The other day I moved a bundle of shingles while rearranging stuff in the barn and discovered two mice nests. One the mices were about the size of one knuckle on my little finger and the other nest's were about the size of the middle finger. I dropped the shingles and scooped up the two bundles of joy and had a huge double handful of mices.
I yelled at the seventeen year old neighborhood boy helping me to open the door to the chicken pen. His eyes were the size of saucers but did as told. As I tossed them into the pen I yelled, "protein".
A little later I heard him mumbling to himself something about "protein".
The next day I offered to give him that day's eggs for breakfast the next day. I pointed out that after his sisters and family commented on how good the eggs tasted he could explain to them that they were once mices.
"I'm good" he said, end of conversation.
Chickens are omnivores, they'll eat anything including each other. I give mine miniature marshmallows because they love them and it makes calling them into the pen at night much easier.