Pregnancy testing cow herd pays off in the long run
Information on pregnancy status can be extremely valuable in a hot, dry year. If the old, open and ornery were culled last year, then culling this year might not only be about identifying open cows but also those expected to calve late.
For years, pregnancy diagnosis in cows largely has been dependent on the skills of a veterinarian who has been trained in rectal palpation. Increasingly, more veterinarians have invested in ultrasound equipment that can detect pregnancy as early as 25 days after mating. The efficiency of diagnosis (i.e. speed and accuracy) is such that 30 days of gestation is a more practical minimum time period. Ultrasound also can be used to determine the sex and approximate age of the fetus.
A relatively new option available for pregnancy diagnosis that does not require a veterinarian or expensive equipment is in the form of a commercially available blood test. Three companies now provide bovine pregnancy tests: BioTracking, LLC (BioPRYN; www.biotracking.com), IDEXX (www.idexx.com) and Conception Animal Reproduction Technologies (DG29, www.conception-animal.com) in partnership with AgSource Cooperative Services and Genex Cooperative.
The tests determine the presence of pregnancy associated glycoproteins, a family of proteins produced by the placenta. The tests can be used 28 to 29 days after mating in cows and heifers. These proteins continue to be produced throughout pregnancy and disappear slowly after calving. Depending on the test, proteins can be detected in the blood until 60 to 90 days after calving. In the case of the DG29 test (protein present until 90 days post calving), if a cow conceives at 50 days after calving, the test would need to be delayed until 40 days after she was bred, or a total of 90 days after calving.
These tests are considered highly accurate on a herd basis. One of the things that can contribute to the inaccuracy of the test is if embryonic loss occurs, the protein still might be detected for a period of time after the loss. So an animal will be called pregnant even though the embryo died. A certain amount of embryonic loss is expected, regardless of the method of pregnancy detection. A majority of embryonic loss that occurs happens early in pregnancy, so the loss might not be apparent if pregnancy diagnosis normally occurs in mid- to late gestation.
If you compare ultrasound and the blood tests for early pregnancy diagnosis, ultrasound enables you to see the fetal heartbeat and know the pregnancy is viable at that point in time. The other advantage of palpation from a blood test is you can make a management decision at the time the cow is in the chute based on if she is pregnant or not.
The advantage of testing via a blood sample is you don't have to compete with the neighbors in scheduling the veterinarian, and producers complete the testing on their own schedule. Collecting a blood sample is a relatively easy skill to acquire and does not require expensive equipment. Recently, one company, ITL Animal Healthcare (www.itlanimalhealthcare.com), has developed a sampling device (TEGO Card) that can be used for DNA samples or pregnancy tests (biogenetic services). The card is held in a plastic container that fits into an Allflex ear tagger. A specialized adaptor pin is used with the tagger to prick the skin and allows blood to be collected on the card. The sample collector is able to store the blood card in its specialized envelope directly after collecting the sample without having to let it dry. This saves the producer time and reduces the chances for cross contamination. The cards can be stored at room temperature.
Determining which cows are pregnant and at what stage can be valuable information for producers in making routine management decisions and even more when forced into tough culling decisions during drought. Given the price of feedstuffs, the cost to determine pregnancy status can be recovered in the savings from relatively few days of feeding. Partner with your veterinarian or try one of the commercial pregnancy tests to determine pregnancy status and take pressure off of limited feed resources.
* Information provided by Sandy Johnson, northwest area Extension livestock specialist.
Stacy Campbell is agriculture Extension agent in Ellis County.