Abstract
Abstract
L-glutamate (Glu) and L-aspartate (Asp) are functional amino acids that play multifaceted roles in mammalian enterocytes and serve as key energy substrates for intestinal epithelial cells, suggesting potential roles in supporting intestinal resilience and disease resistance in weaned piglets. This study investigated their effects on growth performance, diarrhea incidence, intestinal integrity, and amino acid digestibility in weaned pigs challenged with F18 enterotoxigenic Escherichia coli (ETEC). Weaned piglets (7.59 ± 1.11 kg BW) were randomly assigned to five treatments (n=13) including control (CON), 1% Glu supplementation (GLU), 1% Asp supplementation (ASP), 1% Glu and 1% Asp combination supplementation (GAC), and an antibiotic control (ABX). All piglets were orally challenged with F18 ETEC. The study was conducted from d 0 to 28. In the present study, the differences were observed in pigs fed GLU, ASP, or GAC compared with CON-fed pigs. GLU, ASP, or GAC supplementation alleviated (P < 0.05) the impact of ETEC infection by enhancing (P < 0.05) overall growth performance and feed efficiency, with effects comparable to ABX-fed pigs. GLU or ASP supplementation also reduced (P < 0.05) diarrhea frequency, similar to ABX supplementation. Pigs fed ASP, GAC, or ABX had lower (P < 0.05) fecal β-hemolytic coliform shedding than CON-fed pigs on d 14. ASP supplementation tended to increase (P = 0.072) duodenal villus height on d 12, whereas other intestinal morphological responses varied among treatments, intestinal segments, and time points. On d 28, ASP or GAC supplementation enhanced (P < 0.05) ileal amino acid digestibility of selected amino acids, with some responses comparable to those observed in ABX-fed pigs. At the molecular level, responses in tight junction- and mucin-related gene expression were modest and varied among treatments and time points. Overall, Glu, Asp, or their combination enhanced growth performance, while Asp and the combined treatment improved selected measures of amino acid digestibility, and individual Glu or Asp reduced diarrhea. These findings support Glu and Asp as promising nutritional strategies to support growth and nutrient utilization during enteric challenge, with potential to reduce reliance on in-feed antibiotics.