Due to current high cattle prices, many producers have intentions of retaining and developing heifers from their spring calf crop. However, developing heifers is expensive usually more so than buying them when the cost of inputs is considered. Before undertaking this endeavor, consult an economist, or pencil it out yourself to determine the economic feasibility of raising your own replacement heifers.
If you decide to retain and develop heifers, the first thing to determine is how many heifers to keep. A typical cow herd will consist of about 17 percent first-calf heifers on an annual basis. This number can be adjusted up or down depending on the particular situation. Keeping at least 10 percent more should cover those that fall out of a group that is properly developed, considering that only about 90 percent of the heifers will conceive during the breeding season.
The best prospects for replacement heifers are those born during the first 60 days of the calving season because they are older, most likely heavier and are closer to reaching puberty compared to their younger herdmates. In order for a heifer to calve as a two-year-old, she must reach puberty and breed by 15 months of age. Since the time at which a heifer reaches puberty is a function of age and body weight, managing heifers to achieve a target weight that is 65 percent to 70 percent of their mature body weight prior to their first breeding season is critical. A typical cow weighs 1,100 to 1,200 pounds, so the target weights for these 15-month-old heifers would be from 715 to 780 pounds.
In order to achieve these target weights, heifers must be supplied with the proper nutrition and should be fed separately from the mature cow herd to eliminate competition with the older cows. Contact a livestock specialist or nutritionist to formulate a ration or identify a forage type that will meet the requirements of the heifers. Adding an ionophore such as monensin or lasalocid to the ration will improve the average daily gain of the heifers and help them reach puberty in a shorter period of time. There are several growth-promoting implants labeled for use in breeding heifers; however, some research indicates that use of implants may cause a reduction in fertility compared to non-implanted heifers.
A complete health and immunization program is an important part of a successful heifer development program. Consult a local veterinarian for assistance with developing an immunization and general health protocol. Ideally, this veterinarian will be familiar with the herd health history and local disease situation.
Heifers should be exposed to bulls or artificially inseminated three weeks to a month ahead of the mature cow herd so they have the opportunity to conceive earlier and calve earlier in the calving season. This will benefit the heifers by allowing them more time to recuperate and prepare for the next breeding season. To help identify and eliminate subfertile heifers, limit the breeding season to a period of 45 to 60 days. A skilled technician can evaluate pregnancy status around 60 days after the bulls are removed from the heifers. Open heifers should be culled at this time. This will allow for a reduction in winter feed costs, and these heifers are still young enough to be marketed and placed in the feedlot.
Once the pregnant heifers are identified and the open heifers have been sold, the work isn't over. The heifers' body condition score (BCS) needs to be monitored closely to make sure they are in good flesh when the calving season approaches. To give these heifers the best opportunity to rebreed in a timely fashion, they must be in good condition at calving. Achieving a BCS 6 or 7 at calving would be ideal; however, this is not always optimal or economical. To avoid poor pregnancy rates in the subsequent calving season, maintain heifers in at least average condition (BCS 5) at calving.
The economic importance of a cow raising a calf on an annual basis is obvious, and a cow's ability to do this is highly dependent on her performance as a heifer. The key to having a productive cow herd is selecting the right heifers, developing them properly and getting them bred early in their first breeding season.