Methods to Determine Pregnancy
There are several alternatives to determine pregnancy.
by Kasey Brown, associate editor
As to deciding which test is best, “best” must first be defined for your operation, Dee Whittier said, offering controlled research showing mistakes can be made with each method. He described advantages and disadvantages of each method.
STAUNTON, Va. (Oct. 16, 2013) — Knowing whether cows are pregnant is incredibly useful for making management decisions, and there are several methods to determine pregnancy, Dee Whittier, professor and Extension veterinarian for Virginia-Maryland Regional College of Veterinary Medicine, told attendees of the 2013 Applied Reproductive Strategies in Beef Cattle (ARSBC) symposium in Staunton, Va., Oct. 15-16.
The first method is rectal palpation. He explained that by feeling for the “membrane slip,” veterinarians can feel whether a cow is pregnant 65 days into a pregnancy. Whittier mentioned the four golden rules for rectal palpation:
- You must examine the entire tract before declaring the cow open.
- You must find one of the positive signs of pregnancy before you call a cow pregnant.
- Pregnancy examination must always be the first step in your examination. If you are not sure, recheck the cow later.
- The only positive signs of pregnancy in the cow are fetus, cotyledons/caruncles, amniotic vesicle and fetal membrane slip.
The second method is rectal ultrasound for pregnancy. The technology has gotten to be affordable and portable enough to be done chuteside. He said that this could allow pregnancy detection at 25 days, though it is clearer at 30 days or later. It is also possible to determine the sex of the fetus with this method.
The third method is blood testing. BioTracking LLC has a test called bioPRYN, which stands for Pregnant Ruminant Yes No. The test, developed by Garth Sasser, detects a pregnancy-specific protein B (PSPB) from the placenta. Genex has a test called DG29, which is said to detect pregnancy at 29 days. Both of these tests require blood samples to be sent to the respective company’s lab, he said.
IDEXX Visual Pregnancy Test allows a veterinarian to buy a testing kit, perform the test in a controlled environment (like the vet clinic) and make a diagnosis quickly. Whittier said that IDEXX also has a milk test, which is useful in the dairy industry by testing the milk for a specific protein.
Test pros and cons
As to deciding which test is best, “best” must first be defined for your operation, Whittier said, offering controlled research showing mistakes can be made with each method. He described advantages and disadvantages of each method.
Rectal palpation advantages include immediate diagnosis, which allows for quicker management decisions; little equipment is needed; determines staging of pregnancy; some assessment of fetus viability; good to fair assessment of normality of the fetus; and low to moderate cost. Its disadvantages include being invasive; a very long learning curve for the technician; potential for damage to dam or fetus; availability of veterinarian or technician; and potential for error.
Ultrasound advantages include immediate diagnosis for quick management decisions; staging of pregnancy; and excellent assessment of viability and normality of the fetus and dam. However, it is invasive; it involves expensive equipment and a long learning curve for the technician; potential for damage to the dam and fetus; availability of the veterinarian or technician; potential for error; moderate to high cost and could take more time.
Blood tests are noninvasive; less skill is needed; available when no technician or vet is available; relatively inexpensive equipment; shorter learning curve; and probably less potential for error. However, it has a moderate to high cost, no immediate diagnosis, no staging of pregnancy, and offers no assessment of viability or normality.
Whittier spoke during Wednesday’s ARSBC session focused on special issues on beef cattle reproduction. Visit the Newsroom at www.appliedreprostrategies.com to listen to his presentation and to view his PowerPoint slides and proceedings paper. This comprehensive coverage of the symposium is compiled by the Angus Journal editorial team. The site is made possible through sponsorship by the Beef Reproductive Task Force.
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.