I would stop mixing the oyster shell in with the food and instead offer it free choice in a separate container if I were you. They seem to know how much they need and will help themselves when they know they need it. Force-feeding it can result in getting too much calcium and they have to...
I have six hens, all good layers. The smallest of the flock, a golden-laced Wyandotte, has begun laying eggs with very rough shells. It is like they are covered with sandpaper. She takes a long time to lay them (at least an hour). It can't be very comfortable for her but I haven't gotten out the...