Most folks who know more than me say roosters don't need all the calcium in layer feed. The only way I could feed him something different would be to keep him separate which I don't want to do, so I'm currently taking the advice of an experienced owner who has done much research into diet. I am feeding my whole flock starter/grower and keeping oyster shell available free choice at all times. This way it is OK for younger non-laying pullets, laying hens, and roosters to co-exist. Only the laying hens will be interested in the oyster shell. They seem to know they need the extra calcium, and eat it when they need it. So far, so good. I knew it was not good for chicks who weren't laying yet to get layer feed because the extra calcium can mess up their bone development. Some folks don't worry that their roosters eat layer feed and have good results, but I imagine the effects of too much calcium for a rooster take a long time to show up.