If it damages the cuticle the gas exchange across the eggshell may be disturbed. This will impact directly on hatchability and chick quality. The disinfectant must not be toxic for the embryo. The disinfectant you use must be able to destroy moulds. Commonly known disinfectants include formalin, chloride and hydrogen peroxide. Hydrogen peroxide (H2O2) is stabilised with acid, glycerol, etc. and given a trade name. Hydrogen peroxide with ethanol (BioClean) is a relatively expensive product, but it has longer effectiveness. It is widely used and can also be applied during hatching. With sufficient knowledge and experience you can also make your own disinfectant solution. General disinfection guidelines: • never disinfect during first 96 hours • observe the max recommended application time • observe the max recommended amount/ concentration • ventilate sufficiently after disinfection

Disinfectants for eggs

Good hygiene can prevent infection with the Aspergillus fungus. Once this fungus is in the hatchery, it is very difficult to eradicate. Not many disinfectants can kill this fungus. Pay extra attention to this when selecting the product. If you have a problem in the hatchery, you can combat it by distributing a mist or smoke through the ventilation system (Clinafarm).

6. E gg t r a n sp o r t a n d s to rag e

Wide-scale ban on use of formalin The use of formalin/formaldehyde has been banned virtually worldwide due to the risk to human health. If hatching eggs are disinfected multiple times with formalin, there is a risk of embryonic mortality (especially in white layer breeds). The formalin solution penetrates through the eggshell. The first 96 hours in the incubation process are the most critical in this respect as the embryos are most sensitive to formalin vapours at this stage. If you still use formalin, observe the following measures: • Never use formaldehyde during the first 96 hours of the incubation process. • Wear a full-face respirator when using formalin! • Never exceed an exposure time of 20 minutes. The ambient temperature must be 20-25°C with a relative humidity of 65-75%. • Ventilate sufficiently within a few minutes with fresh, but not too cold, air after using formalin. This will prevent recontamination. Yellow day-old chicks are thought to be healthy chicks that result from a successful incubation process, so farmers want yellow chicks. Formalin is also known to induce a yellow colouring. A small dish of formalin is therefore often placed in the hatcher. The first chicks to hatch have a brighter yellow colour (afterwards it no longer works, so there will be wide variations in chick colour). Use of formalin during hatching may decrease yolksac infections, but increase respiratory diseases. Ciliated epithelium layers in the chicks’ throats can get severely damaged by formalin. Formalin is mainly used to mask bad hatching egg quality management.

CHAPTER 7:

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Setting

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Eggs with the same origin and production characteristics are placed in setter trays after being gradually warmed up in a setter room or incubator. The embryo in a hatching egg is a living being that develops,

in stages, from a single cell stage into a fully-fledged chick. Keep this in mind at all times.

You need to know the following before setting each batch of eggs:

•

The quality of the hatching eggs (eggshell quality, age, parent stock, results of the previous batch set, storage time)

•

Incubation conditions (program: temperature, relative humidity, ventilation, turning)

•

Developments in the hatching egg (% fertile, early embryonic mortality)

•

Assessment of the previous hatchability (% hatched and chick quality)

During the first 10–12 days, the temperature has a particularly important effect on embryonic growth and development. After that period, the embryo adapts tentatively to the microclimate. From the sixteenth day, the embryo reacts to excessively high or low temperatures by increasing or decreasing its heart rate. With a higher heart rate, more heat is transferred to the eggshell, while the embryo retains its metabolic heat at a lower rate. However, embryos only have very limited capacity for temperature regulation. This is mainly dependent on environmental conditions. An embryo can survive well for a few hours with a lower ambient temperature (25-28°C). A longer period with an excessively high temperature (> 39°C) has a negative effect on embryo development, and on the heart in particular.

Ha tc he ry S i gnal s

Critical embryonic stages Period

Point for attention

Differentiation: different organs develop.

In the hen, ﬁrst week in setter.

Avoid cold spots for a narrow hatch window.

Growth: exponential increase metabolism.

Second week in setter.

Be aware: risk of overheating. Start ventilation to sustain the oxygen requirement.

Maturation: physiological control circuits mature.

Second half setter + hatcher + ﬁrst week at the farm.

The right temperature to control development of body temperature. All organs mature best when incubated at the optimal temperature. Any deviation from optimal delays developmental stage at hatching.

Phase

There are three phases of embryonic development. During incubation, the climate conditions must be just right to support each embryonic stage.

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In most incubators, it is unwise to mix eggs with different origin and production characteristics because each type of egg requires different incubator settings. If you mix eggs, it is impossible to maintain the incubation conditions at the optimal levels for all the eggs. This applies less with incubators with sectional control. If mixing is necessary, stick to this order of importance: 1. Origin (incl. vaccination schedule) 2. Parent stock age 3. Fertilisation rate (based on history) 4. Storage duration A few days difference in the storage period is less important than a couple of weeks difference in the ages of the parent stock. Note: the laying date determines the planning of the hatchery, not the day the eggs arrived at the hatchery. Some incubator manufacturers supply a help program, showing how to fill the unit (the positions for each trolley), based on the expected heat production of the egg mass.

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Do not mix

Development of membranes and chambers

allantois amnion

yolk sac

embryo

air cell

amniotic cavity

eggshell

Eggs from the same flock are coded with the same colour, so you can see, at a glance, which eggs are in which machine. Here you can see that eggs have been mixed.

7. S et t i n g

chorion

yolk

albumen

This embryo is 8-10 days old. The foundation for development of all the organs is laid during this stage. There are four components of extra-embryonic tissues and compartments in the egg: 1. The amniotic cavity: protects against impact and dehydration 2. Blood vessels and yolk: nutrition 3. Outer membrane with the allantois: gas exchange 4. Inner membrane (amnion) surrounding the embryo: protects, supports embryo movements, delivery of maternal antibodies (immunoglobulins), and the allantois (storage of metabolic wastes, e.g., urates).

Variation in maternal antibody levels in day-old chicks

Origin

6 5 4 3 2 1 0

Level of maternal antibodies (expressed in titre group or 2log titre)

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You see two peaks within this flock (sample: 28 chicks) So, the ideal vaccination moment is nine days earlier for one half of the flock than for the other. If you vaccinate at the ideal time for the chicks with lower titres, the other group will not respond to the vaccination. If you wait for the optimal time for the other chicks, the earlier half of the flock is unprotected for nine days. Perhaps the chicks were offspring of different flocks of parent stock.

Number of chicks

The origin of the hatching eggs is important because different breeder farms may have varying bacterial loads. This can lead to slight variations in the vaccination schedules of the parent stock, and therefore the broilers’ maternal antibody titres. To put it very simply: the hen programmes her eggs to prepare the chicks optimally for the conditions in the house where she is housed. Infection pressure, temperature, feed, etc. But the chicks will actually end up in a completely different house, under different conditions! If eggs (or day-old chicks) from two parent flocks are mixed, there can be a great deal of variation in antibody levels among the broilers. And performance can vary significantly. Mixing hatching eggs is also not desirable for track-and-trace purposes (for broiler meat). This leads to the broiler producer receiving less uniform day-old chicks, and that results in problems in the broiler house (growth rates, height of the drinking nipples). If you have to mix eggs, use ones from the same age class of parent stock, or with a difference of one age class, at the most. Parent stock are often divided into three age categories: 1. Young: < 35 weeks 2. Prime: 35 – 50 weeks 3. Old: > 50 weeks So, you should use flocks with the same vaccination programme and, preferably, with age differences of no more than six weeks. With young parent stock, up to 35 weeks, the age difference should be the least possible because this is where the most variation occurs for each week of difference. Take this into account in your setting plan!

All the egg data is registered in the computer, but it is important to have it clearly shown with the eggs, so that you can immediately see which ones you are handling.

Each incubator cabinet has fixed positions for the setter trolleys inside. These positions correspond to the ones on the trolleys. This is intended to prevent errors and to improve the traceability from day-old chick to the breeder farm.

Ha tc he ry S i gnal s

Laying date

There is a great deal of difference between eggs from young and old parent stock. Size, uniformity, eggshell thickness and quality, and the bacterial load vary. This requires different incubator settings. An older flock is less uniform, so you get a batch of eggs with lower uniformity. This means the variation in hatching times (the hatch window) will also be greater. Some hatcheries weigh 300 to 600 eggs and the average and standard variation are measured to calculate the coefficient of variation (CV). Eggs from older parent stock can be stored for slightly less long before there is an effect on the hatchability (%). And the lower hatchability (caused by a lower fertilisation rate) also leads to reduced heat production in such a batch. Young parent stock lay more floor eggs, which means that the bacterial pressure in the hatcher is higher (although ground eggs are actually not suitable for hatching). Old mothers have fewer floor eggs, but the poor shell quality can lead to a higher infection pressure.

A first-in, first-out principle is usually applied to eggs arriving at a hatchery. If there is a very large supply of eggs, this leads to some older eggs always being placed in the setter trays. So, at certain moments, it can be a good idea to dispose of part of the egg stock and hatch fresher ones, to ‘catch up’. Preferably load an incubator with batches of eggs that have no more than three days age difference.

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Eggs from younger parent stock require different temperature settings: a little higher. The settings vary between hatcheries.

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Heat production (mW/egg)

Egg size The risk that some of the eggs will become too warm or cold increases in proportion to the variation in size. This is not good for embryonic development, nor beneficial for chick quality. Large eggs (from old parent stock) have a greater risk of damage during transport. This is due to the thinner eggshell, but also because they do not fit as well in the transport or setter trays. A batch of eggs laid in the peak production period (30-45 weeks) can vary in size, but they will have uniform yolk weights. So, age is the guiding factor for selecting eggs from different flocks. Never base the selection on egg weight. If you want to select based on weight, select only to remove the extremes from the same batch.

Parent stock age

Parent stock age and heat production

160 140 120

old

100

young

80 60 40 20 0

6 8 10 12 Incubation time (days)

Hatching eggs from older parent stock produce more heat than those from a younger flock, even if they weigh the same. The eggs increase in size during the laying period, have larger yolks, and that means larger embryos too.

Egg characteristics vary with different parent stock ages 28 weeks

40 weeks

52 weeks

64 weeks

72 weeks

Egg weight (g)

47.6

55.2

61.7

60.4

61.1

Yolk weight (g)

13.1

17.2

18.5

19.4

20.8

Yolk (%)

27%

31%

30%

32%

34%

Yolk size primarily depends on parent stock age. So, a large egg in a batch will probably have a lot of albumen compared to a small one because the yolk size within a flock varies less than the albumen weight. 7. S et t i n g

Preparing the incubator

Calibration

PRECISION

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Regularly check and calibrate every sensor. A computer can easily display a reading with several places after the decimal point, but is this actually a reliable, correct reading? A faulty sensor can also result in an incorrect reading. The ultimate accuracy of measurements depends on correctness and precision. A measurement might be very precise, or completely wrong. That is perhaps even more risky than measurements that are not accurate but correct on average! So, have all devices calibrated, and preferably by a specialised company. And always replace sensors if they deviate too often.

For the fan in a setter, there is an option of direct drive or a belt drive, where the motor is installed outside the cabinet. The advantage of the latter is that any malfunctions can be solved while the eggs are being incubated, and the motor does not produce any unwanted heat inside the incubator. Check the v-belt every time, before starting up. A slipping v-belt can cause poor fan operation.

Once the eggs are in the incubator, it is better not to open it again, and certainly not during the first couple of days. Prevent all possible causes of malfunctions by inspecting the machine thoroughly. Pay attention to: • Hygiene (check the disinfection) • Mechanical components (fan, v-belt, cooling coils, and the turner) • Sensors (check for functionality, and that protection has been removed) • Ventilation inlets and filters (nothing blocking air exchange) Ensure that the areas outside the incubators have a stable, warm climate (approx. 25°C, RH min. 50%). This prevents large temperature fluctuations and condensation during movements, checks and other moments when the incubators are opened.

High precision Low accuracy

Low precision Low accuracy

ACCURACY

Ensure there is good air circulation, to maintain a uniform temperature in and around all the trays. These fans provide a vertical airflow that distributes the air through the setter.

High precision High accuracy

Low precision High accuracy

The computer sets the position of valves and ventilators, but you have to check this! Not the positions, but the actual effect. If you measure air velocity (with an anemometer, see photo) and you know the diameter of the inlet/ exhaust pipe, you are able to calculate ventilation rate. Air velocity * π r2 * 3,600 = ventilation rate (m3/h). An inlet pipe with a diameter of 20 cm and an air velocity of 2 m/s gives you a ventilation rate of: 2 * π 0.102 * 3.600 = 226 m3/h.

Ha tc he ry S i gnal s

Setting eggs

LOOK-THINK-ACT

You should aim to only place eggs from 1 breeder, 1 house, and 1 breed into the setter. An average breeder farm produces 30,000 to 40,000 eggs per day. The eggs are collected from breeder farms every 3 days, which means that about 100,000 eggs must be placed in the setter. An incubator can hold from 5,000 to 200,000 eggs. For example, there can be 150 eggs in a tray, 2 trays per level, 16 levels per trolley (150 * 2 * 16 = 4,800 eggs). With 12 trolleys in a setter, you have a total of 57,600 eggs. Often, more eggs are delivered than the number required to fill the incubator. Hatcheries often ‘overbook’ on the capacity of their incubators. It is actually better to sell or dispose of excess eggs than to have empty spaces in the incubator. The machine needs to be loaded to full capacity to function properly. If you do have empty spaces, leave the lower or upper positions in the trolley empty.

What does this thermal image show you?

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This infrared image shows that the temperature in the trays is not the same everywhere. The eggs are much warmer in the middle. The ones on the bottom tray are colder. Some unfertilised eggs remain even darker coloured (produce no heat). This is due to poor air circulation. Good heat distribution starts with preheating. Eggs are preheated in the machine or in the pre-hatching room (min. 12 hours) with plenty of space between the trolleys so that the eggs all warm up well and uniformly. The temperature must be maintained uniformly throughout the machine, with no more than 1% variation.

Before starting up, check that all sensors (temperature, CO2, and RH) are functioning properly, their protective caps are removed, and the automatic turner is operational. Turning is essential during the first seven days.

Do you always have to ﬁll the incubator completely?

Separate incubator for risk-eggs

The incubator design is based on it working at full capacity. The incubator works best in this situation. The effect of air velocity is sometimes difficult to recognise. There is always the risk that the airflow will take the route of least resistance: so any empty spaces can affect the air circulation around the eggs and in turn the heat transfer from individual eggs. So, this is a good reason to always fill the incubator completely. But sometimes it is better to leave a few spaces empty, such as spots where, structurally, high eggshell temperatures are measured. This will prevent chick quality problems.

Some hatcheries use separate setters for risk-eggs, such as dirty or washed eggs. These machines have separate exhaust systems that discharge directly outdoors. Every week, suspect eggs and suchlike are removed and disposed of in a bath of disinfectant. Always handle these eggs at the end of the working day, to avoid cross contamination. Lay paper in the hatcher baskets, to avoid contaminating the other chicks. Take off these chicks manually, to prevent extra bacterial contamination on the automated systems. Preferably, put these chicks in a special ‘emergency farms’. This will prevent administering antibiotics to the entire broiler ﬂock. If you do still deliver them to a broiler producer, supply them separately, so the farmer can decide what to do with the chicks. But deliver them with other eggs from the same origin (so that there is common maternal immunity).

7. S et t i n g

Pre-warming (multi-stage)

Eggs must be pre-warmed before placing them in the incubator, unless pre-warming is an integral part of the incubation program itself. With single-stage prewarming, warming the eggs helps to limit the variation in hatchability because all the embryos have the same temperature when the incubation program starts. Another advantage of pre-warming is that it avoids condensation. If cold (< 27°C) eggs are set in a warm, moist incubator, they ‘sweat’. Condensation forms on the eggshell, which allows bacteria to penetrate the egg. And this can cause rotting, and ‘bangers’ (rotten bacteria-loaded eggs, which explode). Pre-warming is even more important when incubating large eggs from older parent stock. The eggs and eggshells also have very little uniformity. This leads to a longer hatch window (hatching period).

Pre-warming is even more important in a multistage incubator because it operates fully with a high temperature and relative humidity. Condensation will form immediately on eggs that are colder than 27°C. With a multi-stage incubator, pre-warm the eggs by placing the trolleys, well-spaced, in the setter room for 12 hours (at 22-25°C/71.5-77°F). Otherwise, newly set hatching eggs, with a temperature of 15°C, will cause a temperature reduction of 5°C in the incubator. And this has impact on the other eggs already in the incubator. It takes about four hours for the machine to reach its correct temperature again. This can delay the hatching time of all the eggs, and can lead to higher embryo mortality. The chick quality will be poorer.

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Pre-warming (single-stage)

Never pre-warm eggs too fast. This comes with a high risk of condensation forming, to the detriment of embryo quality. The embryos need to adapt gradually to the higher temperatures. The albumen acts as a buffer for embryos because they are deep inside the egg, on the yolk.

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With a multi-stage incubator, pre-warming is even more important than with a single-stage system. Otherwise, cold eggs come directly into a warm and humid incubator, with the risk of condensation forming on the cold eggshell surface. In addition, pre-warming reduces the hatch window because the chicks hatch more uniformly.

Gradual pre-warming

An example of a pre-warming schedule

Eggshell temperature (°C)

35 30 25

pre-warming to 27°C (5 hours) slow pre-warming (12 hours)

20 15 10 12°C storage 5 temperature 0

27°C

37.8°C/100°F incubation temperature

18°C

Time

With a storage temperature of 12°C, place the eggs for at least one night in another (second) storage room where the temperature is 18°C. These storage rooms should be adjacent, so the eggs can be transferred internally! After this, you often pre-warm in 2 steps, to avoid condensation formation (with singlestage). The dew point under hatching conditions (37.8°C/100°F, RH 55%) is 27°C. You can also use extra ventilation during the first few hours, to prevent condensation. The pre-warming strategy depends on the type of incubator and the hatchery manager’s experience. 100

Eggshell temperature (°F)

pre-warming to 37.8°C (12 hours)

The effect of warming on eggshell temperature development 101 99 97 95 93 91 89 87

with pre-warming

without pre-warming

16.05 16.35 17.05 17.35 18.05 18.35 19.05 19.35 20.05 20.35 21.05

Time (hour of the day) When pre-warmed eggs are added, the temperature maintains its set value better. Adding cold eggs reduces the temperature by a few degrees. This will delay the hatching time of the other eggs and cause wider variation in hatch times.

Ha tc he ry S i gnal s

Influence of incubation temperature on incubation time and hatchability

100 90 80 70 60 50 40 30 20 10 0

hatchability

Hatchability %

23 22 21

incubation time

96°F 35.6°C

98°F 36.7°C

20 100°F 37.8°C

19 104°F 40.0°C

102°F 38.9°C

Eggshell temperature (°F/°C) Setting a higher temperature in the incubator slightly reduces the incubation time. There is a clear optimal peak in the hatchability percentage here.

Only start the incubation process when the eggs are pre-warmed. The pre-warming time is not part of the incubating time. In a single-stage incubator, the air temperature is adjusted in line with embryo growth and the increasing heat production of the embryos. The machine temperature is high to start with, and then reduced in stages. When incubating a batch of eggs with a high fertilisation rate, the total heat production will also be high. In this case, it is difficult to regulate the climate balance in the incubator. This is why good air circulation in the incubator is so important, to ensure that all the eggs have the optimal temperature regardless of fertility.

Average incubation time (days)

Climate conditions during setting

Filling the machine

There seem to be two hotspots in this incubator (white spots) and a cool spot at the bottom left. A hotspot is often caused by poor air circulation. Do not take temperature uniformity for granted. Check the number of revolutions of the pulsator annually/semi-annually and replace the pulley motor if necessary.

Heat and temperature during the incubation process development

growth

internal external plateau phase pipping pipping

350

104/40.0

300

103/39.4

250

102/38.9

200

101/38.3

heat production

100/37.8

150 heat loss by evaporation

50 0

embryo temperature machine temperature 6 7 8 10 12 14 Incubation time (days)

99/37.2

Temperature (°C/°F)

The terms air velocity/airflow/air speed are often mixed with the term ventilation. But these are two different things. Ventilation is the exchange of air. Incoming air is different than air that is exhausted in terms of composition (CO2, O2, RH) and air temperature. This is determined by the inlet opening and expressed as the ventilation rate (m3/h). Air velocity is all about the flow of air within an incubator, influencing heat exchange. Air that is not moving has an insulating effect, whereas moving air facilitates heat exchange and moisture loss. This is determined by the fan speed and expressed as speed (m/s). In fact, you can have a high air velocity without any ventilation (closed incubator). However, a high ventilation rate without air velocity is not possible.

Heat production or loss (mW)

Air velocity ≠ ventilation rate

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In a multi-stage system, the air temperature in the setter must be kept as constant as possible. The machine must be ﬁlled in the correct way to ensure a stable temperature (not too empty or full, and well distributed). Some multi-stage machines work best when alternating setter trays with cold and warm eggs are placed in the trolleys (ﬁxed rack system).

98/36.7

The transition point here is day 7: from that moment, cool the eggs instead of warming them. This precise moment depends on heat transfer. The air velocity over the eggs has the greatest influence on this (also see page 41). In machines with higher air velocity, the transition point can be day 10 or day 11. 7. S et t i n g

101

Transition from warming to cooling Airﬂow variation

Between day 7 and 11 there a transition from warming to cooling. The embryos’ heat production becomes sufficient to maintain egg temperature, and now the primary emphasis shifts to removing heat. This depends on incubation conditions, such as air velocity. How and when warming or cooling is applied depends on the type of system. For example, does the system only use a fan or cooling coils too? A system with higher air velocity may have a slightly higher air temperature setting because it removes heat faster. The transition point from warming to cooling will then also be a little later.

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Minor changes in the incubator can cause major changes in air movement, and therefore its cooling/heating effect on the eggs. Factors such as the side on which the setter trays are tilted, are the trolleys closer to or further from the fan, egg size, etc., can all influence the airflow. This can result in cold or hot spots. You can compare this to the effect of a spoiler on a Formula One racing car. Adjustment of just a few millimetres can have an enormous effect on the airflow, and therefore on the car’s behaviour. The air velocity over a spoiler on a racing car is obviously much faster than the ventilation speed in an incubator, but the principle is relevant.

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Temperature distribution

Old parent stock Old parent stock

Young parent stock

Distance to fan

Old parent stock

Air velocity 2 2 air velocity (m/s)

Young parent stock

0 0

Flexible ducts often provide the ventilation in the setter room. Remember to clean them regularly, to maintain good ventilation. Otherwise, you might think the ventilation level is fine, but the filters are blocked.

Young parent stock

Old parent stock Young parent stock

Distance to fan

If different types of eggs are incubated together, e.g., eggs from young and older parent stock, place them in the machine so the air flows from the eggs that produce relatively more heat (from older parent stock) towards those that produce less (from young parent stock). The air velocity close to the fan is much higher than at the sides, creating the largest cooling effect in the centre. So it is wise to put the eggs that need the most cooling and allow the least 1 0 2 airflow closest to the fan (= eggs from older parent stock).

Air inlet and exhaust units above the setters to regulate gas exchange optimally and to separate the airflow between the different incubators.

Ha tc he ry S i gnal s

Humidification during setting

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LOOK-THINK-ACT

What do you notice here? You can see pipework with limescale close to the spraying nozzle. The further away from the nozzle you look, the fewer deposits on the cooling pipes. Water with a very high lime content causes scale deposits on the heating/cooling pipework close to the nozzles. Remove these deposits to ensure proper operation of the system. The best solution is to handle this problem at source and prevent scaling by using a water softener for the spray water. Before starting each incubation cycle, check that the nozzles are creating a ﬁne spray, in other words, that they are limescale free and operate at the right pressure.

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Humidification is not advised. It is only necessary if the machine has limited cooling capacity or when a high level of ventilation is required because the CO2 concentration is too high. Beware of large droplets. Large water droplets falling on eggs will cool them down. This will reduce temperature uniformity among the eggs in the setter, and cause wide variation in hatching times. In addition, eggs will get wet. Moisture is an ideal breeding ground for bacteria and moulds, which can lead to ‘bangers’. But, on the other hand, air with high RH transfers heat more uniformly. A higher ventilation rate will extract more moisture. Some incubators activate humidifiers when the ventilation based on CO2 extracts too much moisture. If you use a humidifier, preferably condition the air before it enters, to prevent condensation formation inside the incubator. Make sure no moisture reaches the temperature sensors. If it does, this sensor will give an artificially low reading, which can lead to the wrong response (too little cooling or too much heating).

This nozzle is clogged up with calcium deposits and rust. Make sure the nozzles are working properly in order to create a fine spray.

Regulate humidification to avoid wet spots on the hatchery floor, as moisture promotes the development of moulds. Make sure the hygiene protocol includes attention to wet spots on the floor. 7. S et t i n g

There are various humidification systems. Spraying and humidity rollers are the main two principles. Spraying involves a risk of water droplets falling onto the eggs. The risk of a humidity roller is that it uses warm standing water, which is an ideal breeding ground for bacteria and moulds. 103

First few days: ventilation inlets closed

CO2 concentration increases In the beginning, the ventilation is restricted, or the setter is fully sealed (ventilation inlets closed). The CO2 level then increases sharply to 0.8%. This occurs particularly with eggs stored for only a short period because the CO2 concentration of their albumen (egg white) is high. This principle can be used to regulate the hatch window: it will become shorter. So the hatching times of the chicks will be more uniform. The embryos can cope well with a CO2 concentration in the air of up to 1% during the first 48 hours. They have more difficulty with this value between days 2 and 6. The CO2 concentration does not rise so much during the first week because the embryo only produces a very limited amount of heat. Higher ventilation is required during the last phase, to remove excess CO2. A CO2 concentration of 3,500 ppm (0.35%) is a good guideline for the entire incubation period.

Risks of reduced ventilation

•

Insufﬁcient eggshell porosity. Insufﬁcient ventilation.

Carbon dioxide • combined with water forms an acid. This • leads to acidiﬁcation and retarded growth.

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Excessive CO2 in the egg

Insufﬁcient eggshell porosity or pores clogged by contamination and/or a disinfectant. Insufﬁcient ventilation (high CO2 concentration).

•

Causes

Acidiﬁcation of tissue • -> reduced growth and weaker chicks. The heart has to work harder to deliver sufﬁcient oxygen to the tissue. • Possibly the beginning of ascites (water belly).

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•

Problems Insufﬁcient oxygen

Fresh air ventilation strategy during the incubation process After day 4

Part 2 of the incubation process

Day 0-4 Regulate based on uniform temperature.

Regulate based on humidity.

Regulate based on CO2.

Closed ventilation inlets High RH (60-80%).

Stimulate moisture evaporation from the egg.

CO2 as a measurement of metabolic activity (O2 is required).

You often keep the ventilation inlets closed, to hold heat and humidity inside the cabinet, and to minimise temperature variations. This causes the CO2 concentration to rise. In a hermetically-sealed incubator, this can increase up to 6,000-8,000 ppm within 4-5 days. The relative humidity will also be high, which means the eggs will lose very little moisture during the first week. This is not necessarily a problem, as long as it is possible to keep the humidity low enough by increasing the ventilation in the second phase of the incubation process (non-linear moisture loss). So, set the RH to around 35-40%. A maximum CO2 concentration of 3,500 ppm is often applied throughout the incubation process (outdoor air has around 400 ppm). This has another positive effect: a higher CO2 concentration during the first few days promotes better blood vessel development because the embryo has to work harder to absorb oxygen. A robust vascular system prepares the embryo better to cope with the ‘stuffy’ conditions it will experience during the later growth and maturation stage. When there is sufficient ventilation, the embryo has extra oxygen available. Be aware: as a result of disinfection, there may still be disinfectant in the pores of the egg shell. If you do not ventilate at the beginning, this cannot disperse and this is harmful to the young embryos.

Restricting ventilation a little during the first days is a commonly used strategy. The humidity level then rises. This moisture is removed more quickly. During the last phase of the incubation process, the focus shifts to regulating based on CO2.

Sensors for measuring various gas concentrations in the air: a temperature sensor, relative humidity meter, and a CO2 sensor. The red cap with the CO2sensor allows it to be covered while cleaning the incubator. 104

A drive belt for the fan in the setter runs through the ceiling, and causes an air leak. For optimal climate control, the incubator must be hermetically sealed. Ha tc he ry S i gnal s

Day 4 to 11: regulate based on RH On day 18, the hatching eggs must - on average have lost 10-12% of its weight (depending on type and age of the parent stock). This is on average about 0.6% per day. If the hatching egg has lost less than this amount, there is a risk that the chick will drown. A breakout analysis will show a fully developed chick but a very tiny air cell. The embryo needs the air cell for its transition to oxygen uptake through its lungs (respiration). If the air cell is too small, the chick will experience problems. In this case, the embryo often suffocates at pipping (it cannot find the air cell).

Relative humidity (RH) and CO2

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Under high RH conditions, the egg loses less moisture. This leads to a smaller air cell (less available oxygen at internal pipping). Under low RH conditions, the egg loses more moisture so its air cell increases in size. Heat transfer is less in dry air, which increases the risk of overheating, and an associated increase in CO2 production.

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An air cell meter allows you to measure the size of the air cell in individual eggs. However, it is common practice to weigh an entire setter tray with eggs to calculate the average moisture loss between day 0 and day 18, which is then used as the basis for your climate settings.

LOOK-THINK-ACT What is happening here? The graph clearly shows when the ventilation inlets are opened: The RH and CO2 values decrease sharply at those moments.

7. S et t i n g

105

Heat distribution in the incubator The air velocity combined with the RH level and air temperature determines the level of heat transfer from the egg. These parameters combined with the egg’s heat production ultimately determine the embryo temperature. The air velocity and, to a lesser extent, the RH help to distribute heat uniformly.

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Never move the trolleys during the incubation process. Leave them as undisturbed as you possibly can, and keep the large doors closed during the process.

Continuous cooling Moisture evaporation from the egg uses energy: evaporating one gram of water uses 2.26 kJ. If 100,000 eggs are set, 1.7 litres of water will evaporate each hour. The energy required for this causes the egg to cool down. If an individual egg did not produce any heat, this factor alone would reduce the eggshell temperature by 0.3°F compared to the air temperature. Cooling through natural moisture evaporation from the eggshell occurs uniformly with all the eggs in the incubator. This is in contrast to other forms of cooling, which can cool down eggs locally much more (spraying or water trays). If, for example, only 10% of the eggs are within the spray range, and the spray volume is 1.7 litres per hour, they will cool down by 3°F!

Heat transfer from the egg to the environment takes place in different ways. The contribution that each of these makes to the total transfer can vary. It is all about the temperature difference between eggshell and air, air velocity, and the extent of evaporation from the shell. In addition to those factors, relative humidity can also influence heat transfer in itself.

Draught strips under and on top of the doors prevent heat leaking from the setter.

106

Tackling symptoms Sometimes trolleys in the incubator are moved to different positions, to prevent hot spots developing and reduce the risk of overheating. However, this is only tackling the symptom: heat distribution in the incubator should simply be uniform! But it can be an adequate solution, particularly in old incubators with insufficient cooling capacity.

A thermal image clearly shows where heat is escaping: through cracks around the doors. Insulation is a very important factor for climate control.

Ha tc he ry S i gnal s

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45°

100

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Horizontal position The trays are sometimes positioned horizontally from day 14-15 of setting. Changing the position is thought to result in better air and heat distribution because it allows more air to flow faster between the setter trays. But this is only tackling symptoms. Find a solution for the root cause: the incubator should function 100% correctly!

Positioning trays horizontally creates an unrestricted flow of air through the trolleys. However, the airflow between the eggs might actually be less, which can lead to insufficient airflow at egg level. Insufficient contact of air with the egg mass will remove less heat (even if the sensor reading indicates otherwise). Check the eggshell temperature regularly.

The most widely used system in Europe is setters with trolleys that can roll in and out (drive-in). The trolleys are connected to the automatic turner in the setter. Each type of setter has its own turner drive system. The eggs are always turned through an angle of 75-90°, usually hourly, and sometimes, 4 times an hour. Exchange of fluids between the various compartments, which are enclosed in embryonic membranes, is essential for good development. Turning ensures this continuous ‘decanting’. Transfer of water from the albumen to the yolk, through the embryo, starts as soon as the incubation temperature is reached and embryonic development continues. The water reaches the sub-embryonic compartment and its maximum level occurs on days 6-7. The egg content is now watery with an embryo floating on the very fluid yolk. After this, the water is distributed between the amnion (enclosing the amniotic cavity) and the allantois. Turning is essential from days 3-7. Not turning during this period will cause very limited embryonic growth and often a high mortality rate between 12-14 days. The eggs should be turned up to at least day 12, and preferably until day 15. Usually turning continues until transfer from setter to incubator on day 18.

Egg turning during setting

Positioning the eggs at an angle automatically reduces the space between them, which in turn can inhibit the airflow. With a bit of mathematics (Pythagoras) you can calculate that at an angle of 45°, the space is reduced to 71% of the distance in horizontal position.

80-90°

40-45° 40-45°

Trays positioned horizontally from day 14-15, to create an undisturbed airflow. This is absolutely unnecessary if temperature distribution in the machine is good.

7. S et t i n g

Turning through 90° in the machine, means that the eggs tilt from 45° to the left on the length axis to 45° to the right, because rotating them completely - as a hen would - is very difficult.

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Effects of turning on hatchability and embryonic growth Day turned

Hatchability (%)

Embryo mass at 16 days (g)

0-21

78.6

18.5

0-3

64.3

15.6

3-7

76.9

17.0

7-21

64.3

16.5

0-3 & 7-21

42.9

15.2

Not turned

50.0

15.5

The importance of turning Without turning, you will lose 30-40% of the eggs: most embryonic mortality occurs at the end of the incubation process. The surviving chicks are small and dirty, not well dried off, and have a lot of yolk residue on them. And you often find a thick clot of albumen in the point of the egg because the embryo was unable to intake all the nutrients. Turning prevents the chorioallantoic membrane (CAM) from growing through to the point. Cold and warm side Often and with most machines, there are varying temperatures in different turning positions. We call this the cold and warm side of the trolley. Turning changes the airflow continuously and creates better heat distribution. And a shifting airflow pattern can lead to better average heat distribution if there are hot or cold spots in the incubator. In some models of incubator, setting the turning speed is an option. Slow turning has less impact on the temperature.

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The best results are achieved when the eggs are turned right from the start and through to day 15. Turning seems to be more important during some periods than others. Applying it during days 3-7 appears to be the most important.

60 40 20 0

Problems with turning often occur with old and worn machines. Here, the turning angle is insufficient, and the setter trays on the left of the cabinet are tilted more than the ones on the right. So, check the turning status regularly. Perform a regular visual check by looking through the window in the setter.

100 Hatchability (%)

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Influence of the turning angle on hatchability

Turning angle (º) Hatchability is affected by both the action of turning and the tilt angle. The angle must be at least 35°. Any less will sharply reduce hatchability.

Effect of turning on embryo development Heat production (mW/egg)

150

turned unturned

100

These racks can be fully tilted. The disadvantage is the amount of space they take up. But the advantage is that the space between the trays is always uniform, ensuring an optimal flow of air. 108

50 0

14 15 16 17 Incubation time (days)

Heat production from unturned eggs is lower. This indicates a slower development (= lower metabolic rate = heat production). Ha tc he ry S i gnal s

Monitor turning Regularly monitor that turning is taking place correctly. This is essential to ensure good chick quality and hatchability. You can use various tools to help you monitor this. Make sure the trolleys are all in the same tilt position at each calibration, otherwise calibration will not be accurate. Calibration is an essential part of maintenance, and the hatchery manager can do this. Replacing sensors is a specialists task. The turning alarm is the least urgent alarm. One night without turning is not a problem. You must respond to a temperature alarm immediately because this is vital. Embryos will die or become damaged when the temperature is too high for a short period. This will compromise chick quality and performance. The CO2 alarm, as indicator of oxygen availability, is especially important in the second phase of incubation. If the CO2 concentration is too high, there is likely to be insufficient O2 and a high RH.

Did you know?

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Eggs can also be placed in a tray horizontally, and then rolled. This method also turns the eggs, and with the effect of gravity and the formation of the air cell, they will automatically end up with the point downwards later in the incubation process.

Check the trolley is connected properly to the automatic turner.

The eggs should be turned 3-5-times a day. Most incubators have a turning program set to once an hour. Check this by reading the counter and noting the tilt position. There is also usually a turning alarm. In this example, the hatchery manager adds a stripe to indicate the tray position at each check in order to monitor the proper functioning.

Check regularly whether the tilt angle setting is correct. The tilt angle must be between 40 and 45°. You can use a digital or analogue measurement. Digital does not always mean more accurate! An incorrect tilt angle leads to a greater number of malpositioned embryos, and therefore unhatched eggs or late mortalities. You can also install a smartphone app for setting the tilt angle.

7. S et t i n g

109

Monitoring setter conditions

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In the past, all the sensors were wired. Nowadays, wireless loggers are becoming more common. They are portable and can be used in different setters (to measure CO2, RH, and temperature).

Sensors provide signals about the climate in the incubator. This allows you to monitor the incubation process continuously. You can put the sensors in the setter, but you can also place them on the eggs. In this way, you can get a picture of a specific location, and also the differences in the incubator. Have the sensors calibrated regularly, to ensure the accuracy of the readings. Always put the sensors in the same location in the incubator. Think things through carefully (and measure yourself) whether a certain spot will give a good average eggshell temperature. If you position it on a relatively hot spot, too many eggs will be incubated at a too low temperature. On a cold spot, too many eggs will be incubated too hot. Make sure no obstacles are mounted on the walls (e.g., cable ducts, guides, reflectors). These can cause unexpected airflow patterns, and some eggs could overheat. You can also place calibrated loggers between the eggs. These are often wireless. Do not place them against the air cell because this will give a false reading. Make sure these loggers are between fertile eggs, so you do not get false eggshell readings from infertile eggs that produce no heat. You can determine this by occasionally taking manual eggshell temperature measurements of all the eggs around the sensor. To check the sensors, you can candle the eggs with sensors attached to check whether the readings correspond to the actual status of the egg.

Here, IR thermometers are integrated into the setter trolleys. They transmit data through a wireless connection.

Sensors are available in a range of formats. They measure the actual eggshell temperature of the surrounding eggs in real time. This gives you a reliable average, but only at the particular location in the machine!

110

Ha tc he ry S i gnal s

Constantly improving measurements Sensors are becoming cheaper and better all the time. They are now often wireless, using Wi-Fi or Bluetooth. This enables measurements to be taken from more locations in the incubator. This data can be linked to results from various hatcheries, setters and incubators, as well as to data measured at different places inside incubators. There is a lot to gain from this data. Remember that the temperature of an infertile egg or an egg with a dead embryo must be excluded from the data used for incubator analysis.

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Here, you can place various sensors in the incubator. This is also a way to calibrate different sensors. If you use more than 3 sensors to take measurements, you can identify the one that deviates at once.

The machine should display reliable data on the conditions inside, however the values are not always a true reflection of reality. It is very important to double-check the accuracy of readings yourself!

7. S et t i n g

You can also use a logger to check the machine temperature and relative humidity at different locations. The disadvantage is that you only read out the measured value afterwards, and that these loggers do not measure eggshell temperature, only the ambient level at those locations.

The ideal would be to measure the temperature inside the egg itself with a probe, but this is not practical. The most accurate method is to use a sensor that attaches to the eggshell using a heat conducting paste. This method measures the true eggshell temperature, and not that of the air. Do not place the sensor on the air cell when measuring on the eggshell. This will give a false reading. 111

Candling

So, the timing of candling depends primarily on the goal. The blood ring stage is one example of a critical moment in the incubation process. If something has gone wrong in the breeder house, in storage, or during transport, you often see the effect reflected in increased mortality on day 3. If eggs with dead embryos have been in the incubator for a prolonged period, it is increasingly difficult to pinpoint the precise time of death. Candling during the process creates more moments to provide feedback to the breeder farm. It also helps you identify the moment a problem starts more accurately. If you only candle on day 18, and you include the storage duration in your calculations, you are already 3 weeks too late to make any changes in breeder flock management.

Caution!

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Candling allows you to see which eggs are infertile, contain dead embryos, or are viable. For example, you can carry out candling with a breakout analysis, at four fixed ages in each parent stock flock (in each house). This will generate a lot of valuable management data, which can help breeder farms and hatcheries. But you must analyse and use this data to create your own hatchery specific reference data. This will give you insight into all the details: the breed, feed used, nest type, feeding system, lighting, ventilation in relation to fertility, hatchability percentage, and chick quality. So, you have a wealth of information! • Candling on day 2 is mainly used to determine the rate of fertilisation, e.g. in young flocks. • Candling on day 10 is not standard practice, and it primarily provides a picture of early embryo mortality. It might be used more often in the future if in-ovo sexing gains in popularity as a practice in the layer production sector. In this case, you would only transfer pullets, and would be able to remove infertile eggs and dead embryos immediately. • Candling on day 18 is the most practical method because it allows you to remove infertile eggs, eggs that contain dead embryos, and, above all, rotten eggs, so the chicks that hatch will not be contaminated. However the data gained from candling at this time can no longer be used to influence the process.

Clear eggs are not all infertile. You need to breakout an egg to determine whether it is infertile or an early embryonic mortality.

Maintain a constant temperature Ensure the ambient temperature is at least 25°C/77°F during candling. If you want to put the eggs back into the incubator, make sure the handling time for candling does not exceed 30 minutes per trolley.

Breakout image at 2 days

Good hatching egg, fertile

Infertile egg

ᅚ 4 mm

You can recognise a good hatching egg by the round, doughnut-shaped embryo. You see a white, symmetrical ring (area opaca) with a clear core (area pellucida). Sometimes, you see a little white point in the centre. This is larger than it is in an infertile egg. 112

2 mm

You recognise an infertile egg by the imperfectly round shape of the embryo, with a jagged edge. Usually, multiple bubbles joined together. You see a little, compact, white point, sometimes slightly grainy.

X Fertile: the germinal disc always has a rounded, doughnut shape and a white symmetrical ring with a clear centre point, sometimes with the white dot in the middle. Infertile: the germinal disc is almost never perfectly round, has a jagged edge, and a very tiny white point. Ha tc he ry S i gnal s

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Candling after 10 days Tenth-day candling is a standard practice in hatcheries for parent or grandparent stock. This is not usually done for every batch at a commercial hatchery that produces broilers or laying hens. Tenth-day candling is often carried out twice for each flock, at about 30 and 40 weeks of age. At about 10 days, 750 eggs per house are candled. Often, there are 150 eggs on each setter tray, so you select 5 random trays. Note where you take each tray from, so that you can link any differences in the trays to their positions in the incubator. If there is no visible embryo with candling, you break the eggs in question (perform a breakout analysis) on the tray, to score them and determine the cause. The goal of tenth-day candling is to make the link between the house, farm, housing system, and feed company. If candling is standard practice, you can collect data and recognise patterns and tendencies that are specific to each poultry house. Hatchability can no longer be improved at this stage, the primary purpose here is to gain more insight into the process. Insight into future hatchability can also be important for the hatchery’s planning.

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Candling/breakout analysis after day 2 Eggs are sometimes manually candled on day 2 in the setter. You use a separate incubator for candling on day 2, so that you do not disrupt the incubation process of the main batch. The incubation conditions in this incubator are not so important because your only goal here is to determine whether the eggs are fertile or not. This is mainly done with young flocks that have just come into production. So, this is not standard practice for every delivery of hatching eggs. Early candling gives you the advantage of being able to respond in good time to infertile eggs or those with early mortalities. You can predict the hatchability and use this to plan your sales. This ensures that you will not disappoint a customer by supplying too few chicks. You have to breakout the eggs to differentiate between infertile eggs and those with early embryonic mortalities because this can only be detected by candling from 3 days onward (the blood ring stage). And, in cases where development is slightly delayed, e.g., in eggs that have been stored for a longer period, this can easily be a day later. This does not apply to brown eggs in the layer sector (thicker eggshell and the brown shell limits how much light shines through the eggs). Candle 450 eggs per house. This makes it workable. It helps to train 1 or 2 people and make them available to carry out these types of measurements and observations.

A day 10 candling image of a fertile egg. You can recognise a fertile egg by the dark patches. To discover the day on which an embryo died, you need to carry out a breakout analysis, to see the embryo’s stage of development. You cannot see this properly with candling. 7. S et t i n g

A full breakout at day 6. Here all dead embryos and unfertile eggs are set aside for later counting.

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CHAPTER 8:

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Transfer

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Take care to prevent excessive cooling, warming, and any damage to the eggs during transfer from setter to hatcher. Carry out the transfer quickly but carefully. This moment is also a good time to collect useful

data about the incubation process so far, which will help you predict hatchability.

Transfer must be handled quickly and smoothly, to avoid the eggs cooling down. Cooling delays hatching. So, empty the setter gradually, and avoid putting all the trolleys in the corridor at once. The eggshell cools quickly, but the contents cool less rapidly. As soon as a trolley with incubated, and therefore heat-producing eggs (+/- 150 W/1,000 eggs) is removed from the setter, the ones in the lower tray cool down and those at the top of the trolley are warmed up by the rising heat. These conditions must not continue for too long because embryos can barely regulate their temperature. A couple of degrees too warm is more damaging at this stage than being a little too cold. So, in view of overheating or excessive cooling, fast and smooth transfer is the essence of the task here.

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Make sure the setter is in transfer mode, otherwise the machine will respond to the doors opening by starting to heat and humidify, or the alarms will be activated. This is especially important if there are still trolleys in the setter.

Causes of embryonic mortality up to day 18: • • • • • • • •

Genetic defect Poor hatching egg quality (abnormal eggshell or shape) Residual formalin vapour after disinfection Infected hatching egg Incorrect storage/rough egg handling Insufﬁcient turning Incorrect temperature or moisture content Insufﬁcient ventilation (excessive CO2)

Ha tc he ry S i gnal s

Which egg has a live embryo? it involves handling very large numbers of eggs, labour costs are high, and there is a high risk of disease cross-contamination. And automation is more reliable than manual candling and transfer. Check the automatic egg candling system regularly. See whether there is a certain pattern in which positions are selected for candling. If the automatic candling unit continuously selects the same position, this could indicate an error in the machine. If the automatic candling unit continuously selects the same area of a tray, this could indicate an error in the incubator.

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All the eggs are candled on day 18, to count and remove eggs (clears) that are infertile, rotten, or contain dead embryos. Any infertile eggs are diverted to the processing industry (liquid egg market). Day 18 is an ideal moment for candling as it is also the day the eggs are transferred from the setter to the hatcher. Candling facilitates removal of embryos that have died up to day 14, but others, which have died later, will still be transferred. Candling through heartbeat detection is much more accurate, often close to 100%. Transfer must be handled quickly and carefully. This process is often automated because

You can track and review all the candling results for each tray.

The setter trolleys are rolled into the destacker. Here, the setter trays are placed separately on the conveyor belt and transported to the automatic candling unit. Destacking is still handled manually in many hatcheries.

Candling is usually done with an automatic candling and transfer unit. Manual candling is still often used at smaller hatcheries.

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Infertile eggs, bangers, late mortalities, and living embryos You can establish which eggs contain dead embryos up to day 7 with lamp candling. After that time, the embryo will have grown and light is no longer able to shine through as well. This depends on the candling machine settings. With the heartbeat method, you can determine which eggs contain dead or live embryos at the time of transfer. Combining different candling techniques gives you an accurate impression of various groups of eggs that you want to exclude from transfer. You can then handle them differently.

The display on the candling unit shows which eggs are infertile (blue), and which have mortalities (red). The remaining eggs contain a living embryo.

Infertile or an early mortality?

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How can you recognise truly infertile eggs when candling on day 10 or 18? How can you detect unhatched eggs (embryos that died after day 18 or live chicks that failed to hatch)?

It is easy to recognise a truly infertile egg on day 18. The yolk and albumen have aged; the egg has been stored at a higher temperature in the incubator for 18 days. The yolk is still dark yellow but it has a thinner membrane, which causes the yolk to form a flat disc or break when opening the egg. The albumen has become watery, and the thick (chalaziferous) albumen has disappeared. You can still recognise a small white dot on the yolk.

Method

Light

If the embryo died before the blood ring stage, there will be clearly recognisable colour changes in the yolk. Formation of sub-embryonic fluid causes the water content of the albumen to pass through the embryo and into the yolk, this changes its colour to light-yellow. The yolk always breaks after 18 days of incubation: in this case, the yolk membrane has become very fragile. Sometimes you can still see extra-embryonic membranes in the broken yolk: a sign that the embryo was there but not really viable.

Heartbeat

Infrared

This is how it looks

How does it work?

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Strong light does not penetrate through the embryo, and it produces a certain image. A dead embryo produces a different illuminated image.

This method detects the embryo’s blood circulation and the oxygen content of the blood. A dead embryo has no circulation of oxygen-rich blood.

The embryo’s heat production is detected. A dead embryo does not produce any heat.

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You can candle up to 60,000 eggs an hour with a heartbeat detector, the same as candling with light. A suction cup attaches to each hatching egg. A light beam then shines through the egg. This detects whether the embryo has active blood circulation. Each setter tray with eggs is illuminated for 5-6 seconds.

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A candling unit that works with heat sensors. This can be installed after a unit that uses light. Candling with light identifies infertile eggs and early embryo mortalities. These eggs can still be used in the processing industry (e.g., shampoo). A heat detection system identifies dead embryos (they do not produce any heat). These eggs are destroyed.

CALCULATION EXAMPLE

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Candling capacity How long does the candling take? With the heartbeat detection method, it takes 6 seconds per tray to determine which hatching eggs have live or dead embryos. Transporting them in and out takes 3 seconds. So, 6 + 3 = 9 seconds in total for a tray. 3,600 seconds: 9 seconds = 400 trays per hour. 400 trays * 150 eggs per tray = 60,000 eggs per hour.

To double-check the candling equipment, it is a good idea to open random samples of the eggs to check for false positives. A bar is used here to separate the selected eggs temporarily. If a spot check reveals too much deviation, contact the supplier, who can then calibrate and adjust the candling unit.

A completely clear egg when illuminated: infertile.

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Here, light candling shows a clear blood ring: mortality around day 3.

Some irregularities in the egg: mortality between days 5 and 10 (black eye).

A dark egg: well developed embryo.

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Hatch of set ‘Hatch of set’ indicates the percentage of set eggs that have hatched. The hatchability percentage depends on the level of fertility and embryonic mortalities during the incubation process. A good breakout analysis reveals the true fertility. So, a distinction is made between early mortality between day 1-2 and true fertiles. When eggs are stored for a long period, the percentage of eggs that are candled out rises, but, of course, this is not a result of lower fertilisation. Different factors can lead to true fertility actually being higher or lower than expected. Fertility is then expressed as a percentage of the true fertile eggs that have been set. Do the same for eggs with abnormalities (cracked, ruptured, or dirty), and for eggs that contain rotten embryos. These embryos have no chance of hatching, and this cannot be attributed to incubation process errors. This is not only an indication of the quality of the incubation process, but also of the quality of the material you started the process with.

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Key indicators provide insight into the hatchery’s performance. You can compare and benchmark your performance with the breeder organisation standards, earlier performances, other flocks, and the performance of other hatcheries. There is broad variation between countries, but also regionally. Establish your own specific standards, based on historic data or data from comparable hatcheries. Primarily, and naturally, the quality of the hatching eggs is essential. During peak production, egg fertilisation rates of 92-94% should be feasible in the broiler breeder, and 97% in the layer breeder sectors respectively. This correlates closely to the age of the parent stock. The older the flock, the lower its fertility. More than 4-6% total mortality should not be necessary. The target is lower than 0.5% mortality through infection, and under 3% during the first week, 0.5% in the second, and 2.5% in the third. It makes a difference whether you calculate hatchability based on the number of eggs you set or the hatchability of the fertile eggs only. Consider what you actually want to measure. This translates into the following key indicators: • Hatch of set • Hatch of fertile • Hatch of transferred A combination of multiple key indicators creates the most complete picture. It also depends on the goal: if you want to compare hatcheries, it is best to use ‘hatch of set’. The other key indicators can be more useful for analysing your own performances.

What do key indicators tell you?

Pattern of embryonic mortality 18-21 days Late embryonic mortality

There should be less than 1-2% embryo mortality in the time between transfer on day 18 and hatching. A good breakout analysis indicates that a lot of hatching failures in eggs that were candled and transferred is often the result of poorer egg quality or mortalities that occurred before day 18. Increased mortality in the last few days is often caused by overheating in the setter, which weakens the embryos, and they remain in the shells. This will help you interpret certain key indicators better.

Critical moment: Changeover to oxygen uptake through the lungs (respiration) early mortality (2 nd quality)

yolk absorption

egg tooth (feathers)

4-17 days Mid embryonic mortality

dark eye

blood ring

Critical moment: Formation of blood vessels

membrane

infertile

Stage

Mortality

0-3 days Early embryonic mortality

Check the key indicators by using breakout analysis

In a high-quality batch of eggs with a short storage period, the maximum embryonic mortality is between 4 and 6% of the fertile eggs. ALWAYS check whether increased late mortalities are caused by the eggshell temperature becoming too high! 118

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Hatch of transferred ‘Hatch of transferred ‘ indicates the percentage of transferred eggs that actually hatch. This allows you to assess how well transfer proceeded, and assess the period between the last three days before hatching up to hatching itself. The eggshells are very vulnerable at this time because the embryo uses calcium from the eggshell for bone formation. This implies an increased risk of fractures and haemorrhages during this stage. Incubation errors (e.g., excessive eggshell temperature) in the setter can also weaken the embryos. This leads to mortalities and malpositions later, in the hatcher. You assume that these embryos were alive on day 18, but this is not necessarily the case, so always check the candling results! Sometimes, too many rotten eggs or eggs with dead embryos are transferred. Occasionally this even includes infertile eggs or eggs with early mortalities. In this situation, the ‘hatch of transferred’ percentage will be lower than expected. A percentage of 98-99.5% is usual. ‘Hatch of transferred’ is highly dependent on the candling method. Light candling will not identify late embryonic mortalities that the heartbeat method does recognise. So, the candling method influences this key indicator. This is why ‘hatch of set’ is probably the most reliable key indicator for comparison (although you still do not know how many eggs were infertile or early mortalities. That information can be obtained from breakout analysis).

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Hatch of fertile ‘Hatch of fertile’ indicates the percentage of all the fertile eggs that have hatched. This includes eggs that have a chance of hatching, so no cracked, ruptured, or rotten eggs. This key indicator is a better measure to compare incubators or hatcheries. In this way, fertility and very early mortality before incubation are separated from the hatchery’s influences. To achieve this, you must have a good picture of the number of fertile eggs at the start of the process. If the maximum embryonic mortality is 4-6%, then the ‘hatch of fertile’ will be higher than 94-96%.

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Damage is not always visible on the outside. Sometimes blood vessels rupture causing chick mortality. You can recognise this from the blood clots you see when you break the egg.

Calculation example of a ‘Hatch of fertile’: Hatchery

CALCULATION EXAMPLE Converting key indicators How can you calculate key indicators? Fertility 96% Hatch of set 91% 91/96= 95% hatch of fertile Consider a ‘hatch of fertile’ lower than 92% to be unsatisfactory.

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% hatched

% fertile

Hatch of fertile %

88.7

90.1

89.4

Hatchery B has the lowest hatchability, but the highest ‘hatch of fertile’ percentage. The high percentage of infertile eggs reduces the hatchability percentage of set eggs but, as a hatchery, it has the best performance.

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In-ovo vaccination

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The vaccination is delivered mechanically using a small A small hole in the needle that penetrates the eggshell and its membrane. egg after in-ovo vaccination.

Once you have determined which hatching eggs contain a live embryo, they can be vaccinated. Vaccination gives the chick a good start because the immune system already begins to develop in the egg. If the chicks are only vaccinated at hatch, there is an element of risk because the chick will still be vulnerable from that moment until the vaccination initiates the immune response. The target is to inject 98% of the vaccinations correctly (into the embryo or amnion). In-ovo vaccination is often more effective than administering spray vaccinations in the house. After all, how can you ensure the same dose is administered to all the chicks in the house? And that the vaccine is sprayed in optimal, equally sized droplets? Embryos for broilers and sometimes those for parent stock can be vaccinated for Marek’s disease, Newcastle Disease (NCD), Infectious Bronchitis (IB), Infectious Laryngotracheitis (ILT), and Fowl pox (or Fowl Diphtheria). Embryos destined for laying hens are not vaccinated in-ovo. After hatch, the chicks will be sexed and many of them would have been vaccinated for nothing. This could change after the introduction of in-ovo sexing.

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Correct in-ovo vaccinations made visible by a colourant. On the left subcutaneously in the neck of the embryo and on the right the vaccine delivered in the amniotic fluid.

Amnion Embryo

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Air cell Allantois

X X

Yolk

First a thick needle perforates the eggshell, and then a thin needle that delivers the vaccine penetrates the membranes. The effect of the actual injection site on effectiveness: a. into the air cell, no response b. into the allantois, a slight response c. into the embryo and/or amnion, 93-95% response 120

Advantages of in-ovo vaccination • early protection: the earlier the better • less stressful for the chick = better immune response • fully automated process: few trained personnel needed • high capacity (60,000 eggs per hour) • more effective and efficient administration of expensive vaccines • increasing number of vaccines available for in-ovo administration • individual dose for each chick (uniform administration) Success factors There are a number of focus points if you want to administer in-ovo vaccinations correctly: 1. Positioning of the egg 2. Correct eggshell penetration 3. The injection site 4. Vaccine preparation and administration 5. Hygiene Make sure the equipment is regularly calibrated. Ha tc he ry S i gnal s

The optimal timing In-ovo vaccination is done at the time of transfer. The vaccination window is day 17 1/2 until day 19 1/4. But you cannot actually measure this in days, it is determined more by the stage of embryonic development. This is determined by looking at the extent to which the chick is in the position to

hatch (head under the right wing) and/or if the yolk is sufficiently retracted. No more than 1-2% of the eggs should show external evidence of pipping. Optimal uniformity is therefore highly important here.

Scoring system A scoring system has been developed for determining the development stage of embryos. If the sum of the scores on two criteria is 3, it is a good time to vaccinate.

1 point: head under wing

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Criteria: Position

3 points: external pipping

2 points: internal pipping

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Criteria: Yolk residue absorption

1 point: organs still outside body

2 points: dual-lobe yolk sac

3 points: single-lobe yolk sac

4 points: fully absorbed

Recommended score and injection site per score

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Allantois/Air cell/Yolk sac

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ᅚ % Amnion

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6+7 % Embryo

With a higher score, more vaccination fluid penetrates the embryo and less in the amniotic cavity. From score three upwards, the vaccination result is better.

Source: Zoetis

Percent in site

100 90 80 70 60 50 40 30 20 10 0

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Suitability of the egg

LOOK-THINK-ACT

Firstly, the eggs must be suitable for vaccination. This means that they must be: • Clean. Dirty eggshells can transfer infections into the eggs. • Free of hairline cracks. The force required to push the needle through the eggshell can break it. • Well-fixed in position. This allows injection into the correct position. • And with the pointed end downwards!

No, a disinfectant ﬂuid is applied to the eggshell before the needle penetrates it. So, it is quite normal to see a wet patch around the injection site. This does not mean an unsuccessful vaccination!

Is this vaccination fluid?

If the pointed end is facing downwards, as it should be, in-ovo vaccination has no negative effects on hatchability. However, it is a different matter if the egg is positioned with its point upwards. Hatchability will be much lower with the eggs set in that position (‘hatch of fertile’ is already 15% less), and vaccination will reduce it even further.

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Hygiene is extremely important Administering an in-ovo vaccination involves breaking through an important infection barrier: the eggshell and the chorioallantoic membrane (chorioallantois). This makes the embryo vulnerable to infections with moulds (Aspergillus) and bacteria. These pathogens are often found on bangers and the humidifying equipment. This is why the injection site is always disinfected just before vaccination.

If you open an egg immediately after in-ovo vaccination, you will see some blood. This is absolutely normal. The needle will penetrate the back of an embryo in an upside-down egg, and the embryo will die.

A mobile in-ovo vaccination unit (on wheels). This can be installed in an existing line if desired. Right: the line with a dummy section in the location where the mobile unit can be installed, when a broiler hatchery decides to hatch layers on specific days.

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In-ovo sexing

There are a number of technologies under development: • Spectroscopy: A beam of light is shone through the eggshell, or a tiny hole in the shell. The gender can be determined by the way the light scatters. • Biomarkers: This method requires sampling fluid from the egg (allantoic fluid). These tests usually only work from day 7 or 8. Genetic modification will probably be an option in the future. So, either a marker will be developed that already shows a result on day 1, or the hens would only produce female offspring. The real question is whether this will be ethically acceptable for the consumer.

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Spectroscopy This non-invasive method has been ready for practical application since mid-2020, and has an accuracy of more than 95%. One machine can test more than 20,000 eggs an hour. No laboratory analysis is required, which makes this technique environmentally friendly (no chemicals required). Currently, the hyperspectral imaging technique only works with brown layer breeds, as of the 13th incubation day. This is actually a form of colour sexing inside the egg based on feather colour (also see page 175).

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There is increasing resistance to the practice of culling male chicks in batches of day-old chicks for the laying sector. And it is financially advantageous to select out male embryos as early as possible. In addition to in-ovo vaccination, in-ovo sexing has also arrived. In-ovo sexing has made great progress in the last few years, and in some countries a ban on culling day-old male chicks is likely within the foreseeable future. The following information represents the situation in 2021. Various factors play a role in the choice of technology: • Invasive or non-invasive: making a tiny hole in the eggshell risks negatively affecting hatchability. So, the non-invasive option is preferable if reliability is comparable. • High reliability: the level of reliability must equal that of the current sexing method, used after hatching. • Timing of gender determination: the earlier, the better. Ideally, before being set in the incubator. • Speed of sexing: the volume of eggs handled at a hatchery is enormous, so a high capacity and throughput rate must be possible. This is important to prevent the eggs from cooling down too much. • Practical and robust technology: a method that works in laboratory conditions must be suitable for practical application at a hatchery.

The spectroscopic gender determination unit.

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Spectroscopic gender determination. The egg is illuminated from below. The gender of the embryo is determined based on the calculated light spectrum. Eggs classified as having female embryos are then incubated normally.

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A single laser beam is too weak to cause any damage, but the cross-point between two beams is powerful enough to bore through the eggshell.

Biomarkers (SELEGGT and PLANTEGG) These are two systems that work based on biomarkers: • SELEGGT: marker reacts to the female hormone estrone-sulphate. • PLANTEGG: uses the PCR-technique (DNA-analysis). On a carousel, lasers create a fine hole in the eggshell of an 8-10-day incubated egg. Then a minimal amount of allantoic fluid is extracted for analysis. The female hatching eggs are returned to the incubator. The inner membrane reseals on its own.

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The carousel for collecting allantois fluid samples.

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The lasers make a tiny hole of 0.3 mm in diameter. A suction mechanism extracts allantoic fluid through this hole (PLANTEGG and SELEGGT).

The laser hole is 0.3 mm in diameter (PLANTEGG and SELEGGT)

Colouring indicates if the fluid contains estrone sulphate (female) or does not (male) contain any (SELEGGT).

The PCR technology provides results within 1 hour (PLANTEGG).

Ha tc he ry S i gnal s

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Biomarkers: InOvo The InOvo system works by indicating a specific metabolite in the allantoic fluid, as a biomarker around day 9. In this system, a tiny opening is pierced in the eggshell. The best location for this hole is determined for each egg. Then some allantoic fluid is extracted by a needle. The hole (< 1 mm) is resealed afterwards. The fluid is analysed very quickly using mass spectrometry. This analysis takes less than a second. The speed of the analysis and the lack of a need for chemical analysis make this concept viable for scaling up.

The sampled eggs have a clearly visible seal-layer that closes the hole made during the process.

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Gender reversal

Mass spectrometry can determine the gender of the embryo based on a small gender specific molecule in the allantoic fluid.

Another option does not involve determining the gender but changing it. Gender is, of course, determined genetically. But suppressing the expression of the gene responsible for male gender will make an embryo develop into a female. An Israeli company is developing a technique based on subsonic sound, with the aim of achieving this. The exact mechanism involved in the inﬂuence of sound on embryonic development is still unknown. In early 2021, they achieved 63% females, and 70% in some parts of the incubator. This technique is still in an experimental stage, but the company expects commercially interesting results within a short time.

After sexing, each egg is stamped with an additional identification code (male or female). The eggs with female embryos are then incubated and the males are removed.

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Transfer The eggs with live embryos are lifted by suction cups and transferred from the setter trays to the hatcher baskets. These baskets are then placed in a trolley and moved into the hatcher. There is a high risk of rotten eggs that explode (bangers) when floor eggs are candled and transferred. The candling-transfer unit is covered in pieces of shell and rotten egg contents, and the stench is horrendous. If a breeder farm always includes a lot of floor eggs in the deliveries, it can be a good idea to invite the farmer to be present at candling, so they can witness and smell the results with their own eyes and nose! Infertile eggs are not suitable for human consumption, but they can be used in the processing industry, e.g., for shampoo or pet foods. The remaining eggs are destroyed.

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In some systems, it is possible to replace eggs removed after candling with ones containing live embryos, either until the hatcher basket is full or up to a fixed percentage. You can achieve optimal hatcher filling in this way and create more uniform heat distribution in the machine.

On-farm hatching involves transporting the hatching eggs, on day 18, to the farm where they will hatch. Some hatcheries also transport eggs, on day 18, to special hatching locations. The embryos are now already far in their development and less sensitive to vibrations, condensation, and temperature variations. However, temperature ﬂuctuations should still be minimised so avoid using an open trailer.

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In some hatcheries, the infertile eggs and eggs with dead embryos are removed from the setter trays, and only good hatching eggs are left in the trays. But there is a risk here: weak infertile eggs can break when being lifted for removal and could then infect the good eggs.

Transporting hatching eggs

During transfer, the infertile eggs and eggs with dead embryos are left in the setter trays. Then they are sub-divided into unusable (late mortalities), and usable (infertile/early embryo mortalities up to day 6-7).

Good eggs are raised slightly so they can be removed by the suction caps. Bad eggs (infertile eggs, or dead embryos) are left in the trays.

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LOOK-THINK-ACT

Bangers are first identified and then removed with a powerful suction device. This avoids touching the eggs, and other eggs are not contaminated.

Too early onset of hatch?

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You already see chicks at the time of transfer. There are even a few day-old chicks running around the setter ﬂoor. All the incubator setter parameters seem to be correct. There are many factors that speed up hatching, even to a stage that pipping starts before transfer from setter to hatcher. If the settings were correct, the problem might be: • In the setter: hot spots in the incubator. • Pre-warming: excessively long pre-warming, reducing incubation time. • During storage: conditions were too warm (early onset of development). • On farm: egg collection too infrequent, leading to egg cooling being too slow.

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Sometimes a second candling installation is installed, to double check. If the pattern shown by the first candling does not correspond with the second, the whole tray is set aside. If, for example, this often occurs at the same place in the tray, the cause could be certain suction cups not working properly.

These eggs are contaminated, possibly by a banger in the setter tray above.

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It is standard practice not to check clear eggs and process them directly. However, regularly checking these eggs is still a good idea, to discover the precise reason for mortality. For example, check 5 trays of 30 eggs, so 150 eggs per batch.

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Hygiene at transfer

LOOK-THINK-ACT

Once the eggs have been set for 18 days and transferred, the setter trays they were delivered on are returned to the parent stock farm. For obvious reasons, the setter trays must be very thoroughly cleaned and disinfected.

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Even a tiny ﬂake left behind in a setter tray is a potential source of infection. So, this tray is not cleaned well enough. Sometimes corners are difﬁcult to clean, and certainly if the batch of eggs included bangers. So, a post-cleaning inspection is necessary. This setter tray was not washed well enough.

Is this cleaned well enough?

Rotten eggs can easily explode during transfer. These bangers cause a great deal of cross-contamination.

Trolleys are not likely returned to the same breeder farm they came from. But the trolleys are cleaned and sampled to check for infections. 128

After transferring the eggs to hatching baskets, egg residues are sometimes left in the setter trays. The content of a banger is sticky, and it dries more while in the setter. This can make the residue difficult to remove.

Setter tray cleaning and disinfecting line.

Ha tc he ry S i gnal s

Breakout analysis on day 18 The primary goal of transfer-candling is to only transfer viable embryos to the hatcher baskets. Carry out a breakout analysis on eggs selected out at the time of candling. Candling and breakout analysis can signal problems in the incubator. For example, you can identify locations in the incubator where embryo development is retarded. But you cannot easily distinguish eggs with early mortalities because they have already been deteriorating for 18 days. Depending on the findings, you could candle on various days, to pinpoint potential problems. Only examining eggs rejected at transfer gives you a limited picture. To obtain a fuller picture, you should also assess unhatched eggs (from the same setter trays). This is, after all, the actual mortality after day 18.

Caution! Don’t take immediate action based on the results of one breakout. Check eggs from the same ﬂock again using another setter. Or check the setter again with eggs from a different ﬂock.

Use standard forms

Always assess the breakout in the same way. Use a standard form, on which you put all important information. You can subsequently enter this in a computer and analyse it. So don’t put all the information on paper in a ﬁle cabinet!

1-2 days: germinal disc

3 days: blood ring stage

A clear, white point, sometimes slightly grainy. Causes: poor quality males or females, or an incorrect ratio, seasonal and/ age-related decline in parent stock fertility, competition among males, diseased flock, or parasites, e.g., mites. Insufficient floor space (= stress).

Enlarged embryonic disc, with no blood, a round embryo, and a light-coloured yolk. Causes: undernourished males or too many of them (= stress for the females), damaged eggs, cooling too fast or slow after laying, and prolonged/incorrect storage. Very young or old parent stock. Excessive washing water temperatures. Difﬁcult to identify at 18 days.

A clear egg with a blood ring or one with whitish-yellow content is a typical image of mortality after three days of incubation. There is still no black eye visible. Causes: excessively long or incorrect storage (temperature ﬂuctuations), incorrect disinfection, incubation temperature too high or low, damaged eggs, old parent stock, and poor nutrition.

4-10 days: black eye stage

11-18 days: feather stage

Rotting egg

Start of the yolk sac with blood vessels. The embryo is lying on its right side, still no egg tooth, but the eye is very clearly visible. This can have the same causes as early embryo mortality before day 3. Or be caused by insufficient ventilation, impenetrable eggshell, CO2 concentration higher than 1%, insufficient turning frequency, incorrect turning angle, or a vitamin deficiency.

You can recognise an embryo that died after day 11 by the presence of plumage.

You see a grey-green mass in the egg. There is an odour of rotten eggs (hydrogen sulphide, and ammonia). The causes include lack of hygiene in the laying nest, setting ﬂoor eggs, incorrect storage conditions, moisture on the eggs.

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Day 0: infertile

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Eggs in a clean hatcher Besides cleaning and disinfection, drying is also very important. After all, moisture is a condition for the survival of bacteria. This applies to trays, hatcher baskets, hatchery floors, incubators, etc. Wet hatcher baskets will also cool down the eggs.

Good cleaning, disinfection, and drying before each new batch is an essential step in the process. With the hatchers, the focus should be on treating the fresh air supply and circulated air. The air entering the hatcher must be pathogen-free. Don’t forget the filters for incoming air. These can offer a nice breeding ground for Aspergillus.

Not only the hatcher should be cleaned and disinfected, also the hatching baskets should be clean and free of bacteria before being filled up with the transferred eggs.

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Proper cleaning of all the materials is vital for chick quality. So, share the inspection results with the hatchery personnel. A simple way to do this is hang up a graph or chart in the canteen. Making the results visual works better than just a paper report.

After a batch has hatched, the hatcher cabinets are cleaned and disinfected, so they are clean and ready to be filled again. On the left image, the hatcher in front has not been cleaned yet, while disinfection is already taking place. It is best to first clean everything, then disinfect everything!

Cleaning transport trays DQG WUROOH\V

Breeders

Egg handling, storage & transport

Cleaning KDWFKHU baskets DQG WUROOH\V

Cleaning VHWWHU trays DQG WUROOH\V

Incubation

Transfer

Hatching

Cleaning FKLFN ER[HV DQG WUROOH\V

Chick processing

Poultry farm

The baskets and trolleys are cleaned and disinfected at various times during the process. 130

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Hatcher baskets After candling and vaccination, the good eggs are carefully transferred to hatcher baskets. Maintain a high level of hygiene during the entire transfer process. The hatcher must be dry and pre-warmed, to avoid the eggs getting too cold. This will otherwise cause delayed hatching and reduced hatchability.

Did you know? Sometimes hatcheries work based on kilograms of eggs per hatcher basket and others use the number of eggs in each basket. A hundred heavy eggs release much more heat than the same number of light ones....

Some hatcheries use paper in the baskets to prevent soiling of eggs and chicks, but often to mask poor egg quality. Paper can obstruct the airflow, so more eggs will become overheated in some places.

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Different hatcher baskets

Hatcher baskets with loose eggs.

The eggs are in fixed positions. After hatching, the chicks drop to the lowest level. The empty eggshells remain in the upper level.

After candling, the good hatching eggs are placed in the hatcher baskets. Some machines can be set to ensure optimal hatcher basket filling. Usually, the eggs from a setter tray (150) are divided between two hatcher baskets (left). If you have a larger hatcher basket (right), it can be filled with the entire content of a setter tray. If there are less fertile eggs in a batch, other hatching eggs are often added to ensure the hatcher baskets are filled optimally.

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CHAPTER 9:

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Hatching

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In the last two and a half days before hatching, a lot happens in the chick’s body. It absorbs more oxygen, because its lungs are activated and it begins pipping into the air cell. The chick begins using

its lungs for respiration, and the blood circulation through the chorioallantoic membrane (CAM) is shut

off (the membranes dry out). This causes the metabolic rate to increase. The chick produces more heat. Then it begins pipping the eggshell, and a healthy chick will see the light of day.

In natural conditions, the hen occasionally stands up around hatching: alternating fresh air and warmth. The CO2 concentration in the hatcher is initially 3,000/4,000 ppm (outdoor air = 400 ppm). At the time of pipping, around day 19, the CO2 concentration can even rise to 8,500 ppm, depending on the air inlet position. At around 20 days, ventilation is used to reduce this to 3,000 ppm at hatch. 132

If all goes well, more than 90% of the transferred eggs hatch and you will have healthy chicks. If the eggs were not incubated under the right conditions or the gas exchange was sub-optimal, the embryos will have been unable to convert all the yolk and albumen optimally into growth and development. These embryos will be smaller and there will be more yolk residue. In order to survive they have taken more energy from their livers, hearts, and muscles, and will feel as if they have just run a marathon... They are exhausted, and it is questionable whether they have enough energy to hatch from the egg. The yolk has not been retracted well, and these chicks often have poorly sealed navels.

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Air temperature in the hatcher

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The eggs are usually lying flat on the bottom of the hatcher basket and are no longer turned. In this situation, the airflow is essentially different than in the setter trays. Less air flows through a hatcher basket. So, the cooling should be adjusted accordingly. The optimal climate conditions for the eggs in the hatcher, just after transfer, are comparable to the conditions in the setter.

Sometimes you can see condensation on the cooling coils. This reduces the cooling effect. The condensation process actually emits energy, while your goal is to remove it. Condensation is not in fact the greatest problem. A worse problem is the fluff that settles on wet coils and insulates them. This reduces the cooling capacity drastically.

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The air/machine temperature in the hatcher is slightly lower than in the setter. The airflow through the hatcher baskets is less than around the setter trays, and the eggs are positioned horizontally. The resulting reduced heat transfer (removal) is compensated for by maintaining a slightly lower air temperature. You should also aim to maintain the eggshell temperature at 37.8°C (100°F) after transfer. The eggshell temperature can increase after internal pipping. The chick’s activity around the time of hatching releases a lot of heat. A lot of cooling is applied to prevent the embryo temperature in the hatcher rising too much. Maintaining RH and CO2 levels are less important that maintaining the optimal machine temperature. If you hatch with a CO2 concentration of 5,000 ppm, you keep moisture in the hatcher, and will see a good humidity peak as an indicator of the hatch window. Ventilation is often limited a little, to avoid a cold draught over the newly hatched chicks. On day 19, a machine temperature of 36.7–36.9°C (98.0–98.5°F) is often sufficient. Once all the chicks are hatched and dry, the temperature is set slightly lower: 36.1–36.7°C (97.0–98.0°F) is high enough. Some machines require even lower machine temperature settings (97.5°F). But take care! The temperature setpoint depends on the type and design of hatcher and, above all, the type of eggs. Hatcheries work with fixed weights (kg) or numbers of eggs per hatcher basket, so there is uniform heat production throughout the hatcher. Avoid too much ventilation in an air-cooled hatcher as this will introduce too much cold air. This involves the risk that some of the chicks will be too cold, especially when they have just hatched and are still wet. In addition, too high ventilation will cause the relative humidity level to drop. Based on the RH setpoint, humidifiers will activate, which will then lead to eggs and chicks at other locations becoming too cold. Broiler chicks hatch at a lower hatcher temperature than laying hen chicks, because a broiler embryo produces more heat than a laying hen embryo. The optimal embryo and chick temperature are equal for both types of chicks. Depending on the temperature in the setter, the first chicks start hatching during day 19. 9. H at c h i n g

Observe the chicks once or twice during hatching, so you can assess the process. The chicks should be evenly distributed and calm. Here, the glass doors make observation very easy. If you need to open a door during observation, be aware that this will disrupt the climatic conditions. A camera in the hatcher is also a good option. Many experienced hatchery managers can base their assessment on the sound the chicks make inside the hatcher.

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Humidity in the hatcher

LOOK-THINK-ACT

The fresh air demand increases and moisture is very important to ensure the eggshell membranes remain soft and supple, so that the chick can free itself during hatching. Preferably let the chicks dry off in the hatcher as this avoids stress caused by cooling down too quickly. After external pipping, each chick evaporates an amount of water equivalent to 3% of the original egg weight. And once the chick hatches and dries off, it evaporates another 3%. The humidity may rise then, but this is a natural development. If you leave the RH setpoint at the original level (and base climate control on the RH), there will be too much ventilation (and chicks will cool down too much), or the system will continually give an alarm. The aim here is to extract moisture, rather than add it. When the humidity level drops again, this is a sign that no more chicks are hatching, and that all the chicks are drying off. The chicks can be pulled between 10 and 12 hours after the humidity peak.

Is it a good idea to use spraying during hatching, to facilitate the process?

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No, this is not a good idea during hatching. The RH should remain constant. Hatcheries sometimes use spray to humidify, but it is risky. The chicks actually need to dry off. Otherwise, there is a risk of wet spots and cold chicks. When using sprays, they are often activated for 20 seconds every 5 minutes. Weight loss of chicks is lower, but sometimes it slows down the hatching process in some trays. And adding water involves the additional hazard of E-coli infection. Disinfectant in the humidity nozzle decreases the risk of contamination. It is much better to condition the fresh air supply to the right temperature and humidity levels. Depending on the design of the ventilation system and hatcher, an air temperature of 22-24°C and RH of 5070% are maintained.

Changing parameters in the hatcher

Temperature (°F)

100

80 60

RH (%) 99

100

ventilation air inlet position (%) hatcher temperature (°F)

CO2 concentration 20

hatch peak: RH 57%, until end of humidity peak (= peak - 3%) 02.00 p.m 10.00 p.m. 06.00 a.m. 02.00 p.m. 10.00 p.m. Time of day

Once the chicks begin external pipping, the RH spontaneously rises quickly. A slightly higher RH makes it easier for the chicks to hatch. However, humidification is not necessary, because a lot of moisture is released during hatching (blue line = humidity peak). Just after the chicks hatch, the RH drops again to 50-55%, so that they can dry off properly. The CO2 concentration used to control the inlet position is the guiding factor here. A lot of CO2 is released, and the ventilation inlets are opened to a higher position (green line) to maintain the required concentration. 134

RH and ventilation air inlet position (%)

humidity peak higher ventilation setting removes start of moisture humidity peak

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The humidity level rises during hatching. But the walls and floor must remain as dry as possible. A wet floor combined with fluff and down offers an ideal environment for bacteria.

Fluff in the hatcher is a good signal. A lot of fluff is usually associated with a short hatch window. A short and intense hatch window like this usually results in high hatchability. Which is why we say: lots of fluff = good hatchability. Ha tc he ry S i gnal s

Position in the egg Most abnormal positions are caused by temperature problems and through the chick wrestling to escape from the eggshell. It is more a result of an inability to hatch than the cause. This usually only occurs right at the end of the incubation process. If an egg is incubated upside down, the embryo is already in an incorrect position inside the egg.

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The beak is not near the air cell. The neck and head are tucked under or on the left wing. The head is between the legs. The legs are pulled up on one side the yolk.

The beak is positioned near the air cell. The neck and head are tucked under the right wing. The legs are pulled up on both sides of the yolk.

Malposition

Good position

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A normally positioned embryo in the egg. Normally, a chick is positioned with its beak under the right wing. This offers the most room for good piping.

The head is between the legs: the beak pips the eggshell properly.

The head is correctly at the blunt end, but the beak is tucked under the left wing.

The head position is normal, but one leg is pulled over the head.

The embryo is twisted, with its head towards the point of the egg.

The head position is normal, but the whole embryo is turned away from the air cell.

The beak is on the left wing.

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Internal pipping The moment of hatch was already determined fairly precisely when the eggs were set three weeks earlier. Broiler chicks begin hatching a little earlier than laying hen chicks (about 480 and 490 hours, respectively). Variations in egg size and the temperature in the incubator also play a role. On day 19, the chick begins to break through the air cell membrane with its beak (= internal pipping). Once the air cell is accessed, it should be clear whether the breathing is working properly. On the last day, the total oxygen consumption increases by 50%. Due to the O2 consumption from the air cell and the CO2 release, the chick becomes short of breath and this motivates it to peck a hole in the shell.

A chick upside down in the egg. This is caused by incorrect egg orientation (point up) in the setter trays.

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The embryo’s oxygen uptake changes quickly around the time of hatching. The oxygen supply through the lungs increases, but the uptake through the umbilical cord reduces quickly. And the umbilical cord starts to dry up. The combined oxygen uptake increases by 50% on the last day.

If the air cell is in the wrong position, this is a sign of faulty turning, an incorrect turning angle, too high or too low incubation temperatures, incorrect RH, or jolts during handling or turning.

Head between the legs is a sign of an excessive weight loss, or abnormal egg composition (yolk/albumen ratio, or vitamin deficiencies in parent stock feed).

Wings under the head indicate insufficient or uneven turning, or the wrong type of tray with too much space for small eggs. This mostly occurs with eggs that have been overheated. It takes more effort from the chick to hatch, and its head ends up on the wing. A large proportion of these chicks will fail to hatch. Head under the left wing with protein residues on the wing (urates). 136

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External pipping

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The chick uses its egg tooth to pierce the eggshell.

The head of this chick seems to look strange with a kind of hump on the back of the head. But this is very normal. The strongly developed neck muscle is the so-called pipping muscle. After hatching, its size decreases again.

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After internal pipping, it takes approximately 3-6 hours before the chick breaks the eggshell (= external pipping). The hatchery manager must not attempt to force this process. During the transition to oxygen uptake through the lungs (lung respiration), the yolk is entirely retracted into the abdominal cavity and the navel seals. The chick rests for a half day after external pipping. The chick starts tapping the shell to enlarge the hole an hour before hatching. At a certain moment, the chick has to turn itself a little, to be able to make the hole large enough. The chick must turn around completely to be able to completely ‘unzip’ the eggshell. The RH must not be too low at this stage, otherwise turning will be difficult and the chick may stick to the eggshell membranes. After hatching, the chick dries off while taking a rest again (3-6 hours, depending on conditions). Some hatchers automatically detect the beginning of the hatch window, based on the increase in RH (humidity peak starts), and start the corresponding program step. You can see the dried chorioallantoic blood vessels in the eggshells and sometimes albumen residue.

The pipping line usually runs counterclockwise (as seen from above).

The chick pips the egg along a diagonal line, until the egg is 80% open. After this, it opens the eggshell section like a lid.

The hatching process Time before hatch 26-24 hours What happens? • Pipping into the air cell. • Oxygen uptake through the lungs (respiration) activates. • A mucus layer is applied to the inner side of the lungs, to protect them from dehydration.

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Time before hatch 24-15 hours What happens? • O2 decreases. • CO2 increases. • The chick experiences a shortage of oxygen.

Time before hatch 15-12 hours What happens? • The chick pips the eggshell with its egg tooth. • Oxygen uptake now fully through the lungs (respiration). • The yolk is completely retracted into the abdominal cavity. • The navel seals.

Time before hatch 12-0 hours What happens? • The chick starts pipping the eggshell again with its egg tooth. • It enlarges the opening by turning around. • The chick begins to kick with its feet.

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The hatch window tion conditions, 95% of the chicks hatch within 24 hours. All the factors that delay or accelerate the incubation process can lead to the hatch window being 36 hours or even longer. A small spread in the hatch window also means the day-old-chicks are all at the same stage of development at the time of dispatch. This makes it easier to set climate and other conditions correctly in the house before the chicks arrive. Ensure the climate in the hatcher is optimal for the hatched chicks, so they can stay in the hatcher for a while without any problems.

The hatch window is the period required for hatching almost all the eggs. There are various factors that influence the length of this period. The more uniform the batch and the incubation conditions, the shorter the hatch window. The optimal hatch window for layer hen chicks is 12-15 hours, and 24-32 hours for broilers. Chicks that hatch first run the risk of drying out. Their weight will fall and quality will decline. Keeping the hatch window shorter reduces these risks. You can reduce the length of the hatch window in different ways. Some hatchery managers increase the temperature a little during the hatching process. Wet chicks cool themselves and the surrounding eggs. Increasing the temperature prevents this effect. This stimulates hatching but increases stress among the chicks. Other hatchery managers decrease the ventilation a little, which leads to a higher CO2 concentration. The embryos experience a shortage of oxygen and are triggered to pip into the air cell and break out of the egg. Decreasing the ventilation prevents cold air entering the hatcher (which can delay hatching). Both methods work easily, quickly, and efficiently, but the question remains whether this is better for chick quality or not. The shorter the hatching period, the higher the uniformity in hatching egg temperatures has been. With a uniform batch of eggs and uniform incuba-

100 90 80 70 60 50 40 30 20 10 0

Pull time: 95% hatched

min. 75% hatched 12 hours before pull time

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Hatchability (%)

Broiler hatch window

max. 25% hatched 24 hours before pull time

-32 -30 -27 -24 -21 -18 -15 -12 -9 -6 -3

Hours to pull time

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Hatching forms a classic S-curve. A few early chicks hatch first, then the largest group follows quickly, and the last chicks arrive in slow spurts. This graph gives a rough guideline. The shorter the period, the better.

- 32 hours

- 24 hours

- 12 hours

Pull time

Duration of hatch window and timing of the first feed

late early

Optimal time for feed and water

mid

Short hatch window

late early

Optimal period for all chicks

Optimal time for feed and water

mid

Long hatch window

No optimal period for all chicks possible

The duration of the hatch window determines the pull time and in turn that of the first feed. The chicks do not need feed and water immediately, but you cannot have an optimal first-feed period for all the chicks if the hatch window is too long.

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Factors influencing the moment of hatching

Variation in the hatch moment Temperatures being too low at the beginning of the incubation process are often the cause of delayed hatching. Too high temperatures at the end accelerate the hatching process, to the point where the embryos suffer too much damage. And this actually leads to delayed hatching again, or embryo mortality in the egg. Variation in embryo temperatures is the most important factor affecting variation in hatch moment. This is particularly the case during the first week of incubation, as a result of lack of uniformity in egg temperature during the start of the incubation process. Embryo temperature in cold parts of the incubator is low and the eggs there will hatch later, whereas embryos in warmer parts of the incubator will hatch earlier.

(Too) early hatching: • • • •

•

• • • •

• • • • •

Setting the eggs too late. Incorrect incubation temperatures (too low). Incorrect ventilation (too much cold air). Seasonal inﬂuences that cause temperature ﬂuctuations in the incubation environment. Egg storage time too long. Egg storage temperature too low. Incorrect setting pattern in the multi-stage incubator. Disease or fertility problems. Egg size (too large), without an adapted incubation program.

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• • •

Pre-warming temperature too high. Eggs were set too early, and incubated too long. Hot spots in the incubator. Seasonal influences that cause temperature fluctuations in the incubation environment. Too many fertile eggs in the incubator, without an adapted incubation program. Egg size (too small). Breed/line. SPIDES. If the eggs have been incubated for a few hours, development has been briefly arrested. This period must be deducted from the incubation period.

(Too) late hatching:

There can also be wide temperature differences in the hatcher. This affects the hatching time, as well as chick quality. Newly hatched chicks can become too hot or cold. The right stack is clearly too warm. And especially at the top, because the heat rises. In this case, the heat could not escape, because the ventilation openings in the partitions were blocked by condensation and down.

Often, there is a fluff corridor at the rear of the hatcher. The negative air pressure draws air through the corridor. The fluff/dust is collected in sacks or the corridor itself.

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Residues are left behind after the hatcher baskets have been removed: eggshells, first droppings (meconium), fluff. There are useful signals here too. Hatchery managers often pay attention to fluff. A lot of fluff means the chicks have dried off well. 139

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The time when you remove the baskets from the hatcher is called ‘pull time’. You do this when virtually all the chicks have hatched. There will always be stragglers but waiting for them will compromise the chicks that have already hatched. And you always have to question whether they are viable (or are they eggs that will not hatch?). The hatchery manager then checks whether the chicks are dried off well enough. A good guideline is to have only 5% of the chicks still with damp neck feathers. This can be difficult sometimes, because the eggs do not all hatch at the same time. If the chicks hatch very irregularly, some will have dried off too much, while others are still too wet, which causes them to cool too fast. We refer to this as a long hatch window. The chicks should not remain in the hatcher baskets for too long after hatching because they will overheat (the hatcher cannot maintain a low enough temperature). If pull time is later, there will also be more variation in chick quality. Future legislation is likely to stipulate a maximum period a chick can be without feed or water or a maximum interval before it arrives at the poultry house. But which point in time is the baseline measurement? From the moment the first chick hatches? In this case it will be even more important to keep the hatch window as short as possible. Leaving hatched chicks in the hatcher for a little while. It is always preferable than placing them outside the hatcher in unsuitable conditions, as this would cause more damage.

Chicks dry out fairly quickly, an individual chick takes about 3-6 hours. For an entire batch, the target pull time is 18-20 hours after the humidity peak.

A chick is still wet when it is freshly hatched. If you observe about 5% of the chicks with moist necks, the pulling time was optimal.

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The noise the chicks make in the hatcher is a good indication of how they feel. These are signals about the climate in the hatcher. Chicks that sleep and cheep softly are feeling comfortable. This indicates the correct climate. Chicks that make a lot of noise (screeching) are distressed and do not feel comfortable. They are too hot or short of breath. You can hear chick noise as soon as internal pipping has started. Behaviour and chick noise are good indications of how comfortable the chicks feel.

Pull time

Signals of timing the pull Pull time too late • • • •

> 5 meconium stained • eggs per basket All chicks are dry • Dry legs • Developed feathers

Pull time too soon Clean eggshells in the hatcher basket Some chicks still wet Viable chicks still in eggs

Here, the long feathers are already well developed. This indicates a late pull time. You should not be able to see the small, white feathers. If day-old-chicks are left too long in the hatcher, ‘white triangles’ protrude from the feather shafts. These dry legs indicate that pull time was too late. 140

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Unhatched eggs/dead in shell

LOOK-THINK-ACT

To intervene or not to intervene?

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Pipping is tiring for a chick. Chicks that cannot pip their way out of the eggshell are often weak, otherwise they would be capable of breaking through themselves. It is better not to intervene, because these weak chicks will often die in the poultry house anyway.

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In general, 2-3% loss occurs during the last phase in the hatcher. These eggs are referred to as unhatched eggs. Most candling machines (except heartbeat detection methods) do not identify embryos that died after day 12 and leave them in the tray. Perform a regular breakout analysis to assess when these embryos died. The most important conclusion you can make is whether weight loss (which should be 11-12% on day 18) was insufficient (wet embryo, visible albumen residue). If the weight loss was insufficient, a lot of the chicks that did hatch will have a poorly sealed navel and an oversized yolk sac. Late mortality can be caused by factors such as insufficient moisture loss, changes in the respiratory system, position changes, pipping, and hatching. But transfer damage and genetic defects play a role too. It is important to identify the causes of late mortalities. This allows you to evaluate the incubation process and take corrective or preventive measures with the next batch.

A hatcher basket after pulling and taking out the live chicks. It contains: • whole eggs • incompletely hatched eggs • dead chicks

In a traditional hatcher basket, the chicks remain among the eggshells and the non-pipped eggs until pull time. In other types of hatcher baskets, the chicks are separated from the eggshell residue immediately after hatching. The chicks are often taken out manually.

Fluff removal using an exhaust system above and at the sides of the hatcher baskets.

Here, the chicks drop between the bars. The eggshells stay on the bars and are removed. Loose down and eggshell particles are removed by suction. So, inspect the batch for unhatched eggs and empty eggshells before these residues are separated.

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Count and assess unhatched eggs

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The unhatched eggs among the empty shells are collected here from twenty hatching baskets in order to analyse the cause of death.

You should also count the unhatched eggs. Perform a breakout analysis of random samples (at least six baskets), to see the stage or day when the embryo died. Carefully examine the distribution of these cases, and try to determine whether most embryos died in the second week (in the setter) or during hatching. Try to think if there is a way to reduce the percentage of unhatched eggs. One possibility is that that too many infertile eggs or eggs with early embryonic mortality were not detected during candling and transfer. If this is the case, check the candling process. If you want to trace the causes of deviations with more certainty, give the setter trays an identification mark before transfer (e.g., upper, middle, and lower trolley positions). Collect the eggs rejected at candling for a breakout analysis and do the same with the hatcher baskets. Then you count these eggs, assess the quality, and collect the unhatched eggs for breakout analysis. Do this for each hatcher basket. In this way, you have a good picture of the process, from start to finish. Do not add any other eggs during transfer: the data must be pure.

Aspergillus causes increased embryo mortality around day 15-16. This fungal infection is clearly visible if you open the unhatched egg at the blunt end.

Perfectly formed chicks but still dead in the hatcher basket These mortalities were possibly caused by external factors. Maybe one of the personnel handled the hatcher basket too roughly, the hatcher basket was damaged, or the hatch window was very wide. If the chicks are fully formed but have a soft body with a bad odour, there is a possibility that the cause is an E. coli or Aspergillus infection. Floor eggs that were still placed in the setter could also be behind this problem. A chick that did not break out of the egg at all but died around day 18.

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Hatching systems and early feeding

If the conditions are not right - for example the chicks are kept too cold - they will not eat anything offered to them. If you decide to feed the chicks early, intestinal development starts and they switch to using energy and nutrients from feed. There is now no way back - the chicks must continue on feed. Breaking the eating pattern is disastrous. You can provide water and feed in various ways: 1. Access to water and/or feed in the hatcher. 2. Access to water and/or feed once they are in transit for a prolonged period (especially with air freight where long waiting times are expected). 3. Chicks hatched in the house have immediate access to feed and water and are not transported.

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The hatch window can be as short as 24 hours, but can also be more than 36 hours. After this, the chicks still have to be selected and possibly vaccinated. The first hatched chicks will only reach the house 40 hours later, and this can be even longer if the transport time is long. There is increasingly more attention for early feeding systems, because this gives the chicks a better start (better growth) and it benefits animal welfare. You must be aware that chicks are well equipped to last a couple of days without feed. Not because they have enough reserves in the yolk residue, but due to the energy reserves they have built up in their bodies. The right conditions post-hatch are more important for young chicks than having immediate access to feed and water.

HatchCare is an example of a system with immediate access to feed, in the hatchery, post-hatch. The chicks have immediate access to feed and water in the basket under the one containing the eggs. This basket is also used to transport the chicks, so there is no need to transfer them to another basket or crate. This reduces stress among the chicks.

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The SmartStart system has the advantage of being easily integrated (particularly the required lighting) for use in existing incubators. The feed is semi-moist: it feels dry, but it has combined nutrients and water locked-in by using Natural Deep Eutectic Solvents (NADES). This means you do not need any water in the warm hatcher cabinet (inherent risk of bacterial growth).

Effect of early feeding and transport on growth in the first 10 days

10 8

230

Mortality (%)

Growth (g)

240 220 210 200 190

Effect of early feeding and transport on mortality in the first 10 days

No transport Feed

2 hours

10 hours

No feed

Withholding feed leads to retarded growth, particularly with long distance transport. In all cases, the growth rate is higher with early feeding.

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6 4 2 0

No transport Feed

2 hours

10 hours

No feed

Sometimes, mortality during prolonged transport can actually be higher if the chicks are fed. In this case, it was the result of incorrect transport conditions: chicks transported with access to feed produce more heat, so they require more ventilation and cooling. 143

Feed during (long distance) transport If the chicks are fed during transport, the transport capacity is reduced. During long distance transport, the chicks are usually given moisture retaining feed, to maintain optimal quality and prevent dehydration. The chicks will not eat while they are in the dark during transport. When is feeding during transport necessary? Suppose the chicks have to undergo transport that takes 24 hours. The 24 hours is counted from pull time. This means 36 hours from the time when the first chick hatched. So, some chicks will be 60 hours without feed and water, and often under suboptimal climate conditions. This implies that providing feed is advised if transportation takes longer than 24 hours.

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A system with special feeders on the sides of the hatcher baskets (HatchCare). This gives chicks immediate access to feed post-hatch. The hatched chicks drop through holes in the upper basket to the one below, where feed is available. The eggshells and unhatched eggs remain in the upper basket. This gives the chicks more space, and they do not come into contact with dirty eggshells.

Feed, water, and light in hatcher baskets With early feeding systems, light is also provided, which produces a more stress-free environment and calmer chicks than ones hatched in the dark. Chicks that are fed in the hatchery produce twice as much heat, amounting to as much as 600 mW. This means paying careful attention to whether the chicks overheat in storage or during transport. They should also be unloaded immediately on arrival at the house, or they will overheat. Overheating becomes an issue faster than you think. Chicks suffer damage within 10 minutes of being too hot.

Gel-form feed for day-old turkey poults is available in the transport boxes. A gel-form feed provides combined nutrients and water for the chicks and is intended for long distance transport. In practice, chicks do not eat that much of the gel. Taking feed in a gel format feels like eating, and if the chicks have no access to water, they will stop eating the gel at a certain moment.

Chicks are usually given moist feed but no water during transport because spillage would make it all very messy. Transport lasting 10-11 hours does not lead to any problems: the chicks have a reserve that allows them to survive some time without feed and water. Sometimes soaked rice with added vitamins is provided in the chick baskets.

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Temperature requirement for on-farm hatching 42

After a good incubation process of 18 days, eggs can be candled and transported to the farm where eggs will hatch under their own steam. This knowledge inspired the idea of hatching chicks in the house, or on-farm hatching. On-farm hatching eliminates the need for chick transport. Chicks that hatch in the house can intake feed and water as soon as they are ready. There are various systems for hatching chicks in the house. They have a less stressful start to life, which keeps them calmer. With on-farm hatching, it is easier to track the hatching curve, and use the information to check that the hatching and chick temperatures are within the desired range. Hatching can take place in a special system (e.g. Patio, X-treck) or on the floor (e.g. One2Born, Nestborn). Uniform and correct air and floor temperatures are critical to keeping the eggs and chicks at the right temperature. On-farm hatching is currently used exclusively for broilers, as they do not need sexing. With the development of in-ovo sexing for laying hen hatcheries, on-farm hatching is also likely to be used in the egg production sector.

Temperature (°C)

100 dry chick: 39.5 - 40.5°C

39 38

dry chick

hatching egg: 37.5 - 38.5°C

hatching egg

37 36 35 32

house (air) floor: 33.0 - 34.5°C

32 19.0

floor (concrete)

32 19.5

20.0

20.5

Hatchability (%)

On-farm hatching

21.0

19 21.5

Incubation time (days)

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The poultry house temperature is normally set for day-old chicks. The set point must be a little higher during hatching, so the newly hatched chicks do not cool down too much. It is often too cold for the first chicks, because heat production from all the other chicks is still too low. It is important to look at the hatching pattern to maintain the optimal house temperature.

A rail system (X-treck) that is suspended above the floor. Setter trays with 18 day-incubated eggs are placed on the rail. The poultry manager can easily regulate the airflow and temperature surrounding the embryo by adjusting the height of the system. The chicks hatch in the house after 19-20 days of incubation and they have immediate access to feed and water.

In this system (Patio), the chicks hatch in the house, on a grid system above the living area. Post-hatch, the chicks drop through the grid to the living area with feed and water. This gives the chicks a good start. The chicks are housed on belts arranged as six tiers, instead of on a concrete floor. This allows more chicks to be housed in one building, which reduces heating costs. Instead of day-old-chicks, the poultry farmer receives 18-day incubated eggs.

9. H at c h i n g

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Hatching on paper egg flats in the house In this system (One2Born), the eggs stay on the paper egg flats/pulp trays in the house after 17-19 days of incubation. These trays do not need to be removed but can be left in the house. They function as enrichment material, and eventually biodegrade into the litter.

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Sensors for eggshell temperature in combination with a sensor for ambient temperature, RH and CO2 provide you with the essential information for fine-tuning the house environment. About 6 egg sensors per poultry house is sufficient.

The air inlets in the paper egg flats ensure sufficient heat and gas exchange. In the poultry house, but also during transport and when the trays are still stacked. Day 15

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Day 8

18-day incubated, fertile eggs hatch in the house, on paper egg flats.

Day 21

Day 32

The paper egg flats are left in the house, and have fully disintegrated by the end of the production period.

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Unhatched eggs and dead embryos are counted. The eggshells remain where they are.

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After 18 days incubation of the eggs are placed on a litter bed.

Eggs in the litter This system (Nestborn) involves placing the hatching eggs carefully on a natural litter bed. This method leaves the least possible amount of residue in the litter. The disadvantage is that a special egg placing machine is required to place the eggs in the litter.

The eggshell temperature is monitored by a logger, with four eggs, placed in the house.

Monitor the temperature regularly. Just as in a hatcher, at a certain moment, the focus shifts from the eggshell temperature to the chick temperature. 9. H at c h i n g

Unhatched eggs are removed, you can leave the empty eggshells in place. You should also remove second grade chicks quickly. 147

CHAPTER 10:

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Chick quality

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Once almost all the chicks are dried off, they are pulled, checked, and selected. Many abnormalities or deficiencies can be traced back to the incubation process. In many cases, the chicks are then treated,

rearing farm.

vaccinated, and/or sexed. The day-old-chicks are kept in a holding area before transport to the broiler or

Emptying the hatcher baskets and first selection, which includes removing unhatched eggs and culls.

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LOOK-THINK-ACT

Signals from empty eggshells Examine the empty eggshells after hatching. This is a simple way to evaluate the incubation conditions. Inspect the height of pipping, the growth of its outer membrane/allantois, and check for the presence of urates and albumen residues. Assess empty eggshells and look for meconium (dark green first droppings from chicks) in the hatcher basket. This provides valuable information on the incubation process. When the incubation process is good, the empty egg shells are clean and dry with visible dried up blood vessels in the membrane.

What is the problem here?

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These eggs have an Aspergillus fungal infection in the air cell. This clearly changes the colour of the eggshell membranes to yellow. Check the biosecurity and take measures to prevent the fungal infection spreading further in the hatchery or incubator.

Hatcher baskets are often completely flipped over when emptied (left). Make sure that rotten eggs detected during candling and transfer are removed before tipping, otherwise they will break and infect the young chicks (right).

Here, the chicks are separated from their waste products; the brush sweeps the last eggshell residue from the chicks.

10. C h i c k q u a l i t y

149

Crush the empty eggshells

If the empty eggshells are brittle, it has taken too long for the chick to hatch and be pulled. The eggshell membranes are coming loose from the shell in some places. The eggshell looks dirty and it is covered with meconium. The chicks are dehydrated and the quality is lower.

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If you crush the empty eggshells, they should not immediately crumble in your ﬁst into small pieces (like the crust of fresh crusty bread). They should feel a little bit leathery. The eggshell membranes must be slightly moist and still attached to shell. You see a substance in the eggshell that closely resembles latex. These chicks are fresh, and the quality is good.

Urates During incubation, the embryo builds up energy reserves in the form of glycogen, stored in the muscle tissue, to be used during the hatching process. But at too high temperatures, the glycogen is exhaused, fat from the yolk is unavailable, so energy is used from the break down of body proteins. Urates are the waste products of this process. The use of tissue proteins is reflected in deformities such as a smaller heart. These chicks are damaged and therefore have a higher risk of mortality, e.g., through ascites (water belly). This is especially a problem when the house temperature is too low at the moment the day-old chicks arrive.

Urates in the empty eggshell (white strands) indicate overheating in the hatcher. This is caused by a stressrelated breakdown of protein.

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Ha tc he ry S i gnal s

Pipping height and pipping line in the setter. Consider the fact that the average moisture loss from a tray of eggs is not the same as it is for an individual egg. If the moisture loss is below 5-6%, the chick will not hatch. If the moisture loss is 7-9%, the chick will hatch but its abdomen will be swollen and enlarged and it will have red hocks. In contrast, a very low pipping height indicates excessive moisture loss, and the lack of amniotic fluid leads to a wrongly positioned chick. In such cases, the legs may even fold around the head, and the chick will not be able to pip the eggshell at all.

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The pipping height provides information about the hatching process. A high pipping height near the blunt end indicates insufficient moisture loss (weight loss). Insufficient weight loss has retarded the metabolism and the embryo is not fully developed, which makes some chicks unable to hatch. If you examine the hatched chicks, in cases of insufficient moisture loss, you will see many chicks with swollen abdomens (thick, filled yolk sac and build-up of fluid in the abdominal cavity). These chicks usually have poorly sealed navels. There are more symptoms that can indicate cases of insufficient moisture loss during the period

A very jagged pipping line is an indication of sub-optimal hatching conditions and poor chick quality.

The pipping line follows the position of the air cell. The ideal pipping height is shown on egg A. If the moisture loss was insufficient, the height of the line is higher (B). With too much moisture loss, the pipping line is low (C).

Correct pipping.

10. C h i c k q u a l i t y

Too high pipping height.

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Infection pressure

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Correct blood vessel development. The blood vessels in the empty eggshells must cover the inner surface. This shows that the egg was turned well during the first week of the incubation process. The blood vessels must be visible but fine in structure. The eggshell should be very clean.

A new critical phase begins when the chicks emerge from the eggs. The embryo was in a protected environment. Now the chicks are exposed to external factors: ambient temperature, RH, wind, bacteria, etc. And they need enough reserves to survive through the time until they can eat and drink. The bacterial count in the hatcher rises as the chicks hatch. Every time an eggshell breaks open, bacteria are released. So, if the hatch window is 36 hours, bacteria are released during all that time. These bacteria reproduce very quickly. The longer the hatch window, the greater the infection risk, especially if there are a lot of riskeggs (many bangers or floor eggs). The chicks become infected through their beaks or poorly sealed navels. The incubation time (between contamination and infection) is 3 to 5 days. Infection can be fatal for the chicks (resulting in increased mortality between day 3 and 5 in the house).

Bacteria on an egg

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Eggshell condition

Here, you can see that the Chorioallantoic Membrane (CAM) is not well closed at the base of the egg. Around day 10-12, it is normally closed into the point of the egg. If you see this phenomenon in many eggs, it is a signal that the eggs were not turned properly. The blood vessels have ‘sunk’ downwards and a clot of albumen is left in the point (unused reserve). You also see this if the chick lost insufficient moisture (and therefore weight) through evaporation.

Left: a clean eggshell. Right: an eggshell stained with meconium. This can be a source of an E. coli infection.

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Clean

Bacteria count per mm2

Of which coli-type bacteria

Mortality within 14 days

600

123

0.9%

Stained

20,000

904

2.3%

Dirty

80,000

1,307

4.1%

The dirtier the eggs, the higher the mortality within 14 days. Once hatched, the chicks come into contact with the dirty eggshells. And the longer they spend in the hatcher, the greater the risk of infection.

Sometimes you see membranes between the chicks that have come loose from the shell (popcorn membranes). This is a sign that hatching went well and chick quality is good. You see it more often in winter with dry air (cold, dry incoming air is warmed up, so RH is very low). Residue of these membranes can also be sucked up and clog the vacuum hoses during down extraction.

Ha tc he ry S i gnal s

Meconium

LOOK-THINK-ACT

Meconium is the first droppings of a newly hatched chick. You can recognise it by its very dark olive brown to black colour. Meconium in the hatcher basket indicates that the chicks were held in the hatcher for a long time. Try to take a lesson from this for the next cycle. A good climate for chicks to dry off in the hatcher has: CO2 lower than 3,000 ppm, RH 50-55%. Chick temperature is of primary importance here. The optimal temperature is 40.0-40.5°C. If all the hatcher baskets are stained with meconium, you can conclude that the chicks were pulled too late: they were held in the hatcher for much too long. If only some baskets show meconium stains, this signals that the hatch window was too long for one of the following reasons: 1. wide variation in egg storage duration 2. temperature variations during incubation

What does this photo tell you?

There appears to be an excessive amount of meconium in the hatcher basket. More meconium on one side of the basket indicates an uncomfortable climate on the other side. The chicks have huddled together, because the other side was too hot or cold. At ﬁrst glance, you see that a basket of chicks could have been pulled earlier: the eggshells are stained with meconium. If this is only the case for a couple of baskets, the hatch window was too long. If you see this in all the baskets, the chicks were pulled too late.

Meconium score

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Early feeding Providing feed and water in the hatcher basket leads to more droppings. And the chicks are sometimes left in the hatcher baskets longer because they have access to feed and water, which enhances this effect. So, it is difficult to define an accurate meconium score when you provide feed and water.

Meconium on brown eggs

If you regularly assess the amount of meconium on the eggshells, you can link the results to the incubation process (hatch window length and pull time). If the chicks are held in the hatcher basket too long, there will be more eggshells stained with meconium. Are all the eggshells very clean? If so, this can indicate a too short incubation time (= pulling too early). Then the chicks will all still be wet. Some ﬁrst droppings are a good sign.

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Meconium on white eggs

Left: clean eggs after hatching. Right: too many eggs stained with meconium.

10. C h i c k q u a l i t y

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Chick temperature Measuring body temperature

Cloacal temperature is not used often, but this is the best method of measuring body temperature. Make sure the thermometer is inserted into the cloaca to a depth of 2 cm, to ensure a correct reading. Lubricate the tip with a little Vaseline to make insertion easier. Using an IR ear thermometer on the chick’s cloaca is more animal-friendly. But this is less accurate and often shows a slightly lower reading.

Make sure your pulling procedures are good, to reduce the risk of overheating. The body temperature of chicks should be 40.0-40.5°C post-hatch. Chicks that suffer overheating are more susceptible to intestinal damage, which reduces their ability to uptake nutrients from their feed. With broilers, this makes a difference of more than 60 grams body weight at 35 days, compared with chicks that started under the right conditions. Conditions in storage can be too cold if the ventilation rate is too high. Prevent chicks being exposed to cold draughts. However, being too cold is less harmful than too hot. Chick behaviour says a lot about their temperature: are they panting or huddled together?

To properly assess chick temperature, it is important to know which measuring method is used. Measuring cloacal temperature with an ordinary thermometer (rectal thermometer) and using an IR-thermometer (ear thermometer) on the cloaca are the most commonly used methods. The IR-method will give you a result 0.5°C lower than the cloacal temperature.

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How to measure chick temperature

If trolleys filled with chicks in transport crates are kept in a holding area for too long, the heat can build up and rise. The chicks in the upper crates will overheat most quickly. Or get cold if too cool air blows over the crates.

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You can assess a chick’s temperature by holding its legs against your cheek. You will notice cold legs very quickly this way.

Ha tc he ry S i gnal s

Chick yield

Assessment of chick yield Investigate cause 69

X X X

68 67

Repeat Ideal

X X X X X

66 65

X 1

Repeat Investigate cause

Flock number Flock 1: Good chick yield. Flock 2: High chick yield, but still acceptable. Flock 3: Low chick yield.

Chick yield is only an indication. If it is too high or low, monitor it closely. If the result is extreme, look for the cause.

Causes of deviating chick yield Low chick yield

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1. Chicks spent too long in the hatcher.

High chick yield 1. Chicks did not spend enough time in the hatcher (maybe they hatched later than planned).

2. Low incubation temperature 2. High incubation temperature (chicks hatch later, and therefore (chicks hatch earlier, and therefore spend longer in the hatcher). spend less time in the hatcher). 3. Low RH in the incubator (chicks are already dehydrated when they hatch).

3. High RH in the incubator.

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< 66%: low chick yield A batch of chicks with a low chick yield has been held too long in the hatcher. Perhaps they hatched earlier than expected, because the temperature was too high.

Chick yield (%)

Chick yield is the weight of day-old-chicks, expressed as a percentage of initial egg weight at the start of the incubation process. It is not a good indicator of chick quality but does tell you something about the time elapsed after hatching (drying up = weight loss). So, the timing of weighing is very important, because once the chicks have hatched, they start drying up and therefore lose weight. If you wait for a couple of hours, you get a completely different picture. Make sure you always weigh at the same time, so the results can be compared. Ideally, use exactly the same eggs as the eggs the chicks hatched from. Calculating chick yield based on the average egg weight in a setter tray and the weight of the hatched chicks gives a far too general average, and gives little information about hatchability. Proper insight into the variation can give you valuable management tools to improve egg quality or the incubation process. Yet, this is still the most practical and commonly used method.

> 68%: high chick yield A batch of chicks with a high chick yield has hatched very recently, or incubated at a too low temperature. This could be caused by factors such as lower heat production by the embryos, use of smaller hatching eggs or eggs stored too long, or other non-optimal conditions.

Chick yield is calculated as the total chick weight expressed as a percentage of the initial egg weight at the start of the process.

10. C h i c k q u a l i t y

Do not forget to deduct the weight of the setter tray to obtain the actual egg weight. When weighing the chicks, deduct the weight of the hatcher basket to obtain the actual chick weight. This is obvious, but is overlooked sometimes.

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Drying off or dehydrating? Eggshell membrane wrapped tightly around the chick

If a chick is not offered any feed and water and its body temperature is right, it will lose no more than 1-2 grams per day. If the chick’s temperature is too high, this can increase to 4-5 grams per day! Chicks that hatch too early have a high risk of dehydration. Drying off after hatching is a desirable process but drying out (dehydration) on the first day can lead to increased chick mortality on days 7 and 14, as well as poor broiler performance. Weight loss and chick temperature 10 8 6 4

2 0

Weight loss after 12 hours (%)

An eggshell membrane sticking tightly around the chick or a very dry membrane is a signal of overheating, eggshell damage, or shock and jolts during transfer (drying out). If transfer is automated, set the machine to a slower rate, and perform maintenance in time. If transfer is manual, draw attention to the need for careful handling.

41°C/106°F

40°C/104°F

Vent temperature

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Broiler weight loss after 12 hours, at two different body temperatures. Chicks with a high body temperature lose much more moisture.

Chick yield development after hatching

optimal temperature

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Just hatched

temperature too high

Chick yield (%)

Time (hours)

Chick yield primarily tells you something about the process after hatching. The chick dries off and out, and this process reduces its bodyweight.

A dead dehydrated chick. The chick has lost too much moisture, because its body temperature was too high. This becomes visible with 10% moisture loss in the first 24 hours and is fatal when the moisture loss reaches 20%.

Different temperatures in the hatcher basket If you look at the temperature in the hatcher basket, you see that the dried chicks are already at the right temperature. Three chicks are clearly too cold. They are still wet (which can also be seen by the colour of their down), which causes them to cool down considerably.

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Ha tc he ry S i gnal s

Early feeding and residual yolk uptake The time between first and last chicks hatching is at least 24 hours with broilers. Variations in egg quality, and storage and incubation conditions can extend the hatch window, up to as much as 36-48 hours. An early chick (often from a smaller egg) can already intake some feed. This also results in better residual yolk uptake in early-hatched chicks. If the chicks have immediate access to feed and water during the first 48 hours post-hatch, there is a positive impact on bodyweight, and lower mortality during the period up to 42 days compared with chicks that had no access.

If a chick absorbs the yolk well, its body is well developed, and the residual yolk serves as a small energy reserve. If yolk absorption is suboptimal, and there is too much residual yolk, you will have a lightweight, weak chick that is unable to uptake and utilise the yolk.

Energy transitions in the egg

Proportional amounts of energy (%)

100

A chick’s colour provides information about the incubation process. Chicks must be yellow. This indicates that they have absorbed the residual yolk well. But make sure no formalin was used! Formalin masks pale chicks because it has a yellow colouring effect. 10. C h i c k q u a l i t y

albumen

burned

80 70 60 50

chick + residual yolk

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Chicks are wet and exhausted when they have just hatched. They spend the first 3-6 hours resting and drying off, then they start consuming feed and water. You can only feel and assess the real crop fill of the first chicks that hatched 18-20 hours after hatching. And this will only be detectable after 33-35 hours with the majority of the chicks. The residual yolk is 2-3 grams per chick, after an optimal incubation process. But this can vary between 1 and 10 grams, depending on the breed, egg size, eggshell quality, and incubation conditions. The residual yolk should not exceed 10% of the chick’s bodyweight at the time of hatching. The lower, the better. The residual yolk is completely used up by four days from hatching. The residual yolk provides the reserve a chick needs to survive the first day or few days of life. So, residual yolk absorption during the last days of the incubation process and the early days after hatching is a crucial process for development. The yolk contains energy, mainly in the form of fats, including immunoglobulins for maternal protection. Ensuring the correct temperature is crucial here. Residual yolk is absorbed at the right temperature and uptake of feed.

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Residual yolk

yolk sac

40 30 20

embryo

10 0

Time (days) During hatching, most of the available energy is used or converted in the chick’s body, but a significant proportion of it remains in the yolk sac. 157

Absorption of residual yolk

Chick B

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Chick A, with a small residual yolk, has absorbed sufficient nutrients, is more vital, and would have had a stronger start (if it was still alive...). The smaller chick B has a large residual yolk. The chicks itself are also smaller. It has absorbed insufficient nutrients.

All factors that delay or disrupt the incubation process influence residual yolk absorption, and therefore chick quality. So, a lot of residual yolk indicates a suboptimal incubation process. These chicks are often paler because they have not absorbed the yellow pigmentation of the yolk. The residual yolk also contains and transfers an important part of the maternal immunity. A chick that has absorbed the residual yolk well has an increased disease resistance and all its bodily functions are better developed. A chick that has absorbed the residual yolk poorly is therefore more susceptible to low temperatures and pathogens. The residual yolk can be fully absorbed within 3 days of hatching. This works best when the chicks are housed under ideal temperature conditions AND when they have been fed. Chicks housed in cold conditions will not eat. So, the earlier they can eat, the better. An excessive amount of unabsorbed residual yolk can also cause a yolk sac infection. Chicks from hatching eggs that were too warm throughout the incubation period are often shorter in length because they were unable to utilise all the nutrients in the yolk for growth. Sometimes they have even utilised protein from muscle tissue as an energy source because the fats from the yolk were not available under the excessively warm conditions. This leads to the chick hatching with a small body and a large amount of residual yolk. Sometimes the chick is unable to absorb all of the residual yolk, and part of it is pinched off. This presents as a navel deformity. These chicks have a poorer technical performance in the house, will become cold easily, and are susceptible to pathogens. They feel as if they have aching muscles, as you might after an intensive training session…

Chick A

H2O CO2

38 + 2 g

32 + 8 g

60 g egg

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heat

Poor development • mortality • diseases • poor technical results

Two chicks with the same weight, but with very different development. On average, a 60-gram hatching egg produces a chick weighing approximately 40 grams. The average chick therefore weighs 2/3 of the hatching egg weight. But that includes the unused yolk. So, a 40-gram chick with little residual yolk is better developed than a chick that weighs 40 grams with a lot of residual yolk.

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Ha tc he ry S i gnal s

Chick weight and length

Relationship between chick length and yolk-free body mass 50

10 8

40 yolk free body weight 30

4 residual yolk

10 0

18 19 Chick length (cm)

Residual Yolk (g)

Yolk free body mass (g)

Chick length and yolk-free body mass (YFBM) are positively related (chick length and residual yolk are negatively related). So, the longer the chicks in a batch, the less residual yolk.

Chick weight says very little about its development. The weight is the sum of its bodyweight and that of the yolk. The goal is to have most of the yolk converted into body tissue. So, the most interesting parameter is the yolk-free body weight (YFBM = Yolk Free Body Mass). Chick length has a strong, positive correlation to YFBM and is therefore a better benchmark for chick development. Because it is non-invasive, you do not need to cull chicks to measure their length. In a layer hatchery, you can use males to measure YFBM. The chick length provides information about the period in the setter. The more yolk the chick has utilised, the longer it will be.

19 cm

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20 cm

To ensure a good comparison of the analysis results, it is best if one person takes the measurements. Routinely check whether other staff arrive at the same result when they measure the same chick.

High CO2 content If incubation takes place when the CO2 content is too high in the second half of setting, the O2 intake is reduced. This means the embryo will burn less fat and the chick will have a larger yolk sac. These chicks lag behind in their development. They have a poorly developed intestinal system, immune system and temperature regulation. Compare it with premature incubator babies. In the hatching phase, a high CO2 (1%) alone is not very harmful. But high CO2 goes hand in hand with high temperatures.

10. C h i c k q u a l i t y

18 cm

Simply use a ruler to measure chick length. Chick length is measured from the tip of the beak to the longest toe (excluding the nail). This is an indicator of the possible growth potential. The task requires a little experience. There is also a difference if you lay one leg or both next to the ruler. In either case, to ensure a correct measurement, avoid stretching the leg too much as it twists the hips, and avoid the other leg being tucked under the chick. 159

Development of chick length in relation to parent stock age at two hatcheries

21.5

The signals given by chick length

Chick length (cm)

21.0

20.5

20.0 north hatchery south hatchery 30

40 45 50 Parent stock age (weeks)

If chick lengths do not increase as the parent stock ages - as shown at the north hatchery in the graph - it is possible that the heavier eggs were not incubated correctly. This will also be reflected in reduced hatchability and generally poor chick quality.

Parent stock age and expected chick length Target length

Too short

26-35 weeks

19-21 cm

< 17.5 cm

36-50 weeks

19.5-21.5 cm

< 18.0 cm

20-22 cm

< 18.5 cm

> 50 weeks

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Broiler parent stock age

19.5

Chick length measurement data must be interpreted correctly. Parent stock age is an important factor here. The older the parent stock, the longer the chicks should be. Chick length is useful for determining the percentage of small chicks. This figure should not exceed 1.5%. How long after hatching you measure chick length is also an important factor, and should be taken into account in the analysis. Chick length increases faster after hatching than in the egg. So, the longer the period between hatching and measuring, the longer the chick will be. A random sample of 10 chicks can give you quite a good impression, but measuring a sample of 100 is much better. This is a full hatcher basket.

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The age of the parent stock is often a determining factor for egg weight. The larger the eggs, the longer the chicks should be. Is chick length shorter than expected based on the parent stock age? If so, you can classify it as too short. These are only average values from the random sample. These are not absolute values: every hatchery must set its own targets. Examining chick uniformity (and their lengths) is actually more important than an average.

LOOK-THINK-ACT What is this black lump? With less well-developed embryos, part of the residual yolk remains on the outside of their bodies, while the navel is already sealing. Part of the residual yolk is then pinched off and a lumpy, black scab forms on the navel. If you compare the heart and liver weights with those of well-developed chicks from the same batch, you notice a considerable difference.

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Ha tc he ry S i gnal s

Working at the take-off table The chicks are taken to the take-off table for selection after hatching. First grade chicks are separated here from poorer quality chicks. The percentage of chicks selected out should be less than 1-2%, otherwise there is cause for concern. The percentage of saleable chicks varies with hatching egg quality, storage duration, and parent stock age. The incubation process also plays a significant role.

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Displays the number of chicks needed to ﬁll 90 per crate. Counts the number of chicks you reject.

Crate with selected chicks

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Even though the speed of the conveyor belt is high, you can assess chick quality by running your hands through the chicks. Observing the number of pale chicks will give you an overview of quality as well.

Good quality chicks to ﬁll the number in the crates up to 90.

Work in sessions lasting no more than 90 consecutive minutes, to ensure good concentration.

In this system the number of chicks in the crate is known, because unhatched eggs have been counted. Chicks are selected out at the take-off table and counted as they pass through the chute. The employee can see on the display how many chicks are needed to make the number up to 90 in each crate.

Running your hand through a crate of chicks will also quickly give you an impression of chick vitality.

Sit or stand at the take-off table, depending on your preference. It is best to alternate between sitting and standing. 10. C h i c k q u a l i t y

A counter at the end of the belt after the take-off table puts the same number of chicks in each basket. 161

Selection criteria There are various abnormalities or deviations based on which chicks are rejected and separated from other chicks. As a general rule: the older the parent stock, the more difficult the incubation process. There is a clear difference between the hatchery manager’s and the quality control employee’s assessment. The hatchery manager’s primary goal is to improve the incubation process.

The aim of quality control at the selection table is to deliver good chicks by removing the bad ones. The manager only needs to be informed if selection flags up many deviations from the required standards. Rejecting 1-2% of the chicks is still acceptable, but the hatchery manager must be informed if the percentage is any higher.

First impression: vitality and uniformity

Lethargic and weak (takes longer than 3 seconds to stand from lying on its back). Separate chicks that are lying on their backs in the crate.

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Lively and active (will stand up from lying on its back within 3 seconds). Normal and preferably uniform in size.

The legs should feel warmer when pressed against your cheek. The thermal image on the left shows warm legs. The legs in the image on the right are cold (they should appear lighter yellow than the hand).

The eyes are clear, clean, and open (but the chick is still wet: pulled too early?). 162

Dull eyes.

Ha tc he ry S i gnal s

Navel and cloaca

LOOK-THINK-ACT

Assess the quality of the navels. You can see the navel easily by blowing gently onto the navel area. The feathers part and the navel becomes visible. A good, well-healed navel indicates that the abdomen sealed nicely after the yolk was retracted into the body. Poorly sealed navels increase the risk of mortalities. Navels seal poorly if the yolk was an obstruction. Usually, the yolk was still too big when the chick hatched (too moist or incubated too hot).

What does this tell you?

The chick has a bloody navel. If this is a general picture (1-2% of the chicks), it indicates early hatching caused by too high temperatures in the hatcher. Check the eggshell temperatures. And check whether the sensors are functioning correctly.

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A well-healed, sealed navel.

This navel is still slightly open. A well-sealed navel must be completely closed.

The golden rule applies here too: to measure is to know. You can establish objective criteria on black navels (navel scab), which are then used for assessment.

Chicks with a large amount of residual yolk are more susceptible to an E. coli infection because their navels are often not well-sealed. A thick clot of residual yolk is also a signal that the chick’s development was suboptimal, and therefore its immune system too. An E. coli infection is more severe with these chicks.

Here, some residual yolk is protruding from the navel. This is a potential portal of entry for infection.

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Abnormal and unacceptable. This navel will not seal.

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Belly a chick’s body, around the head and belly, are the result of a torn blood vessel. This is mainly caused by damage that occurred during transfer from setter to hatcher: shocks, jolts, etc., which could be caused by a worn bearing or an abrupt stop.

A swollen, distended belly is usually a signal of insufficient residual yolk resorption. A swollen belly is caused by excessive temperatures or whenever development has been retarded in some other way. Blood clots on the outside of

It is easy to assess belly quality by feeling it.

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A supple belly and well-formed navel.

A ‘water sac’. This chick has to be rejected.

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The swollen belly is caused by a large residual yolk. Suboptimal incubation conditions always lead to excessive residual yolk.

The well-known classifications of cooking steak (rare, medium, and well-done) also serve well for assessing chick bellies. Touch your index, middle, and ring finger sequentially with your thumb, and feel the palm at the base of your thumb with the other index finger each time. The chick’s belly should feel supple like the palm at the base of your thumb feels when touching the index finger (left). A hard belly indicates too much residual yolk.

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Feathering If the chick hatched too early, white wing feathers protruding like a flag from the edge of the wing are already visible.

The down is dry and shiny. It has a pleasant odour.

The feathers are smeared with albumen. This is often the result of eggs with poor shell quality that are not properly candled and break in the hatcher basket.

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You can learn a lot about a chick’s development by the state of its feathering. The chicks must look fluffy. A newly hatched chick’s wing feathers, in particular, are still in the shaft.

Seeing this type of chick (clubbed down syndrome) too often, indicates a riboflavin (vitamin B2) deficiency in the parent stock feed. You can also see this in large numbers when an incubator lost heat for some reason. Embryos that have been warmed to incubation temperature in an early stage of incubation and are then cooled down might have this condition.

Over-developed, incubated at a too high temperature, and hatched too early. The chick is lighter, has shorter down, and longer wing feathers.

The right level of development.

The down is wet and sticky. This chick has red hocks, a string navel, poor down development on the wing and belly and signs of blood around the navel feathers. Probably caused by overheating.

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Legs Red hocks

The state of the legs says a lot about chick quality. They are vulnerable, and the most visible part of a chick’s body. Did this chick have difficulties hatching? Is this chick dehydrated?

Red hocks are caused by high temperatures in the setter phase, or in the hatcher. The chicks have no more energy reserves, and they had to work too hard during hatching. The chick literally had to wrestle its way out of the egg. You often see red hocks combined with a swollen belly (large amount of residual yolk) and a damaged comb on the beak. The chick needs a long time to recover after pipping, and during this time rests with its beak poking through the hole in the eggshell for a long time. This damages the comb and beak. Other casues of red hocks are: low weight loss (RH in incubator), cold incubation (low weight loss), and bacteria.

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Legs should be straight, with a normal colour. The legs and toes must not appear dried out.

Several chicks with bent toes is abnormal. Besides genetic defects, this could be caused by too high temperatures in the hatcher. Overheating midway through incubation may result in similar vitamin deficiencies conditions.

Chicks with spraddle leg (or splayed leg). This chick is not viable.

If you see a discoloured toe, this is often the result of the leg being trapped between something, e.g., the latticework of a crate. 166

Chicks with short legs and small heads are a sign of a vitamin deficiency in the parent stock. This can be caused by the wrong premix composition or infections. If this condition occurs with more than 3% of the chicks, there is a serious problem! This could also be a poorly developed chick from early in incubation. Ha tc he ry S i gnal s

Beak

The beaks of day-old chicks should be straight and pink.

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Beaks are vital for feeding, so every chick with a beak abnormality should be removed. If you see a few chicks with abnormalities, separate them. This is not a particular problem. However, if you notice this among more chicks, and it occurs in multiple crates, it is a problem. Chicks incubated too warm have used up their built-up glycogen reserves, and they have very little energy left for pipping and hatching. After pipping, they still need a lot of time to actually hatch. A chick’s beak can be damaged in the hole in the eggshell. This damage can be recognised by a red dot on the beak. This indicates the quality of the incubation process, but is not a reason for rejection.

A case of ‘parrot beak’ (stunted beak) is a signal of extreme concentrations of disinfectants or excessively long exposure to them. It indicates chemical poisoning.

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A red mark on the beak is a signal that the temperature was too high in the setter or hatcher. This is often associated with a swollen belly caused by a large amount of residual yolk. The chick had to make an exerted effort to hatch from the egg.

A crossed beak (scissor beak) indicates incorrect temperatures during the first few days of the incubation process.

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Serious abnormalities Some abnormalities look awful, but are not very common. If these abnormalities do occur, inform the hatchery manager right away.

If the brains of dead embryos are visible, this indicates that temperature was not optimal at the beginning of incubation. Mostly too warm; sometimes this is seen when incubated too cold (in multi-stage incubators).

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Chicks with extra limbs, limb parts, or eyes are the result of an excessive incubation temperature, or the setter trays being shaken or bumped during the first 2 to 3 days.

Chick deformities are caused by incorrect incubation temperatures, extremely low RH, insufficient egg turning or ventilation, diseases, vibrations and jolts during transport, or incorrect nutrition of parent stock.

LOOK-THINK-ACT What could cause this phenomenon? Wry neck, ‘crook neck’, ‘twisted neck’, or ‘stargazing’ is caused by a brain infection. This can be a consequence of a Salmonella, Streptococci, Enterococci, or fungal infection. Good biosecurity on the parent stock farm is key to prevent these infections.

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Tona score The Tona method is an assessment system with a total score between 0-100 based on a wide range of parameters. The various parameters have a different weight in the scoring method and there are various grades per parameter. This is different from the Pasgar score where chicks score either 0 or 1 on each parameter. A score of 100 means high quality chicks.

Did you know? A lower number of quality chicks is expected, as standard, from older parent stock. Hatchability is lower, and you have to downgrade more chicks. The cause is that fertility and eggshell quality decrease in older ﬂocks. Also, embryonic mortality might increase with parent stock age because it is more difﬁcult to provide the optimum circumstances for these larger eggs. This is why more eggs are set per batch when the eggs originate from older parent stock.

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There are a number of scoring systems that can be used to quantify chick quality. These scores are based on qualitative characteristics: reflexes, navel area, legs, eyes, beak, belly, and yolk absorption. By giving numeric scores to characteristics, you can compare the results, in a time frame, for different hatcheries and breeders. The Pasgarscoring was developed by PasReform and inspired by the Apgar-scoring used for newborn babies. Later, Jacob Tona refined this system after further research. This is not used much in practice for selection. At the take-off table employees concentrate more on freshness, colour, and liveliness. This is done quite subjectively, and is mainly based on experience. But these are fine systems for assessment and research purposes.

Scoring systems

Tona Score

Assessment

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Parameter Characteristics

Score

Lay the chick on its back and determine how quickly it returns to its Good feet. A quick spring back is ‘good’, but struggling to get back onto its Weak feet or remaining on its back is ‘weak’.

Down and appearance

Examine the body dryness and cleanness. It should be dry and clean. Clean and dry Wet Wet or dirty, or both, is not good. Dirty and wet

10 8 0

Retracted yolk

If the height of the abdomen is estimated to be higher and harder to touch than normal, then the retracted yolk is large and consistent.

Normal retracted yolk Retracted large yolk, hard to touch

12 0

Eyes

The state of brightness and wideness of the gape of the eyelids.

Opened and bright Opened and not bright Closed eyes

16 8 0

Legs

If the chick remains upright with difﬁculty, examine articulations of the knees to detect signs of inﬂammation and/or redness.

Normal legs and toes One infected leg Two infected legs

16 8 0

Navel

Examine the navel and surrounding areas for closure and colouration. If the colour is different to the chick’s skin colour, it is bad.

Completely closed and clean Not completely closed and not discoloured Not closed and discoloured

12 6 0

Remaining membrane

Observe the navel area to estimate the size of any remaining membrane. The size of any remaining membrane is classiﬁed as ‘very large’, ‘large’, or ‘small’.

No membrane Small membrane Large membrane Very large membrane

12 8 4 0

Remaining yolk

Observe the navel area to estimate the size of any remaining yolk. The size of any remaining yolk is classiﬁed as ‘very large’, ‘large’, or ‘small’.

No yolk Small yolk Large yolk Very large yolk

16 12 8 0

Activity

6 0

The Tona-score is made up of 8 parameters. A chick can score up to a maximum of 100 points. 10. C h i c k q u a l i t y

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Pasgar score Chick

Reflex

Navel

Leg

Beak

Belly

Pasgar Score

8 10

Total

Pasgar score The Pasgar score is a good tool for research and analysis. It is particularly helpful for evaluating the hatching process. Select 50 chicks randomly, and assess each chick against the 5 criteria. Each chick starts with 10 points. One point is subtracted for each negative score. The average score is an indicator of chick quality: 9 is good, 8-8.95 indicates medium quality, and scores under 7.95 are poor quality. These scores quickly reveal which aspects need attention.

An example Pasgar score. The average here is 61/7 = 8.7. The issue here is navels.

Bad

If the chick needs more time or remains lying down, its score is 1.

A navel that is open or has a black knob, a tear, show inﬂammation or is red, scores 1.

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Navel: a perfect navel scores 0.

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Reﬂexes: check whether a chick on its back will stand on its legs again within 3 seconds. The score here is 0.

Good

Legs: good, strong legs with normal skin colour will score 0.

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Dried out, red or very skinny legs, or ones with red hocks and clearly visible blood vessels, score 1.

Beak: a clean, normally coloured, beak with a nice clean comb scores 0.

A chick with dirty or red beak, and a dirty comb scores 1.

Belly: a soft and supple belly scores 0.

Chicks with a distended, hard belly, or that immediately excrete meconium when their belly is touched score 1.

Ha tc he ry S i gnal s

Abnormalities and their causes The causes of many abnormalities are known. If you suddenly notice a high incidence of the same abnormalities, try to trace them back to a common cause. Make sure the cause of the problem is tackled well from now on.

If there is one chick with a specific disorder (e.g., ‘parrot beak’) in six crates (so 1 in 900 chicks), investigate the issue.

Too warm

If eggs are incubated too cold, the following abnormalities occur: • Late and irregular hatching • High embryo mortality • Many deformities caused by irregular organ development • Navels not well sealed -> navel infections • String navels, large yolks, yellow down around the navel

Too dry

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If eggs are incubated too warm, the following abnormalities occur: • Early, irregular hatching • High embryo mortality. The skin is red • Many abnormalities such as crooked toes, and short or thin legs • Navel seals too quickly -> navel lump • Sticky down • Smaller or shorter chicks • Weak, tired chicks, caused by an underdeveloped heart • Smaller hearts and digestive system, and weaker immune system • Larger residual yolk (less uptake) • More susceptibility to bacterial infections (E. coli) • Exposed brains, extra limbs or eye (incubation conditions too warm during the ﬁrst 3 days)

Too cold

If eggs are incubated too dry, the following abnormalities occur: • Large air cell • Poor hatchability with weak chicks • Residual yolk dry and thickened • Small, weak, pale chicks • High chick mortality during the ﬁrst days of life • Reduced hatchability from pipped eggs (down stuck to the shell and excessively tough membranes) 10. C h i c k q u a l i t y

Too moist

If the eggs are incubated under too moist conditions, 8-10% of the chicks will present one or more of the following abnormalities: • Poor hatchability, weak chicks with sticky beaks • Analysis of non-pipped eggs shows many full grown, wet chicks with a lot of moisture • Small chicks with a large, distended belly • Many cases of poorly sealed navels • Sticky down, egg content on down • Red hocks 171

Downgraded chicks

Communicate with the breeder farm!

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Chicks that are downgraded at selection are sometimes kept separately (stacked offset, to help prevent overheating). Then, at the end of the day, they may be added to the other day-old chicks or sold separately. The choice depends on the market price. But lower quality chicks always have a lower technical performance: so it is seldom worthwhile.

Sometimes chicks that have been separated by selection are inspected a second time. Some chicks may well be added to the previously selected batch of first grade chicks. This is an option when grading has to be done at a very fast pace. The first batch is selected for delivery very quickly and this rough selection is then double checked afterwards. In some countries second grade chicks are marketed for a lower price, and in some cases third grade quality chicks too. This is not common practice at large hatcheries in Europe: downgraded, rejected chicks are culled. The prime target must be to deliver good chicks exclusively. But what happens if things have not gone according to plan and there are too few chicks? Apply a less strict selection procedure? That is not a good idea. It is better to simply deliver fewer chicks, change the planning schedule, or source extra chicks from elsewhere. Delivering inferior quality chicks will only jeopardise the reputation of your hatchery.

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Hatchability is important but chick quality is equally as important. Some breeders balance a ﬁne line in how they feed parent stock. This strategy is reﬂected in the chicks: higher mortality and a poorer start. So, be selective in your choice of breeder. And give feedback on your hatchability and chick quality data to the breeder! Include agreements about aspects such as feed and vaccination schedules.

With broiler chicks, the number of chicks to be culled is relatively low. A small-scale euthanasia unit is adequate.

With laying hen production, the number of chicks that must be culled is inevitably high. Besides rejected chicks and unhatched eggs, about half of the chicks will also be males. A system that is more highly automated is used here. 172

Non-viable or surplus chicks (including males in the laying sector) are euthanised in an animal-friendly way, using high concentrations of CO2. Ha tc he ry S i gnal s

Sex determination

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Vent (cloaca) sexing This gender determination method is based on the different shape of a female’s or male’s cloaca. This is definitely more difficult to see, and requires a lot of training and experience. Experienced chick sexing operatives are often flown in from abroad. How does it work? 1. The first droppings (meconium) are carefully pushed out of the chick. 2. This will open the cloaca a little. 3. If there is a little bulge in the cloaca, it is a male chick.

You can only see the genitalia when the meconium is removed beforehand. That is the purpose of the bowl.

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Sex determination (often called: sexing) is mainly carried out with chicks destined for the egg production sector, but broiler chicks are also separated in some countries. Nowadays, there are various methods that are applied to determine the gender while the chick is still in the egg. The way you identify gender depends on the breed of chicks: • feather sexing (simple and fast) -> with broilers and some white laying hen chicks. • vent (cloaca) sexing (difficult, mainly used on grandparent stock farms). • colour sexing (simple and fast). • in-ovo sexing (still under development but it will soon be obligatory in some countries).

Vent sexing is done by inspecting the state, size, lines, and folds of the cloaca. With males (above), you see a protrusion (a very small penis). With females (below), after opening the cloaca carefully, you see a clear bulbous and smooth bulge.

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Sexing and sex-linked genetic traits Feather and colour sexing are based on sex-linked genetic traits. In humans, the presence of the Y chromosome specifically leads to formation of a male: males have XY and females XX. The combination is the reverse in chickens: males have ZZ and females ZW. Recessive traits on the Z chromosome of the males are inherited by female chicks, and are expressed directly. This is true for white feather colouring (I), but the same principle applies to dominant silver (S) and slow growing wing feathers (K). Feather sexing A sex-linked gene (Kk) carries the code for wing feather length. A cross between a fast-feathering male and a slow-feathering female produces slow feathering males and fast-feathering females. Look at the outer wing section. The lower row are primary plumes, the upper row are covert plumes. If the primary plumes are longer than the covert plumes, the chick is female. If the primary plumes are shorter than or equal in length to the covert plumes, the chick is male.

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Feather sexing has to be done incredibly quickly on the selection belt.

I-

Female. The primary plumes are longer than the covert plumes.

The female has sex-linked, dominant, white feathering, and the male has recessive, coloured feathering. Cross breeding results in a reversal: all the female chicks are coloured and all the males are white.

š Male. The primary plumes are equal in length (or shorter) than the covert plumes.

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Colour sexing in a laying hen hatchery. The white chicks (males) are removed, the coloured ones continue on the conveyor belt.

Colour sexing Colour sexing is based on a trait carried on the sex-linked chromosome. This is a relatively simple method, but it does require a very experienced eye. How can you tell a male from a female? Females are mostly uniformly brown, or predominantly brown, with a light stripe running over the middle of the back. Most males are uniformly white, and sometimes have a stripe or 4 small, narrow stripes on their back. So, colour sexing is certainly not a clear-cut task. The vast majority are single-coloured and clearly identifiable, but a small minority show a different picture, which requires a trained eye. Breeding organisations offer clear photo charts showing how to differentiate genders.

There are exceptions in the colouring of females, but this only applies to a tiny minority.

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Females

60% of the female chicks

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30% of the female chicks

Males

Normal colouring of male chicks

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Exceptions in the colouring of males

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Vaccination at the hatchery

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IB vaccinations for broilers are administered, as standard, in a spray. NCD is also a spray vaccine, but this is only administered on request from the customer. Make sure the droplet size is optimal for good, uniform distribution over the chicks. Prevent the chicks from becoming too wet, which will lead to them cooling down too much.

Sometimes the chicks are vaccinated before they arrive at the rearing or broiler farm. Make sure that the ambient temperature in the chick room where they are vaccinated is 23-24°C, this also depends on how long they are held in this room. Avoid any direct airflow onto the chicks. This will prevent the chicks becoming too warm or cold. RH of 65-70% ensures that the chicks will not dehydrate. Vaccination protects the health of poultry. This is an important condition for animal welfare, food security, and public health. Vaccination also helps to reduce antibiotic use and the associated costs, as well as increasing production efficiency.

A vaccination carousel for manual vaccinations. The chicks arrive on the inner ring, and are transported onwards by the outer ring after vaccination.

A colourant is added to the vaccine fluid, to provide a check mark that vaccinations have been carried out correctly.

Automatic laying hen chick vaccination in a carousel. If required, install a heat lamp above the equipment, to take the chill off the stainless-steel channels.

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Vaccination by semi-automatic subcutaneous injection as used in a vaccination carousel.

Administering a vaccination (Marek’s disease) to laying hen chicks with an injection above the hock. Vaccinating against Marek’s is generally done for slow growing broiler breeds. The problem of Marek’s disease is less in standard breeds. In broilers often administered in-ovo.

Ha tc he ry S i gnal s

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Spray vaccination of chicks in crates is administered on the feathers. The droplets on the feathers attract the attention of other chicks, and they pick up the vaccine in this way. A gel spray vaccination stays on the feathers for a longer period to be picked up (left, middle). With regular spray vaccination, avoid exposing the chicks to draughts at all times, and especially wet chicks who risk undercooling (right).

Spray vaccinations can also be administered in the house. The spray should resemble fine vapour. In this case, the droplets are too small, and they will be inhaled too deeply. This leads to vaccination reactions.

Chicks are treated with probiotics for some customers. Wet chicks will suffer from cold faster than dry ones. Use warmer storage conditions to compensate until they have dried off. Pay attention: chicks can cope with slightly colder conditions much better than being too hot.

Beak treatment Beak treatment is used increasingly less all around the world, but it is still practised. Infrared treatment, in the hatchery, is the most animal-friendly method. This is often done at the same time as vaccination.

Infrared beak treatment and Marek’s disease vaccination in the hatchery.

10. C h i c k q u a l i t y

A day-old chick before and after IR beak treatment.

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CHAPTER 11:

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Chick transport and delivery

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Transport and delivery are stressful for the young chicks. Mortality in the first couple of days can often be linked to chick quality. After the first few days, success or failure depends mainly on the poultry

heat.

farmer. The main difference between laying hen chicks and broiler chicks is that broilers produce more

After selection and any treatments (vaccination, beak treatment, sexing), the chicks are often held in storage before being transported to the poultry farm. Keep this time as short as possible, and use the time to allow the chicks to dry off after vaccination. During the first week, chicks can only partially maintain their correct body temperature (40.5°C). For this reason, the chick storage temperature is usually maintained at 22-28°C with RH 50-65%, and a CO2 concentration below 2,000 ppm. The temperature in the chick crate should be 30-32°C (no higher), to prevent the body temperature rising above 40.5°C. Chick temperature and behaviour are crucial factors!

Blue or less intense lighting contributes to less stress, which results in calmer chicks.

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Chick storage Maintaining the temperature of the chicks is the most important factor at this stage. The chicks still do not need feed yet. You can quickly and adequately determine whether the climate is comfortable by simply listening to the sounds a group of chicks makes and observing their behaviour. If chicks are too hot, they will screech (making a lot of easily recognisable noise). The chicks are

expressing their discomfort. They pant to cool themselves (through evaporation). A panting chick uses more energy and will dehydrate faster (a chick can lose up to 2 grams of moisture in this way). You will also see gasping chicks and chicks with their beaks open. If conditions are too cold, the chicks will huddle together. A combination of very little noise and calm chicks in the crates is a good sign.

temperature sensors

ventilation panel Marking a particular colour on the bumper ring around a storage room floor is a helpful aid for correctly spacing the trolleys.

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Temperature sensors have been installed at two heights on the wall of this chick storage room. Ventilation is delivered through a panel with small perforations, to avoid any cold airflow blowing directly onto the chicks.

X Make sure there is sufficient space between the trolleys for fresh air and cooling (as in the upper image). The trolleys on the right are too close together. Each chick should have at least 21 cm² of floor space in the chick crates. The trolleys in a storage room with good climate control can be placed a little closer together.

11. C h i c k t r a n s p o r t a n d del i very

It is too cold close to the fan due to the high air velocity (and possibly cold incoming air). Make sure that the fan is not aimed directly at the chicks. Blow the air along the rows of trolleys. The chicks’ behaviour indicates whether there is enough ventilation.

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Preparation for chick transport Considerations with transport crates or boxes: • • • • •

ﬂoor area per chick/maximum number in each crate or box crate height (air space above the chicks) stackability (stability) sturdiness perforations (% of the walls and ﬂoor area)

Characteristics of transport packaging

Advantages + good air circulation possible for heat and CO2 removal + stable and good stackability + washable

Disadvantages – poor air circulation and CO2 removal because of the thick material and small perforations – not reusable – loss of stability if they get wet

Disadvantages – complex logistics to return crates – risk of cross-contamination (cleaning/disinfecting)

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Advantages + single-use, so no return freight + low cost + hygienic (single-use)

Plastic transport crates

Cardboard transport boxes

Preparation for transport is always a priority task at hatcheries. Chicks must not spend any unnecessary time in the trailer. Chick transport vehicles are specially designed with a conditioned climate for the chicks. Shocks can occur during transport, through braking, and sharp bends or uneven road surfaces (see chapter 6). Always cool down or heat up the trailer’s cargo area before loading. The climate is always controlled based on temperature, and specifically set for each load. Keep transport times to a minimum. Attention to creating the correct transport conditions is important for every load of chicks, and particularly so for long distance (international) transport. The packaging materials should be carefully considered too. The most important choice is whether to use plastic crates or cardboard boxes. Singleuse plastic is also used, which offers the advantages of both types. In future, legislation is likely to become stricter, and may stipulate that chicks have to be in the house within 48 hours of hatching. But when precisely do you start counting the 48 hour period? Should it be from the first chick to hatch or from pull time? This is also an important factor for the poultry farmer, to be able to estimate the age of the chicks accurately (younger chicks are more temperature sensitive and dependant than older ones).

The trailer must be dry. Moisture has a cooling effect on the chicks.

Sometimes a climate controlled loading bay is used to maintain the most stable conditions possible during the process. The trailer docks hermetically to a loading room or a loading bay accessing the chick storage room. 180

Avoid all the doors being open at the same time during loading. This will create excessive temperature fluctuations. An easily closed curtain can help to maintain a stable climate. Ha tc he ry S i gnal s

Cargo area climate

d te ec CO2 sensor in the trailer. The glass jar is used to cover the sensor when the trailer is being cleaned. But do not forget to remove it after cleaning!

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Temperature or CO2? Ventilation has multiple purposes. Ventilation air cools the chicks and removes CO2, but its main purpose is to maintain a uniform, stable climate in the trailer. Using intensive cooling with low air circulation has the inherent risk of temperature variations in the trailer (too cold close to the cooling source and too warm in other places). If high ventilation is necessary to maintain an optimal CO2 concentration, there is a risk of the temperature becoming too low (especially in winter if the incoming air cannot be pre-warmed). The minimum ventilation requirement is 34 m3/ hour/1,000 chicks during winter (< 5°C). And this is twice as much during warm weather (> 25°C).

The driver must be able to read out the important climate data in the trailer from the cab, so adjustments can be made during transport if necessary. Many chick transport systems have an on-board computer that shows the driver the status of the system/climate in the trailer. The warmth in the trailer must be uniformly distributed.

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The cargo area climate must be right for the chicks. This applies to both transport by road and airfreight. The microclimate in the chick crates or boxes is actually more important than the climate in the loading area. Chick temperature and behaviour are the determining factors regarding transport conditions, but the general guideline is to maintain a temperature around the chicks of 32-35°C. This means the temperature in the crates or boxes should be 28-32°C, which requires the following climate conditions in the loading area: • Temperature 22-28°C • RH 50-60% • CO2 500-600 ppm If plastic crates are used, the truck’s cargo area temperature needs to be a little higher (24°C) than with cardboard boxes (20°C), because of the material’s insulating properties.

Stack and position the crates in a way that creates an unobstructed flow of air around them. Firmly secure the crates to prevent them moving during transport.

11. C h i c k t r a n s p o r t a n d del i very

The heat production of a chick (still only taking nutrients from residual yolk), is 0.35 W; twice the level of that in the setter on day 18. Chicks that have already taken feed produce even more heat, 0.6 W. Take this into account when entering the transport temperature settings. Suppose you are going to transport 75,000 day-old early fed chicks in a trailer with a capacity of 50 m3. These chicks produce 75,000 * 0.6 = 45,000 Watts of heat. For comparison: you could heat a similar space to room temperature perfectly with only one 5,000-Watt heater. But the heat production of these chicks is equivalent to nine times that heating capacity!

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Ventilation during transport With insufficient horizontal ventilation, the chicks in the upper and lower crates, in particular, will not get enough fresh air. Convection causes heat to rise and creates the highest temperature in the uppermost crates. The space under the roof of the trailer can also become particularly hot, especially in tropical regions.

Horizontal ventilation is the simplest method. However, the risk here is sufﬁcient ventilation for the crates in the middle layers, but insufﬁcient ventilation for the upper and lower layers. And chicks at the front of the trailer will have more ventilation than those in the rear.

Vertical ventilation from the ﬂoor ensures good ventilation throughout the trailer.

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The chicks need a continuous supply of fresh air during transport, to remove heat and CO2, and ensure a sufficient oxygen supply. Ventilation is essential. The system may operate according to a horizontal or vertical ventilation principle. This is partly determined by the ventilation openings in the crates or boxes. Vertical ventilation is not usually possible with cardboard boxes.

Ventilation system that uses the principle of laminar airﬂow. Here the stacks of crates are separated by perforated radiators that distribute fresh air at all levels.

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Ventilation in a V-shape is a more sophisticated method. When loading the stacks of crates, you ensure that the air pressure remains stable towards the rear of the trailer instead of decreasing, so that the same volume of air is blown sideways through all the crates.

These laminar radiators can be folded away when loading the truck. Little room is required between the crates, because the fresh air is distributed evenly at chick level.

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Ha tc he ry S i gnal s

•

International transport

• • • •

vibrations air pressure increase

vibrations air pressure reduction

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Landing and take-off are the primary stress points in airfreight, because they involve variations in air pressure, temperature, etc. The cargo itself is climate controlled, but the cooling and ventilation are always shut down during takeoff, and that involves a real risk of overheating.

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High numbers of day-old-chicks are exported, and as this transport takes more than a couple of hours, feed and water must be provided in transit. The number of chicks in each transport crate depends on the ambient temperature at the supplier’s location AND the destination (moderate climate: 100 chicks per crate, tropical climate: 80 chicks per crate). The chicks must be unloaded immediately on arrival. International logistics (e.g., airfreight) sometimes involve longer waiting periods so it is vital that the chicks are not left in direct sunshine or cold places for too long. At the airport, the cardboard boxes with chicks are stacked in the animal hotel on special aircraft pallets, usually in a pyramid shape and fitted with spacers (which have to be supplied by the hatchery) that guarantee uniform box spacing for good airflow and stability. Always opt for a direct flight because landings before the final destination is reached usually lead to things going wrong. Make sure that the plane will be connected to a power supply immediately on landing, to maintain the temperature/ventilation conditions. Some distant destinations do not have sufficiently equipped airport services, and the unloading conditions can be far from optimal. Make sure you are well aware of all official procedures and official documents that are necessary before you ship chicks to an airport, or even pick them up.

stable and calm

Exporting day-old chicks can be a smooth process but it often goes wrong when there are landings, stopovers or transfers before the final destination.

11. C h i c k t r a n s p o r t a n d del i very

Plastic crates are also used for international transport. This makes better ventilation possible and plastic has a lower insulation capacity, which reduces the risk of overheating.

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Transport to and from airports

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If the plane lands more than an hour early and the trailer has not yet arrived, unload the chicks from the plane and place them in a room with a temperature between 20 and 22°C. Make sure there is sufficient space between the chicks and sufficient ventilation and air circulation around the boxes or crates.

For air freight, the chicks have to be delivered to the airport 4 hours in advance of the flight. This requires the correct facilities there. The animals have to spend a long time in the boxes. Ensure the trailer arrives at the airport an hour before the flight carrying the chicks arrives. Cooling is a major problem in a plane that has just landed and is still moving. After landing, unload the chicks onto the transport vehicle quickly, and avoid unnecessary transfer delays. So, it is better to drive the chicks some distance and put them on a direct flight, rather than using multiple short flights with transfers.

Cardboard boxes are mainly used for international transport, but they must be sturdy enough to withstand all the handling they will be subjected to.

Loggers are installed in some chick boxes, to monitor the temperature around the chicks.

Polystyrene bars and wood dividers help minimise shock effects and ensure stability.

This vehicle is used to transport the chicks from the trailer or temporary storage area to the plane. The vehicle can be closed to protect the chicks from exposure to cold, heat, wind, or direct sunlight.

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Ha tc he ry S i gnal s

Feed and water during long transport Chicks need feed and water during international transport. It can be provided in different ways. Feed and water can be provided in the form of a gel, but sometimes a simple method will suffice. Chicks are sometimes given a hydrating injection containing a physiological salt solution, in the neck fold (often 1 ml). This method is only used with parent stock or laying hen chicks because it is very labour intensive, so expensive. A hydrating injection is often combined with a Marek’s disease vaccination.

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In this system, water can be stored in the hollow frame of the transport trolley and is made available to the chicks via nipples.

The maximum duration of day-old-chick transport is 36-72 hours. The chicks are sometimes provided with feed in the transport box, e.g., halved oranges, melon peel, cooked rice etc.

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Loose feed and water in gel form for long-distance transport. There are also combined feed and water gels for chicks.

If the outdoor temperature is high, load fewer chicks in each box, e.g., 80 chicks instead of 100.

In hot climates, it is wise to deliver chicks very early in the morning or at night.

11. C h i c k t r a n s p o r t a n d del i very

Do not leave the chicks in a hot place for any longer than necessary. The heat from the lower boxes or crates builds up and rises. This causes overheating in the upper boxes.

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Chick delivery

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The driver must be familiar with each house, and precisely where the chicks should go. Only unload the trolleys when there is an employee ready to take them over from you. Do not leave chicks outside for a while during the process. The hatchery must know the unloading sequence of the houses, so the trailer can be loaded in the correct reverse order.

Sometimes more chicks are delivered than were ordered, to provide a buffer for mortalities. This is inadvisable. Many countries have a legally regulated amount of kg/m2 you are permitted to set up in a house (varies per breed and system). On delivery, park the truck with the cab to the wind, to prevent the chicks cooling excessively during unloading. The driver often enters the house to check floor and litter temperatures. In line with biosecurity measures, it is important that a driver entering the house wears special work clothing and footwear. Unloading should be quick and efficient, so the chicks do not cool down or get overheated. Set protocols help to improve quality. Being well prepared to receive the day-old chicks is especially important to achieve good technical results in cases where initial uniformity is less than ideal. Chick temperature and reducing variation in body temperature are crucial factors. You can support this by creating a temperature gradient in the poultry house, so the chicks can find the optimal location themselves!

A plastic curtain at the rear of the trailer is useful for keeping warmth in if the chicks cannot be all unloaded in one go. Have the driver phone in advance with the expected time of arrival. Current live tracker technology permits vehicle tracking in real time. This means you can unload the chicks without unnecessary delays.

Unloading the chicks directly into the house is the best method in terms of heat production. When you leave the crates stacked up, the heat builds up from the lower layers and the chicks in upper levels overheat. 186

The trolleys with crates often have to be pushed over paved surfaces at the broiler farm. This is stressful for the chicks, due to temperature fluctuations and vibrations. Park the trailer as close to the house as possible.

Hygiene during delivery

The house must be clean, dry and disinfected before placing the chicks in it. Once the chicks are all in the house, the crates and the trailer must be thoroughly cleaned and disinfected, to prevent cross contamination.

The driver takes the empty crates, etc. away immediately and waits until all the chicks are placed in the house.

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Disinfect the paved surface outside the poultry house before the trailer arrives to prevent pathogens entering the house.

The crates are then washed and disinfected at the hatchery. Only reuse them when they are completely dry!

Once the trailer is fully unloaded, clean and disinfect it completely before it returns to the hatchery again. Ensure the pressure on the jet washer is high enough to clean surfaces properly but not so high that it diffuses contamination through the air.

In cases with multiple delivery destinations, the wheels of the truck and trailer must be disinfected after each farm visit. In this case, the vehicle has an automatic disinfecting unit integrated in its wheel arch.

11. C h i c k t r a n s p o r t a n d del i very

187

On the poultry farm

The poultry farmer has to carry out a lot of preparation before placing new chicks in the house. During the first 7 days a mortality rate of 1% is normal. With whole-house brooding, the ambient temperature must be 30°C, and it should be 32°C for spot brooding. A slightly higher temperature is used for laying hen chicks than for broilers. The optimal litter temperature is 28-30°C, and the RH should be 60-70%. Chick temperature is the guiding factor here too. Chicks cannot yet regulate and maintain their own body temperature at the right level, so the correct temperature is a vital factor for a good start and a healthy metabolism. This is why you should maintain a comfortable ambient temperature after hatching, from storage through transport and after arrival in the house.

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Chick body temperature should be 40.0-40.5°C, when measured in the cloaca (39.5-40.0°C with an IR thermometer). There will be 10% mortality, between day 3 and 5, among chicks with a body temperature of only 37°C at the time of unloading from the trailer.

You get an impression of the chick quality (vitality, temperature) by running your hand through the box or crate. They will climb onto your hand, which allows you to feel their legs well.

A cold floor has a considerable influence on the survival chances of broilers. A cold floor can increase mortality by several percent. 188

After one day, feel the crops to see whether the chicks have taken enough feed.

A litter temperature of 26°C can lead to about 2.5% increased mortality. Raising the litter temperature to 32°C at placement and through the first week can help reduce mortality to below 1%. Ha tc he ry S i gnal s

House conditions inspection Arrival check The poultry farmer must always carry out a arrival check. 1. Measuring chick temperature on arrival (= checking the transport conditions). 2. Check the chick temperature again 4 hours later (= checking the house climate). 3. After 8 hours, check the crop ﬁll (85% of the chicks should have a full crop). 4. They should all have full crops by 8 to 12 hours after arrival.

Set out the required climate conditions in the house. The target values are: • Floor temperature: 28/29°C • Litter temperature: 30°C • Ambient temperature: 34°C for broilers and 36°C for laying hen chicks • CO2: max 3,000 ppm • RH: 70%

Variations in chick temperature after hatching

42 41

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Claocal temperature (°C)

optimal chick temperature

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The body temperature (cloaca) of day-old chicks must be between 39.5 and 40.5°C. This fluctuates according to ambient temperature and airflow. The graph shows that body temperature fluctuates quite a bit in practice. Try to minimise fluctuations in both severity and duration.

Inspect the house before placing the chicks. The house inspection must be done before the delivery, to avoid claims. Floor temperature is one aspect that must be checked (the concrete, not the litter). Always do this in collaboration and agreement with the broiler farmer, with the aim of helping to improve each other’s operations. 11. C h i c k t r a n s p o r t a n d del i very

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The driver often performs the house inspection, observing all the hygiene regulations (over-shoes, disposable or clean overalls, hairnet as well as washing and disinfecting hands). This reduces the risk of cross-contamination from one farm to another, or infecting the truck cab, which is difficult to disinfect. The floor temperature in the house is particularly important. The chicks are unable to regulate their body temperatures well during the first 4 to 5 days. If the floor is cold, the legs are chilled and the chick cools down. This will lead to inactivity, and the chicks will not intake any water and feed, resulting in mortalities. The floor in the house must be at the right temperature when the chicks arrive. That is why it is necessary to already start warming up the house 3 days before delivery. This applies in particular to houses with concrete floors. The floor should be properly warmed up before spreading the litter. Litter has an insulating effect and will stop the floor warming up. It is more important to pay attention to the floor temperature than the litter temperature (which is derived from the floor and ambient temperatures). Starting to warm the house just a few hours in advance can result in a good ambient temperature, but the more important, optimal, floor temperature will not be reached. Once the chicks grow older, they can regulate their body temperatures (41.0-41.5°C). Chicks from young female parent stock (< 35 weeks) are capable of this after 7 days. Chicks from older female parent stock can do this after 5 days.

A piece of chick paper is taken from one of the crates, to detect any diseases the chicks might have on arrival.

189

First week mortality Signals from ﬁrst week mortalities The pattern of mortality during the ﬁrst week provides a clear picture of the cause.

Mortality (%)

Peak in the first few days: poor quality broilers

normal

3 4 Chick age (days)

First week mortality is a good indicator of chick quality. A mortality rate of 1% is acceptable. Higher mortality is a signal of a problem. Immediate mortalities indicate poor conditions around and post-hatching. High mortality a couple of days later is often caused by a bacterial infection. Mortality at the end of the first week is a signal of poor placement conditions at the poultry farm. Vaccination reactions can occur in cases where a live vaccine has been administered, and this can lead to higher mortality during the first week.

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3 4 Chick age (days)

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Mortality (%)

Peak at day 4-5: bacteria

A mortality peak around day 4-5 is usually caused by bacteria (e.g., through poor hatching egg quality).

Increase mortality from day 5 onwards: poor broiler management

Mortality (%)

Mortality during the first 3 days is associated with the day-old chick quality and the post-hatching conditions.

Chicks with a white-grey (cement-like) deposit on the cloaca often have a serious bacterial infection (e.g., Salmonella) or a (viral) kidney disorder. It can also be caused by overheating chicks (after hatch) or a turning issue. With a turning issue the tail is not formed properly and urates are deposited in the abdominal and cloacal areas. Remove these chicks. Peritonitis retards intestinal peristalsis, and urine runs out of the cloaca spontaneously. When this dries up it has a cement-like appearance.

normal 0

3 4 Chick age (days)

A later peak is a consequence of poor broiler management.

You can recognise a chick with helicopter-wing, by its poor feather development: the down and feathers are inter-mixed. This is caused by Runting Stunting Syndrome (RSS), also known as malabsorption syndrome (MAS).

190

Ha tc he ry S i gnal s

Index Packing 47 Paper egg flats 47, 146 Parent stock age 97 Pasgar score 170 Personnel 69 Physiological zero 45, 46 Pipping 136, 137 Pipping height 151 Pipping line 151 Placing chicks 188 Planning 9 Plastic tray 47 Point setting 60 Preparation 98 Pre-warming 100 Pull time 138, 140 Pulp tray 47, 146 Red hocks 14, 166 Relative Humidity (RH) 36, 37, 105 Residual yolk/yolk sac 19, 157, 158 Routing 65 Scoring system 169, 170 Selection criteria 162 Setter trays 82 Setting 94, 99 Sexing 173 Signals concept 13 Single-stage 7, 42, 43 Slow-growing broilers 28 Spectroscopy 123 SPIDES 58, 89 Storage (chicks) 179 Storage (eggs) 58, 76, 84 Storage conditions (eggs) 58, 59, 85 Storage duration 86 Take-off table 161 Temperature 25 Temperature development 46, 78 Temperature requirements 25 Temperature settings 32 Temperature variation 31, 32 Tona score 169 Track and trace 61 Transfer 114, 126 Transition 102 Transport 144 Transport (chicks) 180 Transport (eggs) 76, 126 Transport conditions 80 Trolley cover 80 Turning 88, 107-109 Unhatched eggs 141, 142 Uniformity 12, 27, 31, 51 Urates 150 Vaccination 120-122, 176, 177 Variation 12, 27, 31, 51 Vent sexing 173 Ventilation 34, 39 Ventilation (transport) 182 Washing 56 Weight loss 27, 37, 38 Wet bulb temperature 78, 79 Yolk Free Body Mass (YFBM) 159 Yolk sac/residual yolk 19, 157, 158

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Embryonic development 20, 21, 45, 95 Employees 71, 72 External pipping 137 Fahrenheit 7 Feather sexing 174 Feathering 165 Filling 99, 101 Floor eggs 54, 55 Floor quality 67 Fluff 134, 139 Formalin 75, 91, 92, 93 Fumigation 91 Gas exchange 26 Gender reversal 125 Hatch moment 139 Hatch of fertile 119 Hatch of set 118 Hatch of transferred 119 Hatch peak 134 Hatch window 138 Hatcher baskets 131, 144 Hatchery manager 8-10 Hatching 132 Hatching egg 19 Hatching systems 143 Heat distribution 106 Heat production 25, 33, 39,181 Heating 102 House inspection 189 Humidification 103, 134 Humidity 59, 134 Humidity peak 134 Hygiene 53, 69, 128, 130, 187 Incubation temperature 31 Infection pressure 152 Infertile 112, 115-117 Information exchange 11, 12 In-ovo sexing 123 In-ovo vaccination 120, 121, 122 Integration 5 Internal pipping 136 International transport 183 Jolts/vibrations 81 Key indicators (KPI) 118 Laying date 97 Laying hens 29 Legs 166 Litter 147 Logistics 82 Long storage 87 Long transport 185 Measuring 34, 38, 154 Meconium 153 Mixing 95 Moisture loss 27, 37, 38 Monitoring 110, 111 Mortality 190 Multi-stage 7, 42, 43 Natural brooding 22, 23 Navel 163 On-farm hatching 145 On-farm traying 48 Origin 96 39 Oxygen (O2)

Abnormalities 76, 168, 171 Air cell 38, 49, 85 Air temperature 133 Air velocity 41, 101 Airflow 102 Airport 184 Altitude 41 Arrival check 189 Artificial incubation 22, 23 Aspergillus 75, 93, 142, 149 Bacterial load 53 Bangers 90 Beak 167 Belly 164 Biomarkers 124, 125 Biosecurity 62 Biosecurity zones 64, 65 Breakout 113, 129 Breeds 29 Broilers 29 Calibration 98 Candling 112, 113, 115-117 35, 39, 104, 159, 181 Carbon dioxide (CO2) Cargo area climate 181 Celsius 7 Chick delivery 186 Chick length 159, 160 Chick quality 148 Chick temperature 154 Chick transport 178 Chick weight 159 Chick yield 155 Cleaning 73, 74 Climate conditions 101 Cloaca 163 Cloaca sexing 173 Colour sexing 175 Condensation 17, 40, 59, 77, 80, 100, 133 Condensation point 77 Cooling 40, 46, 47, 102, 106 Cracks 52 Critical batches 15 Critical locations 15 Critical moments 16, 17 Dew point 77 Dirty eggs 50, 53 Disinfectants 93 Disinfection 57, 63, 75, 90-93 Downgraded chicks 172 Dry bulb temperature 78, 79 Drying off 156 Drying out 156 Early feeding 143, 153, 157 Early mortality 46 Egg grading 48 Egg handling 44, 49 Egg inspections 83 Egg quality 44, 50 Egg shape 49 Eggshells 49, 149, 150 Egg size 49, 51, 97 Egg weight 49, 51, 97 Eggshell temperature 30, 45 Embryo position 135

Roodbont Publishers Roodbont Publishers considers its core business to be supporting agriculturalists by providing the right information at the right time. Agricultural publications from Roodbont can be ordered from bookstores or direct from Roodbont, tel. +31 (0)575 54 56 88, e-mail: info@roodbont.com or from the website: www.roodbont.com or www.poultrysignals.com. Language editions: Check availability of various language editions via www.roodbont.com. POULTRY SIGNALS A practical guide to bird focused poultry farming

TURKEY SIGNALS A practical guide to turkey focused management

Proper management starts with recognising signals in practice. This means being alert, watching, listening, and paying attention to their behaviour. This provides much information about animals’ health, well-being and production.

On a global scale, turkey production volumes are relatively stable. Efficiency improvement is the main challenge for every turkey farmer. Turkey Signals follows the cycle on a commercial turkey farm. ISBN 978-90-8740-262-4 200 pages, 20.5 x 26.5 cm

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Broilers grow fast in a short period of time. That’s top sport and the slightest disturbance can disrupt this delicate process. So you need to quickly respond to signals, but more important is to avoid problems.

BROILER SIGNALS A practical guide to broiler focused management

ISBN 978-90-8740-079-8 112 pages, 20.5 x 26.5 cm

Egg Signals follows the egg’s progress through all the links in the chain. It describes the creation of the egg’s unique composition. Egg Signals uses 650 photographs and images to illustrate the basis of thinking about egg quality, and describes how to act accordingly. ISBN 978-90-8740-272-3 164 pages, 20.5 x 26.5 cm POULTRY SIGNALS - AFRICAN EDITION A practical guide for bird focused poultry farming A special edition of Poultry Signals has been developed for Africa, based on African circumstances concerning climate, farm size and management. Published in both English and French. ISBN 978-90-8740-349-2 130 pages, 20.5 x 26.5 cm

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LAYER SIGNALS A practical guide to layer focused management

EGG SIGNALS A practical guide to improving egg quality

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LAYER SIGNALS A P R A C T I C A L G U I D E T O L AY E R F O C U S E D M A N A G E M E N T

Kept in cage or floor systems, for a good performance during the production period, the management must be on point. This edition focuses purely on layers with a great deal of attention paid to breeding and egg quality. ISBN 978-90-8740-124-5 120 pages, 20.5 x 26.5 cm

BREEDER SIGNALS A practical guide to optimal management of broiler breeders This book contains practical information about broiler breeders to ensure a maximum production of first grade hatching eggs. It follows the day-oldchick arriving at the rearing house towards the laying period up to egg transport to the hatchery. ISBN 978-90-8740-332-4 187 pages, 20.5 x 26.5

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