I had a "Chicken person" tell me today that only Oyster shell has any value to chickens and that feeding egg shells is worthless. So I decided to ask. I have always feed the shells back to my chickens. My Flock is free range all the time except at night. During the summer I provide layer feed for about an hour in the am and in the winter they get it free choice. They also get scraps and treats. I keep the shells in the freezer until I have the amount I want to grind. Grind it up and mix it with something. Today its greek yogurt. One of their favs. I have always fed them their shells. So did my grand, great and so on parents. What are you thoughts on this and is there really a difference or is it more personal?