I have 11 chickens that are almost 18 weeks old. I take food out to them every morning and again about an hour before they go up to roost for the night. Every time I feed them they act like they are starving and gobble up all the food at once. Based on how long it takes me to get through a 40lb bag of feed, they should be getting the 4 ounces a day each that I've seen recommended. Is it normal for them to act like this? Or am I not feeding enough? The way they act leads me to think they'd eat the entire bag of feed in one day if I put it out for them!