I've been grass developing mostly old line angus heifers for a few years now, breeding them to calve at 2 years old. What i've found is that in a 2-3 cycle breeding season, about 10% less will get bred (60-75% bred at 50-60% of adult weight), and I have 1-2% more dystocia. It separates the most fertile, most efficient, most adapted to the environment really quick. The worst part about it is that, for the most part, first calf crop is sub-standard, and cow doesn't get to full weight/maturity til 4 years old. This year i'm trying to provide even more nutrition through annuals and grazing management/stocking rate, but no feed, so that they breed at 55-60% of adult weight, and are at BCS 6 at calving. I'm hoping this well help with that first calf crop. Two years ago i had a heifer wean 72% of her body weight with a bull calf over 500lbs...she wasn't much bigger than him...but she got bred back on time. She will probably mature out around 1000 lbs. I'm in south GA, so our low energy grasses and mild winters favor a slightly smaller animal, from an environmental standpoint.