The cornish cross grow out quick so I wont be feeding them for too long.
I can tell you from personal experience you are in for an eye opener. I've raised Cornish before and even though they reach full maturity at only 8 weeks 30 birds ate 500 lbs of feed in that time. My smaller hens were 8-9 lbs live weight. The largest rooster I butchered was 12.5 lbs