Abstract #789

# 789
Effect of additives on survival of swine delta coronavirus (SDCoV) in complete feed.
Katie M. Cottingim*1, Harsha Verma2, Fernando Sampedro2, Pedro E. Urriola1, Gerald C. Shurson1, Sagar M. Goyal2, 1Department of Animal Science, University of Minnesota, St. Paul, MN, 2Veterinary Population Medicine, University of Minnesota, St. Paul, MN.

Swine delta coronavirus was first discovered in 2012 in China, and the first confirmed case in the US was in Ohio in 2014. Feed contaminated with feces from infected pigs is a potential route of transmission of SDCoV. Organic acids (OA) and feed additives are included in diets to improve nutritional value. The objectives of our study were to determine if OA or additives at recommended or twice the recommended concentrations are effective in reducing the survival of SDCoV in feed. Five g aliquots of complete feed were placed in scintillation vials followed by addition of 1 of 8 additives at recommended concentrations of 150mg Ultracid P (orthophosphoric, citric, fumaric, and malic acid; Nutriad), 20mg Activate DA (organic acids and 2-hydroxy-4-methylthio butanoic acid; Novus Intl.), 10mg KEM-GEST (phosphoric, fumaric, lactic, and citric acid; Kemin Agrifoods), 10mg Acid Booster (phosphoric, citric, and lactic acid; Agri-Nutrition), 56µL Luprosil (propionic acid; BASF), 46µL formic acid (formic acid; BASF), 20mg salt, or 20mg sugar. Virus was grown and titrated in swine testicular (ST) cells and was added to all vials at 1mL/vial (initial virus titer = 3.2 × 105 TCID50/mL) followed by vortexing and storage of vials at room temperature (25°C) for 5 wk. Exp. 2, twice the recommended concentration of additives was added to aliquots and experimental conditions were identical to those used in Exp. 1 except that virus survival was evaluated on d 0, 1, 3, 7, and 10 of storage. Samples were eluted with 3% beef extract-0.05M glycine solution and inoculated in ST cells to calculate TCID50/mL. Data were analyzed using Weibull inactivation kinetics model. In Exp. 1, we observed that it takes 0.86 d to reduce the concentration of virus by 1 log. None of the additives tested reduced the inactivation kinetics of the virus at recommended doses. However, adding twice the recommended concentration reduced the time for 1 log inactivation in feeds with Acid Booster (0.28 d) (r2 = 0.93), Activate DA (0.12 d) (r2 = 0.72), and salt (0.09 d) (r2 = 0.91). Thus, using these feed additives may reduce virus survival in complete feed faster.

Key Words: feed additive, organic acid, swine delta coronavirus