Hi everybody! I have five hens, four Americaunas and one White Leghorn. The White Leghorn is the only that is fully feathered. The others have no tail feathers and are, to varying extent, lacking body feathers. Their yard is 32-ft x 12-ft and has two separate roosting and laying coops. We've dusted them several times for lice and mites. We've tried the "feather foods", as well. Any suggestions?