The actual amount of oyster shell they need is fairly small, relative to the amount of other food they are eating. They might eat something like 2 pounds of oyster shell for each 100 pounds of food, which is not much on a day-to-day basis.They are 20wk old hens and started laying a week ago. I bought to much chick feed, so they have been eating medicated chick feed. So far their egg shells have not been soft. I had tried giving it mixed in, but they scratched in out.
Yes, when you mix anything into the food, they do pick through looking for more of one thing or the other, and they waste more that way.