They don't need oyster shells until they are laying. They do need to have grit (crushed granite) available all the time. Grit comes in two sizes, one for chicks, one for grown birds. You can feed all of them an all flock/flock raiser type feed. I start my chicks on chick starter/grower and once they've gone through one big bag, they are switched to flock raiser, that's what I feed mine. Purina makes one that is pretty widely available, and is a crumble. Flock raiser feeds do not have the extra calcium in them, better for chicks, roosters, older hens that don't lay anymore, and birds out of lay due to season, molt, etc. I feed flock raiser and have oyster shell in separate feeders all the time. If the flock raiser is out of stock, I will get chick starter/grower and feed that to every body until the other is back in stock. I never feed layer feed anymore, I have so many mixed ages, and multiple roosters. My birds don't care for Dumor, and they prefer crumbles as well.
