30 August 2002

Environmental pathogens are mastitis cause

RESULTS of a study identifying bugs causing mastitis on dairy farms in Devon has shown that environmental pathogens are now a more common cause of clinical mastitis than contagious pathogens.

Maureen Milne, of the Vale Vet Group, Tiverton, and associates at the vet centre and Glasgow University Vet School, say the last major UK survey 20 years ago showed contagious pathogens were most common.

But according to their report in Vet Record, 37% of bacteria isolated from 2257 samples was Strep uberis, 23% was enterobacteriaceae – including E Coli – and 10% coagulase-negative Staphylococci.

The study involved 130 producers with an average of 94 cows. Milk yield ranged from 4750 to 12,500 litres and averaged 8000 litres. Cell counts ranged from 70,000 to 300,000 with an average of 142,000.

Producers took samples from each cow suffering clinical mastitis between October 1999 and February 2001 and they were all tested at the vet centres lab. Herd mastitis incidence ranged from one to 73 cases/100 cows/year.

But there was little variation in the bacteria found between farms with Strep uberis and enterobacteriaceae most common, says Miss Milne.

These two isolates were also most common in each month of the study. &#42