when you plan to breed chickens on long tracks, you lure them with seeds into fenced space, so they can not escape. But the bug happens in the intersection of fences (where is the 90degrees angle, the corner). The little chicken in time get stuck in that corner and can not move out even lured. In that situation, it will not grow at all, 'till you destroy that corner of fence and release it. But, this happens too often! This will not happen with cows or sheeps (for horses and pigs i do not know).