A STUDY ON PREVALENCE OF SUB CLINICAL MASTITIS IN DAIRY COWS IN SOME SELECTED DAIRY FARMS UNDER CHITTAGONG DISTRICT

Abstract

This study investigated the current status of sub clinical mastitis in 12 dairy farms in 306 dairy bovine udders at Chittagong metropolitan area over a one-month period. The prevalence of sub clinical mastitis was assessed by the results of physical examinations of the mammary gland and by California Mastitis Test (CMT) from a total of 1224 quarters. The samples were randomly collected from udders apparently normal and those affected by sub clinical mastitis. The cow-based prevalence of sub clinical mastitis defined by a cow having at least one CMT positive quarter was 70% of them affected with sub-clinical mastitis .The prevalence of sub clinical mastitis was higher in sahiwal x Friesian cows (90%) than other breeds and the lowest prevalence of sub clinical mastitis found in ( local x Friesian ) x Friesian cows. The prevalence of sub clinical mastitis was higher in large dairy farm (73%) than small (68%) and medium farm (72%) size. The dairy cows of 5-6 years aged were most susceptible to sub clinical mastitis than other age and old aged cows were less susceptible to sub clinical mastitis. Frequency of mastitis was found to be increased steadily with advancing age.The prevalence of sub clinical mastitis was higher in early lactation (83%) and in mid lactation (80%) than late lactation (74%). Prevalence of sub clinical mastitis among cows of first parity (78%) were higher than others (1-6, 7 & above 7 parity).The frequency of mastitis in front quarter was higher than hind quarter (1.045 times) and the rate of quarter infection was 45%. Prevalence sub clinical of mastitis in pregnant animals (88.61%) were higher as compared with fresh (61.45%). Higher prevalence of sub clinical mastitis (90%) was found in cows producing 5 to 10 liters milk in the morning. Higher prevalence of sub clinical mastitis was found in dirty barn (38%) and dirty teat and udder (40.42%) 0f cows.