398 Young Scholar Award Talk: Influence of a Lifetime Regimen of a Modified-Live Viral or Killed Viral Vaccination Against Bovine Viral Diarrhea Virus on Beef Cattle Performance

Abstract

Abstract Bovine viral diarrhea virus (BVDV) is a major viral pathogen affecting the cattle industry. Control of BVDV occurs through preventative vaccination or elimination of persistently infected animals. However, evaluation of the longevity of cows vaccinated during pregnancy has not been conducted. In experiment 1, heifers born in 2014 (n = 32) were randomly assigned to receive a modified-live viral vaccination (MLV; Bovishield Gold 5 FP) at 3 months of age, and subsequently receive a MLV or killed viral vaccination (KV; Cattlemaster Gold 5 FP) against BVDV beginning at weaning for the duration of their lifespan in the herd. Heifers born in 2015 (n = 29) were randomly assigned to receive a MLV or KV beginning at 3 months of age for the duration of their lifespan in the herd. Heifers were bled for analysis of antibody titers throughout their first year of life, and twice-yearly beginning at 2 years of age. Titers for infectious bovine rhinotracheitis (IBR) and BVDV, herd longevity, and reproductive performance were collected. Vaccination type did not influence IBR titer (P ≥ 0.18), herd longevity (P ≥ 0.86), or reproductive development (P ≥ 0.19). Cows born in 2015 and their calves were used in experiment 2 (n = 24) to evaluate responses in the preweaning period. Cow and calf samples of blood and ruminal contents, and colostrum and milk were collected at d 1, 7, 35, 63, and 205 of age. Cows receiving KV vaccinations have ~60% more colostral IgG than cows receiving MLV vaccination (P = 0.02). Experiment 3 observed postweaning feed efficiency and ruminal fermentation of calves from experiment 2. Cow vaccine treatment did not affect average daily gain, gain:feed, ruminal fermentation, or metabolites (P > 0.05). An immune challenge was conducted in experiment 4. Calves (n = 8) were early-weaned and inoculated with BVDV Type 2a strain 1373. Samples were collected over 28 days to evaluate blood counts, virus isolation, and metabolites. A tendency for increased clinical scores, including mucosal discharge, and temperatures were observed for calves born to MLV cows (P = 0.08). Calves born to KV cows had increased leukocyte and lymphocyte concentrations compared to MLV calves (P ≤ 0.03). Overall, blood metabolites (glucose, non-esterified fatty acids, and blood urea nitrogen) were unaffected by treatment (P ≥ 0.8), however, metabolites did differ by day post-challenge (P ≤ 0.01). Metabolites were altered by the viral challenge and indicate the nutritional status of the animal shifted to support immune responses. Vaccination treatment had little influence on the calf’s ability to mount an immune response. These four studies indicate that both KV and MLV vaccination programs can be used to protect against BVDV without negatively impacting cow longevity, calf growth performance, and calf immunocompetence.