Abstract

The apparent prevalence of clinical mastitis was determined in 38 spring calving dairy herds as part of a larger field trial conducted on behalf of Boehringer Ingelheim NZ Ltd between the 8th of July and the 21st of August, 1997. A total of 798 quarters from 595 cows were diagnosed by herdowners as having clinical mastitis. Bacterial culture was performed on all clinical quarters and antibiotic sensitivity testing was performed on selected bacterial isolates. Clinical mastitis was diagnosed in an average of 10.0% (± 0.8%, range 0.9% to 21.4%) of calved cows within the herds. No bacteria were cultured from 28.2% of clinical quarters. Of the quarters from which bacteria were cultured, 74.7% were Streptococcus uberis, 10.2% were coagulase negative staphylococci, 4.7% were Coliforms, 4.1% were Streptococcus dysgalactiae, 2.9% were Staphylococcus aureus and 3.3% were other species of bacteria. Penicillin resistance was detected in 25% of 44 Staphylococcus aureus isolates, 0% of 10 Streptococcus uberis isolates and 100% of 12 E. coli isolates.

S, McDougall

Proceedings of the New Zealand Society of Animal Production, Volume 58, , 76-78, 1998