I have been looking all over for a spot to ask this question. I hope this is it. If not, please point me in the right direction. I am totally baffled! I recently put together an incubator and have been hatching chicks from my own flock. I don't have a 100% hatch rate, but so far it has been great. I have several roosters in my flock, and I seldom come across an egg that is not fertilized. The first batch I did, I also had 7 eggs from my brother. Not one started to develop. At day 8, I removed them and cracked them all open to see what was going on. 6 were not fetilized, one was fertile but did not start. So he has been checking his eggs to see if they started being fertilized again. When he started getting fertile eggs, he started collecting them for me to try again. Every 3rd day he would crack one open to make sure they were fertile. Everything was set, and I put 7 more of his in 7 days ago. I candled them tonight, and there is no development. However, every one of the ones from my hens are developing just fine. So, I am wondering what would cause his hen's eggs to be fertile one day, and not the next. Why is it so hit or miss? If I crack open his eggs and find that they are fertile but did not develop, why would that be? What would cause them to not even start, when my hens' eggs set on the same day are developing great?