PSIII-1 Effects of functional additives on performance and gut health in E. coli-challenged weaned pigs.

Abstract This study investigated the effects of complex additives in weaning pigs challenged with Escherichia coli (E. coli). The complex additive included essential oil (thymol and carvacrol), organic acids, vitamin E, and selenium. Twenty-four LYD pigs (28 days old; 9.61 ± 0.81 kg) were used in a 17-day study, including a 3-day adaptation period. Pigs were assigned to four treatments: PC (basal diet), NC (PC + E. coli challenge), T1 (NC + 0.05% complex additives), and T2 (NC + 0.10% complex additives). After adaptation, the challenged groups received 3 mL E. coli (10¹⁰ CFU/mL). In our results, the PC reduced (P < 0.05) average daily gain (ADG), average daily feed intake (ADFI), villus height (VH), and tight junction protein expression, while increasing (P < 0.05) crypt depth (CD) compared to the NC. However, the T1 had higher (p < 0.05) ADG and ADFI than the NC at 0 to 7 days. At 28 days, the complex additive increased (p < 0.05) the VH to CD ratio and the levels of claudin-1 and mucin-1. The T1 had a lower (p < 0.05) CD and a higher (p < 0.05) level of zonula occludens-1 than the NC. At 3 days, the T1 and the T2 had higher interferon-γ levels (p < 0.05), and the T2 had a higher (p < 0.05) interleukin-8 level than the PC. At 3 days, 16S rRNA sequencing showed that the T2 differed (p < 0.05) in quantitative beta diversity from both the PC and the T1. At the genus level, the T2 had a higher (p < 0.05) abundance of Lactobacillus and Megasphaera, while the NC had a lower (p < 0.05) abundance of Phascolarctobacterium and Christensenellaceae R-7 group than the others. At 14 days, quantitative beta diversity differed (p < 0.05) between the T2 and both the NC and the PC. At the genus level, the NC revealed a higher (p < 0.05) abundance of Oscillosporaceae and a lower (p < 0.05) abundance of Ruminococcus than the others. The PC had a lower (p < 0.05) abundance of Parabacteroides and a higher (p < 0.05) abundance of Prevotella than the others. In conclusion, the supplementation of complex diet additives enhances immunity during infection and improves growth performance and intestinal morphology by modulating gut microbiota. Also, the optimal inclusion level of complex additives is considered to be 0.05%.