Prevalence of Bacteria Associated with Subclinical Mastitis in Haramaya University Dairy Cattle, Goat and Sheep Farms
A cross-sectional study was conducted from November 2011 to May, 2012 to estimate the prevalence of major bacteria associated with subclinical mastitis in lactating animals. Lactating animals were screened for subclinical mastitis using California mastitis test (CMT). The CMT positive milk samples were cultured on media to isolate major bacterial pathogens. An overall prevalence of 31.6, 26.3, 21.1, 15.8 and 5.3% were recorded for Staphylococcus aureus, coagulase-negative Staphylococcus (CNS), Acinetobacter species, Micrococcus species and coliforms, respectively. The result revealed a subclinical mastitis of 48, 30.8 and 25% in cows, goats and ewes, respectively. The dominant bacteria isolated in cow milk was S. aureus (33.3%) followed by CNS species (25%), Micrococcus species (16.7%), Acinetobacter species (16.7%) and coliforms (8.3%). Similar frequency of S. aureus, CNS and Acinetobacter species were obtained for doe (25%) and ewe (33.3%). The prevalence of Micrococcus species in doe was 25%, while it was not present in ewes. Among the isolated bacteria, S. aureus and coliform species are important in clinical as well as subclinical mastitis, and they are human pathogens that cause septicemia and gastrointestinal illness. Therefore, attention should be given to the management of the dairy animals in the farm in order to reduce potential loses of productivity as well as risk of human illness due to infection and intoxication.