Pregnancy testing cows | TSLN.com

Pregnancy testing cows

Photo by Heather Smith ThomasA cow being preg checked via rectal palpation.

Most beef producers routinely pregnancy test cows after breeding season to determine which to keep and which ones to sell. Jeff Hoffman, a veterinarian near Salmon, ID, says the biggest reason to know which cows are open is that it’s a major cost to feed them through winter, and this is a waste of money if they’re not going to have a calf. You may want to sell them in early fall before the cull cow market drops, and in some cases (if they’re too thin to bring a good price), you may choose to fatten and sell them later in the winter.

“The other major reason to pregnancy test is that finding more than a typical number of open cows can alert you to a disease problem,” he says. Trichomoniasis, vibriosis, IBR, BVD, and lepto may cause cows to lose their pregnancies. Typically the sexually transmitted diseases like trich and vibrio cause early abortion and the cow returns to heat, ending up open or calving very late. If bulls are left with cows all summer, some of these cows may become pregnant again. Finding you have a bunch of open or late cows is a little bit after the fact, but at least you’ll know there’s a problem and can take measures to correct it.

“Nutritional deficiencies in the herd may also show up as open cows, especially in second calvers,” says Hoffman. “Most people feed yearling heifers adequately and they breed up fairly well – but they are not raising a calf.” The two-year-olds with calves at side are still growing, plus trying to feed their calf. That age group may end up with a high percentage open.

“Some people overfeed and pamper replacement heifers (weanlings and yearlings) to make sure they’ll breed, then after their first calf they don’t get any special treatment and lose weight – and don’t rebreed,” he says.

This group has the hardest job; the ranch might give them a little leeway if they didn’t breed up as early, especially if they’re raising big calves.

“Yearling heifers, by contrast, should have a short breeding season (45 days, the equivalent of two heat cycles),” he says. This is the age to sort and cull, regarding fertility and efficiency. Pregnancy testing heifers soon after a relatively short breeding season is helpful because you should never keep a yearling that’s a slow breeder – and you can then sell the open ones early in the summer.

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If you are trying to determine when they were bred, preg-checking is never 100 percent accurate.

“There’s enough individual variation among cows to make it difficult,” says Hoffman. “A cow can calve up to two weeks early, or late. An example that illustrates this was a study looking at length of calving season. In this study, 100 heifers were synchronized and bred on one day. Even though they were all bred the same day, their calving season was a month long, with some calves arriving two weeks ahead of their due date and some two weeks late.

“Personally I’ve noticed when ultrasounding cattle, that I’m not as accurate in my palpation (in determining stage of gestation) as I thought. There’s enough variation in cows, when palpating rectally, that you can be fooled. Some are farther along than what they feel like (when assessing the size of the uterus, amount of fluid, etc.) and some are little shorter,” he says.

Taking the bull out after a defined breeding season helps when it comes time to pregnancy test because it eliminates those questionable ones that may have just been bred but can’t be definitively determined by palpation.

“Early in pregnancy the veterinarian can determine and date pregnancy by the size of the uterus,” says Hoffman. “As the cow gets a little farther along you can actually bump the fetus within the uterus. When she gets to about 100 to 110 days of gestation, the uterus has dropped down farther below the pelvic rim and you can’t reach the entire uterus. At this point you start going by the size of the buttons (cotyledons). As a back-up you can assess the diameter of the uterine arteries. When you get past about four months, you do a lot of the aging mainly by the size of the cotyledons. There will be some tiny changes, so it is easy to be a couple weeks off in your estimation of length of pregnancy.”

Ultrasound is another option.

“It’s more accurate, especially for dating when the cow was bred and when she should calve,” says Hoffman. “Ultrasound can be done earlier than palpation and be very accurate. You can diagnose pregnancy earlier, and send the open ones to market sooner. With ultrasound, you can actually see the embryo or fetus at 21 days or even a little earlier.

“The cost of ultrasound is about twice that of rectal palpation, but the improved accuracy is worth it, to many producers. Ultrasound is the standard method in most dairies, not only because of better accuracy, but also because you can diagnose ovarian problems and other reproductive issues. In beef cattle, ultrasound isn’t used as much yet, but I have a friend in Montana who is ultrasounding most of the larger beef herds in his region. They have corrals out on the range and he runs an inverter off his truck to power the ultrasound machine.”

Ultrasound isn’t 100 percent accurate, according to Hoffman, but more accurate than palpation, especially when checking cows early. By the time a cow is five or six months along the odds of calling her open when palpating are small, compared to checking her at 30 days.

Another advantage of ultrasound is ability to see the sex of the fetus. This is helpful in purebred operations if they want to sell a group of cows or heifers that will all have bull calves, or all have replacement heifers.

“In our region I’ve only done a few commercial herds,” says Hoffman. “One producer had me ultrasound a bunch of older cows that had only been bred for a short time. He wanted to make sure they were pregnant before he sold them, and at that stage of their pregnancy ultrasound was more accurate than palpation.”

One down-side to early checking is that it’s possible to have some early abortions; a cow you thought was pregnant may end up open. If you leave the bull with the cows this may mean some of those cows will breed back to be late calvers.

Most beef producers routinely pregnancy test cows after breeding season to determine which to keep and which ones to sell. Jeff Hoffman, a veterinarian near Salmon, ID, says the biggest reason to know which cows are open is that it’s a major cost to feed them through winter, and this is a waste of money if they’re not going to have a calf. You may want to sell them in early fall before the cull cow market drops, and in some cases (if they’re too thin to bring a good price), you may choose to fatten and sell them later in the winter.

“The other major reason to pregnancy test is that finding more than a typical number of open cows can alert you to a disease problem,” he says. Trichomoniasis, vibriosis, IBR, BVD, and lepto may cause cows to lose their pregnancies. Typically the sexually transmitted diseases like trich and vibrio cause early abortion and the cow returns to heat, ending up open or calving very late. If bulls are left with cows all summer, some of these cows may become pregnant again. Finding you have a bunch of open or late cows is a little bit after the fact, but at least you’ll know there’s a problem and can take measures to correct it.

“Nutritional deficiencies in the herd may also show up as open cows, especially in second calvers,” says Hoffman. “Most people feed yearling heifers adequately and they breed up fairly well – but they are not raising a calf.” The two-year-olds with calves at side are still growing, plus trying to feed their calf. That age group may end up with a high percentage open.

“Some people overfeed and pamper replacement heifers (weanlings and yearlings) to make sure they’ll breed, then after their first calf they don’t get any special treatment and lose weight – and don’t rebreed,” he says.

This group has the hardest job; the ranch might give them a little leeway if they didn’t breed up as early, especially if they’re raising big calves.

“Yearling heifers, by contrast, should have a short breeding season (45 days, the equivalent of two heat cycles),” he says. This is the age to sort and cull, regarding fertility and efficiency. Pregnancy testing heifers soon after a relatively short breeding season is helpful because you should never keep a yearling that’s a slow breeder – and you can then sell the open ones early in the summer.

If you are trying to determine when they were bred, preg-checking is never 100 percent accurate.

“There’s enough individual variation among cows to make it difficult,” says Hoffman. “A cow can calve up to two weeks early, or late. An example that illustrates this was a study looking at length of calving season. In this study, 100 heifers were synchronized and bred on one day. Even though they were all bred the same day, their calving season was a month long, with some calves arriving two weeks ahead of their due date and some two weeks late.

“Personally I’ve noticed when ultrasounding cattle, that I’m not as accurate in my palpation (in determining stage of gestation) as I thought. There’s enough variation in cows, when palpating rectally, that you can be fooled. Some are farther along than what they feel like (when assessing the size of the uterus, amount of fluid, etc.) and some are little shorter,” he says.

Taking the bull out after a defined breeding season helps when it comes time to pregnancy test because it eliminates those questionable ones that may have just been bred but can’t be definitively determined by palpation.

“Early in pregnancy the veterinarian can determine and date pregnancy by the size of the uterus,” says Hoffman. “As the cow gets a little farther along you can actually bump the fetus within the uterus. When she gets to about 100 to 110 days of gestation, the uterus has dropped down farther below the pelvic rim and you can’t reach the entire uterus. At this point you start going by the size of the buttons (cotyledons). As a back-up you can assess the diameter of the uterine arteries. When you get past about four months, you do a lot of the aging mainly by the size of the cotyledons. There will be some tiny changes, so it is easy to be a couple weeks off in your estimation of length of pregnancy.”

Ultrasound is another option.

“It’s more accurate, especially for dating when the cow was bred and when she should calve,” says Hoffman. “Ultrasound can be done earlier than palpation and be very accurate. You can diagnose pregnancy earlier, and send the open ones to market sooner. With ultrasound, you can actually see the embryo or fetus at 21 days or even a little earlier.

“The cost of ultrasound is about twice that of rectal palpation, but the improved accuracy is worth it, to many producers. Ultrasound is the standard method in most dairies, not only because of better accuracy, but also because you can diagnose ovarian problems and other reproductive issues. In beef cattle, ultrasound isn’t used as much yet, but I have a friend in Montana who is ultrasounding most of the larger beef herds in his region. They have corrals out on the range and he runs an inverter off his truck to power the ultrasound machine.”

Ultrasound isn’t 100 percent accurate, according to Hoffman, but more accurate than palpation, especially when checking cows early. By the time a cow is five or six months along the odds of calling her open when palpating are small, compared to checking her at 30 days.

Another advantage of ultrasound is ability to see the sex of the fetus. This is helpful in purebred operations if they want to sell a group of cows or heifers that will all have bull calves, or all have replacement heifers.

“In our region I’ve only done a few commercial herds,” says Hoffman. “One producer had me ultrasound a bunch of older cows that had only been bred for a short time. He wanted to make sure they were pregnant before he sold them, and at that stage of their pregnancy ultrasound was more accurate than palpation.”

One down-side to early checking is that it’s possible to have some early abortions; a cow you thought was pregnant may end up open. If you leave the bull with the cows this may mean some of those cows will breed back to be late calvers.