Mastitis research update from the University of Nottingham Dairy Herd Health Group

In the UK, the average dairy herd size is currently ~133 cows and the incidence rate of clinical mastitis (CM) is likely to be somewhere between 47 and 65 cases/100 cows/year. The national average bulk milk somatic cell count (BMSCC) is currently ~167,000 cells/ml and this number has been falling steadily since 2009. Clinical mastitis in the UK is caused predominantly by pathogens traditionally classified as ‘environmental’, with Strep. uberis and E. coli being the most commonly diagnosed pathogens. In contrast, pathogens traditionally classified as ‘contagious’ now account for only around 10% of diagnoses made.

In light of this UK context, much of the previous research activity by members of the Dairy Herd Health Group at Nottingham University has focussed on the design and delivery of a farm-specific mastitis control strategy that utilises in-depth data analysis methods and current mastitis literature to make farm-specific recommendations. The resulting approach was tested in a randomised controlled trial (RCT) in 52 UK dairy herds in 2004. Results from the RCT showed a mean reduction in the proportion of cows affected with clinical mastitis of 22% (having accounted for confounders) in intervention herds compared with control herds. There were also significant reductions of around 20% in the incidence of clinical and subclinical infections (Green et al., 2007). After some further developments, the Dairy Mastitis Control Plan (DMCP) was launched by the Agriculture and Horticulture Development Board (AHDB) at a national level in April 2009.

The DMCP consists of three main stages; i) analysis of the herd data to assess patterns of mastitis and categorisation of each herd according to