A field investigation of the effects of bovine viral diarrhea virus infection around the time of insemination on the reproductive performance of cattle.

During a study of methods of synchronizing estrus in Bos indicus cattle, blood was collected from 169 heifers and 38 cows 2 to 3 days prior to artificial insemination (AI), and then again at Day 51 and Day 210 after AI to determine the incidence of infection with bovine viral diarrhea (BVD) virus. Prior to insemination 53 and 68% of the cows and heifers, respectively, were seronegative to the BVD virus. At Day 51 after AI, 70 and 32% of the seronegative cows and heifers, respectively, had seroconverted; but between Day 51 and Day 210, only 17 and 3% of the seronegative cows and heifers, respectively, had seroconverted. The Day- 51 pregnancy rate of cows which were immune (seropositive) to BVD virus infection at the time of AI was similar to the rate of the cows which became infected around the time of AI. However, the pregnancy rate of the immune heifers (44%, n=54) was significantly (P=0.04) greater than the rate of the heifers which became infected around the time of AI (24%, n=37). It was concluded that infection of susceptible females with BVD virus around the time of AI may significantly lower the pregnancy rate.