Prevalence, aetiology and risk factors of mastitis of dairy cows kept under extensive management system in west Wollega, western Oromia, Ethiopia.

introductionMastitis is an inflammation of the mammary gland that could either be clinical or subclinical, and can be caused by infectious agents. It has different aetiological pathogens such as Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli that pose different economic and health impacts. In Ethiopia, previous studies on mastitis have been focused on semi-intensive and intensive dairy production system. The objectives of this study were therefore to estimate prevalence, aetiology of causative pathogens and identify different risk factors of mastitis in extensive management systems. A total of 532 lactating cows were randomly selected for a cross-sectional study carried out in four districts of west Wollega, western Oromia, Ethiopia.

resultBased on the clinical examination and California mastitis test, 39.67% overall prevalence of mastitis on cow level was recorded. Of them, 16.70% and 22.70% were clinical and subclinical mastitis, respectively. Among 2,128 quarters examined 210 were blind teats. The associated risk factors age ≥8 years (16.35%), parity 1-3 calving (27.63%), milk yield 1-2 litres (21.98%), lactation stage <4 months (18.04%) and tick infestation (26.70%) were significantly associated in the occurrence of mastitis. Staphylococcus spp. (15.60%) were the dominant bacteria isolated from collected mastitic milk.

conclusionMastitis is an important disease for dairy cows kept under an extensive management system. Its occurrence is determined by risk factors like age, parity, milk yield, lactation stage and tick infestation. This study is indicated Staphylococcus species as the major bacteria isolated from mastitic milk. This study warrants further study on the prevalence, aetiology, economic impact and potential risk factors of mastitis in dairy cows kept in extensive production system.