I asked a couple of years ago (I didn't check exactly when) about a rooster we butchered and which was inedible because he was so tough. I thought I'd share what I have since learned was the cause of that. We butchered, processed and then put the bird in the crockpot over the timespan of a half a day. I have since learned that you should either freeze or prepare chickens within the first hour after butchering or let them rest for a couple of days in the fridge before you do anything with them. This makes that rigor mortis has dissipated and the meat is tender. If you process while the bird is in rigor, the muscle will be very tough. I just thought I'd pass this along as someone else my have the same experience/question. Our last batch of meaties was delicious and I let them sit in the fridge for 3 days before freezing/throwing some legs in the frying pan.