Abstract:
Mastitis is a multifaceted dairy cattle disease with multiple causative agents and economic
loss. Cross-sectional study on bovine mastitis prevalence and subclinical mastitis milk yield
loss in Durame town and its surrounding district was conducted from January to September
2019 to estimate the prevalence, milk yield losses, associated risk factors and antimicrobial
susceptibility testing of the isolates. Californian Mastitis Test, bacteriological culturing,
antimicrobial susceptibility test and split-udder trial was conducted to determine production
losses. Out of 384 lactating dairy cows were selected from the sampling frame list picked
randomly by the simple random sampling method, a total 220 (57.3%) cows were found
positive for mastitis: 2.1% clinical and 55.2% sub-clinical. The prevalence in Durame and its
surrounding were 78.2% and 53.8%, respectively. Among assessed risk factors, mastitis was
2.5 times higher in the crossbred than local. Prevalence was 2.6 times higher in cows having 6
or more compared to cows having 1–3 calving, Cows in the early lactation were more likely
to have mastitis than cows in the late lactation stage. Cows in herds without bedding material
were more likely to have mastitis than those cows in farms with bedding material. Cows in
farms that did not milk mastitic cows last were more likely to have mastitis than those cows in
herds that practice milking mastitic cow at last. Herds feeding their cows before milking were
5.128 times more likely to have mastitis than herds feeding their cows after milking, house
floor with non-concrete and barn cleaning once were more likely associated with the udder
infection. The most common bacterial isolates were Coagulase-negative Staphylococci
(35.5%), Staphylococcus aureus (30.5%), Streptococcus agalactia (15%), E. coli (11.6%),
Staphylococcus intermidus (1.8%) and streptococcus uberis (4.3%). The majority of isolates
were highly sensitive to Gentamycin (98.3%) and resistant to Polymixyn. The mean milk
yield for uninfected healthy quarters was 0.995kg per milking and the rates of milk reduction
in infected quarters were 6.2%, 24%, and 50.5%. Quarters with Californian Mastitis Test trace
and 1 were combined and considered negligible. Subclinical mastitis lost an average of 22%
of its milk production and causes an estimated total loss for each cow per lactation was
2884.59 Eth Birr. Reducing risk factors, early diagnosis and regular screening of cows
together with the proper therapeutic management are important to reduce mastitis
