Study on prevalence of bovine mastitis and its major causative agents in West Harerghe zone, Doba district, Ethiopia

A cross-sectional study was carried out in Doba district, West Harerghe, Eastern Oromiya State, Ethiopia from November 2010 to April 2011 with the aim of determining prevalence of mastitis in Zebu cows and to identify associated risk factors and major etiological agents. A total of 384 lactating Zebu cows were included in this study and out of these, 89 (23.18%) were found to be reactive by California mastitis test (CMT). Bacteriological analysis of milk samples collected simultaneously yielded positive result in 76 (19.79%) of the samples. Out of 1536 quarters examined 34 (2.21%) were blind and 152 (10.12%) were positive by CMT. Bacteriological analysis carried out at the quarter level showed that 121 (8.03%) of the samples were positive for various bacteria. The predominant bacteria isolated were Staphylococcus species (47.11%),Streptococcus species (31.40%) and coliforms (9.92%). Other bacterial species were isolated at lower rates. Antimicrobial susceptibility test showed that most of the isolates in the study area were found to be highly sensitive to cloxacillin, gentamycin and amoxicillin, and moderately sensitive to ampicillin and oxytetracycline. Nevertheless,Streptococcus and Staphylococcus species isolated were resistant to streptomycin and penicillin. Age, parity, stage of lactation and hygienic conditions were found to be important risk factors associated with the occurrence of mastitis.   Key words: Bacterial pathogens, cows, Doba, masttitis, prevalence, risk, Zebu.