EPIDEMIOLOGIC-STUDY OF CLINICAL MASTITIS IN DAIRY-CATTLE

The incidence rate of clinical mastitis in primiparous Swedish Friesia n cows was 15%. The risk of mastitis was greater for calving in July a nd August and increased with age at calving. Calving disorders and ket osis increased the risk of mastitis 1.8 and 2 fold, while tramped teat s and udder injuries increased it 6 and 3 fold, respectively. Herds ac counted for 13% of the variation in incidence of mastitis and the risk of mastitis was 1.4 and 1.25 fold greater in high and average produci ng herds relative to low producing herds. High production predisposed cows for mastitis. Cows with clinical mastitis produced 260 kg less mi lk and were 2.8 fold more likely to be culled.