The Montana BVD-PI Herd Biosecurity Project
By Clint Peck, Director, Beef Quality Assurance, Montana State University
The 2009 Montana BVDPI Herd Biosecurity Project continues efforts begun in 2006 by Montana State University (MSU) in conjunction with the Montana Stockgrowers Association. The focus is to assist ranchers in adopting an array of biosecurity practices that will prevent transmission of bovine viral diarrhea (BVD) virus within cattle breeding 
herds.
The project began after some leaders of the Montana cattle industry determined that a state-wide, concerted effort to educate producers about BVD biosecurity could help put the disease on the run in the state. Technical help and assistance provided through MSU’s Beef Quality Assurance (BQA) program continues today.
Nearly 600 Montana ranches and feedlots have participated in the project, with enrollment expected to soon reach 200,000 head of cattle over the project’s four years.
We have found 176 PI cattle:
- 155 new-crop calves (including 23 “fall-born” calves)
- 13 weaned calves
- 5 yearling replacement heifers
- 2 mature cows
- 1 yearling purebred bull
Because the primary source of BVD virus transmission is persistently infected (PI) cattle, protecting non-PI cattle from these animals is the target of the Montana project. Therefore, immunizing cattle herds with the appropriate vaccine protocol to protect against transient infection should be the first consideration in
a herd biosecurity program.
BVD biosecurity also addresses all aspects of livestock movement and handling, mixing and sorting, identification, record keeping, and documentation. It includes testing or screening herds where the virus may be circulating. The centerpiece of this project is a systematic screening protocol that guides the producer through a series of steps to identify PI animals in the herd or potential new arrivals to the herd.
Recent innovations in diagnostics allow us to screen large numbers of cattle for the BVD virus at a relatively minimal cost through reverse transcriptase polymerase chain reaction (RT-PCR) technology using pooled animal tissue samples. This assay on pooled fresh tissue samples has been reported to be a “sensitive and specific method” of screening cattle for persistent infection with BVD virus. The Montana project has contracted with the services of Animal Profiling International, Inc., Portland, Ore. (API), and has full faith and confidence in the processes used by API to find the virus and isolate individual PI animals.
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Not all producers can justify screening herds because of the low prevalence of PI animals. However, integral to BVD-PI biosecurity is an assessment of risk for BVD virus transmission between herds and within an individual herd. Experience working with hundreds of ranchers on anecdotal BVD-PI risk analysis has yielded the Montana BVD Virus Biosecurity Risk Assessment. In about 20 to 30 minutes most ranchers can work through the 15 “yes” or “no” questions contained in the Risk Assessment and place their herd’s risk of BVD into Low, Moderate, or High-Risk categories.
It is important to note that this risk assessment tool is only an estimation of risk and should not be considered a predictor of BVD infection. Also, “low” risk should not be thought of as “no” risk! Embedded in the risk assessment is a BVD “Vaccination Reliability Guide” developed by Auburn University’s Dr. Dan Givens. This guide helps producers and veterinarians make decisions on vaccination protocol.
Ranchers wanting to conduct a BVDPI risk assessment can contact Clint Peck at (406) 896-9068, cpeck@montana.edu, or Mo Harbac, (406) 994-4323, mharbac@ montana.edu. To learn more about the project and go through the Montana BVD Virus Biosecurity Risk Assessment, visit www.mtbqa.org.