Every breed is different, but here ya go. Page 24.
http://www.ers.usda.gov/media/935958/ah697_002.pdf
So I was just thinking about how to go about figuring what age I should be processing my project roos, as it affects how many will end up in the run at one time after hatch and brooding.
My thought was to take a few at 10 weeks, a few at 12, and a few more at 14 weeks. My calcs say the bigger the bird, the higher the project margin, but of course at some point there's a diminishing return on quality of meat.
WalnutHill, you've done this for your breed...how did you think it out?