I don't have chickens yet, but I want to know how often I'll have to buy feed for them. They'll be large breeds like an Orpington, Australorp, Barred Rock, Golden-Laced Wyandotte, and a Speckled Sussex. They'll be free-ranging chickens when I'm out with them, and inside a run when I'm not ( I don't want a hawk or some other predator attacking them when I'm not around). If given free choice of food, how many pounds will they go through? I don't want to buy too much feed where it'll turn bad.