There’s a drawback to checking cattle for pregnancy via rectal palpation.
OK, maybe more than one.
And even though inserting an arm into the rectum of a cow is the most common method of preg checking in Western Canada, other methods are available and can be more accurate.
Dr. Jessica Gordon, a veterinarian and assistant professor at the Ontario Veterinary College, said pregnancy can also be checked using rectal ultrasounds and blood tests.
“Rectal palpation is by far the most widely available and most widely used, though rectal ultrasound is becoming much more common,” she said during a Sept. 15 webinar organized by the Beef Cattle Research Council.
Determining pregnancy allows producers to monitor reproductive efficiency in the herd, identify disease and nutritional issues and gauge the effectiveness of bulls. By identifying and selling open cows, producers can also reduce feeding costs.
Gordon said rectal ultrasound involves insertion of a probe that projects images on a monitor. It can detect pregnancy as early as 28 days of gestation.
At 35 days, the calf’s heart can be seen and at 60 days a trained person can identify the head, limbs and sex.
The procedure requires specific equipment and skill in manipulating the uterus to get the needed images, and that requires practice to master, said Gordon.
Accuracy varies by practitioner, but in the hands of a skilled person, rectal probes can offer 99 percent accuracy, said Gordon.
Cost varies by veterinary practice, she added, but ranges from $5 to $10 per head. An additional fee may apply if the producer wants sex identified rather than simply a yes or no on pregnancy.
However, Gordon said some veterinarians will charge the same rate for rectal probes as they do for rectal palpation because the former method is quicker and easier on the person doing the work.
On the blood test front, producers can draw a sample themselves and send it for analysis.
“It’s a much easier skill to learn than rectal palpation or rectal ultrasound,” said Gordon.
“There are actually videos on YouTube that can teach you how to blood test cows.”
Blood test kits cost about $5 per head, including the appropriate needle and blood tube. Shipping samples to a lab is an additional cost. Pregnancy can be determined as early as 28 days of gestation.
Accuracy is 99 percent on open cows and 93 percent on pregnant ones. Gordon said that is because the test checks for a specific protein in the blood, and the protein can still be detected if the test is done within three months of calving or near the time a cow has aborted or reabsorbed a fetus.
“It’s likely the most cost effective if you have a small herd and you’re far removed from a veterinarian,” Gordon said.
“Veterinarian farm calls can be quite expensive if you are in a remote area so this is a really good option for some of those producers.”
However, blood tests can’t determine a calf’s viability, sex or age, and results can take a week or more to obtain.
“If you’re hoping to make a decision on that animal immediately when the animal is in the chute, it’s just not possible with this test,” she said. “It’s going to require rehandling those animals to get rid of any open cows.”
As for rectal palpation, cost varies by veterinary practice, but Gordon said $5 per head is the ballpark figure. It requires no special equipment beyond a sleeve and lubrication, but accuracy varies by the skill of the person and age of fetus.
“The skill required takes a lot of time and practice to really be efficient and effective at it,” she said, noting the need to manipulate the uterus and correctly identify the signs of pregnancy.
“That can definitely be a challenge depending on the skill of the practitioner … and it can take a lot of time if the skill is not high.”
Earliest detection of pregnancy by rectal palpation is about 35 days. It provides immediate results and can also provide information on calf age and therefore expected calving date.
Regardless of the method used, Gordon cautioned against pregnancy testing before about 60 days of likely insemination because fetal losses before that are about 15 percent.
“The earlier you check your cows, obviously the more loss is expected,” she said.
Gordon also said the type of testing that producers choose may vary from year to year. For example, a year with scant early pasture may prompt earlier testing to get rid of open cows, and that might mean a simple yes or no test rather than a test with more available data done later in the year.
A quick and dirty comparison
- Pros: immediate results; provides information on calf age; requires no special equipment; cost relatively low (range of $5 per head)
- Cons: requires extensive training and practice; can’t reveal sex of calf or fetal viability; physical strain on practitioner; potentially high error rate
- Pros: immediate results; information on age, sex, viability of calf, high accuracy if experienced practitioner
- Cons: higher cost ($5-$10 per head); requires special training and equipment; accuracy varies with skill of practitioner
- Pros: no veterinarian required; easy to learn skill of collecting sample; less invasive; cost effective (approximately $5 per head plus shipping cost of samples)
- Cons: can’t assess viability, age, sex of calf; potential for false positives; results can take week or more