A few of my chicks have lost their feathers on top of their back and their tail. I thought that my roosters were were hittin them too much or too aggressively but now my jersey rooster has got the same thing. They lose all their feathers in one area and their skin gets very red. I've tried dusting them with diatomaceous earth with no results. About six out of my fifteen chicks have this condition. The girls that previously had this are all growing their feathers back now but I'm just wondering what this is and how I can prevent this with my others in the future.