Ranchers, vets share disease-prevention methods

Bovine virus diarrhea can be mild to fatal in cattle. It is a major cause of respiratory disease in young cattle going into stocker operations, backgrounder operations and feedlots. It causes abortions and reproductive failure in cows, but it is the persistently infected (PI) animals that are of the greatest concern.

BVD-PI animals contract the disease in utero. Many of these calves are born alive, but they cannot develop immune protection against the disease. PI animals shed billions of virus particles every day in their saliva, urine and feces, and these animals will infect the entire herd.

John Maas, beef extension veterinarian at the school of veterinary medicine at the University of California, Davis, said vaccination is the most important method of control for BVD.

Myron Openshaw, a cattle rancher in Oroville, said he hasn't had trouble with BVD because he vaccinates for it.

"So far, we've been lucky enough to avoid it," Openshaw said.

Openshaw said he also is careful about the animals he brings on the ranch.

"The animals that I purchase, like at the sales yard, I eyeball them and check them out as much as I can before purchase. And as soon as they get on the premises, we vaccinate them," he said.

Maas encourages vaccination, but he said it does not always provide complete protection.

Maas also warned to watch for fenceline contact with stocker cattle, as they may not be tested, and said he knows of a ranch that vaccinated religiously for years and still had a catastrophe.

"They had a bunch of stocker cattle come in on the fenceline at just the wrong stage of pregnancy," Maas said, adding the cows were less than 120 days pregnant, and the rancher lost the entire calf crop.

"At least one of the stockers had this BVD-PI status," Maas said.

Equally as important as a good vaccination program and preventing fenceline contact is being cautious about the animals brought into the herd, Maas said.

"Don't bring any PI cattle (bulls, heifers, cows) into the herd without a negative PI test," he said.

Testing is inexpensive and quick, Maas said.

A cow/calf producer who stays isolated, has a good vaccine program, tests all the incoming cattle, and keeps the contact risks at a minimum or zero probably doesn't need to test all his animals, Maas said.

"We do have cow/calf producers who do test all their calves every year," Maas said, adding that they try to go into a program where they can get a little bit of a premium for PI-free cattle.

Colorado has initiated a voluntary program to reduce or eliminate new BVD infections. The program is divided into three levels:

• First, the producer must complete a short educational program with the herd veterinarian and answer 20 standardized questions. Using the producer's responses to the questions, a herd-specific BVD bio-security plan is designed that includes a vaccination program formulated for the herd.
• Second, some level of testing is done for the presence of BVD-PI in the cattle.
• Third, all calves or cattle are tested for evidence of PI animals. Any cattle that test positive are removed from the herd, then the herd can be certified BVD free.

The Colorado program is a "wonderful" educational advantage, Maas said.

"Producers get to understand this very complex viral disease, and then if they want to either certify that they're free, or if they want to take a look at decreasing the risk, they can do all those things based on the science that's available," Maas said. "In Colorado, too, they have more feedlots there, and the feedlots are more interested in having no BVD carriers coming into their feedlots.

"I think it's a good idea. Is it a silver bullet that solves all the problems? No it's not, but it certainly is a good idea," Maas said.

California hasn't initiated a PI-free certified program as far as the cow/calf producers are concerned, Maas said.

"Our seedstock producers, most all of them, when they sell bulls and heifers, those animals have all been tested, and they're all BVD persistently infected-free," Maas said.

Openshaw said he thinks a certified-free BVD program has promise.

"It sounds like it would be something that would be beneficial if you could certify that your ranch was certified free," Openshaw said, adding it could possibly be a marketing tool.

Maas said getting rid of the animals with PI means you can get rid of BVD.

"It's not that hard to do," Maas said, adding countries like Norway have eliminated the BVD virus completely.

Norway started with milk tank samples because the tests are very sensitive, so they can pick up the virus there, Maas said. Then they went back to that string of animals and got rid of the infected animals, he added.

"The same thing can be done in a beef herd by testing all the calves at weaning," Maas said.

There is good news with BVD-PI, Maas said.

"The number of tests and the quality of the tests to detect BVD-PI cattle has advanced a lot, and the costs have gone down as well as the turnaround time," he said.

The price of the testing has dropped to less than $3 a head and pool sampling can be done, making it even more affordable, Maas said.

The important points Maas emphasized were: prevention first and foremost with vaccination of young cattle and replacement cattle, annual vaccination boosters for the herd, and testing for PI animals when bringing new cattle into the herd.

(Kathy Coatney is a reporter in Corning. She may be contacted at kacoatney@gmail.com.)