For what it's worth, my Spitz have the silver dominant gene, are out in the sun all summer, eat corn, and never show any sign of brassiness.It was told me to me by a bantam white rock breeder a few years ago to breed the silver gene into white birds, and that's what prevented them from turning brassy in the sun. I asked him because there were probably 80 bantam white rock entries at that show, and maybe 20% of them looks bright white, his being some of them. He stated that he runs them outdoors all year long and never gets a brassy feather.