In order to maximize the productivity of a female within a beef cattle operation she must produce a marketable calf on every 365 days. In order to police this production requirement, pregnancy diagnosis is practiced in a majority of operations. In many production scenarios across the western United States, beef producers are allowed the convenience of diagnosing pregnancy in their cow herd following fall weaning. However, during a drought situation, such as the one being faced in the summer of 2012, alternative management may prove to be beneficial. The identification of a viable pregnancy can accurately take place as early as 25 to 28 days following conception via the use of transrectal ultrasonography and by 30 to 35 days by an individual whom is skilled in rectal palpation. The cost of pregnancy diagnosis will range from $3.00 to $12.00, depending on the technician and distance they must travel to the farm.
Traditionally producers have waited until the completion of the breeding season to identify unproductive females within their herd. However, in a time of extreme drought, early pregnancy diagnosis may allow producers to save valuable forage for their most productive females. The length of the breeding season in South Dakota normally ranges from 45 to 80 days, in most management scenarios. If drought conditions are limiting forage and/or water quality and availability, a producer may be able to utilize early pregnancy diagnosis. For example: Producer A has deduced that they will be able to retain 100 of the 150 cows in their herd and are 45 days into their breeding season. Originally they planned to cull cows following the conclusion of the breeding season. However, if they were to utilize early pregnancy diagnosis, it is likely that the needed 67% of their cow herd may have already become pregnant and those cows that did not become pregnant may be culled sooner in conjunction with early weaning.
The same theory would apply for replacement heifers. They are typically bred to begin calving 30-45 days prior to the mature cow herd, making them prime candidates for early pregnancy diagnosis. Those yearling heifers that aren’t pregnant can be easily marketed as guaranteed open feeder heifers. Considerations:
If replacement heifers are developed correctly they should be the most fertile females within a herd. In addition, they should be the most genetically advanced females in your operation. Therefore, any replacement heifers that do not become pregnant during their first breeding season, calving for the first time as coming two-year olds, should be culled from the herd. The replacement heifers that become pregnant early in the breeding season, likely reached puberty at a younger age and have the potential to be the most productive females in the future.
Females that calve earlier in the calving season, become pregnant sooner in the subsequent breeding season, and are the most productive females within the herd over their lifetime. Therefore, by culling females that either have not become pregnant, or did so in the later portion of the breeding season, allows a producer to retain the most fertile and productive females within their herd.
Early pregnancy diagnosis may work well in conjunction with early weaning. If calves are weaned from cows that have not yet become pregnant, their future in the herd should be strongly considered as they are no longer productive members of the cow herd. In addition, if open cows are identified and culled, a smaller portion of calves may need to be early weaned.
Early identification of unproductive females within the herd will allow more time for management decisions to be made. In normal production circumstances, it is estimated that every open cow within your herd costs approximately $94 per cow exposed with an 85% pregnancy rate. In a time of drought, the cost of production can dramatically increase, driving this number even higher. While there is no secret formula to help producers make the correct decision in the time of a drought, the early identification of any unproductive females within a herd can be a valuable management tool for producers to consider.