PATHOLOGICAL INVESTIGATION OF MASTITIS IN DAIRY COWS AT BALIADANGI UPAZILA OF THAKURGAON DISTRICT

Abstract

The present research was carried out by a cross-sectional study in lactating dairy cows at Baliadangi, Thakurgaon to determine the prevalence of subclinical mastitis (SCM) and to investigate the udder pathology of clinical mastitis (CM) during the period from January to June, 2018. To determine the prevalence, milk sample from a total of 280 dairy cows (245 crossbred and 35 local) were screened for subclinical mastitis using two indirect tests viz. California Mastitis Test (CMT) and Surf Field Mastitis Test (SFMT). Of all cows tested, 42.50% (n=119) and 41.42% (n=116) cows showed positive reaction for SCM by CMT and SFMT, respectively. The overall prevalence of SCM was 41.96% and CMT showed better performance in detecting SCM (37.58%) between the two indirect tests used. Higher prevalence of SCM was detected significantly (P<0.05) in milch crossbred cows (44.89%) in comparison to indigenous cows (25.71%). The prevalence gradually increased with advancing age where the prevalence of SCM was higher (47.05%) in age group more than 12 years than other age groups. The prevalence of SCM was significantly (P<0.05) highest in early lactation (50.41%) followed by mid (38.73%) and late lactation (31.25%). There was significant (P<0.05) association where the prevalence is higher (60.52%) with the increasing number of parity. High yielding cows showed higher prevalence and the prevalence of SCM was significantly (p<0.05) higher (66.66%) in cows yielding >10L of milk than others. Clinical inspection revealed discoloration of glandular tissue, blockage and nodule formation in teat canals, pus formation in the glands etc. Histopathological findings revealed significantly lower alveolar diameter, mass destruction of alveoli and udder parenchyma, reactive cell infiltration and fibrous tissue proliferation in mastitic dairy cattle. Results of this study may have application in selection of dairy animals and in a better understanding of the pathological consequences of mastitis.