I was wondering if anybody knew at what age it is ok for growing chicks to get the extra calcium in a layer feed without hurting their kidneys. Do they need to be laying eggs or just around that age (18 wks or so)? I have two laying hens and three 12 week old chicks and I wondered when I could begin feeding them the same food. I'm keeping them separate but it would be nice to know when it is safe to let them be (and eat) together. Thanks!