In the past 4 years, I've tried several brands Dumore, Purina, and Country Roads. Two of my girls (golden buff) lost their feathers and they never grew back. I eliminated all scratch and snacks. The only thing I could think was that they weren't getting enough protein. I then tried organic, thinking the bigger price tag equates quality, and things seemed to get even worse and I had a case of wry-neck.
I finally tried Kalmbach all flock. The girls love it and after a year finally began growing their feathers back and everyone seems happy. My new Cochin girls are about 6 months old and have gorgeous feathers. I'll never change again.