I have a mixed flock of 32, Black Australorps, Welsummers, Wyandottes, Turkens, Dominiques, Buff Orps, Americanas, and Marans...10 cockerels who are getting along quite well and the rest pullets. 11 weeks old now, outside, super healthy and active. They eat mesclun mix lettuce from the garden, along with june bugs and crickets and various treats including scratch and some table scraps. My question is, is it ok now to feed them grit that has calcium carbonate in with it? I have read that you don't want to feed oyster shell to young chicks as the calcium affects them adversely. But they are "teenagers" at this point, eating a variety of food, and I want to be sure they're able to digest everything they're taking in properly. My chicken guy at the feed and seed says they don't need grit yet, but the majority of natural chicken raisin' books say, let perch and scratch as early as they want. Help! I've had birds all my life, and my instinct says they need grit and can handle it, but I would love some confirmation! Thanks! Peace. Mutha.