Beef farmers running blind to BVD impacts
BVD is a widespread problem in the New Zealand beef cattle industry, but many farmers are unaware of just how much the disease could be impacting their herd’s performance. Starting with a simple pooled antibody ELISA screening test to check whether your cattle have been exposed to BVD is a great way to start discussions around BVD management.
Background
Since BVD was first identified in New Zealand in the 1960s, it has become a widespread problem for the cattle industries with an estimated 15-25% of dairy herds and 45-55% of beef herds currently actively infected with the virus. With the introduction of bulk milk tank testing as quick and easy method for dairy farms to screen their milking herds for BVD, almost 70% of dairy farmers are now getting updated information on their BVD status every year. This has led to more farmers taking action against BVD, which has translated into substantial decreases in the number of actively infected dairy farms in New Zealand.
For the beef industry, the pooled serum antibody ELISA test is the equivalent of bulk milk testing for performing annual screening. The test involves collecting blood samples from 15 unvaccinated replacement heifers between 10 and 18 months of age to measure the level of antibodies against BVD and can easily be done when vets are already out on farm for other things like pregnancy testing. If the results come back high, there is a very good chance that a PI animal is (or has recently been) present in the mob. However, less than 15% of beef farmers are currently performing annual screening tests and we’re still seeing the same percentage of herds with active BVD infections as we did 10 years ago. This raised some interesting questions around farmer level of awareness of BVD in their herds and how this may be impacting decisions towards BVD management.
Study Objectives
The objective of this study was to determine the practices and opinions of farmers towards BVD control and their association with real and perceived herd BVD status.
Methods
A total of 75 commercial beef herds across New Zealand participated in this study. Blood samples from 15 replacement heifers that calved in the 2017/2018 season were collected prior to mating and again at pregnancy scanning or weaning. Antibody ELISAs were run on both individual and pooled samples to determine the herd’s previous exposure to BVD. 71 beef farmers provided additional information about their herd management practices and opinions towards BVD.
Results
Farmers were asked whether they believed BVD was in their herd. When we compared their responses against the antibody screening test results, 11 out 36 farmers (31%) who thought their herd was negative had strong evidence of BVD exposure. Over 80% of farmers who either did not believe BVD was present on their farm or were unsure of their BVD status had not undertaken any form of BVD testing in the past 5 years.
The uptake of BVD management and biosecurity practices was generally low amongst beef farmers, particular those that were unaware of their current BVD status:
Only 18 of the 71 farmers (25%) had performed any kind of BVD testing in the past 5 years.
Only 20 farmers (28%) had vaccinated their female breeding cattle in the 2016/2017 season, although most (87%) reported vaccinating bulls.
There were 62 out of 71 farmers (87%) who purchased cattle in the 2016/2017 season. Fewer than half of farmers asked about the BVD infection and vaccination status of these animals.
A common theme in the free-text comments from the survey were that farmers had to experience a BVD outbreak before they were willing to have discussions with a veterinarian about BVD management rather than taking measures to pro-actively prevent this disease. Many beef farmers were also unaware that impacts of BVD extend beyond just poor reproductive performance to include issues like stillborn calves, birth defects, poor growth rates, and higher incidence of other diseases like calf scours.
Clinical Relevance
Many farmers with BVD positive herds are unaware that BVD could be significantly eroding their bottom line from it’s impacts on animal health and performance. A simple pooled BVD antibody ELISA test on 15 youngstock between 10 and 18 months of age can easily determine whether the herd has recently been exposed to the virus.