Efficacy of intracisternal application of Benestermycin (R) to dairy cows at drying off

In two dairy herds comprising 252 (herd A) and 289 (herd B) cows, 45 cows a nd 37 cows, respectively, were treated with one dose of Benestermycin in ea ch quarter at drying off. Udder health was determined by somatic cell count s, bacteriological results and electrical conductivity. Samples were taken at weekly intervals for three weeks before drying off and three weeks after calving. In addition a sample was taken at calving for bacteriological exa mination. The predominant mastitis pathogen was S. aureus. The cure rates w ere 61% and 55%, respectively. The evaluation of these cure rates have to t ake account of the mean duration of the dry period, of 60 days, which may h ave an effect. The new infection rate in herd A was 6% and 17% in herd B. T he gl eater infection rate in herd B may have been associated with the abse nce of post milking teat disinfection and the lack of segregation of health y and diseased cows at milking time. The results stress the importance of t reatment with antibiotics at drying off in conjunction with the use of hygi enic management practices for successful mastitis control.