Help solving hatch mystery?

[ZZZ]

Hi all!

I placed two dozen fertile eggs in incubation, from two hens in my own flock. One hen is a 2-3 year old Australorp, and the other is a Black Copper Marans who started laying fairly recently. All but a few of the eggs developed nicely; I could see embryos with candling, and air sacks looked good going into lockdown. All of the BCM eggs hatched, and none of the Austra eggs even pipped. Can there be some sort of genetic issue -- she was not inbred by me -- that causes my Austra's eggs to be fertile, develop well, but just not be able to break through the egg at hatch time?

Any ideas?

p.s. We have two roos -- a BCM and a Cream Legbar. Any chance it could be something to do with the fact that the roo breeds are smaller than the Austra?

 

[Carter Martin]

Some chickens have harder shells than other which makes it difficult for chicks to hatch. But I think that BCM have very hard shells so that doesn't necessarily make sense. Also I don't know if this applies to any breed or just to some in particular but I heard of at least one breed that has certain alleles or something that causes them to die in the shell shortly before it is time to hatch. This was one of the blue egg layer breeds.

 

[ZZZ]

Some chickens have harder shells than other which makes it difficult for chicks to hatch. But I think that BCM have very hard shells so that doesn't necessarily make sense. Also I don't know if this applies to any breed or just to some in particular but I heard of at least one breed that has certain alleles or something that causes them to die in the shell shortly before it is time to hatch. This was one of the blue egg layer breeds.

Good thoughts! Thanks!