I wish I could add advise for mean chickens..I have been breeding for so many years for temperament I do not have issues with injury except with fenced in males. They will fight with each other through the breeding fence..as soon as breeding season is over and they are all let loose, I do not have fighting. I do have a hen who will kill other young birds and chicks when they get too close to her own. Only one. She will try to kill me too when she has young. Other than that she is sweet as pie. I tolerate a mean hen when she is protecting her chicks. I need that in my line a bit more. Most of my broodys are good feeders to chicks, but lack aggression to attack other animals when chicks are approached. One of my hens will even let the dog approach chicks. I dislike that more.