A few years ago my baby roosters all became crippled - one at a time. I couldn't figure out what was wrong. They'd be fine and then they couldn't walk, but just drug themselves around. No one else could figure it out either until one day I caught my rooster throwing a baby into the air and dropping on gravel. He was literally breaking their backs. He left the little hens alone, but the little rooster would be fine for a day or so and then he'd be crippled. Didn't want competition, I guess. The adult rooster has been fertilizing my flower bed ever since.