Time to get on top of BVD!
Bovine Virus Diarrhoea (BVD) is widely recognized as the most important viral disease of cattle in New Zealand (NZ).
Around 80% of NZ herds have been exposed to BVD virus and the National BVD Steering Committee estimates that at any one time around 15% of dairy herds have an active infection. BVD is extremely costly and having an active infection in your herd leads to substantial financial losses... So what can you do about it?
Many of our clients use the Livestock Improvement Corporation (LIC) BVD monitoring package to keep track of the level of infection in their milking herd. Lately we are seeing quite a few positive PCR's. In most cases this means there is a persistently infected (PI) animal in the milking herd. In such cases it is also not uncommon to have the bulk milk antibody show high or very high exposure. This generally means there is an active BVD infection in the herd and we need to question where this exposure is coming from.
The simple way of thinking about BVD exposure is IN, OUT, OVER:
IN = bought in stock. Any cattle coming onto the property. This includes the unborn calves of pregnant cows! When buying in new stock, always consider the BVD status of the property they are coming from. If the status is unknown, it is highly recommended that you quarantine the new animals and have them tested before they have any contact with your existing herd. You have every right to ask for certification proving that bought in stock (especially bulls) have been tested negative for BVD and/or have been vaccinated.
OUT = cattle leaving the property and returning at a later date such as heifers or carry-over cows going away grazing and coming back pregnant. Assess the risk that your stock may have been exposed to BVD while away on a grazing property. Could they come into contact with stock from other properties? If they are exposed to BVD while pregnant, they could produce a PI calf.
OVER = could your cows be encountering BVD at boundary fences? Are your boundaries double fenced and/or well demarcated to create separation such as by a train track, road or river? Just touching noses with neighbouring stock can be enough to infect your cows.
Once we know where the BVD exposure is coming from, we can identify ways to protect your herd. If farm biosecurity is low and difficult to improve, vaccination can be an extremely effective strategy. Vaccinated stock are far less likely to be infected if they are exposed to BVD. This means they won't become a temporary carrier and shedder of BVD and most importantly they won't produce a PI calf.
Your vet can help you identify the BVD risk on your farm and come up with a management plan to minimize your losses to BVD, so talk to them today and take control of BVD this season!