Quote:
Originally Posted by
Beekissed 
The toughness of the bird can vary, depending on how the bird is being raised. If in a pen/run where there is very little activity going on, you can fatten them a little longer than I can on free range. On free range the bird is very active, thus developing stringy, tough muscles...I usually butcher mine by 6 mo. or shortly thereafter.
One OT suggests that you can even take an older range bird and pen it for a few weeks, allowing the muscles to lose tonicity due to lack of exercise, and turn out a fairly tender bird~no matter the age. This is something I will try the next time I plan to cull older birds, if I have the space for containment.
Back in the day, any game fowl taken would hang for a time before being consumed...presumably to let the meat fibers start to decompose so they were easier to cook and eat. I wouldn't want to attempt this but holding the live birds in a pen until their muscles get a little flabby isn't a bad idea. 
Yeah, I had a friend from Scotland years ago. He would hang pheasant up for a few days by the feet, wasn't even dressed. Called it "high pheasant". Not my thing. But then again he turned green when I talked about eating squirrel, said that was just a bushy-tailed tree rat. lol
I know when you are butchering, there is a "sweet spot age" where they have no pin feathers and they seem to pluck easier. To be honest, I've never gone through the trouble of finding out what that age is though. We butcher when a) We want chicken for supper and there is none in the freezer b) I see one needing culled and see no point on wasting feed on a bird I know I'm not going to keep, or c) When I do my major culling in the spring and fall. I don't pay much attention to the age of the bird. I've dressed them from about 5 or 6 weeks old all the way up to 7 or 8 years old. We just cook them differently depending on the age and condition of the bird. I've had lots of people laugh at me for dressing cull birds right out of the brooder at 5 weeks old, but you just cook more of them. Jeez, they are bigger than quail at that age and the same people eat quail.
I have noticed that an older bird is a bit more tender if you let it rest in the 'fridge for a couple of days after butchering but before cooking, but again, I'll admit it seldom happens around here.
I do put all our free range cull birds in the cull coop every spring and fall when I do my major culling and can't say I've ever really noticed a difference in the meat though. Maybe it's not small enough, they can still walk around a good bit. I might but 50 birds in there, but it's a coop with around a 20' X 20' pen off the side, then I just butcher from 3 to 10 birds at a time until the coop is empty again. My hands hurt too bad to do more than a few at a time unless I have help.