Firstly, a big thank you to all the regulars here who answer the same questions time & time again asked by overly concerned newbies LOL I did search,but couldn't find an answer to this question - at what age should I add oyster shell? I have four 14 week olds (RIR/Delaware & delaware) that are eating an 18% starter/grower crumble. I also have two eight week old (delaware & BR) on the same food (together during the day, but separated at night until they become integrated). Hopefully they should be together 24/7 within two weeks or so. I can't change the older girls over to layer, because of the youngsters, so, my plan is to keep them all on the grower/starter until the youngest are 16 weeks or so, then all onto layer. In the meantime, at what age should I make oyster shell available? - and, what is to stop the younger ones eating it (and the excess calcium causing them growth/bone problems)? TIA advance for answers, and suggestions.