I had a 20 week old Plymouth Rock x Cochin rooster that I found dead yesterday morning. He had to have died in the night. He was still in the coop and rigor had come and gone. Mr. Fluffy Butt had no wounds, no broken neck, nothing. I looked his whole body over and could find nothing wrong with him. I wonder if he just had a heart attack. He was perfectly fine the day before. This is the first unexplained death that I've had to deal with. I hatch him out and no one else in his pen has been sick or anything. I've had him with much younger chicks because he was soooo good with them. He was a sweetheart with a big fluffy butt!!!! We haven't had ANY sickness in any of our pens. Everyone is disgustly healthy (which is a good thing).