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EDITORIAL
➤ Marianna Caterino
The recent Fieravicola conference on in-ovo sexing has once again highlighted a pressing issue within our industry: the elimination of male chicks in laying lines As of 2026, multiple European countries - including Germany, France, Italy, and more recently the Netherlands - have enacted or endorsed legislation to prohibit the culling of male chicks. The shared goal is to prevent male chicks from hatching by using in-ovo sexing technologies.
This is a regulatory change that affects the entire European poultry supply chain. In-ovo sexing technologieswhich enable the determination of an embryo’s sex before hatching - are advancing rapidly. Methods based on artificial intelligence, imaging, hyper spectral spectrometry, and magnetic resonance imaging are already being adopted in several hatcheries across Europe. Recent estimates indicate that approximately 20% of laying hens in the European Union are already hatched using in ovo sexing techniques - a figure that continues to rise.
However, the adoption of these solutions still faces significant challenges. In particular, small and medium-sized enterprises face high implementation costs and the need to adapt their infrastructure. Institutional backing through tangible support measures is crucial to ensure that the transition is inclusive across the supply chain and does not undermine its competitiveness.
In-ovo sexing is not merely a technological innovation; it marks a step toward more ethical and animal-friendly poultry farming.
Improving broilerbreeder performance with 25-hydroxyvitamin D3 of fermentative origin
MARKETING
Dynamics and structure of meat production and meat trade in the USA between 2019 and 2023. Part 2: meat trade
4 8 12 14 18 24 28 36 44 47 48 MAY 2025
TECHNICAL COLUMN
Warm weather ventilation management
MANAGEMENT
The manureshed concept: a solution to poultry litter nutrient recycling?
VETERINARY
Clinical coccidiosis in broilers with concurrent infection of Eimeria maxima and Eimeria praecox
MARKET GUIDE
UPCOMING EVENTS
INTERNET GUIDE
A NEW STRATEGIC COLLABORATION FOR THE INTERNATIONAL EGG FOUNDATION
Building on the recent outstanding success with the Honduras Outreach International (HOI) programme, the International Egg Foundation (IEF) and OneEgg have announced a strategic collaboration to significantly extend the reach, sustainability and impact of their shared mission to provide children with essential nutrition through eggs.
This partnership unites the IEF’s network and expertise in egg production with OneEgg’s proven model of creating sustainable agribusiness operations to deliver essential protein to vulnerable children and to drive positive change in communities around the world. The collaboration will focus on achieving the following shared objectives:
• Expanding Reach – To increase the number of children benefiting from egg-based nutritional programmes.
• Enhancing Sustainability – To develop and implement viable egg production models that ensure long-term food security and community empowerment.
• Maximising Impact – To improve the nutritional status and overall well-being of children through access to highquality protein, in the form of eggs.
In 2024 and early 2025, the IEF and OneEgg realised the impact of their collaboration at Honduras Outreach International (HOI) in expanding the reach of the 1,000 Days of Life programme by building a 3,000-capacity egg barn. HOI and OneEgg deserve recognition for initiating the partnership in this incredible initiative, which aims to enhance nutrition during the critical first 1,000 days of a child’s life—from conception to around their third birthday. The programme, which provides pregnant mothers and her family with one egg per day throughout this period, supports overall household nutrition. With OneEgg and IEF working hand-in-hand with HOI and other key partners, the programme has laid a strong foundation for future growth. It is now able to expand its reach of the current roughly 50 families to 100 or even more, expectant mothers and families, receiving this vital nutrition during this crucial development period.
Looking ahead, the next collaboration will focus on expanding egg production capacity at the Blessman
Project in South Africa. This initiative aims to reach even more children, enhance the project’s self-sufficiency, and strengthen its positive impact on the community by increasing access to vital nutrition.
Bruce Dooyema, Chairman of the IEF, highlighted the significance of this expansion: “We are excited about the opportunity to collaborate with OneEgg on the Blessman Project, which is currently feeding 50,000 children 5 days a week, with a goal of reaching 100,000. Our shared vision is to provide an egg a day to these children and to launch the ’First 1,000 Days of Life’ programme in South Africa, supporting expectant mothers and their families. In partnership IEF, OneEgg, and Hy-Line, plan to take egg production from the current 1,200 birds at the project and expand to 4,700 layers in 2025. This partnership could help to scale even further, ensuring more children receive the essential nutrition they need to thrive.”
Source: IEF www.internationaleggfoundation.com
LA CARIDAD STARTS TO SUPPLY HUBBARD
EFFICIENCY PARENT STOCK IN
VENEZUELA
Hubbard and Grupo La Caridad are very pleased to announce the start of supply of the locally produced Hubbard Efficiency Plus Parent Stock to their customers.
In August 2024, La Caridad placed the first Grand Parents which are now starting to produce the Hubbard Efficiency Plus Parent Stock to meet the needs of the conventional broiler market in Venezuela.
Mark Barnes, Hubbard LLC General Manager, emphasizes: “Grupo La Caridad is a historical and major Venezuelan agricultural company with subsidiaries involved in poultry breeding, broiler chicks, and broiler meat as well as feed milling. Working together with such strong company is a great new step for our business to be able to make the Hubbard breeders available from local production.
Johnny Jose Curbelo Monroy, legal representative of Grupo La Caridad, says: “The main objective of this
important development is to meet the national demand for the product throughout the territory of the Bolivarian Republic of Venezuela, guaranteeing quality standards and having Hubbard’s support for our customers.”
For further information, please contact your regional sales representative or communication@hubbardbreeders.com
TPI-POLYTECHNIEK
INTRODUCES THE ECC500:
INNOVATION IN EGG TRANSPORT PROTECTION
TPI-Polytechniek, producer and supplier of ventilation components for the agricultural sector, is proud to announce the launch of its latest innovation, the ECC500. The ECC500 is developed to help companies transport eggs safely and efficiently without compromising on quality or cost.
Why the ECC500?
In the poultry industry, protecting eggs during transport is essential. With a focus on protection, durability, and versatility, the ECC500 offers more than standard protection. Its durable construction ensures a long lifespan, reducing maintenance and replacement costs. Thanks to its versatility, the ECC500 fits various transport systems and can easily handle bends, inclines, and other transport challenges. Whether it’s protection against temperature fluctuations, shocks, or other environmental factors, the ECC500 ensures eggs arrive undamaged. This solution not only guarantees higher yields but also helps maintain consistent quality – a benefit felt throughout the supply chain.
The solution
Made from high-quality polyurethane, the twelve-sided ECC500 offers superior insulation and protection, and can be opened and closed easily. The cover is secured to an adapter base, allowing installers to use their own bracket suited to specific situations. The cover can follow any route, with fully customized bends, inclines, and declines. The ECC500 is compatible with various egg conveyor systems,
providing a standardized, effective long-term solution for poultry farmers.
Key features and benefits
• Lightweight and durable: made from high-quality polyurethane with a long lifespan.
• High insulation value: maintains consistent egg temperatures, protecting against harmful fluctuations and environmental influences.
• Easy to install and remove: simplifies maintenance and cleaning.
• Flexible installation options: suitable for bends, inclines, and declines.
• Ideal for long distances: perfect for extensive setups.
• Versatile fit: compatible with multiple egg conveyor systems.
Loic van der Heijden, Managing Director of TPIPolytechniek: “We are excited to introduce the ECC500. This product represents a significant advancement in egg protection technology. Our goal is to provide poultry farmers with a reliable, cost-effective solution that boosts yield and productivity.”
Aviagen Turkeys Ltd (ATL) held an exclusive 'Customer Open Day' giving a unique insight into a selection of techniques that are applied in the Aviagen Turkeys Breeding Programme, to breed the birds for the future.
ATL welcomed many valued customers to the Customer Open Day. The event started on Monday 17th March with a drink’s reception and a private dinner at Carden Park Hotel. The evening was a great opportunity for everyone to socialise and network before the annual event.The event continued on Tuesday 18th March at Carden Park Hotel.
Clay Burrows, Managing Director of ATL, kicked off the day with a welcoming presentation and demonstrated the new facilities, improvements and major projects within ATL, Le Sayec, and Aviagen Turkey Inc. Leading on from this Clay also showed the estimated industry poult placements as well as some current trial results relating to the B.U.T. 6 and B.U.T. Premium.
Dr. John Ralph, Director of R&D then gave a presentation on ‘Driving Turkey Production Efficiency’. This focused on ways ATL is breeding for improved efficiency through
selection traits and breeding programme operation. Firstly, he showed the competitiveness between turkey and the other meats, discussing how to grow turkey consumption in areas such as feed conversation and genetic improvements with balanced breeding goals. John concluded his presentation by explaining what to expect with the annual improvements in the coming years with the B.U.T. 6 and B.U.T. Premium. He showed how far we have come since 1977 and how far we can still go with these breeds.
The customers were split into smaller groups and taken around four different demonstration areas. This included a presentation from Dr. Samuel Sosa, Research Geneticist Samuel spoke about “Innovating Turkey Breeding: The Role of Genomics in Shaping Tomorrow. Samuel Sosa delivered a presentation about how ATL has applied genomics in its turkey breeding programmes over the years.
He explained the relationship between genomics, genetics and animal breeding. This led to an introduction of the two breeding programmes at ATL, the selection scheme and the importance of genomics for the turkey industry. He described how genomic information is utilised, starting from the genetic markers (SNP-single nucleotide polymorphism), through to the SNP-array, genotyping, the machines used and the entire process at Aviagen’s Genomic lab in Scotland. The next part described the main implementations of genomics in ATL from checking pedigree integrity though to the use of genomic evaluations in the selection process. He highlighted the remarkable impact of genomics in improving rates of progress in breast, health and reproductive traits. Finally, he spoke about future developments in genomics.
Luke Ramsay, Management Specialist, spoke about “Broody Control and preventing this behaviour”. Luke began his presentation by describing the definition of broodiness, along with the factors that promote the behaviour and also the signs to look out for to recognise it. He then went on to talk about the different systems that can be used to identify broody birds, such as spray marking and manual inspections. This then led to Luke discussing the design and use of broody pens, including the daily management and possible duration of the broody treatment. The final part of the presentation focused on management of automatic nests where Luke presented internal trial results to show training the females to use the nests will help to reduce the number of females laying eggs
The 17th Turkey Science and Production Conference (TSPC), the leading meeting point for the turkey industry, welcomed over 330 delegates. ATL continues to support and sponsor the event that aims to provide an opportunity for members of the turkey industry, suppliers and ancillary bodies to update on the latest scientific developments and production trends
on the floor, and in turn help the effectiveness of broody control.
Greg Hansen, Poultry Intellimetrics, Inc, was invited by Aviagen Turkeys Ltd to present at the customer open day. Greg began with explaining the systems for grading birds, defining grade A standards and common defects which result in downgrades. He then went on to discuss how downgrading occurs and how to investigate when or where the decline occurs. Within this presentation, Greg also discussed breast blisters, live weights and foot pad scoring. Greg then stayed on for the TSPC conference on behalf of Aviagen Turkeys to present a similar presentation to a larger audience.
Sam Jones, General Manager of Production, had a hands-on presentation with virtual reality (VR) headsets. The audience were given VR headsets and were able to view Sam taking them on a tour around one of the pedigree rearing farms. Within this virtual tour, customers were able to see all of our biosecurity measures on farm, understand how our feeding systems work and explore the housing of our birds. This was thoroughly enjoyed by all customers, making them feel like they were on farm experiencing all the aspects of an Aviagen Turkeys pedigree facility.
After some lunch Customers visited our Research & Development commercial trials farm. Dr. John Ralph, Director of R&D, gave a presentation on our commercial trials. Firstly, he spoke about how and why we run these trials and their key role in breed and technical development. He discussed our facilities, differences between our breeds and competitor breeds, improvements in performance over time and some of the highlights from
technical and nutritional research over the years. This helped customers to understand our breed testing that is carried out alongside how we develop management and nutritional advice to help the industry reach the maximum potential from our turkey breeds.
The remainder of the week was then spent at the 17th Turkey Science and Production Conference (TSPC), the leading meeting point for the turkey industry, which welcomed over 330 delegates. ATL continues to support and sponsor the event that aims to provide an opportunity for members of the turkey industry, suppliers and ancillary bodies to update on the latest scientific developments and production trends.
ATL had two representatives presenting at the conference, which included:
Dr. Kenton Hazel, ATL’s European Veterinary Health Director, along with Gerard Leveque will discuss ‘Strain typing of Pasteurella outbreak isolates and biosecurity implications’.
Greg Hansen, Poultry Intellimetrics, Inc, on behalf of Aviagen Turkeys Ltd, will deliver ‘Turkey Grade and Condemnation’.
The whole week was a huge success and a great opportunity to network with everyone involved in the turkey industry.
In April, the World Organisation for Animal Health (WOAH) published a report providing an update on the highly pathogenic avian influenza (HPAI) situation, based on information submitted by member countries. The goal is to raise awareness of the global situation.
Since its initial identification in China in 1996, the H5Nx Gs/GD lineage virus has caused several waves of intercontinental transmission. Between 2005 and 2024, HPAI resulted in the death and mass culling of over 633 million poultry worldwide, with a peak of 146 million in 2022. During that peak year, 84 countries and territories were affected, similar to the 82 affected in 2024. There have been occasional human infections with various avian influenza subtypes, including H5N1, H7N9, H5N6, and H9N2, with over 2,500 reported cases since 2003. As outlined in WOAH’s Animal Health Situation Worldwide report presented at the 91st General Session of the World Assembly of Delegates in May 2024, HPAI has been a global concern, especially since October 2020. Key
developments include its unprecedented global spread, a surge in the number of poultry outbreaks and losses, an increasing impact on wildlife and biodiversity and a rise in detected cases in domestic and wild mammals.
Poultry outbreaks
According to the report, the new HPAI season, which began in October 2024, continued into March 2025, with 142 outbreaks reported in poultry and 214 in non-poultry birds and mammals across the Americas, Asia, and Europe. Approximately 5.6 million poultry were either killed or culled during this period, with the majority of cases
▲ Figure 1 - Distribution of HPAI new outbreaks in poultry, and corresponding subtypes
occurring in Europe. The number of poultry outbreaks reported in the first six months of the current seasonal wave (October 2024 – September 2025) continues to rise. Similarly, the number of outbreaks in wild birds during the same period has already surpassed the total number of outbreaks reported during the previous wave (1,332 outbreaks in the current wave compared to 1,062 in the previous one).
Based on immediate notifications and follow-up reports submitted to WOAH through WAHIS, the report outlines the current status of HPAI in poultry and non-poultry birds, including: (a) a list of new events beginning in March 2025; (b) information on ongoing events that began prior to March 2025; (c) the geographical spread of new outbreaks in March 2025, along with figures on the number of outbreaks, cases, losses, and animals vaccinated in response. The various subtypes of HPAI circulating in March 2025 are also listed.
WOAH recommendations
Given the global spread of HPAI, ongoing surveillance of wild and domestic species is essential. As this pathogen impacts wildlife, livestock, and public health, adopting a One Health approach to its management will be beneficial. WOAH encourages its Members to maintain robust
surveillance efforts, implement biosecurity and preventive measures at the farm level, and continue to report HPAI outbreaks in both poultry and non-poultry species in a timely manner. WOAH categorizes avian influenza into three types: infection with high pathogenicity avian influenza viruses (HPAI) in poultry; infection of wild birds and other non-poultry species with HPAI; and infection of domestic and captive wild birds with low pathogenicity avian influenza (LPAI) viruses that have proven natural transmission to humans, leading to severe consequences. Specific recommendations have been issued regarding mammals. Authorities and veterinarians are encouraged to consider avian influenza as a potential diagnosis in mammals that are at high risk of exposure to the virus. It is essential to report any outbreaks of avian influenza across all animal species, including those involving unusual hosts, to the World Organisation for Animal Health (WOAH). Furthermore, sharing the genetic sequences of avian influenza viruses, along with related metadata, in publicly accessible databases is strongly recommended to facilitate global monitoring efforts. Special attention should also be given to protecting humans who are in close contact with infected livestock and their products, while ensuring that no unjustified trade restrictions are imposed. High-quality information remains crucial to support effective prevention strategies and enable a rapid response to highly pathogenic avian influenza (HPAI).
IMPROVING BROILER-BREEDER PERFORMANCE WITH 25-HYDROXYVITAMIN D3 OF FERMENTATIVE ORIGIN
25-hydroxyvitamin D3 from a fermentative source was supplemented to broiler-breeders in two separate trials, compared to standard basal diets without a 25-hydroxyvitamin D3 source. Benefits in terms of reduced day-old chick (DOC) and early embryo mortality were recorded in a dose-response manner for animals supplemented with 25-OH D3, as well as an overall improved eggshell quality.
➤ W. Van Der Veken and K. Bierman Huvepharma NV, Uitbreidingstraat 80, 2600 Antwerp, Belgium
Poultry diets have developed over the years, including an increased interest in nutrients such as vitamins and minerals. A good example of the latter is vitamin D, mainly known for its involvement in the calcium metabolism and bone strength (Khan et al., 2021). However, there is more to vitamin D than this. Vitamin D (sub-)deficiencies have been clearly associated with increased mortality and reduced immunological responses, highlighting the broad importance of the vitamin beyond skeletal integrity (Khan et al., 2021; Hashim et al., 2023). This has led to more recent research focusing on the use of different vitamin D metabolites to improve other parameters in poultry, including its use in broiler-breeder diets. Of these metabolites, 25-hydroxy vitamin D3 is of major interest: it has a long half-life, acts as the major reserve form of vitamin D within the body and does not rely on the liver in the remainder of the metabolic vitamin D pathway (Sakkas et al., 2018). Within the group of 25-OH D3 metabolites, the main difference comes down to the production process: either via a synthetic pathway, or via fermentation. In the trials at hand, the first commercially available 25-OH D3 of fermentative origin was put to the test (Bio D®, Huvepharma).
Method
Two trials were performed at a commercial research centre in France with the treatments listed in Table 1. For the first trial, a total of 1080 female broiler breeders of the Hubbard D line were used. These were divided at random into 3 batches of 360 female broiler breeders each, divided over 45 repeats of 24 females each (4 hens/cage x 6 cages/ repeat). The trial ran for 70 days, from week of age 52 to 62. Egg quality and embryo mortality were evaluated at two different time points (57 and 62 weeks of age).
For the second trial, a total of 720 female broiler breeders of the Hubbard D line were used. These were divided at random in 3 batches of 240 female broiler breeders each, divided over 10 repeats of 24 females each. The trial ran for
■ Table 1 – Vitamin D supplementation in both trials (expressed per kg of feed).
1
of
in Bio D® equals 80 IU.
Figure 1 – DOC mortality (%) of the three treatment groups over the full trial. Di
Table 1 – Vitamin D supplementation in both trials (expressed per kg of feed).
One µg
25-OH D3
105 days, from week of age 48 to 62. In this trial, hatching performance as well as DOC and embryo mortality were evaluated.
Data was analysed using SAS software with the correct statistical models (GLM procedure, alpha = 5%). Models had the following constraints:
• data from each population had to be normally distributed with an even variance;
• data was obtained independently.
Normality was tested with a Shapiro test. Evenness of variances was tested with Bartlett test. If one of the constraints above was not respected, a KruskalWallis test was used.
Results
In the first trial, the inclusion of 25-OH D3 in the feed significantly improved mortality parameters, in a dose-response fashion (Figure 1).
In both trials, the addition of 25-OH D3 had clear benefits related to the performance of broiler-breeders. The observed effects occurred in a dose-response manner in trial 1 and were most pronounced in mortalityrelated parameters. The current hypothesis to explain these results would be a maternal transfer from 25-OH D3 to the developing eggs, where the increased levels of vitamin D support the early development of the embryo. This transferhypothesis is supported by the established use of dietary vitamin D to increase final vitamin D levels in eggs for human consumption, known as “functional food”. Regarding improved eggshell quality, the role of calcium in the formation of eggshell is well-established. As vitamin D is tightly linked with the calcium metabolism, improving the vitamin D status of the animal impacts its calcium metabolism as well.
The results underline the importance of adding an effective 25-OH D3 metabolite in broiler-breeder operations, even if animals are already supplemented with standard levels of regular vitamin D3.
References are available on request From the Proceedings of the Australian Poultry Science Symposium 2024
DYNAMICS AND STRUCTURE OF MEAT PRODUCTION AND MEAT TRADE IN THE USA
BETWEEN 2019 AND 2023
Part 2 - Meat trade
The first part of this analysis (Zootecnica 4/2025) showed that the USA played a significant role in global meat production between 2019 and 2023. It ranked first for beef and broiler meat and second behind China for pork. The aim of this article is to analyse the role of the USA in world meat trade and to document the export and import flows for the three most important meat types.
➤ Hans-Wilhelm Windhorst Professor Emeritus at the University of Vechta, Germany
While it was possible to maintain first place in the export of broiler meat despite Brazil’s dynamic development, Spain displaced the USA from first place in the export of pork. Due to the rapid rise in exports from Brazil and India over the past decade, the USA dropped to fourth place in beef exports, while Australia was able to defend its second place.
The role of meat exports in USA’s agricultural exports
Although the value of meat exports reached a new peak of almost $20 billion in 2023, they only contributed 10.2% to the total export value of agricultural products.
■ Table 1 - The development of the share of meat exports in US agricultural exports between 2019 and 2023; data in % (source: own calculations, based on USDA, GATS)
Table 1 clearly shows that beef and veal, despite the lower export volume (Figure 1), achieved the highest share in export value at around 5%. Broiler meat, on the other hand, only accounted for about 2% of the total value of agricultural exports, despite the three times higher export volume. The much higher value per tonne of beef and veal exported ($8,810) compared to broiler meat ($1,250) explains the difference. Pork contributed 3.5% to the export value and occupied a middle position ($2,790). Secondly, Table 1 documents that the Covid-19 pandemic had different impacts on exports of the three meat types. While the rising demand for beef and veal resulted in an increasing share in the total value of agricultural exports, the falling demand for pork led to declining world market prices and a significant decrease in the export value. The impacts of the pandemic were also evident in broiler meat.
Large differences in the trade balance
The foreign trade balance for the three most important meat types varied considerably in 2023, as can be seen in Table 2. While there was a deficit of almost 300,000 tonnes for beef and veal despite a domestic production of over 12 million tonnes, large surpluses of 1.65 million tonnes
respectively 3.32 million tonnes were achieved for the other two meat types.
Remarkable dynamics in the development of export volumes and export values
The next step will analyse the development of export volumes and export values between 2019 and 2023 for the three meat types considered here. Figure 1 shows that export volumes developed differently for the three meat types. Beef and veal exports increased by 180,000 tonnes or 18.7% between 2019 and 2022, but fell almost back to the 2019 level in the following year. During the peak of the Covid-19 outbreaks in 2021 and 2022, demand for beef increased not only in the USA because more meals were prepared at home due to the closure of restaurants. When the restrictions were lifted, the previous trade volumes were reached again. In contrast, pork exports fell by 432,000 tonnes or 18.4% between 2020 and
▲ Figure 1 - Development of the USA’s beef and veal, pork and broiler meat exports between 2019 and 2023 (design: A.S. Kauer, based on USDA GATS)
■ Table 2 - Balance of US foreign trade in meat in 2023; figures in 1,000 tonnes (source: USDA, GATS)
2022. Only a small amount of pork was prepared in private households, which resulted in falling demand not only in the USA but also on the global markets. Exports did not increase again until 2023 when the restrictions were lifted, but were still below the 2020 value, although 7.3% above the 2019 figure. Exports of broiler meat changed only slightly during the analysed time period. The temporary closure of the restaurants was compensated for by consumers buying microwave-ready products, including some plant-based meat substitutes. The closure of restaurants had a far greater impact on the value of exported meat (Table 3, Figure 2). The rising
■ Table 3 – Development of the value of US meat exports between 2019 and 2022; figures in $ million (source: USDA GATS)
▲ Figure 2 – The development of prices achieved by the USA on the world market per tonne of exported meat between 2019 and 2023 (design: A.S. Kauer, based on USDA GATS data and author’s calculations)
domestic demand for beef and on global markets led to a supply shortage. This was also strengthened by the fact that some large meat companies were forced to reduce their production or stop it completely for a few months due to high infection rates with the coronavirus among their employees. Between 2020 and 2022, the value per tonne exported rose from $6,950 to $8,895, or by 28%. In the following year, the price per tonne remained at a high level. As demand for pork decreased for the reasons mentioned before, the prices achieved fell until 2021, then rose by 14% in 2022, but were unable to maintain this level because there was an abundant supply on the global market despite demand increasing again.
Figure 2 impressively shows the significantly lower price that the USA was able to achieve for broiler meat on the global market. The price fell at the beginning of the pandemic, but then rose by $211/t from 2021 compared to 2020, an increase of 23%. In the following year, another price increase of $167/t or 14.8% was realised. With demand continuing to rise, prices in 2023 were also about 25% higher than in 2019. However, in addition to the late effects of the Covid-19 pandemic, this also reflects the general trend of the consumers to prefer white meat. It is worth noting that the pandemic had a decisive impact on the price dynamics on the global meat markets and brought the companies high profits for two years. A similar development occurred in global egg trade. The world’s largest egg-producing company, Cal-Maine Foods (Richland, Mississippi), was able to increase its corporate profit from USD 2 million in the 2021 fiscal year to USD 758 million in the 2023 fiscal year (Windhorst 2024).
▲ Figure 3 - The shares of the ten leading countries of destination in beef and veal, pork and broiler meat exports in the USA’s total exports in 2023 per meat type (design: A.S. Kauer, based on USDA GATS data)
High regional concentration in the target markets for meat exports
Meat exports from the USA showed a high regional concentration regarding the countries of destination. Figure 3 documents the shares of the top ten countries in total exports per meat type. In the case of beef, the ten most important importing countries accounted for 91.7%. The three leading countries, the Republic of Korea, Japan and China, alone shared 61.6% in the total export volume. Mexico and Canada, the two partner countries in the USMCA (United States-Mexico-Canada Agreement, formerly NAFTA), accounted for a further 17.5%. Seven of the ten destination countries listed were located in East or Southeast Asia, which impressively illustrates the importance of these regions for beef and veal exports. The regional concentration for pork was even higher than for beef and veal. Here, the ten most important importing countries accounted for 93.0% of total exports, Mexico alone for 42.6% and Canada for 5.8%. This reflects the advantages of free trade within the USMCA. Other important target countries were Japan, the Republic of Korea and China. In contrast to beef and veal, four countries in Central and South America were important sales markets. At 63.8%, the regional concentration for broiler meat exports was significantly lower than for the other two meat types, as exports were made to a much larger number of countries. Mexico was in the leading position with a share of 21.9%. Together with Canada, the two partner countries in the USMCA achieved a share of 26.3%. As can be seen from the composition of the target countries, the regional distribution of exports was similar to that of pork. It is worth noting that, apart from the United Arab Emirates, the USA has not really been able to gain a foothold in West Asia. Brazil dominated the markets here.
USMCA - most important for USA’s meat imports
Although domestic production was higher than consumption, with a self-sufficiency
beef, self-sufficiency was only 97%, which made imports necessary to meet the demand.
Table 4 documents the share of the five leading countries of origin in the imports of the three meat types in 2023. The regional concentration was very high for all three meat types, but there were considerable differences in the shares of the individual countries. For beef, the two USMCA partner countries together accounted for 46.9% of the imports; for pork, they accounted for 75.6%, with Canada alone sharing more than two thirds in the import volume. Imports from Denmark and Italy were predominantly ham.
■ Table 4 - The five leading countries of origin for the USA’s beef, pork and poultry meat imports (2023) (source: USDA GATS; USDA ERS)
Obviously, it was valuable pork cuts that were imported, as the value of $4,180 per tonne was almost $1,400 above the average value for exported meat.
Official trade statistics did not show separate figures for broiler and turkey meat, but only data for poultry meat imports. Here, Canada ranked in first place in 2023 with a share of 56.2%, followed by Chile with 38.5%, The contribution of the other countries was comparatively insignificant. Data from the USDA’s Economic Research Service shows that mainly broiler meat was imported. Chile, however, also supplied over 20,000 tonnes of turkey meat. This is surprising given the USA’s high level of selfsufficiency. There may have been supply shortages due to the production losses caused by the avian influenza outbreaks in the winter months of 2023, when over 3,5 million turkeys either died from the Avian influenza virus or were culled as a preventative measure to stop the further dissemination of the disease (Windhorst 2024a). Breast fillets were predominantly imported, which explains the high average value of $5,570 per tonne,
Summary and outlook
In summary, it can be noted that in the five years analysed here, the USA held a leading position in world trade in
meat alongside Brazil and some EU member countries. It ranked first for beef, veal and broiler meat and second behind Spain for pork, The regional concentration on a comparatively small number of countries of destination was high for all meat types analysed here. The top ten countries of destination accounted for over 90% of total beef and veal exports, and less than two-thirds for broiler meat. In addition to the two partner countries of the USMCA, other important sales markets were countries in East and Southeast Asia.
Despite the high level of domestic production, the USA did not achieve full self-sufficiency in beef and veal. Valuable cuts were mainly imported from the two partner countries in the USMCA, but Australia, New Zealand and Brazil were also important countries of origin. Canada and Mexico were important supplier countries for pork and poultry meat. Overall, this documents the outstanding importance of the USMCA for the USA’s foreign trade in meat,
In its long-term projection to 2033, the USDA predicts that exports of all three meat types will increase. An increase of 1,1 million tonnes is projected for pork. However, this is a very optimistic estimate, which is primarily based on the assumption that outbreaks of the African Swine Fever virus in East and Southeast Asia cannot be controlled in the coming decade. In contrast, no significant change
is expected for beef and veal because global trade in this meat type has obviously reached a plateau. According to the forecast, exports of broiler meat will only increase by 430,000 tonnes or 12%. Further market shares may be lost to Brazil, as the main competitor is expected to increase its export volume by 1.9 million tonnes or almost 40% in the same time period. The gap between the two main exporting countries will widen further.
Data sources and additional literature
USDA: Agricultural Projections to 2033: https://www.usda.gov/ sites/default/files/documents/ USDA-Agricultural-Projections-to-2033.pdf
USDA, FAS GATS: Global Agricultural Trade System: https:// apps.fas.usda.gov/gats/default. aspx?publish=1
USDA, NASS: Meat Animals Production and Value (verschiedenen Ausgaben): https://de.search.yahoo.com/ yhs/search?hspart=trp & hsimp=yhs-005 & type=Y149_ F163_202167_012724 & p=USDA+NASS+Meat+animals+production+and+value
USDA, NASS: Poultry Production and Value, Annual Summary (verschiedene Ausgaben): https://www.nass. usda.gov/Publications/Todays_ Reports/reports/plva0421.pdf
Windhorst, H.-W. The dynamics of the U.S. broiler industry. Part 2: US profits from the rising demand of white meat. In: Fleischwirtschaft international 2022, no. 2, p. 52-54
Windhorst, H.-W.: Meat production and consumption in the USA between 1970 and 2020. In: Meatingpoint 44 (2023), issue 52, p. 30-34
Windhorst, H.-W.: Cal-Maine Foods: a portrait of the world’s largest egg producer. In: Zootecnica International 46 (2024), no. 10, p. 22-27
Windhorst, H,-W.: Dritter Seuchenzug in den USA. In: DGS Magazin für die Geflügelwirtschaft 76 (2024a), no. 9, p. 34-37
WARM WEATHER VENTILATION MANAGEMENT
A poultry house ventilation system is arguably the most important management tool for a farm manager to use. As the birds grow and climates change the system needs to be able to adapt and cope with the changing demands to keep the birds in their comfort zone which ensures optimal biological performance.
During the periods of hot and/ or humid weather, it is essential that we provide the birds with cooling. This will be provided through the “wind-chill effect”, which is created by air movement and evaporative cooling. The only way to determine if the ventilation system is set correctly is to look at bird behaviour. Always use climate control systems as a guide and never the sole gauge of a turkey houses suitability for bird comfort. If bird behaviour indicates that changes to ventilation are required, those changes should be made swiftly to ensure birds are kept as comfortable as possible. We need to remember that the actual temperature felt by the bird is influenced by relative humidity (RH). So, for a given temperature, if the RH is low, the birds will feel cooler than if the RH is high. A high RH reduces the bird’s ability to lose heat via evaporative loss or in other words “panting” so we must then lower the ambient temperature to account for RH.
The actual temperature felt by the bird is influenced by relative humidity (RH)
Tunnel ventilation
Tunnel ventilation should be a secondary measure for when transitional ventilation is no longer keeping the birds in their comfort zone. In general, the exhaust fans are located at one end of the building and at the other end two large openings where the air is drawn in. When the tunnel ventilation is operating, air is drawn along the length of the house at speed. This air flow creates a wind-chill or cooling effect on the birds so that they feel a lower temperature.
It’s important to exchange all the air in the house frequently to minimise the heat build-up. If the air exchange isn’t on a frequent basis, then there will be a vast temperature difference between the front and rear of the house. Another problem of the air moving too slowly down the house is that it not only picks up heat but also contaminants like dust, ammonia and humidity.
To avoid this the system should be capable of exchanging all the air in the house within 1 minute. The equation to work outhow many fans we would require is to divide the volume of the house by the air exchange time (1 minute).
Length x Width x Average Height
Fan Capacity Required =
Air Exchange Time (1 minute)
It won’t be necessary to exchange the air this quickly all the time but a ventilation system should be able to deal with all weather conditions including the warm/humid temperatures during the summertime. It’s also important to note that if the temperature isn’t high enough to run at least half of the exhaust fans, then the transition ventilation should still be utilised.
Another area to consider when using tunnel ventilation is how quick the air will move (air velocity), as this provides most of the cooling. Cooling produced in this way is typically referred to as the “wind-chill effect”. It is hard to determine exactly what temperature a bird feels when the air moves at a certain speed as there are a lot of variables.
However, designing a tunnel ventilation system to reach at least 2m/s of air speed, should give a rough ‘wind-chill effect’ of 5º C. Air velocity can be worked out by dividing the total fan capacity by the cross-sectional area of the house.
Total Fan Capacity
Velocity =
Shed Width x Height
A great way to increase the speed of air when using tunnel ventilation is by using air deflectors. These are installed from the ceiling to the top of the sidewalls, which reduces the cross-section area of the house. This temporarily increases the air speed under each deflector and if the deflectors are positioned no more than 10 meters apart, the increased velocity becomes very consistent all the way along the house. Air deflectors are a great way to increase air speed at a minimal cost.
It’s critical to ensure the inlet opening is not open too much or too little, as this can have an impact on both fan performance and bird production. The total inlet space will depend on whether the air is being drawn through cooling pads. In general, for a 15cm (6 inch) pad there should be one square meter of pad for every 6,400m3/hr of exhaust fan capacity. For houses without cooling pads, its generally equal to the cross-section area of the house, width x average height. For example, in a house with a width of
The only way to determine if the ventilation system is set
correctly is to look at bird behaviour
15 meters and an average height of 3 meters, there would need to be 45 m² of inlet area. It is worth noting that inlets should be placed on either side of the house or across the gable end as this will ensure the most uniform and efficient air movement.
There are a couple of things to keep in mind if including a misting system in a poultry house to guarantee maximum evaporation of the water, these include droplet size and nozzle placement. Misting lines should be placed near to the air inlets of the house and close to the ceiling, as this maximises the time the water droplets are kept aloft in the air. This is important as the greater time it is kept in the air, the more evaporation can occur which increases cooling. To ensure that the droplets are kept in the air as long as possible its important to make them as small as possible. The size is determined by two things, the size of the nozzle and the water pressure. So, the smaller the nozzle and higher the pressure of the system makes for a smaller and more effective droplet size.
Furthermore, in every case you should refer to the manufacturer’s guidelines and recommendations for your own situation. Please see Aviagen’s “Essential Ventilation Management” booklet for a more detailed description of ventilation management.
References
Aviagen (2019). Essential Ventilation Management
The University of Georgia (1990). The Design and Operation of Tunnel-Ventilated Poultry Houses
THE MANURESHED CONCEPT: A SOLUTION TO POULTRY LITTER NUTRIENT RECYCLING?
Surface waters in the United States are regularly assessed as a part of the Clean Water Act to determine whether the water quality protects aquatic wildlife and provides for safe recreation. This assessment determines in large part whether surface waters are “fishable and swimmable.” When surface water quality standards are not met, the water body is formally listed as “impaired.” Once listed, strategies and controls are required as part of a watershedbased conservation plan which is designed to improve water quality. In some watersheds, animal feeding operations, including poultry farms, are associated with impaired water quality that results from high surface water nutrient concentrations that cause excess algae blooms.
➤ Tom Tabler, Professor and Extension Specialist, Department of Animal Science, University of Tennessee
Shawn Hawkins, Professor and Extension Specialist, Department of Biosystems Engineering and Soil Science, University of Tennessee
Yi Liang, Associate Professor, Departments of Biological and Agricultural Engineering/Poultry Science, University of Arkansas
Victoria Ayres, Assistant Professor, School of Agriculture, Tennessee Tech University
Jonathan Moon, Extension Instructor, Department of Poultry Science, Mississippi State University
Pramir Maharjan, Assistant Professor and Extension Specialist, Department of Agricultural and Environmental Sciences, Tennessee State University
Perception versus reality
Unfortunately, the implementation of many watershed-based conservation plans has failed to deliver significant water quality improvement within the timescales predicted by scientists. The conclusion reached by many water quality conservationists is that conservation efforts are not being effectively implemented at a sufficient scale and intensity. More specifically, in nutrient-impaired watersheds with a significant number of poultry farms, the lack of water quality improvement can be interpreted as
an indication that litter nutrients are not being managed agronomically.
The reality is that within watersheds impaired by high nutrient concentrations, and particularly high phosphorus concentrations, it can be a difficult task to improve water quality. In areas where years of overapplication of poultry litter have occurred, excess soil phosphorus (P), which is referred to as “legacy P,” is problematic because it can be mobilized from agricultural fields and repeatedly recycled in surface waters for years, decades or even centuries. Current conservation plans likely do not take adequate account of “legacy P” issues arising from past land management practices. Spiegal et al. (2020) developed the concept of a “manureshed” — the lands surrounding animal feeding operations onto which manure nutrients can be redistributed to meet environmental, production and economic goals. Manuresheds can be managed at multiple scales, for example, on individual farms with both animals and crops, among animal farms and crop farms within a county or localized area, or regionally among animal farms and crop farms in distant counties covering a large area. This manureshed concept may present a possible solution to the challenge of proper poultry litter nutrient recycling?
Manure nutrient recycling
Over the past several decades, livestock and poultry production has become increasingly specialized and concen-
trated. This is in part a result of vertical integration which has greatly improved the efficiency of poultry production since the 1950s. US agriculture has become acutely specialized in the last several decades to the point that crop and livestock production are now highly disconnected and concentrated, with fewer but larger farms now producing most of the country’s food supply. This has disrupted a longstanding closed nutrient cycle that existed for centuries before the 1950s and which bonded livestock and crop farms in close proximity out of a need to recycle nutrients from crops to livestock and then back again to crops using manure. As agricultural systems became more specialized and intensive, to feed a growing US and global population, few guidelines were put into place to ensure that surplus manure nutrients from livestock operations were returned to the croplands where animal feed was produced. In some locations today, this has resulted in manure nutrients accumulating in soils near livestock and poultry feeding operations to the point where it is affecting water and air quality. Without a system to distribute manure nutrients more evenly and widely, the result is a surplus of nutrients, particularly nitrogen (N) and phosphorus (P), in local soils that repeatedly receive manure. The overaccumulation of manure nutrients in an area is considered an important cause of eutrophication, the biological enrichment of water bodies with nutrient pollution. Today, because of the fragmented nature of crop and livestock production, regions supporting particular livestock types (beef, dairy, poultry and swine) do not necessarily overlap with regions that produce the livestock and poultry feed. We see this in the case of corn, which is produced in the upper Midwest and then transported to the Southeast to be fed to chickens — nutrients originally used to produce the corn are displaced to the South in the form of poultry litter. Because few technologies, polices and incentives exist to return the manure from regionally specific animal feeding operations to regionally specific croplands to produce more feed, nationwide nutrient cycles have become increasingly fragmented. Spiegal et al. (2020) explored the concept of a “manureshed,” defined as the geographic area surrounding one or more livestock or poultry operations where excess manure nutrients can be recycled for agricultural production. The “manureshed” concept builds on the understanding and mechanisms used to manage livestock and poultry manure to ensure that manure nutrients return to agricultural lands where they are needed at scales that vary locally, within and across county lines, and across state lines regionally.
Poultry litter as fertilizer
Poultry litter land application improves crop yields, increases soil tilth and organic matter, enhances soil health, provides a liming effect for acidic soils and supports beneficial soil bacteria. However, when litter is repeatedly ap-
plied to the same fields at rates that exceed crop nutrient needs, soil nutrient concentrations can increase substantially and be prone to environmental losses that can degrade surface water quality. This is particularly true in the case of phosphorus which tends to overconcentrate in soils that receive manure applied at N rates. This P concentrating effect is exacerbated when litter is applied without incorporation because the soil surface can become highly concentrated in P — this is a common occurrence in Tennessee where no-till row crop production systems are used extensively to control erosion. Even with low erosion rates, the loss of even small amounts of surface soils with very high P concentrations has been scrutinized as significant causes of water quality impairment in the form of eutrophication characterized by excessive algae blooms.
Poultry litter can be a valuable fertilizer source because it can contain all the essential plant macro-nutrients and many of beneficial plant micro-nutrients, depending on types of feed, supplements and enzyme additions used at a given poultry production operation. Poultry litter has been used most extensively on forage and pasture crops grown near poultry houses. In recent years, interest in using poultry litter as a low-cost alternative to expensive inorganic chemical fertilizer has increased among row crop farmers seeking to improve yields through increased soil organic matter and improved soil quality.
However, traditional barriers exist to widespread poultry litter use, including: 1) limited availability at the appropriate time, 2) lack of expertise on how and where to best use it, 3) variability in nutrient contents (thus the need for a litter nutrient analysis) and 4) lack of information on how it performs under different tillage and crop management systems. Dry poultry litter is nutrient dense, but its physical nature and handling characteristics make long-distance transportation challenging and costly. This is the primary cause of repeated application to agricultural lands within short distances of poultry houses even though this practice can lead to negative environmental impacts on air, soil and water quality.
While new and innovative methods of utilizing litter continue to evolve, land application remains the most sustainable option.
In poultry production, the housing and flock management methods, including for manure collection and storage, vary depending on the type of poultry being raised, stage of production, targeted product market and environmental factors. As a result, the amount and quality characteristics of poultry litter from different operations is highly variable. For example, broiler litter is often stored until needed either on the floor as recycled bedding in poultry houses (Figure 1). Alternatively, it can be removed and placed in a litter storage shed (Figure 2). Ashworth et al. (2019) emphasized that values for the quantity and quality of “as excreted” poultry manure is a poor estimate for agronomic/manure application planning purposes. The only sure way to verify nutrient content of litter from a particular poultry farm is with a litter nutrient analysis. Accurate assessment of litter nutrient content is a critical aspect of any nutrient management program, including for the manureshed approach.
Understanding and addressing the phosphorus problem
Meeting the energy and food demands of a growing and increasingly urbanized population has dramatically altered P, N, and carbon (C) cycling in the natural environment. Modern agriculture is heavily dependent on mined phosphate fertilizers, characterized by low crop-use efficiency — this practice disrupts natural P cycles (Elser and Bennett, 2011). In intensively managed agricultural systems, where feed and fertilizer inputs of P and N are significantly greater than outputs in the products, biological controls can become overwhelmed because of large environmental losses that result in degraded water quality. We see this
▲ Figure 1 - Poultry litter is often stored until needed for land application either as recycled bedding within poultry house
▲ Figure 2 - Removed and stacked in a separate litter storage shed.
in poultry production areas of the southeastern United States and on the Delmarva peninsula where poultry litter has been spread on fields near poultry growout operations for decades. Repeated overapplication of P to fields in excess of crop removal has resulted in an accumulation of soil P which presents a “legacy P” challenge to improving surface water quality. Even as inputs of P are now curtailed in these areas with conservation plans, legacy P can be mobilized directly as particulate P or indirectly as dissolved P and thereby constitute a major source of P at the land- freshwater interface. What is clear today is that the capacity of soils to adsorb P led early land managers to incorrectly conclude that its transport in dissolved form in runoff and in subsurface flow was either absent or unimportant. We now know that even though P readily accumulates in soil, there is still transport of P along pathways of concentrated surface water runoff and preferential groundwater flow that transfers significant loads of P from agricultural fields to water resources. Legacy P reserves in soils have developed in regions where specialization and intensification of crop and livestock production result in localized manure nutrient imbalances, such as those found in the intensive poultry-producing regions of the Delmarva Peninsula and northwest Arkansas. There is broad agreement that loss of dissolved P from legacy P soils is one of the greatest challenges to improving water quality. Reducing these high legacy soil P concentrations to levels that have a lower potential to enrich runoff, for example by ceasing P applications today, can take decades to take effect, depending on the degree of soil P accumulation. Movement of P in most landscapes arises because a large fraction of total P loss from soils is in particulate form, highlighting the significance of erosion as a mechanism for mobilizing all forms of P, including legacy P. Eroded sediments are typically enriched with P relative to the bulk soil due to the preferential re-
moval of fine surface soil particles with greater P content. Soil conservation efforts (no-till, grass waterways, riparian buffer areas, cover crops and diversion drainage) are then vital to managing legacy P movement from landscapes to waterways. Changes in land use that increase erosion can dramatically increase legacy P transfers, as noted by Duran et al. (2012) who observed significantly higher particulate P loads in watershed effluent following residential development of agricultural land.
Agricultural producers in the United States commonly
use poultry litter as a source of crop nutrients. In some locations, local community programs have been established that promote manure transport from areas of intensive animal production to nutrient-deficient agricultural lands – this is in part an effort to address water quality concerns associated with the concentration of manure nutrients. Numerous logistical and market factors have hindered these programs, and for them to survive requires expert guidance for producers and recipients as well as technologies that help overcome challenges of using manures as fertilizer. A logistical infrastructure for transporting litter in a safe, timely and affordable fashion and a supportive regulatory climate are required. Understanding where the opportunities exist to transport litter from areas of surplus to areas that need crop nutrients is vital to optimize any manure transport and relocation/redistribution network.
The fact is that best management practices to improve water quality in P-rich watersheds have yielded slower and smaller results than expected. As a result, water conservationists have called for stricter land and nutrient management strategies even though limited success has resulted from the implementation of past management practices where legacy P masks the effects of current reductions in edgeof-field P losses. It is also important to accept that in any watershed-P reduction strategy it is essential to address the overall physical and social complexity of individual systems and the mitigation of non-agricultural P sources. In addition, P is a finite resource and as mined mineral P sources become scarcer and costlier to extract and process, it may become cost effective to recycle P. For example, many farm ponds and lagoons contain large amounts of P collected in runoff from agricultural facilities. While these ponds are efficient at trapping P on farms, they can become a source of dissolved P with potential recycling use.
Manuresheds
Spiegal et al. (2020) classified the 3,109 counties of the contiguous United States by their capacity to either supply manure P and N from confined livestock production (sources) or to remove excess P and N via crops (sinks). These researchers defined four manuresheds in the continental US (poultry, swine, dairy and beef) based on P source and sink strength. As expected, source counties for manure P greatly outnumbered those for manure N (390 for P and 100 for N). The vertically integrated structure of poultry and swine production, as well as the regional cooperatives and processing centers common to the dairy industry, may showcase and offer opportunity to implement the manureshed framework. However, liquid dairy and swine manures, which often have low nutrient density and a transport limit of about six miles, seriously limit opportunities for transport to distant crop producing regions that need N and P. The front end of the beef production sector (cow-calf production), in which nutrients are returned to pasture by grazing animals, also creates an obstacle to the manureshed approach with regards to manure collection and transport. However, the latter stages of beef production (backgrounding, finishing) offer the concentration of animals, a dry manure product and connection to transportation infrastructure required for wholesale manure transport and is a much better fit to the manureshed concept.
Solid poultry litter can be transported much farther than other types of manure, but its bulkiness and other handling characteristics (flowability, moisture content, etc.) still create long distance transportation challenges. One challenge with dry poultry manure is that considerable N is volatilized in storage and handling. This creates a low N to P ratio so that application of litter to meet crop N needs accelerates the accumulation of P in soils relative
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to inorganic fertilizers. At a national scale, however, more poultry-dominated counties were identified as sources of manure nutrients than for any other livestock industry. The vertical integration structure of the poultry industry offers more opportunities for coordinated storage and relocation of poultry manure than for other manure types. For example, in the Illinois River Watershed of northwestern Arkansas, in-house and land management of poultry litter are regulated through mandatory nutrient management plans that have evolved from historical litigation between Arkansas and Oklahoma. As a result, large amounts of poultry litter are moved out of the northwest Arkansas P source area into P sink areas such as southeast Kansas and the Mississippi Delta of eastern Arkansas. Across the country, the poultry industry has been the focus of the most effort to redistribute manure nutrients and has more experience than the beef, dairy or swine industries at nutrient redistribution programs on a regional scale. Identifying source and sink areas are critical to the future management of manuresheds. Data for US broiler production from 2012 to 2017 indicate that Alabama, Arkansas, Georgia, Mississippi and North Carolina account for 57 percent of annual US broiler chicken production. Therefore, future expansion of poultry production should be preferentially located in in nutrient-dense sink areas, a strategy that can benefit agricultural enterprises and the environment. Due to its generally dry nature, poultry litter is best suited for transport programs that are central
to achieving nutrient balances within a manureshed. However, redistribution of manure nutrients from source to sink areas is only one solution to achieving nutrient balance within a manureshed; other strategies and opportunities for promoting the recycling of nutrients should also be a part of overall manureshed nutrient management.
Manure treatment is one such option that must be considered. Though most poultry litter is relatively dry, its bulkiness, water content, flowability and challenging handling characteristics are major drawbacks to transportation of poultry litter in raw form. Reaching the full distribution potential of litter nutrients in a manureshed framework may require the treatment of poultry manure for more economic redistribution. Treated litter/manure can be expected to significantly decrease nutrient transportation costs increase economic value and market potential. Pelletizing and composting are two of the more traditional treatment processes, but there are a variety of nontraditional biological, physical and chemical treatment processes that are being developed. In recent years, animal manures have also received attention as a potential feedstock for bioenergy and biochar production through techniques such as pyrolysis, gasification and hydrothermal liquefaction. However, feedstock use is an area still in its infancy and requires more research to be economically feasible.
The manureshed concept should have increased appeal to the poultry industry because the industry has participated
in government-driven efforts, as well as local, informal efforts, to redistribute poultry litter away from its source. However, in addition to coordination between government and industry to frame the structure and expected outcomes of manureshed management, systematic innovation and implementation of technologies, both on and off the farm, are needed for large manureshed-scale nutrient management to succeed. This includes technologies and management strategies that concentrate nutrients, eliminate harmful pathogens and produce a material with a consistent quality. Future work is necessary, including defining manuresheds in relation to individual confined animal feeding operations, which could help identify intra-county and intra-state pathways for redistribution of manure nutrients that considers the legacies of past management of confined livestock and manure application.
Summary
For centuries, a cornerstone of sustainable crop and livestock production systems has been the recycling of manure nutrients. This worked well until we began to separate crop and livestock production in different regions of the country, a process that has increased food production efficiency but at the same time upset the balance and recycling of manure nutrients. Highly specialized crop and livestock production in recent decades has fragmented and concentrated the two industries to a point that manure nutrients have accumulated in and around livestock feeding operations to a level that is affecting the quality of water, air and even quality of life in some areas. The vertical integration of the meat and egg production segments of the poultry industry lends itself well to the infrastructure requirements and decision-making approach needed to accomplish manureshed management. However, even with widespread vertical integration, the beneficial nature of dry manures as a soil amendment, and the considerable experience with local and regional manure management and transport on a smaller scale that currently exists, the poultry industry faces numerous challenges in achieving widespread implementation of manureshed-scale nutrient balances. Recycling manure nutrients on lands where they have not been previously used will require changes not only in manure processing and transportation, but also in agronomy, bioenergy, cropping systems, landscaping and horticulture. However, the manureshed concept can increase the understanding needed to reconnect crop and livestock agricultural systems and target manure nutrient redistribution efforts. Managing this redistribution challenge will require the efforts of the poultry industry, crop and livestock farmers, government officials, manure brokers, transporters (haulers and applicators) and others.
References are available on request
By courtesy of The University of Tennessee Institute of Agriculture and UT Extension
VETERINARY
CLINICAL COCCIDIOSIS IN BROILERS WITH CONCURRENT INFECTION OF EIMERIA MAXIMA AND EIMERIA PRAECOX
Coccidiosis is a complex disease in chickens caused by protozoan parasites in the genus Eimeria . As Eimeria species are ubiquitous in poultry facilities, coccidiosis is one of the most common and prevalent diseases in commercial poultry operations. Conducting health surveys, posting sessions, and OPG counts on a regular basis plays a crucial role in understanding the gut health of the flock.
➤ Vijay Durairaj1, Nicholas Brown2, Daniel Coleman1, Emily Barber1, and Ryan Vander Veen1
The profitability of the poultry industry depends on the overall flock health and production performance. Coccidiosis adversely affects intestinal health contributing to morbidities, mortalities, and prophylactic/therapeutic costs. With a significant economic impact, coccidiosis is one of the biggest challenges faced by the poultry industry. This case report details clinical coccidiosis in broilers associated with E maxima and E praecox progressing to necrotic enteritis.
Introduction
Coccidiosis is one of the most common intestinal diseases of chickens caused by protozoan parasites of genus Eimeria. Among the nine Eimeria species described, the seven recognized globally are E. acervulina, E brunetti, E. maxima, E. mitis, E. necatrix, E. praecox, and E. tenella (5). Coccidiosis causes malabsorption, enteritis, impaired feed utilization, poor feed conversion ratio (FCR), reduced weight gain, and mortalities. It also increases susceptibility to secondary bacterial infections. Coccidiosis poses a burdensome challenge to the modern poultry production system by affecting short as well as long-lived birds. Coccidiosis inflicts substantial economic losses on the poultry industry. The economic impact of coccidiosis is not limited to the lowered production performances and mortalities, but also includes the cost of prophylactic and therapeutic measures.
In a 2022 USA survey, coccidiosis ranked number one in broilers and cage free layers, while it ranked number two in caged layers (11). Coccidiosis is one of the top concerns of
antibiotic free (ABF), raised without antibiotics (RWA), and no antibiotics ever (NAE) commercial poultry operations.
Eimeria species are ubiquitous in commercial poultry operations. Poor litter management, high humidity in the barn, and high stocking density are considered as risk factors contributing to subclinical/clinical coccidiosis. Higher oocyst burden in the litter and shorter downtime periods are potential risk factors for coccidiosis. Husbandry, management, and biosecurity practices, in conjunction with anticoccidial prophylactic/ therapeutic measures, help to keep coccidiosis under control.
“Posting sessions” are routinely performed in commercial poultry operations and “cocci check” is one way to assess the intestinal health. “Cocci check” helps in detecting the intestinal lesions and is a valuable tool to assess anticoccidial treatment/coccidiosis vaccine program. Oocysts per gram (OPG) helps in understanding the shedding of Eimeria oocysts in the barn. Diagnostic evaluation of oocysts helps in identifying circulating Eimeria strains in the field. Proactive measures to combat coccidiosis can be implemented based on these findings. In some cases, subclinical or clinical coccidiosis can be seen as early as the second week after placement depending on the Eimeria oocyst burden in the litter. This case report details a field investigation study of clinical coccidiosis in broilers.
Case report
Case history and field investigation
In Spring 2023, a broiler complex with two houses in Southeast USA had enteric issues starting from second week of age. At 20 days of age, a field investigation was conducted. A cumulative mortality of 1193/60900 birds (1.96%) was documented in house 1. Birds with clinical signs were euthanized and necropsied. Postmortem investigation of dead birds was also conducted on site.
Evaluation of mucosal scrapings
The intestinal mucosal scrapings were collected from the necropsied birds and visualized under a microscope.
Sporulation of oocysts
The intestinal contents from the necropsied birds were homogenized and mixed with 2.5% potassium dichromate and sporulated in aerated flasks placed in a shaking incubator at 28°C for 48 hours (12).
(Invitrogen) was used to identify the size of the amplicons. The amplicons were purified following the instructions using a QIAquick PCR purification kit (Qiagen) followed by submission for sequencing (Eurofins, KY).
Results and discussion
DNA extraction, PCR, and gel electrophoresis
DNA was extracted from the oocysts by using glass beads to rupture them followed by proteinase K (Qiagen) digestion. The DNA extraction was performed by using QIAamp Fast DNA Stool Kit (Qiagen) following manufacturer recommendations. Each PCR reaction (25 µL) had 5 µL of the template along with 1x GoTaq® G2 Hot Start Master Mix (Promega) and 0.4 µM of each primer. The amplicons (2 µl) generated from the PCR reactions were electrophoresed and visualized in E-Gel™ EX Agarose Gels, 2% (Invitrogen). PCR was performed against E. brunetti, E necatrix, and E. tenella (6), E. praecox, E. mitis (10), E maxima and E acervulina using in-house primers. A reference E-Gel™ 1 Kb Plus DNA Ladder
On field investigation, a few sick birds were euthanized and necropsied. Necropsied birds had ballooned intestines with flaccid tone (Figure 1.A). The serosa had numerous pinpoint petechiae (Figure 1.B) and the intestinal lumen had orange mucoid contents (Figure 1 C). In the necropsied birds, the intestinal lesions were very severe with roughened mucosa and velvety (“turkish towel”) appearance suggestive of necrotic enteritis (Figure 2). On lab investigation, oocysts of E. maxima and E. praecox were identified in mucosal scrapings (Figure 3.A, B, C) and sporulated (Figure 4.A, B, C). The oocysts of E. maxima are ovoid shape and larger in size (30.5x20.7 µm) compared to other Eimeria species of chickens. The oocysts of E. maxima are easy to identify due to their larger size. The oocysts of E. praecox are ovoidal shape with an average size of 21.3x17.1 µm. Both species of Eimeria were confirmed by PCR (Figure 5.A, B, C).
Based on the severity of the disease, coccidiosis can be classified into three types: coccidiasis, subclinical coccidiosis and clinical coccidiosis (14). Coccidiasis is a mild type of infection without causing any adverse effects (9). Subclinical coccidiosis circulates in the farm without clinical signs or unnoticeable very mild clinical signs and has a moderate impact on the production parameters and FCR. The subclinical form is the most prevalent form of coccidiosis and remains a subtle challenge to the poultry industry. It is very difficult to diagnose subclinical coccidiosis. Clinical coccidiosis exhibits clinical signs such as watery or bloody droppings, soiled vent, depression, and huddling. It
A. Ballooned intestine. B. Numerous petechiae on the serosa. C. Orange mucoid contents in the intestinal lumen.
▲ Figure 2 - Gross pathology images of 20-day-old broiler intestines. Roughened intestinal mucosa with velvety appearance “Turkish towel”.
drastically affects the production parameters, growth rate, FCR, and increases mortalities.
E maxima is one of the most common Eimeria species documented in chickens (4, 13). E. maxima is classified as a moderate to highly pathogenic Eimeria species, inducing moderate to severe lesions (5, 14). It affects the mid-small intestine and induces lesions in jejunum and ileum. In severe infections, the lesions may extend throughout the small intestine. Serosal surface may have a few small red petechiae to numerous petechiae. Intestinal lumen may be filled with yellow-orange mucus to bloody contents. The mucosal surface may be roughened and have mucus and blood clots. The pathological manifestations of E maxima can induce ballooning of intestine. In severe infections, the intestine may be loaded with bloody contents (5, 8).
E. maxima infection results in poor feed conversion, poor weight gain, diarrhea, and mortalities.
E. praecox is classified as a less pathogenic species, inducing no lesions or very minimal lesions (2, 14). E praecox affects duodenum and does not induce any notable lesions in the
intestine (5). Heavy infection of E. praecox may result in pinpoint hemorrhage in the mucosa of the duodenum and intestinal contents may be watery. Heavy infection of E praecox may result in reduced weight gain and poor feed conversation (2, 5).
Eimeria replicates in the intestine and damages the intestinal epithelium, compromising intestinal function as well as integrity. This provides an opportunity and niche for secondary bacterial pathogens to invade and colonize the intestine. Pathogenic bacteria such as Clostridium perfringens type A can use this opportunity resulting in necrotic enteritis (3,14). Coccidiosis followed by secondary bacterial infections influences the microbiome diversity and can result in conditions such as dysbacteriosis and necrotic enteritis. Concurrent Eimeria infections are common in poultry operations (1,7) as well as concurrent Eimeria infections and secondary bacterial infections (3,14). In this clinical case, severe infection of E. maxima resulted in necrotic enteritis. A concurrent infection of E. praecox was also documented in this case. Both coccidiosis
▲ Figure 4 - A. Microscopic evaluation of Eimeria oocysts after sporulation. *Sporulated oocysts of E. maxima #Sporulated oocysts of E. praecox. B. *Sporulated oocyst of E. maxima. C. #Sporulated oocyst of E. praecox.
▲ Figure 3 - A. Microscopic identification of Eimeria oocysts. *E. maxima oocyst. #E. praecox oocyst.
B. *E. maxima oocyst. C. #E. praecox oocyst.
▲ Figure 5 - Gel images of amplicons generated against Eimeria species primers.
Gel 1: M- Molecular size marker (1 Kb Plus DNA Ladder); Lane 1- Intestinal mucosal scraping; Lane 2- Negative control; Lane 3- Positive control- E. maxima primer set 1; Lane 4- Intestinal mucosal scraping; Lane 5- Negative control; Lane 6Positive control- E. maxima primer set 2; Lane 7- Intestinal mucosal scraping; Lane 8- Negative control; Lane 9- Positive control-E. mitis.
Gel 2: M- Molecular size marker (1 Kb Plus DNA Ladder); Lane 1- Intestinal mucosal scraping; Lane 2-Negative control; Lane 3- Positive control- E. necatrix; Lane 4- Intestinal mucosal scraping; Lane 5- Negative control; Lane 6- Positive control- E. praecox; Lane 7- Intestinal mucosal scraping; Lane 8- Negative control; Lane 9- Positive control- E. tenella Gel 3: M- Molecular size marker (1 Kb Plus DNA Ladder); Lane 1- Intestinal mucosal scraping; Lane 2- Negative control; Lane 3- Positive control- E. acervulina; Lane 4- Intestinal mucosal scraping; Lane 5- Negative control; Lane 6- Positive control- E. brunetti.
and necrotic enteritis cause significant economic losses to the poultry industry. Several intervention strategies such as synthetic compounds/chemicals, ionophores, natural alternative products, and vaccines are used to mitigate coccidiosis in commercial poultry operations. In modern poultry production facilities, conducting “health surveys,” “posting sessions” and “OPG counts” on a regular basis plays a crucial role in understanding the gut health of the flock and initiating proactive measures to prevent intestinal diseases, especially coccidiosis.
Acknowledgements
We thank the poultry producer for providing the opportunity to study the coccidiosis outbreak in this flock. We extend thanks to Trish Gray for her support.
Husbandry, management, and biosecurity practices, in conjunction with anticoccidial prophylactic/ therapeutic measures, help to keep coccidiosis under control
References
1. Aarthi S, Raj GD, Raman M, Blake D, Subramaniam C, Tomley F. Expressed sequence tags from Eimeria brunetti--preliminary analysis and functional annotation. Parasitol Res. 2011 Apr;108(4):1059-62.
2. Allen PC, Jenkins MC. Observations on the gross pathology of Eimeria praecox infections in chickens. Avian Dis. 2010 Jun;54(2):834-40.
3. Al-Sheikhly F, Al-Saieg A. Role of Coccidia in the occurrence of necrotic enteritis of chickens. Avian Dis. 1980 AprJun;24(2):324-33.
4. Blake DP, Marugan-Hernandez V, Tomley FM. Spotlight on avian pathology: Eimeria and the disease coccidiosis. Avian Pathol. 2021 Apr 20:1-5.
5. Cervantes HM, McDougald, LR, Jenkins MC. Coccidiosis. In: Swayne D, Boulianne, M, Logue C, McDougald L, Nair V, Suarez D, deWit S, Grimes T, Johnson D, Kromm M, et al., editors. Diseases of poultry. 14th ed. Ames (IA): Wiley-Blackwell. 2020. 1193–1216.
6. Gautam Patra, M. Ayub Ali, Kh. Victoria Chanu, L. Jonathan, L. K. Joy, M. Prava, R. Ravindran, G. Das and L. Inaotombi Devi. PCR based diagnosis of Eimeria tenella infection in broiler chicken. International Journal of Poultry Science. 2010. 9: 813-818.
7. Györke A, Pop L, Cozma V. Prevalence and distribution of Eimeria species in broiler chicken farms of different capacities. Parasite. 2013. 20:50. doi: 10.1051/ parasite/2013052.
8. Johnson J, Reid WM. Anticoccidial drugs: lesion scoring techniques in battery and floor-pen experiments with chickens. Exp Parasitol. 1970. Aug;28(1):30-6.
9. Levine, N.D. Protozoan Parasites of Domestic Animals and Man. Minneapolis: Burgess Publishing Company.1961.
10. Schnitzler BE, Thebo PL, Tomley FM, Uggla A, Shirley MW. PCR identification of chicken Eimeria: a simplified read-out. Avian Pathol. 1999. Feb;28(1):89-93.
11. USAHA. Report of the USAHA committee on poultry and other avian species. United States Animal Health Association. 2022. https://usaha.org/ transmissible-diseases-of-poultry-avianspecies/.
12. Venkateswara Rao P, Raman M, Gomathinayagam S. Sporulation dynamics of poultry Eimeria oocysts in Chennai. J
Parasit Dis. 2015. Dec;39(4):689-92.
13. Wang M, Tian D, Xu L, Lu M, Yan R, Li X, Song X. Protective efficacy induced by Eimeria maxima rhomboid-like protein 1 against homologous infection. Front Vet Sci. 2023. Jan 4;9:1049551.
14. Williams RB. Intercurrent coccidiosis and necrotic enteritis of chickens: rational, integrated disease management by maintenance of gut integrity. Avian Pathol. 2005. Jun;34(3):159-80.
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