What should I be feeding my roos?

[Godiva]

We just butchered our first two roos and they were rather scrawny despite being 17 weeks old. THey have been doing a lot of chasing of the other roos but I really expected them to be a lot meatier than they were! THeir thighs and drumsticks were ok but nothing great and since they are BUff Orps I was expecting something meatier than the rather puny little carcasses we discovered under all that fluff! We have been feeding them the start and grow Purina crumbles and were unable to find a broiler ration in this area. Do you think this is the problem? They are all very healthy looking and yet just not much meat on any of them at the moment. What would you recommend I feed them? How do I get them to flesh out more? I am hoping that having the two bullies out of the way will give the others a chance to eat more and relax a bit but I think the food may need changing too after seeing those two without their PJs. Help.