My pullets range in age from 14-20 weeks. In the last few days, some of the girls are singing the egg song, others are practicing in the nest box, others are squatting. I went and bought some layer feed and a bag of Oyster Shell. I put the Oyster Shell in the barn-on a shelf. My girls found it and ripped it open. I don't know which of them got into it and how much was eaten. I caught one in the bag. Will it hurt them to have it so soon? I was thinking maybe they broke the bag and got into it because they felt they needed it. I just want to be sure it can't make them sick.