I've been playing with the protein percentage in the feed for my mixed breed dualie roos. Jury's still out on that, but so far: it seems that the ones that just got layer ration grew about as fast as the ones that got 22% protein, and even 24%, up until about 16 weeks. After that, higher protein seems to get them filled out more quickly. There's a big growth spurt about then, they get much bigger in a very short time, at that stage. Most of mine are part Brahma, and they are slow growers.
Earlier in the year, I butchered 4 Brahma-Dark Cornish crosses, somewhere between 20 and 25 weeks old, (I think) 2 were around 6 1/2 lbs. dressed, the other 2 were around 7 1/2 lbs. I just butchered 3 Brahma-EE-and maybe dark Cornish, around 18-20 weeks old, smallest was just under 4 lbs, the other 2 about 4 1/2 lbs. Reasonably meaty, all of them, breasts on the 4 older Brahma-Cornishes were not bad at all. Not quite like C.X's, but not what you'd call scrawny.
The birds develop better flavor as they get older. That's why older roosters are preferred in many traditional French recipes. Supermarket birds are 6 weeks old, that's why they have less flavor than most homegrown birds, because most people who raise them at home let them go 8 weeks or more. When we used to raise C.X's now and then, we let fryers go 8 weeks, roasters 10 weeks. The dualies and mixed breeds are usually at least 16 weeks when people butcher them, so far, mine don't really fill out until at least 18-20 weeks, sometimes a little longer. It will vary, depending on breed(s), climate, and diet.
Another member, Kstaven, said he fed his dualie roos whey, and it made them come out more tender. That makes sense, because the lactic acid would act as a tenderizer. It's why buttermilk works so well to tenderize meat. I used it on some venison stew meat last night, and it cooked up beautifully tender, a lot faster than it usually gets tender.
