Progress noted in drive to eradicate BVD from the NI cattle population

Recent analysis shows that the prevalence of BVD infection at the individual animal level has fallen by over a quarter and that herd level prevalence has fallen by over a third since the commencement of the compulsory phase of the NI BVD Programme.

After the first year of the Programme, at February 2017, the rolling 12-month animal prevalence of BVD was 0.66%; by the end of September 2018 it had fallen to 0.49%.  During the same period, 12-month herd prevalence levels have fallen from 11.46% to 7.52%, demonstrating a decrease in the proportion of herds affected by the disease of over a third.

BVD is a highly contagious viral disease of cattle, so these encouraging results have come about as a result of many herd owners making responsible decisions to isolate and cull calves that have been identified as being persistently infected (PI) with the BVD virus.  All PIs shed enormous amounts of virus and pose a very significant risk to other cattle on their holding as well as to cattle on neighbouring premises, so their identification and removal is the key to disease control.

While the progress noted is welcome, the biggest impediment to a faster decline in disease levels is the fact that PIs are still being retained commonly.  Figures for calves born during August 2018 show that only three-fifths of those with a BVD Positive status were culled within 5 weeks of getting the initial BVD result.  Where PI calves are detected in a herd, retesting of a blood sample may be carried out for confirmation: approximately 9 out of every 10 resamples return a further positive result.  Additional testing is required to identify any other PI cattle that may be present.  If decisions were made to cull all positive animals promptly, the risk of spread of infection would be reduced markedly.  

As the level of circulating virus decreases in herds that are tackling the disease successfully, it will become increasingly important for farmers to follow good practice in biosecurity protocols, including greater scrutiny of bought in animals and, in consultation with a veterinary practitioner, consideration of vaccination in certain circumstances.

There are major benefits to be gained by the eradication of BVD, such as lower production costs; a decreased need for and use of anti-microbials; and improved animal welfare.  Stakeholders have worked well together to achieve the progress that has been made so far, and efforts are being made to bring in new legislation that will strongly discourage PI retention, as the goal in dealing with BVD is to achieve eradication as soon as possible.