I provide oyster shell, but after the initial "gobble up" of the first pound I bought (50 cents at the local feed store), they rarely touch it anymore. I also feed them back their own shells. I just rinse the shells really well (no slime left) and let them dry for a day or two. Then, I pulverize the shells in my mortar & pestle and combine it with the yogurt they get. They all love it! Once it gets cold, I'll be mixing shells, red pepper flakes, & yogurt into a good helping of oatmeal for the girls in the mornings (3 hens, they get about 1/2 cup and are golden).
As for feeding egg shells back though...I wouldn't suggest "tossing it in the nest boxes"...they might figure out where that "yummy calcium" is coming from!
As for feeding egg shells back though...I wouldn't suggest "tossing it in the nest boxes"...they might figure out where that "yummy calcium" is coming from!