Hairline cracks
LOOK-THINK-ACT
Chick mortality
rig
50.5% 56.4%
45.0 g
43.5 g
py
Chick weight
Hairline cracked eggs
74.4% 80.9%
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Hatchability • Eggs set • Fertile eggs
Good quality eggs
ht
Poorer results for all aspects Characteristic
2%
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.
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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
