In order to remain an economically practical member of the herd, a beef cow must produce a calf annually. Most non-pregnant cows in a herd, after breeding season, are either young (first calvers breeding back) or old cows. Rather than waiting until calving season to determine if a cow got bred, utilizing pregnancy checking of each individual cow as a management tool will improve reproductive efficiency of a herd. The majority of non-pregnant cows are generally a result of environmental conditions such as management, nutrition, or genetics. If a cow has been pregnant at least once, under the right conditions she can likely do it again.
Knowing which cows did not breed back allows a producer to strategically manage and market their cows. This can allow for alternatives such as weaning calves early and selling open cows at peak market prices. Additionally, feeding thin cows to develop body fat or getting high value out of open heifers. Also, finding large amounts of open cows early can detect disease, nutritional deficiencies, or environmental factors that reduce pregnancy rates. Some producers even use pregnancy testing to determine calving dates, and then sort cows into groups based on calving.
Moreover, culling open cows and heifers will boost herd fertility in subsequent calf crops, while improving pounds weaned per cow exposed. More added benefits of removing reproductively inefficient cows includes a combination of increased pounds weaned per cow exposed and lower costs per pound of calf raised, generating more revenue per cow. Recognizing and removing open cows allows for more sensible usage of valuable feed commodities and pasture resources for more productive livestock. Below are methods of evaluating pregnancy status.
Palpation is traditionally the most common method for determining pregnancy status in beef cattle. This option can be conducted by a trained veterinarian who can accurately detect pregnancy at day 45 of gestation. This is done by using touch to observe the uterus, ovaries and uterine arteries through the rectal wall. Importantly, detecting gestation status between 90-120 days of gestation provides a more accurate fetal age. The accuracy, speed, and cost of palpation ($3-$10/hd), makes it a viable option for pregnancy diagnosis. The largest drawback of transrectal palpating is improper handling of the uterus which can lead to embryonic loss.
Ultrasound technologies can detect pregnancy around day 21 of gestation but requires more expensive equipment. The cost of an ultrasound is approximately double that of palpating ($7-$15/hd), but the improved accuracy is highly valued by producers who utilize it. Furthermore, an ultrasound will present more information than palpation, such as viability of the fetus, if a cow is carrying twins, and identification of sex. Predominately all ultrasound technologies go into the cow’s rectum with a probe, but this form of handling the uterus is less disruptive.
Tests that measure hormone levels in the blood have popularized commercially since entering the market nearly 20 years ago. The main advantages of the blood test are that the tests are cheaper than ultrasound ($3-$5/hd) and can be executed quickly and easily. The blood is drawn from the vein under the tail, which is less invasive than palpating and more accurate as well. However, cows must be 90 days post-calving to ensure accurate results. Some of the disadvantages of blood testing include (inability to) detect twins, miscalculate the viability of the fetus, inaccurate determination of fetal age and sex, and slower result processing.
For more information on Nebraska Beef Extension or pregnancy checking reach me at (402) 624-8007 or follow my twitter page @BigRedBeefTalk.