AEROBIC BACTERIAL ISOLATES, INCIDENCE RATE AND THE ASSOCIATED RISK FACTORS OF HEIFER MASTITIS IN AND AROUND DEBRE-LIBANOS WOREDA, NORTH SHOWA, OROMIA, ETHIOPIA
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Date
2014-06
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Abstract
Mastitis is a major disease in dairy cattle of Ethiopia. The objectives of this study were to
identify aerobic bacterial pathogens, estimate the incidence of mastitis, identify the
associated risk factors and assess drug resistance patterns of bacterial isolates in heifers
mastitis. The study was conducted for eight months and a total of 124 quarters were
examined to detect clinical mastitis and subclinical mastitis by udder physical
examinations and the California mastitis test (CMT) respectively. California mastitis test
positive milk samples were used to isolate and identify bacteria. The study revealed that
the incidence rate of mastitis per gland month at risk was 39.45%. The incidence of
mastitis was found to be affected by management system, udder hygiene, dry cow
therapy and lactation stage (p < 0.05). The percentage of CMT positive glands that
remained positive after a month and the percentage of CMT negative glands that
remained negative after a month were 57.14% and 79.91% respectively. Staphylococcus
aureus (25.11%), Coagulase negative staphylococci (CNS) [14.70%] and Streptococcus
species (14.70%) were the predominant bacteria. In the present study, out of eight in vitro
antimicrobials used; gentamycine (0%), kenamycin (0%), ampicillin (62%), penicillin G
(89%), chloramphinicol (8%), Cefoxitin (16%), tetracycline (84%) and trimethoprim
(8%), showed resistance to heifer mastitis pathogens. Gentamycine and chloramphinicol
were the most effective antibiotics among all the tested ones. Finally due to the high
resistance level detected in the study, it was believed that it is necessary to set up
antimicrobial resistance surveillance programmes in the country. It was also concluded
that the prevalence of Staphylococcus aureus warrants serious attention, the application
of antibacterial agents earlier before calving may help to reduce the incidence of mastitis
during the early lactation period.
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Keywords
Heifer mastitis, incidence rate, risk factors, bacterial isolates