I took my little roo into the vet for this very thing, and he said it is a genetic thing in my chicken, that his crop overfills and is stretched. He said I need to cut back on food, just put a little out at a time, or there will be problems in the future. He recommended switching from crumbles to mash, because they don't eat as much of the mash at one time. I was so glad it wasn't a tumor. I had worried. But I hadn't realized I needed to cut back on the food, that he was eating so much it was stretching his crop too much and if they stretch it too much the damage can become irreversible. He mentioned crop bras. Cockatiels wear them and are also subject to this malady, and I have read that Araucana type chickens are, also. He said crop bras are too small for my roo but I did find some larger ones online that are made for chickens. I don't think my chicken is to the point he has to have one yet, so I'm taking preventive steps now so he doesn't have to wear one. I don't think a rooster would enjoy wearing a bra! I am rather worried he is set up for crop problems on down the road... He's a chow hound and loves to eat so limiting his portions is hard. He doesn't understand why I am doing it. But it's doctor's orders!