Influence of bovine viral diarrhea virus infections on AI conception and breeding season pregnancy success in vaccinated beef herds
Bovine viral diarrhea virus (BVDV) causes reproductive and economic losses in cattle. The objective of this study was to evaluate the influence of BVDV infections on reproductive success in previously vaccinated herds. Vaccinated cows (n=370) and heifers (n=528) from 9 herds were synchronized and artificially inseminated (AI). On d 28 following insemination, blood samples were collected and pregnancy status was determined. Non-pregnant animals were resynchronized and inseminated a second time. Blood samples were tested for the presence of BVDV antigen. Animals that tested positive were considered infected with BVDV. Herds with at least 1 positive animal were determined to be BVDVinfected (n=4 infected, n=5 non-infected). Statistical analyses were performed using the GLIMMIX procedure of SAS with herd as a random variable. Herds with BVDV infections at d 28 had significantly decreased (P < 0.01) AI conception rates compared to non-infected herds (34 ± 2.3% vs 56 ± 2.3%). Breeding season pregnancy rates were also decreased (P < 0.01) in BVDV-infected herds compared to non-infected herds (68 ± 3.1% vs 88 ± 6.9%). In conclusion, BVDV infections in previously vaccinated herds had a negative impact on AI conception rates and breeding season pregnancy success.