Pregnancy Check with a Blood Test
for Tri-State Livestock News
Over the years, several pregnancy tests have been developed using hormone measurements on an animal’s blood or by testing the milk. The one most commonly used today is a blood test developed by Dr. Garth Sasser at University of Idaho. In his research he discovered a protein produced by the placenta of ruminant animals, detectable in their blood. He founded a company called BioTracking; his blood test called BioPRYN (Pregnant Ruminant Yes/No) for cattle, sheep, goats, and other ruminants became commercially available in 2002. There are now 25 labs around the world that handle the blood samples.
One of those is run by Tanya Madden (Eagle Talon Enterprises) in Laramie, WY. She recently attended a meeting of bovine practitioners and was pleased that many of them didn’t consider her to be in competition with them for pregnancy testing, but rather as another option for some of their clients.
“My lab can also do BVD and Johnes tests from the blood samples if a customer wants these. Some of the older vets appreciate the blood test option. One of them told me that even though they like clients to think their accuracy is perfect, they may get tired after 50 head and their accuracy goes down. But they might tell the client they are not 100 percent sure on a certain cow – and to ensure accuracy they could recommend taking a blood sample on that one,” she said.
She has clients in Wyoming, Oklahoma and South Dakota. “They all have various reasons for wanting to use the blood test,” says Madden.
One of her customers is Buttons York of Webo Angus, near Lusk, WY, and raises registered and commercial Angus. “Right now we have 400 cows and sell about 70 registered Angus bulls every spring,” York said.
“We’ve been sending bred heifers to Kazakhstan (originally part of Russia) the past three years. They need those heifers in August. We calve in March and April and this rushes us to make sure they are pregnant,” York explained.
“We AI the heifers and 10 days later turn in our clean-up bull. We check them as soon as possible for pregnancy. The vet can’t always be 100 percent sure – with palpation – at that short time. That’s how we started using the blood test.” It can detect pregnancy at 28 days, which is earlier than ultrasound or palpation.
York also likes the convenience of testing for BVD and Johnes. “This is a big deal for us, as seedstock breeders. This year we had our replacement heifers on leased pasture because of the drought – possibly exposing them to other cattle. So as a safety measure we tested all our replacement heifers,” she said.
York and her youngest daughter, Odessa (an Animal Science major at the University of Wyoming) took the blood samples themselves. “There are advantages in being able to do this yourself, at your own convenience. It’s often hard to get a vet out here to preg check in the fall. We are down to one vet and he is really busy this time of year,” York said.
It was also handy to check their commercial heifers early in pregnancy. “With the drought we were short on grass and wanted to get the open ones gone as soon as possible. We were able to ship our open heifers in a hurry.”
Results come back quickly. “Within 24 hours of when she receives the samples, Tanya e-mails us with the results,” York said. Samples don’t have to be refrigerated – the vials can be banded together and cushioned with bubble-wrap in any kind of package.
Another client is Boreen Hay and Cattle Company, in the Bighorn Basin area of Wyoming. Kate Boreen has used the blood test for two years. “I had never tail bled a cow before. There was a video on Tanya’s website (www.eagletalonent.com ) showing how to do this. The first year, my husband was in the hospital for five days after a serious accident, so another woman and I preg-tested all our cows, using this new method!”
“It worked great. The supplies were easy to get. I’d priced it and felt the cost was comparable to palpation. On a small herd it’s probably cheaper than palpation, without a ranch call fee from the vet,” she said.
“When we started doing the cows this year, we did them in small batches at our convenience, without having to schedule the veterinarian,” Boreen explained.
Mark DeBoo of Diamond D Angus near Valier, MT, has also used the blood test for two years. “We calve in May and June and don’t start breeding until August 10th. At our annual bull sale November 8th we sell some bred females, and use blood tests to make sure they are pregnant before they are sold,” DeBoo said.
“This is more accurate than palpation if the cow hasn’t been bred very long, and cheaper than ultrasound, and we can take the samples ourselves. The blood test is also less invasive, with less stress on the cow and no risk to the fetus,” he says.
The blood test is 99 percent accurate in detecting open cows. It’s accurate as early as 28 days post breeding and 73 days after calving. If a cow is checked too soon after calving there may still be some hormone in her bloodstream from the earlier pregnancy and you might get a false positive.
Jack Holden (Holden Herefords, Valier, MT) has been using blood tests for four years. “We run 400 cows. About 250 are registered and the rest are commercial cows, mainly used as recipients,” he said.
“Often we use the blood test on our recipient cows, after we put embryos in. It’s nice to know early on if they are pregnant, for putting embryos back into any that aren’t pregnant,” he said.
“We’ve used the blood test on some of our registered cows, too, if some might be short bred or we happen to be working them early. There are times we need to know, as soon as possible, and this is cheaper and more convenient than ultrasound,” he said.
“Even the good vets have to take more time with ultrasound, to find a 35 day pregnancy. The blood test is simpler, and less invasive,” Holden said.
“The blood test is inexpensive (about $2.50 per cow), and the lab is very good about getting results back to us quickly. From when I put the samples in the mail until I get the results is usually about three days,” he said.
This is the biggest disadvantage to the blood test, for people who need to know immediately. If you have to make a decision to keep or cull a cow when she goes through the chute – to determine whether to give her vaccinations or just sort her off to be shipped – the blood test is not as useful. “But if you will be keeping her around for awhile before selling her, the blood test will work,” Holden said.
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