Effect of mastitis‐related bacteria on total bacterial count of bulk milk supplies

Abstract

Seven hundred and fifty‐four bulk milk samples from a total of 9,066 tested by the Aberdeen and District Milk Marketing Board in 1984 had total bacterial counts greater than 45,000 per ml. Of the failed samples, 43.8% had more mastitis‐related bacteria present than non‐mastitis types. More than a quarter of the failed samples had almost pure cultures of Streptococcus agalactiae, Str. dysgalactiae, Str. uberis, Staphylococcus aureus or coagulase‐negative staphylococci. No relation was found between the failed samples resulting from subclinical mastitis infections and the somatic cell count of the bulk milk. Seventy‐five per cent of the financial penalties imposed on producers were attributable to mastitis bacteria in bulk milk samples.