I'm new to raising chicken, I now have 40 Amber Whites I've had since they were 1 day old, now 14 weeks later they start killing each other. In the last two weeks I have lost 8 chickens. I thought some thing was killing them. This morning I found them pecking one to death several had blood all over them. I was told that maybe the needed oyster shells or more protein. Has any one else had this problem. I have them in a 12' x 12' caged pen.