Do not feed chickens moldy food,or it will make them sick and possibly kill them.
Do not clean your chicken coop out and put fresh manure on your garden.It carries pathogens which can cause disease in humans.
Do not feed egg shells to chickens as that entices them to eat your eggs.
Do feed your chickens gritty sand or oyster shells,so they can digest their food and it also creates a harder egg shell.
Do feed you chickens a grass of some type to help with maintaining healthiness and a better tasting egg.
I feed mine Rabbit pellets instead of hay when I can't find Alfalfa hay.