The feed we randomly bought contains limestone, but no warning about not feeding to males (not that we have any). It has 18% protein, which is actually higher than their grower feed. I may need to look around a bit more...Calcium Carbonate passes quickly through the digestive tract, Oyster Shell and Crushed Limestone stay in the Gizzard till they dissolve to a smaller size.
Most conventional Layer feeds that I've bought have Calcium Carbonate and don't have a warning about Male birds. View attachment 2850325
Layer feeds with Oyster Shells that I've bought and currently feeding do have a warning. View attachment 2850326