Somatic cells (SCC) are predominantly white blood cells (neutrophils) that enter milk in response to udder infection. Low counts indicate healthy udder tissue; elevated counts indicate inflammation — mastitis. Bulk SCC represents the average across all cows milking into the bulk tank, weighted by milk output.
EU and UK legal limit for cow milk: 400,000 cells/ml (bulk). Many premium milk contracts require below 200,000.
Regular tracking of BSCC trends over time is more informative than individual readings. Rising BSCC indicates worsening udder health and increasing welfare burden. Seasonal patterns often reflect changes in management (turnout, housing, calving patterns). Comparison with industry benchmarks enables herds to assess where they stand relative to peers.
Monthly parlour recording schemes (e.g., AHDB DairyCo) provide individual cow SCC data alongside yield and composition. This enables identification of high-SCC cows (chronic infection), tracking of new infection rates, and targeted dry cow therapy decisions. Composite milk sampling allows quarter-level identification of infected quarters.
High BSCC represents ongoing cow suffering from mastitis. Prevention strategies include: milking machine maintenance, teat condition monitoring, effective post-milking teat disinfection, hygiene at calving and throughout lactation, dry cow therapy decisions, and culling decisions. Reducing mastitis incidence and prevalence directly improves welfare, reduces antibiotic use, and improves dairy economics.