Bovine viral diarrhea virus (BVDV) status in cow-calf herds and associations with biosecurity and production practices among Montana beef producers
Keywords:cow-calf, BVDV, persistent infection, biosecurity, beef cattle, beef cows, calves, cows, risk factors, vaccination, vaccines, viral diseases
Bovine viral diarrhea virus (BVDV) manifests in several clinical syndromes. Cattle persistently infected (PI) with BVDV are lifelong shedders and the primary reservoir of the virus in the herd. The Montana BVD-PI Herd Biosecurity Program assists Montana beef producers with BVDV education, detection, and prevention. A survey was conducted to determine associations among specific biosecurity and management practices and herd BVDV status. Of the 585 beef herds enrolled in the program from 2006-2009, 6.5% (n=38) detected greater than or equal to 1 PI animal. Among these positive herds, the within-herd PI prevalence ranged from 0.12% to 20.0%. Among the respondent herds with known BVDV status (n=230), 4.3% (n=10) were previously diagnosed with greater than or equal to 1 PI animal. Herds that annually vaccinated home-grown heifers and bulls prior to introduction to the resident herd displayed a significantly reduced risk of being BVDV positive (P less than 0.10). Producers with high self-perceived BVDV knowledge were more likely (P less than 0.10) to annually vaccinate the resident herd for BVDV, less likely (P less than 0.10) to participate in communal grazing practices from breeding to weaning, but more likely (P less than 0.10) to transport pregnant heifers off-site with subsequent reintroduction to the resident herd. These data suggest that although beef producers in Montana engage in management practices potentially increasing the risk of BVDV introduction, educated producers have taken steps to mitigate that risk.