As long as it's the instand kind that is still just plain, quick cooking oats.... I'm not sure if you're talking about the kind in packages with the flavors and stuff, but those will have too much sugar for the chickens.
Ummmm, mine prefer it cooked first. If I give it to them uncooked they give me dirty looks and walk away but they return after I've gone and eat it. If it's cooked they purr "thanks mom."
Okay, I have spoiled rotten chickens so sue me.
oatmeal is very binding and recommended for feeding chicks when they have a diarrhea
so I would not give them a lot of it
they may get the pasty rear ends