STUDY ON PREVALENCE AND RISK FACTORS OF SUBCLINICAL MASTITIS IN LACTATING DAIRY COWS IN RAJSHAHI AND RANGPUR DIVISION OF BANGLADESH

A cross sectional epidemiological study was run on subclinical mastitis to determine its prevalence and to identify associated risk factors in total of 261 dairy cows of different breeds and ages distributed in different villages in Rajshahi and Rangpur division of Bangladesh during January 2008 to December 2010 through field screening surveys by using of the California mastitis test (CMT) for each quarter milk sample. The dairy cows were differed from the breed point of view as 147 local Zebu breed and 114 Holstein x local Zebu cross (LxHF) breed. All dairy cows were apparently healthy with clinically sound udder secreting apparently normal milk. Based on CMT results, prevalence of subclinical mastitis was significantly (p<0.01) higher in crossbreeds (53.5%) as compared to indigenous Zebu cattle (36.1%) at cow level; and at quarter level 31.6% and 19.2% in crossbreds and local Zebu, respectively. In the present study, some potential risk factors such as age of cows, parity, stage of lactation, body condition in addition to some environmental factors and farm management factors were studied to find out their effects on the frequency of subclinical mastitis of lactating cattle. Among the host related potential risk factors breed, age, parity and body condition were found significantly (p<0.01) associated with the high prevalence of subclinical mastitis. Some environmental factors including type of housing, different husbandry systems, periodical disinfection of floor and hand washing before milking also influenced the prevalence of subclinical mastitis in lactating dairy cows. Some recommendations as intervention strategies were forwarded for improved control of mastitis in the region. Key word: Epidemiology, Subclinical mastitis, California mastitis test (CMT), Intramammary infection, Risk factors.