Frequency of bluetongue and bovine parvovirus infection in cattle in South Carolina dairy herds.

A survey of South Carolina diary cattle in 12 commercial herds was conducted, using serologic testing to determine the frequency and impact on reproduction of bluetongue (BT) and bovine parvovirus (BFV) infections. Results of the study of serum antibodies titers and dairy cattle health records indicated that the majority of the cattle surveyed was adequately protected against the major reproductive tract diseases through vaccination programs. The frequency of reproductive dysfunction was common in vaccinated herds, however. Six of the 12 herds in the survey had cattle which were BT serotest reactors, although total numbers of these reactor cattle were relatively small. Further, reproductive performance of reactor cows indicated that BT was of little consequence and was not associated with reproductive problems. All herds contained BPV serotest reactors and the latter comprised 59.7% of the total number of cows surveyed. The BPV seroreactor cows were commonly associated with the group of reproductive problem cows which experienced higher rates of embryonic mortality and more services per conception than did nonreactor cattle. The results of the survey emphasize the need for continued investigation and efforts to control BT, and especially BPV infection, in dairy cattle.