We have been giving our hens (no roosters) 17% layer pellets, we switched to pellets from crumble when they started laying eggs, now that the eggs have been dropping off, and the hens are almost a year and a half, we will start switching to 18% (all non-GMO) layer pellets. They have access to a mixture of crushed egg and oyster shells, a large dust bath, plenty of water and small bits of gravel for digestion. In the afternoon we open up another yard that is all grass for their grazing pleasure; but we still be get some wonky looking wrinkly eggs and some thinner shelled eggs too. We still try to think of ways to help the hens produce better looking eggs (because we sell ours); but sometimes I think it's a crapshoot. The only upside is we keep all the weird looking eggs and eat them ourselves. Sorry I couldn't be more helpful.