Many cattle producers retain a few heifers from their calf crop every year without evaluating the cost to develop those heifers into productive cows.
Developing heifers is expensive — usually moreso than buying them — when producers consider the costs of inputs and lost opportunities. Before undertaking this endeavor, consult an economist or pencil it out yourself to determine the economic feasibility of raising your own replacement heifers.
First, 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, probably heavier, and closer to puberty compared to 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 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 715 and 780 pounds, respectively.
To achieve these target weights, heifers should have proper nutrition and should be fed separately from the mature cow herd to eliminate competition with 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 average daily gain of the heifers and help them reach puberty sooner. Several growth-promoting implants are labeled for use in breeding heifers; however, some research indicates use of implants may cause a reduction in fertility compared to non-implanted heifers.
If you choose to utilize implants in your heifer development program, be sure to read the label carefully and use them only as directed.
A complete health and immunization program is an important part of successful heifer development. Consult a local veterinarian for assistance with 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 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, work remains. The heifer's body condition needs to be monitored closely to make sure it's in good flesh when calving season approaches.
To give heifers the best opportunity to rebreed in a timely fashion, they must be in good condition at calving. Achieving a body condition score (BCS) of 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) through calving and lactation.
The economic importance of a cow raising a calf annually 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.