The feathers on some, not all, of my checkens are falling out and not coming back. Primarily it seems to staying localized from middle of their back to the tail and the upper legs. It is mainly effecting my Jersey Giants but a few of my other breeds have it as well.To begin with I thought it may have been my rooster was being too rough but then he started having the same problem. I've tried looking disease web sites but you have to be an avian major to understand most of it. I've tried vita supplement, worming, DME and dusting them for parasites. I don't know if it's related but in the past month I've lost 2 of them to unknown causes. The only common thread was this had spread to over 2/3 of their body. I've been raising chickens for 15-20 years and never came across this. Does anyone have any ideas? Thanks!