Determining the impact of commercial feed additives as potential porcine epidemic diarrhea virus mitigation strategies as determined by polymerase chain reaction analysis and bioassay()

Gebhardt, Jordan T; Woodworth, Jason C; Jones, Cassandra K; Tokach, Mike D; Gauger, Philip C; Main, Rodger G; Zhang, Jianqiang; Chen, Qi; DeRouchey, Joel M; Goodband, Robert D; Stark, Charles R; Bergstrom, Jon R; Bai, Jianfa; Dritz, Steve S

Upon completion of PCR testing, 16 samples were selected for assessment of virus infectivity via a bioassay at Iowa State University. The samples selected were d 0 negative control (FEED and SDPP which was not inoculated with PEDV), d 0, 1, 3, and 21 FEED samples with no feed additive, d 0, 3, and 21 SDPP samples with no feed additive, d 0, 1, 3, 7, 14, and 21 FEED treated with both EO and BA, and d 7 SDPP samples treated with both EO and BA. Each sample consisted of three supernatant aliquots that each were gavaged into a single pig within bioassay room. Positive control samples included untreated FEED and SDPP samples at d 0, 3, and 21 post-laboratory inoculation as well as d 1 FEED positive control for seven total positive control bioassay rooms. The d 0 and d 1 FEED positive control samples were from this study; however, the other five positive control samples were in conjunction with additional research from our group An initial tissue culture (2.5 mL diluted virus inoculum, 10 5 TCID 50 /mL) was inoculated into 22.5 g of gestation diet (FEED) or SDPP treated with 0.02% EO product, 0.5% BA product, combination of EO and BA products (EO + BA) (DSM Nutritional products, Parsippany, NJ), or no chemical treatment. †Ct required to detect genetic material. A higher Ct value is indicative of less genetic material present. ‡ Matrix × treatment × day interaction, n = 3 for each value. SEM = 0.90, P = 0.094. * An initial tissue culture (2.5 mL diluted virus inoculum, 10 5 TCID 50 /mL) was inoculated into 22.5 g of gestation diet (FEED) or SDPP treated with 0.02% EO product, 0.5% BA product, combination of EO and BA products (EO + BA) (DSM Nutritional products, Parsippany, NJ), or no chemical treatment. A total of 168 samples were used for the analysis with each treatment represented by a mean of n = 21 for the matrix × treatment interaction, and n = 42 for the main effect of treatment. †Ct required to detect genetic material. A higher Ct value is indicative of less genetic material present. ‡ Swine gestation diet. ║ SDPP (APC Functional Proteins, Ankeny, IA). a,b,c Means within item lacking common superscript differ (P < 0.05).