I collected 2 ex-battery hens just over a month ago to add to my existing 2 hens. This is the 3rd time I have had ex-batts and I am used to their initial appearance. The more timid of the 2 has pretty much grown all of her feathers back already, and is looking great, but the other one doesn't seem to be showing any signs of feather re-growth, and her back is quite red. I have watched the hens together to see if there are any signs of pecking, but I haven't spotted any real bullying issues since the first couple of days. It did take a few days for the hens to all get along together, but they are fine now.
I add poultry spice to their layers mash, and am also feeing dried cat food soaked in water for extra protein.
Should I be concerned about my hen with a bare back? She is very perky and doesn't seem ill to me, but I don't understand why she isn't growing her feathers back.