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The pros and cons of different preg-check options for cows

Herd size and speed of test can point to the best technique

Dr. Brett Terhaar from Frontier Veterinary Services in Winterset, IA using ultra sound equipment for prep checking cattle.

Pregnancy testing methods include palpation, ultrasound and blood tests. Dr. Don Driedger of Driedger Veterinary Services in Lloydminster, Alta., does a lot of pregnancy testing in his area, and uses both palpation and ultrasound.

“The main reason most producers preg-check is to decrease the number of cows that are just freeloading through winter,” says Driedger. “If a producer has 1,200 to 1,400 cows and 100 open cows, they not only are costing money in hay, but they are also cycling. With a 21-day cycle there might be five cows in heat every day, being ridden by other cows.”

The bulling behaviour is not a good situation for pregnant cows. Some may abort or slip on ice and become injured and down. “This is another reason for not having any open cows in the herd,” he says. “Some guys get around that by not pulling bulls — just leaving them with the herd year-round. Those late cows are fed for a long time and then the producer has to sell them in June because they’re not going to calve until August.”

That year-round breeding has its consequences. You’ve put a lot of feed and labour into that cow, and even though you might get a better price for her as a pregnant cow, you’ve might have used up that profit or exceeded it in your cost of running her that long. This is especially true if hay and pasture are short during drought.

“Feed is short this year in many regions, and bulls may be pulled out a little earlier,” says Driedger. “Some of the preg-checking might be for the purpose of decreasing herd size. If you’ve left the bull with the cows, the earlier we can preg-check, the better we can find and take out those late-calving cows and sell them now, as opposed to later when feed is less available.”

By then the price for pregnant cows will be lower because if feed supplies are short no one will be buying extra cows.

Driedger says it’s important the person doing the pregnancy testing knows what they are doing with no question about which cows are open. “The producer may also ask the veterinarian to pick out the late calving cows as well. I like to mark the late calvers with an ‘L’.” Some veterinarians put a mark on the hip if a cow is open, on the shoulder if she’ll calve early, and on the ribs or mid-back if she’ll calve late. Then the client can easily pick out the cows to sort into proper management groups or sell.

Driedger asks clients when they want to be done calving, and when the bulls were put out, and when or if the bulls were pulled. “If the bulls were not pulled, we know there will be some late calves,” he says.

Depending on the information the producer wants, timing of preg-checking is important, he says. Sometimes a producer wants the veterinarian to come out very late in the fall to preg-check and wants to know which cows will calve early or late. “I have to tell them it’s too late to tell the difference between a late calver and an early one,” he says. “The window for that determination is past. The next year they phone me a lot earlier and we can figure out the proper schedule for doing it.”

Some smaller beef operations use the blood test for pregnancy diagnosis if it’s difficult to get a veterinarian to come out to do just a few cows. It’s easy to draw blood to send to the lab for checking. Every method has advantages and disadvantages. Sometimes the smaller producers get together with neighbours and have a vet come do them all, and share the mileage cost.

Ultrasound improved

Using ultrasound to determine pregnancy has become a lot more convenient and easier. The cows are more comfortable when they come out of the chute — it’s much easier on them — and the whole job might take half a day to do the herd as opposed to a full day, and everyone is happier. “The work goes smoothly, and flows better, and it’s not as big a headache,” he says.

If a ranch has proper facilities for preg-checking, it makes the task easier on both animals and the veterinarian. “We are usually working with 200-plus cows now, and a person needs a good facility,” says Driedger. “It especially helps if they want their veterinarian to come back and do it again in the future!”

Some of the improvement is due the use of hydraulic chutes. They are quieter, smoother, and faster. “Ranchers find that their shoulders are not as sore afterward, and it’s easier to catch and contain the animals, and there’s less chance for a cow to push on through and get away,” says Driedger. “There’s less running and trying to close a gate or having to re-sort a group of cows because one got away. Facility improvement is partly due to an ageing population of producers; they are looking for something that isn’t as hard on them, too.”

Blood test option

Dr. Bruce Hill of Sunny South Veterinary Services, an animal health supply outlet in Lethbridge, Alta., says some producers use a blood test to determine whether a cow is pregnant, although it does take time to get the results back.

Most people favour palpation or ultrasound as most people want to know more quickly whether the cow is pregnant or open while it’s still in the chute. Many producers make a decision at that moment whether to keep or cull that cow.

But for producers who have more time, such as when preg-checking cows two or three weeks ahead of weaning the calves or when giving the calves their pre-weaning vaccinations, the blood test can work nicely.

“The blood test works well for anyone who has individual ID on their cows,” says Hill. “It’s just a matter of bleeding the cows, sending the samples to the lab, and getting the results back to know which cows are open.”

There are advantages, especially for small herds that are a long way from a vet, saving an expensive farm call, and not having to worry about scheduling a vet during the busiest times for preg-checking.

“A person with a large herd can probably get a veterinarian to come palpate or ultrasound cows, but some big producers may not want to run 1,000 cows through the chute in a day,” Hill says. “They might prefer to do smaller groups at different times. That’s why some of the larger operators have their own ultrasound equipment because they can preg-check on their own schedule. That’s the nice thing about the blood test as well.”

The blood test is accurate as early as 28 days after conception. If you have a short breeding season on heifers you could do this test 30 days after pulling the bull. With a synchronized AI program you can check them 30 days after they are inseminated, says Hill. Then you’d know which ones are open, early enough to sell them as open heifers to a feedlot market when the price is best.

“If you only have a few heifers to check, and your vet is several hours away, the farm call can be costly,” he says. “With the blood test you can collect samples yourself, send off the tubes, and save money. Even with dairies, and we have many Hutterite colonies as well that use the blood test a lot because they can be two or more hours away from a veterinarian. They check for open cows every two weeks, so the blood test is a less expensive option.”

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