It was so tough that none of us could eat it. I think it was about forty years old. We finally chopped it up and fed it to the other chickens. Chickens don't have any teeth in their mouths. They swallow things whole if the pieces are small enough, so it makes no difference whether the meat is tough or not.
Chickens have their teeth in their gizzards and chew their food there.
Their teeth consist of stones and pieces of glass which grind against the food and work it up small. I once saw a chicken's gizzard which had a common pin stuck clear through one side of it, the head of the pin being inside. Once, in 1870, two very small city boys visited our house. A rooster flew out of the barn. The smallest boy was much frightened and began to cry.