Lotsa luck. I have been frustrated by this for all the years I've been keeping chickens. When molt is finished each year, I hurry up and enjoy the beautiful plumage of my two roos as it lasts all of a few short weeks before the hens have shaved every single slender neck and saddle feather.
My EE and Welsummer hens are the main perps. Of course the roosters are willing victims. They seem to enjoy the hens yanking out their feathers as they stand perfectly motionless while their feathers are being liberated. I've tried pinless peepers and they don't do anything but slow down the process.
It's not lack of protein. It's not boredom. It's an obsessive behavior originating in the brain. The only thing I've found that works is to keep the roosters apart from the hens except for when they sleep and free range. And the hens still manage to munch feathers in those brief periods.