Abstract:
A study was conducted in Jimma town cross breed dairy farms to determine the
prevalence contagious mastitis, risk factors and antimicrobial susceptibility profile of the
isolates between October 2012 and May 2013 using California Mastitis Test (CMT) for
screening subclinical mastitis. All milk samples were cultured for bacteriological
identification by following the protocol described by National Mastitis Council. Clinical
mastitis prevalence was determined through examination of abnormalities of milk, udder
or cow during sample collection. Out of the 206 cows examined 101 cows were positive
to mastitis. Out of 824 quarters examined, 50 (6.06%) were found blind and 774 quarters
were found to be functional. Out of the total quarters examined, 404 (52.2%) were
affected, 34 (8.4%) clinically and 370 (91.6%) sub clinically. Of 404 infected quarters, 57
quarters were found positive to contagious mastitis. The overall prevalence of contagious
mastitis at cow and quarter level was 27.7% and 7.4% respectively. Potential risk factors
for the occurrence of contagious mastitis were wood or soil floor type, source of water,
milkers, lactation stage and purchasing heifers into herd. The pathogens isolated in this
study were S. aureus and S. agalactiae, S. aureus was the most dominant species
identified in this study area. Antimicrobial susceptibility tested was conducted on 57
isolates against seven antimicrobial agents for S.aurues and nine for s.agalactae. All
strains were resistant to Amoxacilline +CLAV(30+15µg), Cefquinome, Streptomycin,
Tetracycline (80µg), Trimethoprim +Sulfa(5.240µg) and polymyxin by 82.5% 3.5%
,7.0% ,42.1%, 3.5%,82.5% respectively. About 18.8% of S.agalactae isolates was
resistant to Ampicillin (30 µg) and Enrofloxacin (10 µg) were resistant to. Good hygiene
in milking process, creation of awareness for milkers on contagious mastitis, milking
clinically infected cows at last, culling chronic mastitis carriers, treating clinically
infected cows and dry period therapy could reduce the prevalence of contagious mastitis
in the study area
