Bacterial contamination of the uterus after parturition and its effect on the reproductive performance of cows on large-scale dairy farms.

The bacteriological status of the uteri of 150 cows was examined on 14 large-scale dairy farms 10 to 20 d after parturition and then twice again in 2-wk intervals during uterine involution. The degree of bacterial contamination and the proportion of the infected uterus as well as the composition of the isolated flora were determined. The antibiotic sensitivity of the important bacterium strains was also studied. The relationship between the reproductive data and bacterial contamination of the uteri was analyzed, and the influence of certain environmental and genetic factors on the rate of infection was examined. The proportion of cows having moderate or more serious uterine infection remained above 30 % at the end of involution on more than 35 % of the farms. Infections were caused mainly by streptococci, E. coli and corynebacteria. The bacterium strains showed broad resistance against commericially available antibiotics. There were significant differences in the length of time from the parturition to the first insemination and conception among cows at the various farms. There was a significant correlation between these differences and the bacteriological status of the uteri. Reproductive data were the lowest in the group of cows infected with Corynebacterium pyogenes. The rate of the infected uteri was considerably higher after the third parturition and in cows producing less than 20 l of milk per day. No connection was found between the bacteriological status of the uteri and the breed, type of housing, and season of the parturitions.