I keep mine on the grower feed(18%protein) and offer oyster shell free choice. I believe most layer feeds are 16%, unless you get it from a feed mill. I have read that they eat more in the winter to keep body heat up. Increasing protein can do this.
Feathers are high in keratin protein so iron, lean proteins, and vitamin A should help improve skin, hair, nails...feathers. Fish is a good source and my chickens LOVE canned tuna. I left it out for a cat but the chickens devoured it. I don't know if it is a recommended chicken food but it would be high protein and hens seem to like it. Also cottage cheese and yogurt are a favorite around the coop. I see my hens occasionally eat a feather but usually one that is on the ground and it seems to be mainly out of curiosity/ the need to peck everything at least once.
well hubby will kill me but I am going to give them one of his cans of tuna.These feathers are not laying on the ground I witnesses them plucking from each other! Thanks at this point I will try anything!