The advice hub Yolk Sac Infection


Yolk sac infection is caused by bacteria (usually E. coli) getting into the yolk of the chick which remains inside the chick after hatching for the first few days of life, as it provides a food source directly into the newly hatched chick’s gut.

These bacteria enter the egg during incubation through dirt on the egg’s shell; this is especially common if the eggs have not been laid in the nest or have been washed prior to incubation.

Bacteria can also enter the eggs during incubation from dirty incubators and hatchers, this is very common if an infected infertile egg explodes. Finally, the bacteria can enter the chick’s navel after hatching during the time the chick is drying off, this is why it is important to keep good hygiene in the incubator and hatcher.

These chicks usually have a smell similar to rotten eggs and tend to be hunched up or depressed and quiet. Sadly most of them die within the first five days of life. Even if they do survive they are commonly stunted.

If you have a high number of chicks appearing unwell soon after hatch contact your vet if you wish to attempt to treat these infected chicks or find out what is going on. Save any chicks which have died for the vet to examine.

Prevention and Treatment

The best prevention is excellent incubator and hatcher hygiene. Follow manufacturer’s instructions carefully with regard to cleaning and disinfecting, this will provide clean conditions in your brooding pen following a hatch.

For more information read our articles in the Breeding section.