contrary to popular belief they dont need oyster shell unless you are planning on shipping the eggs. my last flock i had never got any oyster shell and the shells were fine, since my girls are penned i buy grit for them and no probs ever my girls now are 6 mon old and never had the stuff and they never will i dont even give them egg shells from the eggs that i buy now. (since they arent laying yet). and i feed them laying mash-as soon as they get through the 16% feed that is. so i say oyster shell isnt useful at all. and they have everything they need in thier feed and they are strong healthy