Can egg shells be too Hard?

[Frenchman Creek]

Hello All. I have a IB hen that last year hatched seven chicks. This year she hatched only one of five. The other four had one die early but the other three went full term and each pecked a quarter inch hole in the shell but then died before getting out. The only thing different this year is I am giving oyster shell free choice to all the peahens. I have noticed on the eggs we have eaten that the shells seem really hard to crack open. These eggs were all under the hen and not in an incubator. Just wondering if others have seen this from a sitting hen?

 

[GitaBooks]

Sometimes chicks can't push out because they are genetically weaker or perhaps didn't have optimal incubation temp/humidity, however, it is very likely it could have been because of a thick egg-shell, as I have one hen who we wanted to set her eggs and they tended to die while attempting to hatch, as the shell is very difficult to open. We helped one hatch and it survived and was strong.

I hope this helps. Best of luck!

 

[Frenchman Creek]

As the eggs were under the hen the temp and humidity should be fine. At first I thought nutrition but checked the protein level of all the feeds and treats the hen received before she started setting and nutrition was probably not the cause. I also found it interesting that all three full term chicks died trying to get out. I have not seen this before where a chick would die full term under a chicken hen or peahen and that is why I asked about a too thick shell being the cause. If anyone has seen this in their own peahen hatching please let me know. Thanks.