I have 17 chickens. 16 are pullets and one is a cockeral. They are 3 weeks old and all eat Purina Medicated Chick Starter. Can the rooster eat layer feed when the hens are old enough to not eat starter? I heard he dosen't need all the calcium, what will happen to him if he eats calcium? I'm very confused. I'm not sure if I can feed them all layer or not.