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Use of BioPRYN to Determine Pregnancy Status and Assign Calving Groups

NDSU researchers compare pregnancy diagnosis via transrectal ultrasound with pregnancy detection via the BioPRYN system to determine pregnancy status and whether BioPRYN is a useful tool for beef producers to group cows according to predicted calving date.

In the U.S. beef industry, less than 20 percent of beef producers pregnancy check their cattle. Producers with larger herds (those who have a greater proportion of their income coming from cattle) are more likely to incorporate pregnancy checking into their management scheme compared with producers who have smaller herds. However, cost control and identifying nonpregnant cows are important for herds of all sizes to remain profitable.

Drawing blood for testingPregnancy-Specific Protein B (PSPB) is a glycoprotein hormone released by certain cells in the bovine placenta that develop between days 18 and 20 of gestation. As the pregnancy progresses, the amount of PSPB found in the blood increases. A commercial test, BioPRYN (www.biotracking.com/), is available to detect the presence of PSPB in cattle, horses, bison, sheep, goats and several types of wildlife. This test is an accurate predictor of pregnancy status in cattle beginning around day 28 of gestation.

With many areas of the country experiencing a shortage of large-animal veterinarians, BioPRYN is a viable alternative to traditional methods of pregnancy determination, such as palpation per rectum and transrectal ultrasonography. In addition, the use of BioPRYN eliminates variation in the accuracy of pregnancy detection resulting from a lack of expertise in technicians performing traditional detection methods.

The objective of this study is to compare pregnancy diagnosis via transrectal ultrasound with pregnancy detection via the BioPRYN system to determine pregnancy status and whether BioPRYN is a useful tool for beef producers to group cows according to predicted calving date.

The study is being conducted with cows at two locations: Central Grasslands Research Extension Center, Streeter, N.D., and Hettinger Research Extension Center, Hettinger, N.D. Central Grasslands maintains a cow herd of 460, with an additional 100 heifers, whereas Hettinger maintains approximately 100 cows. All cows are part of the project detailed in the June 2011 Research Corner section of The Ranch Hand.

All cattle were scanned via transrectal ultrasonography 49 days after the beginning of the breeding season to determine the presence and age of the fetus and proportion of cattle that became pregnant during the first 21 days of the breeding season. The cattle also will be scanned at least 35 days after the end of the breeding season to determine final pregnancy status and fetal age.

At the time of the final ultrasound scan, 2-milliliter blood samples will be collected from either the jugular or tail veins in blood tubes and submitted to BioTracking LLC for determination of the concentration of PSPB and optical density.

Results of the PSPB pregnancy test will be compared with results of the ultrasound pregnancy determination to determine the sensitivity and specificity of the test. In addition, all cows will be monitored through calving. Results of the BioPRYN test will be compared with calving data to retrospectively determine whether cattle can be sorted into calving groups accurately based on PSPB results.

Results from this project will allow producers to see the usefulness of a blood-based pregnancy test and offer insight into the utility of using this test in expansive beef operations. Also, these data will be used for a future article about why producers may want to consider different methods of pregnancy detection in different scenarios.

Phil Steichen, Sharnae Klein and Quynn Larson, Graduate Students; Carl Dahlen, NDSU Extension Beef Cattle Specialist; Bryan Neville, Animal Scientist, Central Grasslands Research Extension Center, Streeter, N.D.; Chris Schauer, Director, Hettinger Research Extension Center, Hettinger, N.D.

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