PS7-23. Effects of Dietary L-glutamate, L-aspartate, and Their Combination on Metabolite Profiles of Weaned Piglets Challenged with Enterotoxigenic Escherichia coli F18.

Abstract L-glutamate and L-aspartate are functional amino acids essential for intestinal functions and physiological metabolism. This study aimed to investigate the effects of L-glutamate, L-aspartate, and their combination on metabolic alterations of weaned piglets challenged with enterotoxigenic Escherichia coli (ETEC). Sixty-five weaned pigs (7.59 ± 1.11 kg BW) were randomly assigned to one of five treatments (n = 13). The dietary treatments included a control (CON), CON with 1% glutamate (GLU), CON with 1% aspartate (ASP), CON with 1% glutamate and 1% aspartate combination (GAC), and CON with 50 mg/kg carbadox (ABX) supplementation. All pigs were orally challenged with F18 ETEC for three consecutive days at the dose of 1010 CFU/dose/day. The study period lasted for four weeks, with a 7-day adaptation period and 21 days post-inoculation (PI). Serum samples were collected on d 4 PI and ileal and jejunal mucosa samples were collected on d 5 PI for untargeted metabolomic analysis using gas chromatography coupled with time-of-flight mass spectrometry (GC/TOF-MS). Metabolomic data were analyzed via MetaboAnalyst 6.0, with statistical significance declared at P < 0.05, false discovery rate (FDR)< 0.2, a variable importance in projection (VIP) score > 1, and fold change > 1.0 for up-regulation and < 1.0 for down-regulation. Partial least squares discriminant analysis (PLS-DA) was conducted to identify discriminative metabolites among treatments, while pathway and metabolite set enrichment analysis were performed with an impact value > 0.1 considered significant. The findings from this study revealed that aspartate abundance was greater (P < 0.05, FDR < 0.2) in pigs fed GLU or GAC compared with ABX-fed pigs in jejunal mucosa. In ileal mucosa, glutaric acid abundance was increased (P < 0.05, FDR < 0.2) in pigs fed GAC compared with CON-fed pigs. In addition, GLU, ASP, or GAC supplementation strongly increased (fold change > 2.0) the abundance of amino acid–related metabolites, carbohydrate intermediates, nucleotide metabolites, monounsaturated fatty acids, and antioxidant-associated compounds compared with the CON or ABX groups. Pathway enrichment analysis of pigs fed GLU, ASP, or GAC also consistently highlighted modulation (P < 0.05, FDR < 0.2, impact value > 0.1) of alanine, aspartate and glutamate metabolism, arginine biosynthesis, taurine and hypotaurine metabolism, the citrate cycle, and glutathione metabolism, and pentose phosphate pathways compared with pigs fed CON or ABX, collectively supporting metabolic adaptation to stress and enteric infection. In conclusion, dietary supplementation of glutamate and/or aspartate altered both systemic and local metabolite profiles, indicating potentially supporting disease resilience in ETEC-challenged weaned pigs.