Genomic testing can help limit cases of BVD in cattle

Dairy calf_resizedSince its discovery in 1946, bovine viral diarrhea (BVD) has been a continuing problem of the cattle industry. In infected cattle, the virus can lead to decreased reproduction, lower feed efficiency, higher mortality and morbidity rates — contributing to astronomical costs for cattle farmers around the world.

Adding up the cost is a daunting task, Derrell Peel, Extension livestock marketing specialist at Oklahoma State University said in a recent article. “BVD impacts all sectors of the industry [but] in different ways,” he says. “An awful lot of the loss is probably not even recognized by producers.”

However, it’s not always easy to tell if cattle are infected with BVD as it is a ribonucleic acid (RNA) virus, and can mutate and change rapidly. This means infected cattle can have diverse clinical signs, not just diarrhea, which is a common symptom many farmers tend to look for. In addition, the virus can spread quickly via nose-to-nose contact or other exchanges of bodily fluid such as milk, semen, feces, urine and saliva. Infected animals will also be shedders of the virus serving as a reservoir of infection to animals they come in contact with.

However, by genetically testing animals for the disease, farmers today can detect BVD-persistently infected (BVD-PI) animals and save themselves the expense and loss of profitability a BVD outbreak can have.

For example, Kelly Cunningham, a managing partner for a group of dairy farms near Atlantic, Iowa has been testing for BVD-PI as part of the management program since 2010. All heifer calves on his farm have an ear notch taken within two days of birth and tissue samples are sent to a lab for a pool testing protocol. Testing with a pool of 20 animals has helped significantly reduce the cost for his operation.

The article explains that pooling costs about $2 per animal. However, should a PI-positive pop up in the pool test, it costs $5 individually to retest. “That’s not a lot of money in my mind,” Cunningham said, compared to the risk of spreading BVD.

Cunningham explains that some outside springers have been purchased in the past to help increase the herd size, and those animals are tested on arrival. “If we do buy cattle from outside of our farm, we try to get them directly from the grower or producer,” Cunningham says. He doesn’t want to buy heifers that are from put together groups, running a greater likelihood of exposure to infected cattle.

Thus far, 9,586 calves and 3,075 springers have been tested. Two purchased springers have tested PI-positive since testing began back in October 2010. Six baby calves have tested PI-positive, and the last two have originated from BVD exposed purchased springers.

“We are working toward a closed herd with the use of sexed semen and better pregnancy rates, and we have been able to generate a lot more heifers,” Cunningham said in the article.

In addition, cows are vaccinated to prevent both BVD Type 1 and 2 at prebreeding, generally at 35 days in milk. Calves are vaccinated at 35 days of age and receive a booster shot 28 days later.

“We believe that herd health and the calf program have gotten better because of these steps,” Cunningham says. “We also believe this is the right thing to do.”

For more information, click here.

Neogen offers BVD testing along with other forms of genomic testing. For more information, click here.

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