PSVI-7 Evaluation of Feed Mitigant Efficacy for Control of Porcine Epidemic Diarrhea Virus and Porcine Reproductive and Respiratory Syndrome Virus When Inoculated Either Alone or Together

Abstract

Abstract Research has demonstrated that swine feed can be a fomite for viral transmission and certain feed additives can effectively reduce viral contamination. However, additional information is needed to evaluate the efficacy of additives when feed is inoculated with more than one virus. The objective of this study was to evaluate the efficacy of two feed additives for mitigation of porcine epidemic diarrhea virus (PEDV) and porcine reproductive and respiratory syndrome virus (PRRSV) when inoculated individually or together. Feed additives included: 1) no treatment, 2) 0.33% commercial formaldehyde-based product (Sal Curb, Kemin Industries, Des Moines, IA), and 3) 0.50% medium chain fatty acids blend (MCFA; 1:1:1 ratio of C6:C8:C10, Sigma Aldrich, St. Louis, MO). Samples were inoculated with PEDV and PRRSV alone or together at an inoculation concentration of 106 TCID50/g for all viruses. Once inoculated, feed was stored at ambient temperature for 24-h before analyzed via qRT-PCR. For samples inoculated with PEDV or PRRSV alone, a qRT-PCR assay was used which was designed to detect PEDV or PRRSV nucleic acid. For co-inoculated samples, an assay was designed to independently detect both PEDV and PRRSV within a single reaction. For PEDV alone, there was marginally significant evidence that feed additives resulted in differences in cycle threshold (Ct) value (P = 0.052), but no evidence was observed for pairwise differences. For PRRSV alone, formaldehyde increased Ct compared to the untreated control and MCFA treatment (P < 0.05). For co-infection of PRRSV and PEDV, MCFA and formaldehyde increased Ct (P < 0.05) in comparison to non-treated feed. In summary, formaldehyde increased Ct values in feed when contaminated with PRRSV while both mitigants increased Ct value in feed when co-inoculated with PRRSV and PEDV.