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 red blood cell (RBC) profiles and amino acid (AA) digestibility 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 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). Blood samples were collected on d 0, 2, 4, 14, and 21 PI, and ileal digesta samples were collected on d 21 PI for RBC profiling and AA digestibility analysis, respectively. Data were analyzed using ANOVA in PROC MIXED of SAS with the individual pig as the experimental unit. On d 14 PI, pigs fed GLU or ASP increased (P 0.05) hemoglobin, hematocrit, mean corpuscular volume (MCV), and mean corpuscular hemoglobin compared with CON. Interestingly, pigs fed GLU showed lower (P 0.05) red cell distribution width (RDW) than CON on d 14 PI, but higher (P 0.05) RDW on d 21 PI. In addition, pigs fed ASP showed lower (P 0.05) RDW and tended to have higher (P 0.1) MCV compared with CON on d 21 PI. Apparent ileal digestibility (AID) of dry matter differed among treatments on d 21 PI, with pigs fed ASP showing greatest (P 0.05) digestibility value compared with the other groups. AID of crude protein, total AA, and the mean of indispensable AA tended to be higher (P 0.1) in pigs fed GAC and ABX compared with CON. The mean AID of dispensable AA tended to increase (P 0.1) in pigs fed ASP and GAC compared with CON. Additionally, pigs fed GAC had greater (P 0.05) AID of lysine, aspartate, and glutamate than CON. In contrast, standardized ileal digestibility (SID) of crude protein was not affected by treatments on d 21 PI. However, pigs fed GAC showed greater (P 0.05) SID of lysine, aspartate, and glutamate compared with CON. Pigs fed ASP also had higher (P 0.05) SID of aspartate compared with CON and ABX. In conclusion, dietary supplementation of glutamate and/or aspartate enhanced ileal digestibility of specific amino acids and modulated RBC parameters, indicating potential benefits for nutrient utilization and hematological status in ETEC-challenged weaned pigs.
Wongchanla et al. (Wed,) studied this question.