Comparative efficacy of three antibiotic products for the treatment and prevention of subclinical mastitis during the dry period.

The comparative efficacy of a product containing 500 mg benzathine cloxacillin (Orbenin D.C.). another product containing 100 mg nafcillin, 300 mg procaine benzylpenicillin and 100 mg dihydrostreptomycin (Nafpenzal D.C.) and a third product containing 250 mg cephalonium (Cepravin D.C.), in the elimination and prevention of mastitis due to gram-positive microorganisms during the dry period was investigated in 1253 cows located in 14 herds in Israël. Although more uniform results were observed after treatment with Nafpenzal D.C. differences among herds were rather large. The mean cure rate for Staphylococcus aureus quarter infections was 81.4 per cent. New S. aureus infections which occurred between drying off and post calving sampling time were found in 7.0 per cent of the quarters. Dry period therapy reduced infection level with S. aureus from 13.5 per cent of quarters to 8.0 per cent. A similar proportional decrease was found in infection level due to non-agalactiae Streptococcus quarter infections.