For BVD Control –
An Integrated Approach is Essential

It’s been more than 60 years since the enteric disease of cattle characterized by outbreaks of diarrhea and erosive lesions of the digestive tract was identified and named bovine viral diarrhea (BVD). This disease is now known to be caused by a virus called bovine viral diarrhea virus (BVDV).

While advancements have been made in identifying and controlling the disease over the past six decades, there is still much to be done in the battle against BVD virus. In late January 2009, the 4th U.S. BVDV Symposium was held in Phoenix, Ariz., to spotlight research and control efforts among the scientific community, veterinarians, and producers.

In remarks he made to symposium attendees, Dan Grooms, a veterinarian and associate professor in the Department of Large Animal Clinical Sciences at Michigan State University, credited the beef industry for its dedicated efforts toward BVD virus control. “The beef industry is moving towards raising the bar on BVD control – with the eventual goal of eradication in North America,” Grooms said. He noted that several bull tests and livestock shows now require BVD testing, and many private seedstock operations test cattle for the virus and advertise that their sale offering is free of the disease.

With that, he emphasized that an integrated approach is essential to controlling the disease. Grooms said, “As we learn more about BVD, there is also an increasing realization that successful control of BVD requires a control program that involves multiple components and is customized to fit the goals and capabilities of each producer.”

Economic Importance

For anyone still questioning the importance of BVD control, Grooms offers a brief history of how the disease is spread within a herd and how it can affect performance – and ultimately profits.

He explains that persistently infected, or PI, animals are the primary source of BVD virus transmission. A PI calf is created if it is exposed to the BVD virus as a fetus between day 40 to 125 of gestation. These animals then carry and shed the disease for life.

Studies have shown the effects of a PI animal within a cow-calf herd can decrease pregnancy rates by 5 percent, as well as cost $14-$25/head/year in decreased returns. At the feedlot, a PI animal can increase morbidity rates among pen mates; one study shows the cost of exposure to a PI animal to be $41-$93 per animal exposed. “So there’s a significant economic impact if we don’t control BVD,” Grooms points out.

By controlling BVD within the herd – and the industry – Grooms cites the return can be increased productivity, animal welfare, and economic return and decreased health risk. 

Designing and Plan

What do experts recommend producers should be doing regarding the implementation of a BVD plan and PI testing?

Grooms suggests a four-step approach to BVD control:

1. Understand herd goals and risk tolerance.

2. Develop a prevention control plan. A control plan should reduce the risk of BVD entering the operation – primarily through biosecurity methods. To design such a plan, operators need to understand the sources of BVD exposure, such as through fenceline contact with other herds or exposure to wildlife. Grooms notes that, commonly, animals being brought into the operation may carry a transient or persistent BVD infection. This means bulls, replacement females, show cattle, embryo transfer recipients, and semen should be considered as potential disease sources.

3. Identify and eliminate PIs. “There are a lot of effective tools to detect BVD PI’s,” Groom states. Among the options are the ELISA blood tests, the IHC skin ear notch test, or PCR pooled tests that use skin or blood samples. If PI animals are found, they should be removed from the herd.

4. Improve herd immunity. Immunizing cattle against BVD through vaccination is also an important tool to help control BVD. Grooms reports there are more than 150 BVD vaccines or vaccine combinations commercially available. “So the vaccines can be used in a variety of different management settings,” he says. He also shares that in most studies where a modified live vaccine (MLV) was administered, the ability to protect the fetus from BVD appeared to be greater.

Grooms does caution, however, that vaccines should not be viewed as a silver bullet. “Vaccines are not 100 percent effective in preventing BVD infection. They are a useful tool – but not the only answer to controlling BVD.”

Instead, he emphasizes that BVD control requires several tools – biosecurity, diagnostic testing, and vaccination. “If we effectively use the entire toolbox in a planned BVD control program, we can make great progress in controlling the disease, not only in individual herds but across the entire industry.”

More Information Online

For beef producers seeking more BVD information, a new website has been developed in order to incorporate all data in one central location. The site is www.bvdinfo.org. It features peer-reviewed research on the topic of BVD, as well as guidelines on BVD testing programs, general articles, a listing of upcoming BVD seminars, and links to other sites with BVD information. The website is hosted by the K-State Beef Cattle Institute.