Estimating the Economic Losses Associated with BVD Infection in the UK Dairy Herd

The objective of this Milk Development Council study was to provide a farm level overview of the economic losses associated with bovine viral diarrhoea (BVD) infection for UK dairy herds. This disease is possibly the most important endemic infectious disease of cattle in Europe. However there have been few farm level estimates of the losses associated with UK dairy herd infection although [2] examined losses for Scottish beef herds. The research team used computer-modelling techniques to build simulation models of BVD outbreaks and contrast them with BVD free herds. This provides a simple way of pooling and interpreting the available knowledge. Here the results of a basic simulation exercise that provides the basis for economic appraisal under different management/market scenarios are reported.

The methodology uses a spreadsheet based Markov Chain Model [1] to integrate the epidemiology of bovine BVD virus infections within the farm animal management system. From each stochastic spreadsheet model a range of outputs was generated to allow the calculation of losses for UK dairy herds as average Net Present Values (NPV) over a 10-year period. Sensitivity analysis of the model showed that herd size appeared to influence the epidemiology of BVD, affected the profitability of the farm and hence on the proportion of income lost due to BVD. Farm. Milk price also influenced the scale of the loss and the death rate for persistently infected cattle (PIs) influenced the range in losses. For example a 50-cow herd with a 50% death rate pa for PIs and a milk price of £0.18/l the median loss due to BVD over a ten-year period is estimated to be £10,300 (range £5,200 to £21,200). When the milk price increases to £0.20/l then the median loss would be £10,400 (range £4,300 to £21, 500). For that herd the proportion of potential income lost would be 19% (range 10% to 39%) at a milk price of £0.18/l but 9% (range 4% to 19%) at a milk price of £0.20/l.

The least expensive outbreaks, on average, would be for small herds with a low milk price and a high death rate for PIs. However, over a 10-year period this would represent 20% loss in income due to BVD. The most expensive outbreaks were for the largest herds when the milk price was high and the death rate among PIs was low. However, over a 10-year period this loss would only represent 8% of those farm incomes. It appears that BVD might be potentially most damaging in small herds.