Thanks for your thought! In this game, roosters are actually not "useless" because they can produce meat. They are "less valuable" compared to hens which can produce eggs and meat.  You are right that in reality, hens cannot produce fertilized eggs without roosters. I removed this rule in my game because I want to keep the economics flow chart clean and straightforward. By adding this rule, I also need to sort out fertilized eggs and unfertilized eggs.