Prevalence and Etiology of Subclinical Mastitis in Barbari and Jamunapari Goats

Clinical mastitis is characterized by visible abnormalities in the udder or milk while sub-clinical mastitis (SCM) is detected by assessment of the milk's cellular content. The goats affected with subclinical mastitis act as reservoirs of microorganisms that lead to infection of other animals within the herd. In goats; subclinical mastitis is 15 to 40 times more prevalent than its clinical form. Mastitis in sheep and goats is mainly caused by bacterial pathogens.Coagulase positive Staphylococci (CPS) is the most common cause of clinical mastitis in goats whereas, coagulase negative Staphylococci (CNS) are the most prevalent bacterial pathogens in subclinical form. The present study was carried out to assess the status of SCM in Jamunapari and Barbari goats, and the involvement of bacterial agents and their sensitivity to antibiotics. In our study, the overall prevalence rate of subclinical mastitis among the goats was determined as 19.9% (36/181). Barbari breed showed higher prevalence of SCM (24.2%; 23/95) than that of Jamunapari (15.1%; 13/86). CNS were found as the most frequently isolated bacteria from subclinical goat mastitis, whereas the second most common cause after the CNS was Bacillus sp.Apart from previously mentioned bacterial pathogens; Streptococcus sp., E. coli, Mannheimia haemolytica and Pasteurella multocida were also isolated from the SCM affected goats. Susceptibility of the bacterial isolates to antimicrobial agents was determined by disc diffusion method using 7 commercially available antibiotic discs namely amikacin, methicillin, amoxicillin, amoxicillin plus cloxacillin, cefoperazone, amoxicillin+clavulanic acid and gentamicin. Antibiotic resistance was not observed among the targeted bacterial isolates in antimicrobial sensitivity test.The study concludes that Staphylococci are the main etiological agent of SCM in the goats.