Goodness, I feel like I am underfeeding mine now. I am down to 7 chickens and I feel like a 50# bag lasts me for a couple of months-- , maybe longer. I worry about it going bad. I have food available all the time and they don't eat much of it except first thing in the morning. They free range and I do fermented feed which is said to reduce the amount fed significantly. I may give them less than a pound each day-- I think I will start weighing it. You will find information on fermenting feed on another thread. This is an interesting question. Clearly other animals are eating your feed. You might want to get a cat. I don't have many birds in my yard and no mice, gophers or flying squirrels can live nearby--poor things.