We started breeding our chickens last year, and have had pretty good success.... Except for the last few chicks that have hatched. (We stopped for a few months, and are starting to breed again) All these chicks are very weak, and won't lift their head. Our chicks are usually very strong. A chick didn't lift its head until it was a day old, and another one of the chicks even appears to have splayed legs. Another chick was hatched with a lot of the yolk unabsorbed, and died a few hours after it hatched. Like I said, this never happened before. It could just be a bad batch of eggs, but I'm not sure. All our hens are anywhere from 6 months-3 years, and our roosters are 6 months-2 years. I'm not sure if age really makes a difference but I just wanted to make sure our hens arent too young, or even too old?? Also, we breed mixed breeds...could that be the problem? Please let me know. This is very strange, because our chicks are usually so healthy, and strong!!