I tried setting a small bowl of crushed egg shells out for the ladies. All they managed to do was spill it. I feed them wet mash (saves a lot of waste!) So I've ground up a bunch of shells into powder, and will just mix it in with their feed. I have 10 ladies, and 1 roo. They normally consume two medium sized dog bowls of mash every morning and evening. Any guesses as to how much shell I should add, and how often?