303 Award Talk: Effects of L-glutamate and L-aspartate supplementation on growth performance, diarrhea severity, immune responses, intestinal barrier integrity of weaned piglets challenged with enterotoxigenic Escherichia coli F18

L-glutamate (Glu) and L-aspartate (Asp) play critical roles in cellular metabolism and immune regulation in pigs. This study investigated the effects of Glu and Asp supplementation on growth performance, immune responses, and intestinal integrity in weaned piglets challenged with enterotoxigenic Escherichia coli (ETEC) F18. Forty-nine weaned pigs (8.18 ± 1.54 kg BW) were randomly assigned to one of seven treatments (n = 7): a negative control (NC) and a positive control (PC) fed a control diet, and five groups supplemented with 1% or 2% Glu, 1% or 2% Asp, or 50 mg/kg Carbadox. All pigs, except NC, were orally challenged with F18 ETEC (1010 CFU/dose/day) for three consecutive days after 7 days adaptation. The study lasted 14 additional days post-inoculation (PI). Body weights, feed consumption, and fecal scores were recorded throughout the study. Fecal and blood samples were collected at specific time points for bacterial shedding analysis through bacterial culture and blood profile analysis via complete blood cell count, respectively. Intestinal mucosa from the jejunum and ileum was collected on d 14 PI for cytokine and tight junction protein expression analysis via quantitative reverse transcription polymerase chain reaction. Data were analyzed using ANOVA in PROC MIXED of SAS. Frequency of diarrhea was analyzed by Chi-square. Compared with PC, pigs fed 1% Glu or 2% Asp had improved (P < 0.05) average daily gain and gain-to-feed ratio during the first two weeks post-weaning. Additionally, 1% or 2% Asp supplementation reduced (P < 0.05) diarrhea severity compared with PC. 1% Asp supplementation also increased (P < 0.05) duodenal villi height and ileal villi width in pigs than Carbadox. Moreover, 1% Glu reduced (P < 0.05) fecal shedding of β- hemolytic bacteria compared with PC on d 14 PI and decreased (P < 0.05) neutrophil-to- lymphocyte ratio on d 2 and d 5 PI, showing effects comparable to Carbadox. Furthermore, 1% Glu or 2% Asp upregulated (P < 0.05) ileal IL-12 compared with PC and Carbadox, while exhibited trends in IFN-γ expression similar to Carbadox. Supplementing 1% Glu upregulated (P < 0.05) jejunal IL-17A and IL-22 expression compared with NC and Carbadox. Furthermore, 2% Asp pigs had lower (P < 0.05) jejunal IL-6 than PC. Interestingly, 2% Asp supplementation decreased (P < 0.05) jejunal CLDN-1, while increased (P < 0.05) ileal CLDN-1 compared with NC. Compared with PC, 1% Asp upregulated (P < 0.05) ileal OCDN and ZO-1. In conclusion, Glu or Asp supplementation enhanced growth performance and disease resistance in weaned pigs challenged with ETEC.