It’s September, meaning that the kids are back in school, pumpkin spice is on everything, and that producers want to get their cows in to get them preg-checked.
Methods of Verifying Pregnancy
Preg-checking is a good opportunity for you to get a close look at each cow in your herd. You and the veterinarian can evaluate body condition, check and replace ear tags, double-check tattoos, and get a look inside the cow’s mouth. It’s a lot easier to see how each cow is doing while she is in the chute. As a producer, you have three ways to verify reproductive status within your herd. The method you choose depends on your herd-management goals, your costs, and the cattle markets of your particular location.
- Rectal palpation—The veterinarian inserts his or her arm into the cow’s rectum and feels the uterus and ovaries. Pregnancy can be detected as early as 35 days, although some vets may want to wait until 45 days to determine pregnancy. Keep in mind that the earlier in the pregnancy cycle, the more difficult in can be to ascertain pregnancy.
- Ultrasound—Depending on what type of ultrasound machine is being used, the veterinarian inserts her arm with the ultrasound probe or just the ultrasound probe into the cow’s rectum. This is a less invasive method that can determine pregnancy as early as 27 days.
- Blood test—The BioPRYN blood test (Pregnant Ruminant Yes/No) tests for a protein found in the placenta. It is extremely accurate, but it does not allow for fetal sexing, fetal aging, or other fetal abnormalities. Also, if the cow’s pregnancy has been lost quite recently, the blood test may still be positive
Generally speaking, it is best to ultrasound cows after they have been bred for 27 days but prior to the 100th day of pregnancy. Prior to 27 days, it can be difficult to verify pregnancy, and after 100 days, it is difficult to determine how far along the pregnancy is. Palpation has long been the method by which cows were preg-checked, and while it can be a very accurate and cost-effect method, it also has some limitations. Dr. Lewis attended a continuing-education seminar last year on the effective use of ultrasound. These points are important considerations when deciding between palpation and ultrasound:
- Fetal aging—Ultrasound can be used to more accurately determine when a cow will calve and is generally performed between 30-100 days bred. (Remember, rectal palpation can detect pregnancy at 35 days, meaning that ultrasound can give you an additional five-day start.) Fetal aging can provide you with the estimated duration of the pregnancy as well as projected calving dates, making it easier for you to sort your cows. There will always be outliers, however. Doc Randall the Elder remembers Al McPhail, an artificial-insemination technician for ABS for 30 years saying, “If you breed 100 cows to the same bull on the same day, they will calve for three weeks.”
- Gender determination—The sex of the fetus can be determined with the greatest accuracy between 60-75 days of pregnancy. And yes, this is a small window. Sexing a fetus is an art form, not a science, and it takes time and practice to get to where this can be done accurately.
- Fetal risks and abnormalities—Ultrasound provides markedly better odds of catching high-risk pregnancies such as twins or fetuses with slow heart rates. Because palpation is a manual practice, it cannot provide a visual of the fetus.
- Fetal loss—Ultrasound is able to determine if the fetus is dead whereas traditional palpation would call a cow bred or “calvy” because the fetus has not yet been reabsorbed or expelled. Additionally, there can be some fetal loss due to palpation simply because it is a more invasive, more aggressive method.
At the end of the day, ultrasounding cattle for pregnancy is less strain and stress on cow, on the fetus, and the veterinarian than traditional palpation. Regardless of what method you decide to use to preg-check your cows, it’s important to remember that preg-checking is not a timed event. This is a good chance for you to get good information about your cows. If you’re trying to move the cattle through too quickly, it’s hard for anyone to do a good job and you’ll have less accurate results.