Our hens started losing feathers on their backs 2 months ago, not all at once but slowly all of them plus our rooster too. Now their backs and buttstock are bare. We live in the desert of AZ... checked them for lice, mites, fleas etc during day and night and no sign of infestation. About 2 weeks ago we switched them to feed with 20% protein and started supplementing with ground beef, fish, etc. Still not sure what's going on with them. These pics are a few weeks old, their butts are more bare underneath.