Occurrence of Sub-clinical mastitis and Associated Risk Factors in Lactating Goats in Selected Areas of Eastern Harerghe Zone, Oromia, Ethiopia

Abstract

Subclinical mastitis reduces the quality and quantity of milk and is a disease of great economic and public health importance. A cross-sectional study was conducted to estimate the occurrence of subclinical mastitis, associated risk factors, and isolate of Staphylococcus aureus in lactating goats in the Eastern Hararghe zone, Ethiopia. A total of 384 lactating goats were sampled and screened by White Side test (WST) to detect subclinical mastitis. The study results revealed that animal and udder/halve level prevalence was 23.2% and 21.8% respectively, while 30 teats were found to be blind. Univariate analysis of the potential risk factors has depicted that mastitis was more prevalent in does with medium age, poor body condition, late lactation stage, does sample from Aweday, does mixing with others, closed housed goat, weakly manure removal and previous history of mastitis showed a statistically significant association with the proportion of subclinical mastitis (p < 0.05). With multivariable analysis, age, lactation stage, and origin of sampled animals showed significant association with subclinical mastitis prevalence, and these factors continued significant in the multivariable logistic regression model after stepwise elimination (p < 0.05). As a result, does in mid-age (OR=9.06, 2.24-36.60, late stage of lactation (OR=2.52, 1.21-5.24), and does sample from Aweday (OR=4.43, 1.37-14.38) were at higher risk of udder infections than younger age, early lactation and does sampled from Haramaya separately. In the present study, S. aureus has been isolated from 37.1% of goat milk. Antibiogram study results indicated that gentamicin and erythromycin were found to be the most effective drug against S. aureus. The present study has also demonstrated the existence of alarmingly high levels of antimicrobial resistance of S. aureus against chloramphenicol (100%), Vancomycin (87.5%), and Ampenciline (81.8%). The results of this study deep-rooted the importance of S. aureus as a possible cause of subclinical mastitis in goats and the spread of multiple drug-resistant S. aureus. It is therefore, recommended to prevent subclinical mastitis in the study area by considering potential risk factors, regular screening and microbiological examination of udder of lactating goats as well as judicious use of antimicrobials to treat subclinical mastitis.