post-laying age of egg influences hatch rates differently

[centrarchid]

Why is it that when my hens brood clutches of 12 eggs laid over a period of 14 days they can get close to 90% hatch yet when I take eggs more than 7 days old from same hens and place in incubator, hatch rate is lucky for me to to be 50%. Younger eggs seem to do just fine.

 

[Ridgerunner]

Have you analyzed the unhatched eggs to see why they did not hatch?

It sounds like a storage problem. Are your storage temperatures too high or too low? Are you turning them during storage? Are they losing too much moisture during storage?

 

[centrarchid]

Storage typically indoors at room temperature with relative humidity of 25 to 35%. Eggs not moved.

Hens lay their eggs either on ground or in hay loft. Former gives best hatch when not disturbed by predator. On ground more natural and likely has higher humidity when in contact with soil. I am not sure if hen moves her eggs prior to setting.

 

[Ridgerunner]

Let me give you a Texas A&M article that discusses storing eggs for incubation. I certainly do not follow it exactly but it is good information and something to strive for.

Texas A&M Incubation site
http://gallus.tamu.edu/library/extpublications/b6092.pdf

I suspect a hen moves the eggs when she is laying a new egg, but no, I do not think they turn them more than that once a day. But there are probably several things going on with natural incubation that we can never imitate.

When storing eggs for incubation, I take the automatic turner out of the incubator and keep the eggs in it. That way I don't have to worry about remembering to turn the eggs. I don't know if that is an option for you or not.

 

[centrarchid]

I can acquire another turner and keep it outside incubator. I will also see about placing unit over most soil in box setting on basement floor to more closely approximate environment of natural nest. Thanks very much for the read.