Across- Sectional Study of Bovine Mastitis in and around Bahirdar and Antibiotic Resistance Patterns of Major Pathogens
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Date
2004-06
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Addis Ababa University Faculty Of Veterinary Medicine
Abstract
Three hundred fi fty one (J 95 local zebu and 156 Holstein x Local Zebu) lactating cows of smallholder private farms in Bahir Dar milk shed were examined from September, 2003 to March, 2004 (0 determine mastitis prevalence, isolate pathogens involved, evaluate the antibiotic susceptibility profi les and [0 evaluate somatic cell count in identifying intramammary infections. Clinical prevalence was detemlined through examination of abnomlalities of milk, udder or cow. Cal ifornia mastitis test (CMT) and culture were used for subclinical mastitis determ ination. Agar disc di ffusion was used for antibiotic susceptibility test. Somatic cell count was conducted following standard procedures described In International Dairy Federdtion for enumeration of cells with direct Microscopic method. Clinical prevalence at cow level was 3.9% in crossbreds and nonc in local zebu breeds. Subclinical mastitis at cow level based on CMT was high (34.4%) in crossbreds compared to indigenous zebu (17.9%) (p < 0.05). Quarter subclinical prevalence based on eMT was 17.90% and 4.95% for crossbreds and local zebu. respectively. Among potential risk factors considered, stage of lactation, parity and breed were found 10 afTecI the occurrence of mastitis significantly (p < 0.05). The pathogens isolated from mastitic milk were coagulase negalive staphylococci (eNS), s. aureus. Srr. agalacliae. Sir dysgalactiae. Srr. uberis. Micrococcus species, C. bovls. A. pyogefls, B. cereus, and S. illtermedius. Among these, the most frequent isolates were eNS (49.6% of the 10lal isolates). S. alirellS (17.9%), Srr. agalacliae (8.2%) and SIr dysgalacliae (6:7%). Seven antibiotics including sulfi soxazole. tetracycline, erythromycin. oxacillin, chloramphenicol, cJindamycin, and streptomycin were tested on 81 isolates. Except for streptomycin, all isolates \\ere sensitive to all antibiotics. All isolates were most sensitive 10 sulfisoxazole. Staphylococcw; allreus was susceptible to all drugs except streptomycin. SllIphylococcus Ollreus was 91.7% susceptible to oxacillin, however, CNS were less susceptible (68.2%) ill vilro. To evaluate somatic cell count (SeC) in identifying imramamary infection for crossbreds. 10 cutoff poims between 100000 cellsl ml and 300000 celJSJml were evaluated for their sensllivity and speci-ficity in comparison with cultural results. Similarly, cutoff points between 80000 cell ml and "250000 cell ml were taken for local zebu breeds. The sensitivity for
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Keywords
clinical subclinical masti tis! prevalence bacterial isolate antibiotic susceptibility Somaric Cell Count threshold crossbred zebu