For cow/calf producers, a first-calf heifer can be a real headache. Even if she makes it through calving without a hitch, rebreeding for the next season usually isn't easy.
To top it off, a first-calf heifer is critical to the beef cattle operation. She doesn't just replace an older cow; she represents the future genetics of the operation. That means she can play a big part in its ultimate profitability.
In order to keep a first-calf heifer productive and in the herd, producers must understand that she faces some significant challenges that set her apart from other, more mature cows, says G. Cliff Lamb, Extension beef cattle specialist for the University of Minnesota.
While coping with the stress associated with her first birth and nursing a calf for the first time, a first-calf heifer must stay in favorable condition so that her uterus involutes and she resumes her estrous cycle. And, in order to produce offspring on a yearly basis, a first-calf heifer must establish pregnancy for a second time within 83 days, Lamb says.
All this must be overcome while she is only 85% of her mature weight, he adds.
Besides reproduction and nutrition, another challenge is dystocia (calving difficulty). Dystocia can interfere with a first-calf heifer's transition to a mature cow. It's also the most common reason a heifer doesn't make it into the herd later.
Dystocia negatively affects detection of estrus, conception rates and overall pregnancy rates, Lamb says.
A number of factors can influence the incidence of dystocia. These include the high birth weight of the dam, an excessively small pelvic area, the high birth weight of the bull and carrying a male calf, which tends to be larger than a female calf.
Producers who wait until calving to worry about these matters may be out of luck. However, those who give replacement/first-calf heifers a little extra attention during the breeding and pre-calving process likely can prepare heifers to avoid dystocia and uphold the operation's calving rate, Lamb says.
Lamb offers these guidelines for keeping replacement/first-calf heifers in the herd and in top condition.
* Feed replacement heifers to fulfill 65% of their mature weight by breeding time so they can satisfy reproductive needs later. First-calf heifers need energy for basal metabolism, activity, growth, energy reserves, pregnancy, lactation, estrous cycles and initiation of pregnancy.
* Have your veterinarian perform a prebreeding reproductive tract exam to determine which heifers are cycling; cull those that aren't.
* Identify heifers with small pelvic areas and breed them appropriately. Consider culling heifers with excessively small pelvic areas because they can require a costly C- section.
* Use estrous synchronization on replacement heifers for earlier breeding, and use it on first-calf heifers to initiate estrous cycles after calving and to reduce the incidence of short estrous cycles. (Estrous synchronization induces ovulation and gets rid of some of the guesswork in insemination timing.)
* Ensure that replacement heifers are bred to low birth weight Expected Progeny Difference (EPD) bulls. A producer can focus on selecting bulls for performance traits after the heifer has had her first calf. Low birth weight dams bred with a low birth weight bull have less difficulty, fewer C-sections and better calf vigor scores.
* Because first-calf heifers usually require a longer period of postpartum anestrus, consider breeding replacement heifers to calve two weeks before the mature cow herd. This head start will allow them special treatment during calving, and it will give them an extra 14 days to resume estrous cycling.
* Monitor and adjust the condition of replacement heifers so they calve at a body condition score of between 5 and 7. Scores in that range improve the likelihood of a heifer's cycling at the start of the breeding season. A lower body condition score reduces calf vigor. A higher body condition score wastes fuel, increases calving difficulty and reduces milk production. Feeding cows to gain condition after calving is too late.
* Reduce the length of the breeding season to 60 days or less. This increases the percentage of females cycling during the next breeding season and gives all cows a high probability for pregnancy at the start of the next breeding season. Culling late calving cows shortens the breeding season gradually.
* Separate first-calf heifers from mature cows when feeding so they don't have to compete for feed.
* As a last resort, let cows enter winter in good condition by weaning calves from first-calf heifers early (less than 200 days). But, carefully weigh the potential advantages of increased fertility against the potential disadvantages of reduced calf weaning weights and increased potential for calf diseases.
Keeping accurate records and maintaining good facilities also are important factors in a beef cattle operation's management of first-calf heifers, Lamb says.