Edited by barredrockobama - 10/20/15 at 5:51pm
Cornish X are not made to exercise or lose weight. They are specifically bred to gain weight quickly and can often suffer from health problems if allowed to continue to grow. I agree with the above poster, although I know that once you've become attached, it's a hard thing to do. You are the only one who can decide what to do with them, but sometimes we have to realize that the hardest thing for us to do is sometimes the best thing for our pets.
Nice that you could keep her that long, But Buffy doesn't look like today's Cornish X chickens. Her legs aren't nearly as thick for one thing. I think the breeding has changed a lot in the last 25 or so years to make them grow even faster. I hope OP can keep her birds as long as they can be healthy and not suffer as many of them do when they get too big.