Abstract

The study was conducted at Holeta Agriculture research center over October 2011 to May 2012 to estimate prevalence of mastitis, assess risk factors, isolate bacterial causes and measure antimicrobial sensitivity patterns of isolates in dairy cattle. A total of 272 comprising 130 cross breed (Holstein x Boran), 75 Jersey and 67 Holstein Frisian were examined using California Mastitis Test (CMT) and clinical examination. An overall prevalence of 55.9% where sub- clinical and clinical mastitis accounted 52.4 and 3.3%, were respectively observed. Quarter level prevalence sub-clinical (28.3%) and clinical (1.2%) were observed. The blind teat accounted 6.0%. Major isolates were Staphylococcus aureus (39.5%), Streptococcus species (29.6%),Escherichia coli (19.7%), Klebsiella pneumonia (13.2%), Enterobacter aerogen (9.9%) and Pseudomonas aeruginosa (5.3%) in decreasing order. Animal factors such as age, breed and parity number have significant effect on prevalence of mastitis. Risk factors analysis revealed that prevalence was significantly differed with the age and breed. Thus, prevalence was relatively higher in adult cows (OR = 0.41), plurimiparas (OR = 2.6) and exotic breed (OR = 0.6) than those corresponding animals. Isolates were found highly sensitive to gentamycin while it was moderate to low for penicillin and amoxicillin. Based on the finding, effort should be made to control mastitis so as to ensure quality of milk, prevent economic loss and public health hazard.

Key words: Antimicrobial sensitivity, Holeta, mastitis, prevalence.