Pregnancy testing beef cows has many advantages. Previous articles have discussed in the importance of pregnancy testing on cow-calf operations. Working with a veterinarian to stage pregnancies in a cow-calf herd has two primary benefits: 1.) identify open cows, and 2.) determine when cattle conceived during the breeding season. This post will focus on the first of these two benefits. Knowing which cows are pregnant allows the producer and their veterinarian to 1.) objectively evaluate their operation’s pregnancy percentage, 2.) if the pregnancy percentage is not adequate, begin an investigation of potential causes of the problem, 3.) plan for resources (hay, supplement, pasture, human labor, etc.) that will be needed during calving, 4.) determine how to manage open cattle to minimize profit losses.
For cow-calf herds, profitability begins during the breeding season. Pregnancy percentage measures the success or failure of the breeding season. An annual pregnancy percentage of 90-95% is attainable goal for most cow-calf operations, although this goal is dependent on environmental and economic factors. Pregnancy percentage is measured by pregnancy checking cattle after the conclusion of the breeding season (i.e. for spring calving herds, this is commonly done in the fall, and vice versa). Pregnancy percentage is calculated by dividing the number of pregnant females by the total number of females exposed during the breeding season. Any females sold between breeding and pregnancy check should not be included in the count of total females exposed because their pregnancy status is unknown. Any cows that die or are culled between breeding and pregnancy check should remain in the total count of females exposed.
When used in comparison to similar operations, pregnancy percentage can provide the producer and their veterinarian with evidence that nutrition, bull power and fertility, herd health, and the match between genetics and the environment are all adequate. A pregnancy percentage lower than that of similar operations or previous years may indicate a problem in one or more of these areas. The value of pregnancy percentage can be further improved by sorting females by relevant management characteristics (i.e. age, breed, pasture, body condition, etc.). For example, it is important to manage the nutrition of first-calf heifers appropriately, as they are often the group most susceptible to failure to rebreed due to problems with body condition after having their first calf. These individuals often need additional nutritional resources to make up for the added metabolic demand of lactation, in addition to growth of the dam. Stratifying pregnancy percentage by age will also help producers find older age groups of cattle that are becoming less efficient, and may require more resources to maintain an adequate pregnancy percentage.