does it mean big bags with big teats? Big bags with small teats? Heavy weaned calves, no matter what bag looks like? IDK, but its pretty hard to 
get a whole herd with ideal bags. Down here in Missouri we have the 'show me select' heifer program. Best program goin I guess, because it's a
program? They dont seem to care much about cow longevity, whether its bag quality or feet or breed back. Seem to have let hard fed heifers become
the norm, which doesnt make for longevity imo. I think pick from your own herd(what YOU like), run through a similar type program and go from 
there.