Let me guess--your roo is a younger fella, less than 2 years old?

If so, he's just being a bit TOO dedicated to his role as rooster and wearing out the back feathers/pulling out the neck feathers of the hens when he mates them. Make sure the girls have room to escape his amorous clutches if they need to--bushes to hide under, corners to turn and be out of his sight. As he gets older, he'll calm down.

You might also look online at 'chicken saddles' which are little aprons that hens wear on their backs to protect their delicate skin & new feathers while they are recovering from too much roo boy attention. :)

Also check the chickens for feather mites--hold up a feather to the light and look for eaten-out lines that go across a feather. Also check the base of the feathers on the hens for a fine, grayish dust that clings to the base of the feather shaft, commonly in the vent area. If you find the grayish dust, those are mites eggs and the girls need to be dusted or sprayed for mites. If you DO spray for mites, do the coop, roosts & nests too.

If the girls have dry, itchy skin, get some human vitamin E oil pills, pop a hole in one end of a capsule and squirt it into her mouth. Do this about 3-4 times a week. It'll help her skin not be so dry and to feel better. You can also mix it into their daily feed ration, but ONLY into that day's feed--don't mix it into the can or bag that holds all the feed, otherwise it could spoil your feed. I'd give the vitamin E orally rather than putting it on her skin because you don't want to soil her feathers with it.

Velvet ~:>