Somatic Cell Count and Dairy Cow Welfare
Somatic cell count (SCC) — a measure of white blood cells in milk — is one of the most important indicators of udder health and welfare in dairy herds. High SCC reflects the immune response to mastitis, providing both a welfare indicator and a trigger for management intervention.
What SCC Measures
Somatic cells in milk are primarily leucocytes (neutrophils, macrophages, lymphocytes) mobilised to the udder in response to bacterial infection. In healthy cows with no udder infection, SCC is typically 50,000-150,000 cells/ml. Above 200,000 cells/ml indicates likely subclinical mastitis (udder infection without visible signs); above 400,000 cells/ml indicates significant ongoing infection.
Bulk tank SCC (BTSCC) — the SCC of the combined milk from the whole herd — reflects the overall prevalence of mastitis in the herd. EU regulations require BTSCC below 400,000 cells/ml for milk to be sold; higher-welfare standards and many farm assurance schemes target lower thresholds (200,000 cells/ml or below).
SCC and Welfare
Subclinical mastitis (elevated SCC without visible signs) is not painless — histological and endocrine evidence shows that subclinical mastitis causes inflammation, tissue damage, and likely pain even without the dramatic signs of clinical disease. Cows with chronic high SCC quarters suffer continuous low-grade inflammatory pain. Herd-level elevated BTSCC indicates widespread welfare compromise from udder inflammation.
Clinical mastitis — with heat, swelling, pain, and systemic illness — causes acute welfare impact. Individual cow SCC monitoring enables detection of clinical and subclinical mastitis cases, allowing targeted treatment and welfare intervention.
Using SCC Data for Welfare Improvement
Modern milk recording provides individual cow SCC monthly. Analysis of SCC patterns — new infections vs. chronic cases, quarter vs. whole udder involvement — guides management decisions. Repeated high SCC quarters may require selective dry cow therapy or, for chronic irreversible cases, culling decisions. Trend analysis (is BTSCC improving or worsening?) indicates whether mastitis control programmes are effective.