If you do not know cow weights, the herd's average frame score can be used to predict mature weight, and hence heifer target weight. However, weight is not the only controlling factor. A minimum age requirement must be reached in order for heifers to reach puberty. Age at puberty can be decreased by selecting for breeds that tend to be younger at puberty, selecting within a breed for younger age at puberty, or crossbreeding with another breed that has a similar or younger age at puberty. Angus cattle are considered to be about average in age at puberty when compared to other breeds.
Some studies indicate exposing prepuberal heifers to bulls or bull urine decreases age at puberty.
However, other studies do not show the same results. Exposure of prepuberal heifers to mature cows or cycling heifers does not decrease age or weight at puberty. Although considered animals with a nonseasonal estrus, cattle are prone to exhibit seasonal effects on reproductive performance. This is shown by a younger age at puberty for heifers born in the fall vs. those born in the spring. Estrogen negative feedback starts to decrease about 50 days before heifers reach puberty, and LH secretion then begins to increase.