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Hatching egg quality
Hatching egg quality
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.
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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.
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.
Embryo
The egg must contain a good quality embryo that is ring-shaped and 4-5 mm in diameter (doughnut shape).
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.
2Φ 2+√2 1 Φ 1+√2 Φ Φ Φ
Φ3 Double-yolk eggs will not hatch. Remove them. This = Geometry of the eggcopyright protected is what an egg with a double yolk looks like under a candling lamp. Two dark spots are visible. These are the two yolks. Eggs from broiler parent stock have much greater variation in hatchability during production than those from laying hen parent stock.
+ = Φ 1
1 = 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 .
Type of bird Parent stock age Hatchability set eggs
Broiler young 24 weeks 70%
Broiler peak 34 weeks 90%
Broiler old
60 weeks 70% Laying hens young 24 weeks 90% Laying hens peak 26-80 weeks 95% Laying hens old 60 weeks 93%
Average egg weight
51 g 61 g 70 g 54 g 62 g 65 g
