109 Effects of dietary L-glutamate, L-aspartate, and their combination on growth performance and diarrhea severity of weaned piglets challenged with Enterotoxigenic Escherichia coli.

Abstract L-glutamate and L-aspartate are functional amino acids essential for intestinal epithelial functions and physiological metabolism. This study aimed to investigate the effects of L-glutamate, L-aspartate, and their combination on growth performance and severity of diarrhea 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, with thirteen replications per treatment. 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). Body weights, feed consumption, and daily diarrhea scores were recorded throughout the experiment. Fecal samples were collected on d -7 and d 0 before ETEC inoculation, and on d 2, d 5, d 7, d 10, d 14, d 18, and d 21 PI to confirm the presence and dynamics of fecal β-hemolytic coliforms. All data were analyzed using ANOVA, except that diarrhea frequency was analyzed by Chi-square test, with the individual pig as the experimental unit. Compared with CON, pigs fed ASP or ABX had increased (P < 0.05) body weight on d 14 PI, and pigs fed ASP, GAC, or ABX had increased (P < 0.05) final body weight on d 21 PI. Pigs fed ASP or ABX also enhanced (P < 0.05) average daily gain from d -7 to d 14 PI, compared with CON. GLU, ASP, GAC, or ABX supplementation increased (P < 0.05) average daily gain from d 0 to 21 PI, compared with CON. Additionally, GLU, ASP, GAC, or ABX supplementation improved (P < 0.05) average daily gain from d -7 to d 21 PI, compared with CON. ASP or ABX supplementation also increased (P < 0.05) average daily feed intake from d 0 to d 14 PI, compared with CON. Furthermore, supplementing with GLU, ASP, GAC, or ABX enhanced (P < 0.05) gain:feed ratio from d -7 to d 21 PI and from d 0 to d 21 PI, compared with CON. Moreover, pigs fed GLU, ASP, or ABX had reduced (P < 0.05) diarrhea frequency compared with CON (15.24 to 20% vs. 29.65%). In addition, pigs fed ASP, GAC, or ABX had reduced (P < 0.05) fecal β-hemolytic shedding on d 7 PI compared with CON. In conclusion, dietary supplementation of 1% L-glutamate, 1% L-aspartate, or their combination improved growth performance and reduced diarrhea in ETEC-challenged piglets.