젖소에 있어서 乳房의 衛生管理實態에 따른 準臨床型 乳房炎의 感染率과 分離菌의 藥劑感受性

INCIDENCE OF SUCLINICAL MASTITIS BY HYGIENE CONTROL IN LACTATING COWS AND DRUG SUSCEPTIBILITY OF ISOLATES

This survey was carried out to investigate the incidence of subclinical mastitis in dairy cows of Gyeongnam area from March 1987 to February 1988. Also performed were the isolation of microorganisms from RBV positive milk samples and drug susceptibility testing of the isolates. Two hundred and thirty-eight cows(43.2%) of 655 cows were found to be infected with subclinical mastitis and infection rate in quarters was 19.9% of 2,595 quarters. The incidence of subclinical mastitis was significantly increased with advancing parity. In the incidence of subclinical mastitis by hygiene control of lactating cows, disinfectant udder wash, teat dipping and post hand-milking treatments were highly effective for diminishing of the incidence of subclinical mastitis, but drying cow therapy was little effect. The causative organisms isolated in order of prevalence were Staphylococcus aureus(40.0%), Staphylococcus epidermidis(18.5%), Micrococcus spp.(15.0%), Bacillus spp.(9.1%). Streptococcus dysgalactiae(7.2%), Escherichia coli(4.3%), Streptococcus uderis(3.1%), Streptococcus agalactiae(1.4%) and Corynebacterium spp.(1.3%). The 404 isolates of Staphylococcus spp., 65 Streptococcus spp. and 50 Bacillus spp. were highly sensitive to cephalothin and chloramphenicol, while all of them were highly resistant to streptomycin and colistin. Twenty-four strains of Escherichia coli were resistant to penicillin, streptomycin and kanamycin. but were mostly sensitive to chloramphenicol.