177 Modulation of fecal microbiome by phytogenics, a postbiotic, and mix of organic acids with essential oils in weaned pigs subjected to F18 Escherichia coli challenge

Abstract This study evaluated the effects of bioactive feed ingredients on fecal microbiome of weaned pigs subjected to F18 enterotoxigenic Escherichia coli (ETEC) challenge. Two blocks of weaned pigs n = 72; Yorkshire/Landrace/Duroc; initial body weight (BW) = 6.62 ± 1.37 kg were balanced by gender and litter and randomly allocated to one of the six treatments with 12 pens/block and 6 pigs/pen. Treatments included: 1) basal diet (NC), 2) NC + 0.1% phytogenic (Fresta Protect, Delacon, Austria; PFP), 3) NC + 0.2% postbiotic (Dia-V Nursery, Diamond V, IA; PB), 4) NC + 0.2% new phytogenic prototype (Delacon, Austria; NPP), 5) NC + 0.2% organic acid and essential oil blend (OA+EO), and 6) NC + 0.1% phytogenic (Fresta Protect) + 0.2% postbiotic (Dia-V Nursery; PFP+PB). The trial lasted 15 d, with a 7-d pre-challenge and 8-d post-challenge periods. Pigs were orally inoculated with 5 x 1010 CFU/mL of F18 ETEC (O147:H2, LT:STb:STa:Stx2:F18) on d 8 and 9 of study after 5-h fasting. Fecal swabs were collected before challenge (d 8) and 3- and 8-d post-challenge (d 10 and 15 of study) and subjected to shotgun metagenomics. Diarrhea score and E. coli shedding (CFU/mL) were monitored daily and analyzed using a multi-level mixed effect ordinal logistic regression with block and pen as random effects. Microbiome data were center-log-ratio transformed and analyzed for diversity, abundance, and interaction networks. At 3-d post-challenge, the OA+EO, PFP+PB and NPP supplemented pigs had reduced (P 0.001) E. coli shedding compared with NC. Diarrhea score tended to be less (P = 0.054) in PFP+PB fed pigs 5-d post-challenge and was less (P = 0.02) in PFP+PB, OA+EO, and NPP 6-d post-challenge than NC. Alpha-diversity declined (P 0.01) 3-d post-challenge with most reduction in PFP and OA+EO but recovered 8-d post-challenge except for PFP and OA+EO (P 0.01). At the baseline and 8-d post-challenge, the largest number of differentially abundant taxa (P 0.05) were observed in PFP+PB compared with NC. The PFP+PB reduced the abundances of Escherichia.sp000208585 and Campylobacter.P585 which were negatively correlated (P 0.01) with average daily gain (ADG) and BW, and positively correlated (P 0.01) with diarrhea score and E. coli shedding. The PFP+PB increased beneficial species including Prevotella.sp900543585, Mitsuokella jalaludinii, and Faecalibacterium prausnitzii with the first two positively correlated (P 0.01) with ADG and BW, and negatively correlated (P 0.01) with diarrhea score and E. coli shedding. By d-8 post-challenge, PFP+PB microbial network had the highest degree of negative connections suggestive of a more competitive microbial ecosystem against opportunistic microorganisms compared with NC. In conclusion, co-supplementation of Fresta Protect phytogenic and postbiotic promoted a microbiome with greater beneficial and reduced detrimental bacteria resulting in low diarrhea score post-challenge.