Your post reads as if you intend them to eat growing wheat and grass. I assume you know better, and that they need the proper feed from d.o. to slaughter. The first thing to do is find your market - always, and for any enterprise you propose. Then, when you have at least an approximate idea of the price you are going to receive, do your other costings. Frankly, I prefer the standard indoor reared broiler. One poster on here rears meat birds to a much greater age, and I have no doubt about his claims that they taste better, but these are not the normal range reared broiler breeds, and on a large scale year-round basis you would have to be 100% certain your prospective buyer will take them.