Pregnancy Detection Beyond Palpation
MU professor explains four methods to detect pregnancy earlier in the breeding season.
SIOUX FALLS, S.D. (Dec. 4, 2012) — Wouldn’t it be handy to know if a cow was pregnant sooner after insemination, so open females could be re-synchronized and artificially inseminated (AI) the second time earlier in the breeding season? Matt Lucy, professor of animal science at the University of Missouri (MU), explained four tests using new technology to detect pregnancy earlier are in the works.
The first test, called Early Pregnancy Factor (EPF), looks at an immunosuppressive glycoprotein in the blood and is supposedly able to detect pregnancy two days after breeding. A pregnancy kit was brought to market in the 1990s, Lucy said, but three different studies found the kit to be unreliable.
The second measures interferon-stimulated gene (ISG) expression. This claims to detect pregnancy by day 16-18, though Lucy said it is more accurate at 20 days. The test uses a process called reverse-transcriptase PCR (RTPCR) to analyze RNA from leukocytes in the blood. Lucy noted that ISGs have not been commercialized.
The third option is progesterone monitoring of blood or milk. Lucy said this is more popular in dairy cattle. The first true example of chemical testing, it detects whether a decrease in progesterone (meaning the cow is not pregnant) has occurred 21 days after breeding. However, since multiple samples increase likelihood of accuracy (and beef cattle are not milked regularly), Lucy said this method has limited applicability in beef cattle.
A more reliable test, he explained, is for the presence of pregnancy-associated glycoproteins (PAGs) in the blood. This test can detect pregnancy after 25 days. PAGs are only produced in the placenta, so there are fewer chances for false positives. These tests are available commercially, he noted.
The original PAG test is available under the trade name BioPRYN® through BioTracking LLC. Blood samples should be collected approximately 30 days after insemination and shipped to the lab at room temperature for analysis. Results are given to the producer by telephone, mail, fax or email. The company reports a 99.9% accurate negative predictive value. The positive predictive value is a little lower (about 95%) because some cows that slip an embryo may have PAGs in the blood.
Lucy was optimistic that PAG tests could assist beef producers in detecting pregnancies sooner, though he said that transrectal ultrasounds could be done about the same time as PAG tests and offer the benefit of detecting dead embryos and nonviable pregnancies. Though, with added certainty of ultrasound comes the added cost of ultrasound equipment and technical skill needed.
These tests offer producers options, but Lucy warned that trying to detect pregnancy too early could backfire with more opens than expected due to later embryonic loss. He recommended deciding on a testing method that coincides with the goals of the reproductive program for each individual operation.
Lucy spoke during Tuesday's ARSBC session focused on vaccination and pregnancy determination. Visit the Newsroom at www.appliedreprostrategies.com to listen to this presentation and to view the PowerPoint slides and proceedings paper submitted by Lucy to accompany it.
Comprehensive coverage of the symposium is available online at www.appliedreprostrategies.com. Compiled by the Angus Journal editorial team, the site is made possible through sponsorship by the Beef Reproductive Task Force and LiveAuctions.tv.
Editor's Note: This article was written under contract or by staff of the Angus Journal. To request reprint permission and guidelines, contact Shauna Rose Hermel, editor, at 816-383-5270.