How does age affect meat in different birds?

[Eichert87]

So, I'm trying to compile some information for butchering a wide variety of poultry. There isn't much in the way of information online to be found.
I realize that butchering a chicken that is over 6 months, or so, old makes it a tough meat. I am wondering how age affects geese, ducks, quail, pheasants, and turkeys. At what age do they start getting too tough to enjoy as fried, roasted, or cooked in anything other than a crockpot or pressure cooker? I am interested for two reasons...
1. My mom has dentures and loves fresh, home grown meat. Tough meat is too hard for her to eat.
2. Many breeds of poultry do not reach full weight until a year old, or more. I wish to find the "sweet spot" of butchering to get the most out, without sacrificing the tender goodness too much.

 

[oldhenlikesdogs]

Tenderness can be found in the meat preparation. Resting, brineing, and slow cookers are you friend. I think any animal that moves around will develop tougher muscles. So how you cook them is more important.

 

[Compost King]

I read where French Bresse chickens are fed some sort of dairy product (maybe grains soaked in milk) the last week or 2 or 3 before harvest. This makes them lethargic to where they do not toughen their meat up. Not sure if its worth the price of milk though.