I've ordered 6 chicks, 3 barred rocks and 3 red/gold stars. The local feed stores only sell in 100 lb bags. Am I going to have extra chick feed left over when it's time to switch to layer feed? Or can I mix the chick starter with scratch or layer feed? The chicks will be in the brooder for the first 4-5 weeks and then in an enclosed run/coop area with supervised yard/foraging privilges (too many neighborhood dogs that cannot be trusted, even if I'm standing over the chickens). I'll be treating them with greens/yogurt/yummies from the treat list.