Please don't put oyster shell IN their food. It should be offered free choice. You could even give them a small hand full of kitty kibble to up their protein. Kitty kibble has animal protein in it.
My silly chickens follow me around evenings at chore time and want dog/cat food even with full crop. They love me then.

My layers are on all flock pellets and my banties eat chick starter crumbles. I toss a handful of oyster shell on the ground in each pen, gives them something to run around and get. I’ve never used layer feed but the protein level could be too low for what your bird breeds need.
