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Value of pregnancy testing

published: June 2nd 2017
by: Joe C. Paschal
source: ICA of Texas
According to the Na-tional Animal Health Monitoring Survey conducted by USDA a few years ago, only about one-sixth of U.S. beef cattle producers regularly pregnancy test their cows after breeding season ends. That is lower than the percentage reported by South Texas ranchers in a survey we conducted several years ago. More U.S. producers conduct a breeding soundness examination on their bulls than pregnancy test their cows, but not by much.
Texas A&M University Extension personnel have conducted thousands of pregnancy testing schools (usually with the assistance of interested cattle organizations or companies) ranging from a single day to a week over the past 50 years. Recently, I assisted in teaching one at Tom Brothers Ranch near Campbellton with Ellen Tom and her uncle, Philip Tom. It was sponsored by the county extension agents in Atascosa, Bexar, Wilson, Medina, and Dim-mitt counties. Participants were encouraged to bring their own cows for a nominal fee and both days had plenty of takers! We covered anatomy and physiology of the cow’s reproductive tract, pregnancy determination (via rectal palpation, but also using ultrasound and either of the new blood tests), estrus synchronization for commercial cattle using natural service (bulls), reproductive tract and body condition scoring, and pelvic area measurement. It was a full day for each of the two days (the activities were repeated) and the participants received lots of hands- on experience. Most indicated that they were going to involve (or continue to use) their local veterinarian for pregnancy testing, but now they had a better understanding of the process and practice.
I still prefer to palpate my cows for pregnancy. If I know the breeding date, I feel comfortable determining 35 days of pregnancy.  If I don’t, I am more comfortable at 45-60 days. Most veterinarians who work with beef cattle are better than I am. All it takes to be good is to be in lots and lots of cows. However, if it is only important to know only if they are pregnant or not, all you really need to know is what an open or non-pregnant reproductive tract feels like. The tract of an open cow feels meaty, like the side of your cheek, and you can pick up both horns (the cow’s uterus has two medium sized horns) in your hand. They are also about the same size. The open cow tract may be small (as in heifers) or large (as in older cows) but the feel is the same. A bred cow, even an early bred one, has a tract that feels thin. This is because the uterine wall has expanded to contain the embryo or fetus and the fluid filled membranes surrounding it. Palpation can also determine if the calf is alive or dead (sometimes a fetus dies and becomes mummified or is resorbed), if the cow has twins, or why she isn’t bred if the cow is open. In addition, having your veterinarian there gives you an extra pair of hands and eyes for other things.
The other methods of pregnancy testing are using ultrasound and blood tests (BioPRYN® and IDE-XX™). I have used both. Ultrasound devices are expensive, but if you are doing a lot of reproductive work, and many veterinarians are, they are worth the expense. With ultrasound, you can detect pregnancy around 35 days, and you can also detect the sex of the calf and twins. Ultrasound can detect open cows as well, and it can be used to scan the ovaries to see if there is a physiological reason for an open cow. Usually the reproductive tract is scanned by holding the device in the rectum, but there is now an extension or wand that can be used that is inserted rectally instead of using your hand.
The blood tests are similar in that they both detect a placenta-forming hormone. Usually, a minimum of 2 ml of whole blood is collected in a red-top tube and is sent unrefrigerated to a laboratory (BioPryn) or veterinarian (IDEXX) for analysis. These tests are very accurate in heifers (they will only have the hormone if they are pregnant) but slightly less so in cows. This is because cows that have had calves recently may still have a little of this hormone circulating and can give a low false positive if they are still open. It is recommended that testing be done 28 days post breeding (60 days after calving) for best results. Both tests require new syringes, needles and tubes for each cow and then they need to be shipped or taken to the laboratory. Depending on your costs, it is usually less than $10 per result. Results take a few hours.
So, now you know. Don’t wait to discover open cows at weaning. Get them pregnancy tested so you can either get rid of them or get them bred. At the cost of about $1.50-2.00 per day to run cows, spending a few dollars to detect pregnancy is inexpensive insurance!

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