Ron, have you ever tried the Tums that someone on here suggested. Or, are you feeding the shells back to your girls. I did that and it made an impact within 24 hours. I haven't tried the tums yet. Now I have oystershell, and my girls seem to like it. I also feed yogurt regularly. When I do, I microwave and then mash the shells up really fine and mix it in the yogurt. Then I add fruit, and grain to it. They scarf it down.