MASTITIS IN LOW SOMATIC CELL COUNT DAIRY HERDS – pre-liminary results from a postal questionnaire survey

A questionnaire survey of dairy farmers with low bulk tank milk somatic cell counts (BTMSCC) was carried out to assess the level of mastitis and to quantify risk factors for mastitis. Questionnaires were sent to 3009 producers with an average BTMSCC in 1997 of less than 100,000 cells/ml. One thousand eight hundred thirty nine replies were received, a 61% response rate. The average reported incidence of clinical was 22.8 cases per 100 cows/year. Simple and complex analyses were done to assess the associations between potential risk factors and a binary (yes/no) outcome variable of more than 25 cases of mastitis per 100 cows/year. The following factors, which were associated with an increased risk of disease, remained in the final logistic regression model: leaking milk in the parlour, leaking milk at other times, milking and dry cow straw yard housing (compared to cubicle housing), infrequent mucking out of the calving area (less than once a month), access to an outdoor yard, changing teat liners more often than every 6000 milkings and sometimes or always wearing rubber gloves during milking. The implications of the results for future research and the development of control programmes for mastitis are discussed.