I've never raised meat birds but have read many times about restricting their feed after a certain age (I believe opinions on when vary) or you will lose them. I believe I'd keep them together til I started restricting feed, if you can handle the poop and smell. I would imagine you will find a lot more info on raising these particular birds in the Meat Birds section.
Honestly there are multiple opinions on feed -- and I don't think they vary all that much, other than in protein and calcium content, and in whether any animal protein (such as fish meal) is included, unless you have access to a real quality feed. It's well established that chicks should not get layer feed before they start laying -- reason is, the extra calcium is harmful to their organs, can actually be fatal or at least shorten their lives. People feed roosters layer feed all the time, as they share coops with hens, but it makes sense to me that it's not the best thing for them, either. People who raise roosters separately I think typically use a game bird feed, which is high protein. My coop has mixed ages, some too young to lay, so I feed a grower or starter/grower to all my chickens -- flock raiser would also be fine -- and keep the oyster shell dish going for the layers (and another for grit.) Have been doing this for a while now and have no trouble with thin egg shells. On the animal protein, I am convinced they do better with it, especially if they do not have regular access to bugs. Chickens will eat bugs and worms any chance they get; it is a natural part of their diet. I recently read this has actually been established as more healthful for them but can't tell you a source, only that I read it from a source I trust implicitly.
