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Preg-check cows to tune up herd

Pregnancy-testing cows and heifers in the fall can help you operate more efficiently, says Chandy Olson, a St. Onge, S.D., veterinarian.

Olson works with cattle herds in the Dakotas, Wyoming and Montana and does ultrasound pregnancy checks on 30,000 cows each year.

Preg-checking provides an immediate opportunity to cull subfertile females from the herd. But in addition to culling open females, Olson encourages producers to scrutinize their late-breeders as well.

“Making excuses for cows that breed late and keeping them in the herd frequently leads to problems the following year. These cows are the least likely to breed when feed conditions are challenging and have the highest risk for being disease carriers. Keeping them in the herd just extends the calving season,” Olson says.

Key Points

Checking cows for pregnancy can help you identify problems in your cow herd.

Aim to cull any open cows and scrutinize those that are late calvers.

Keep an eye on body condition score, too, to prevent future problems.


With the calving date information pinpointed from the ultrasound, producers can add some extra efficiencies to their operation, she says.

Cows can be divided into calving groups that are 20 to 30 days apart (i.e., early-, middle- and late-calving groups) to help target feed resources to cows as they enter their third trimester and focus labor efforts during calving.

Pregnancy-checking is also a great way to evaluate the productive health of a cow herd.

“Herds with an abnormal amount of late-calving cows may indicate a reproductive disease problem, a bull fertility concern, or more frequently a nutritional or stocking rate issue,” she says.

Olson advises that the best time to ultrasound is when the cow is between 30 and 100 days in gestation — but it can be done as late as 120 days in gestation.

Monitor body condition

While pregnancy checking, Olson keeps an eye on cows’ body condition.

“Cows in poor body condition during the winter usually leads to poor body condition prior to and after calving, which can delay estrus and lead to higher incidence of open or late-calving cows, as well as greater susceptibility to disease.”

She suggests adding weight to thin cows after weaning so they can maintain that condition through the winter and into calving. This strategy is usually less expensive and more successful than trying to add weight to cows just prior to calving next winter or spring.

“Adding weight to thin cows later in gestation during extreme cold is virtually impossible due to high energy requirements to maintain body temperature, growing gestational requirements and increasingly limited rumen capacity,” she says.

The optimum body condition score range is usually 5 to 6. Because it is a subjective measure, she suggests producers consider having a third party verify their cows’ body condition scores after weaning.

Fall breeding or prebreeding vaccinations might be good ideas. But they are not a silver bullet.

“Cows in poor condition won’t breed well regardless of mineral, vaccine or fancy bulls,” she concludes.

Gordon writes from Whitewood, S.D.

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PREG CHECK: Vet Chandy Olson checks to make sure a cow has a calf. She says pregnancy checking can be used to tune up the cow-calf enterprise.

This article published in the September, 2011 edition of DAKOTA FARMER.

All rights reserved. Copyright Farm Progress Cos. 2011.