When it comes to breeding heifers, there are several questions that often come up. Should they be bred to calve at 24, 30 or 36 months old? Should they be bred to calve a month earlier than the cow herd? How long should the breeding season be?
In most situations, calving heifers at 24 months old works well. With a good forage program, heifers can be developed to reach target breeding (65% of mature weight) and calving weights (85% of mature weight) with limited energy and protein supplementation. However, if the forage program is lacking because of overstocking, drought conditions or something else, then more supplementation will be needed. Calving heifers at 30 months old is often not practical unless the operation uses two calving seasons or purchases heifers. Calving at 36 months old increases development costs and increases the time for a heifer to pay for herself.
There are both pros and cons to calving heifers a month earlier than the rest of the cows, and these may change depending on the size of the operation, available labor and calving season. If heifers are calved a month earlier, then their calves should also be weaned a month sooner. From a management standpoint, this results in a second weaning date for the operation and may also complicate vaccination and other management considerations. If their calves are not weaned earlier, then the heifers have been required to nurse a calf for longer than the cow herd, which can have negative impacts on the body condition score and future reproductive success of these first-calf females.
Additionally, if calving seasons have been established to match forage production, then calving heifers a month early often means they are consuming lower-quality forage right after calving compared to the forage the cows are consuming right after calving. Because of this, there is not as much benefit from a postpartum-interval standpoint of calving heifers early as might be expected.
For the cow herd, the length of the breeding season is about 90 days for most operations. In most situations, it is beneficial to shorten the breeding season for heifers to 30 or 45 days or only keep the heifers that are bred in the first 30 to 45 days and sell the later-bred heifers. This helps select the most fertile heifers and increases their chances to breed back in future years.
