I think Redsox and LilyD are right on.
The only place I have any disagreement at all with what either of them said is I have eaten roosters more than a year old and thought they tasted great and were not tough. They had some texture but I don’t consider that tough. I had no trouble eating them. It does depend a whole lot with the older birds especially how they are cooked, but if you have an age appropriate recipe, any chicken can be cooked.
Thanks LilyD for the info, it is very helpful! How do you age the meat?
Farmer123:
I age my meat in the fridge and you can do it one of two ways. First you can put it in the fridge right after processing and let it rest until the rigor has passed. It will be different for different birds and you have to go more by the feel of the bird than age so I can't give you an exact time. You will be able to move and manipulate the muscles and it won't feel stiff when it's done with rigor.
You can also put it in the freezer right after processing and then let it age before cooking it. This also works although some people swear it doesn't. I think that more often than not birds aren't aged long enough and that causes the problems with the tough birds.
Here's what I do. When I am processing I have two large 20 gallon tubs full of ice water that has about 4 cups of salt in it. The salt helps the water to be a little bit colder, and it also helps to draw any blood that's left in the bird after processing. They stay in the tubs of ice water while I kill, pluck and gut all the birds. I usually do batches of 10 to 15 so I don't have many waiting to be processed and I do it early morning when it's cooler so there is less chance that the birds will spoil. I also have two tubs of just plain water for birds that are plucked and waiting to be cleaned out so they stay cold as well. In my view the birds start aging there before I even get them inside. Because I don't have a fridge that is just for the birds once they are all done and processed I cut them up into their respective pieces if I am parting them out or bag them whole and I put them right in the freezer. When I want to eat one I will put it in the fridge and let it thaw all the way and often will brine it in salt water (1/2 cut salt to 1 gallon of water plus seasonings) for 12 to 24 hours before cooking. Then depending on age I choose how to cook them. Birds 6 months or under I use as whole roasters, fryers or to bake. 6 months to a year I will cook low and slow either in the oven in a roasting pan or in a crock pot often with lots of moisture to keep them from drying out. 1 year and above I usually part out and can to use later for tacos, casseroles and other things that need chicken meat but not whole chicken parts. So far I haven't had a tough bird in the lot and mine free range until the week of processing so they definitely build up muscle, unless of course I cook it wrong and I have done that in the past wanting to cook something like store chicken, taking short cuts and regretting it afterwards.
Hope this helps