Disease frequencies in dairy cows in Sweden. v. mastisis

Abstract

An epidemiologic study of mastisis in dairy cows in Sweden covering 137 002 calvings and subsequent lactations is presented and various risk factors identified. Swedish Friesian breed (SLB) had a higher incidence of mastisis than Swedish Red and White breed (SRB). The incidence was higher during the first part of lactation and increased with parity until the seventh lactation in SRB and the sixth lactation in SLB. Dystocia, retained placenta and parturient paresis increased the risk of mastisis during the first part of lactation in SRB, and retained placenta increased the risk of mastitis during the first part of lactation in SLB. No associations between these periparturient disorders and the occurrence of mastitis in the latter part of lactation could be found. The incidence of mastitis was increased among teat-tramp-positive cows, and a positive report of mastitis increased the risk of mastitis in subsequent calvings. The influence of environmental factors on the occurrence of mastitis was demonstrated by a higher incidence during housing as opposed to pasture, and a decreased incidence in loose-housed cows when compared to tied zero-grazing cows during the later part of lactation. During the first part of lactation, no seasonal variation could be found, and loose-housed cows had only slightly decreased incidence during this part of lactation when compared to tied zero-grazing cows. The removal rate was increased in the mastitis-positive cow population.