264 Effects of L-Glutamate and L-Aspartate Supplementation on Growth Performance, Severity of Diarrhea, and Systemic Immunity of Weaned Piglets Challenged with F18 Enterotoxigenic Escherichia Coli

Abstract

Abstract L-glutamate (Glu) and L-aspartate (Asp) exhibit multifaceted roles in cellular processes and immunological regulation in pigs. This study aimed to investigate the effects of Glu and Asp on growth performance, diarrhea, and systemic immunity of weaned piglets challenged with an enterotoxigenic Escherichia coli (ETEC) F18. A total of forty-nine weaned pigs (8.18 ± 1.54 kg BW) were randomly assigned to one of seven treatments, with seven piglets per treatment. The treatments included negative control (NC) and positive control (PC) that were fed with control diet without or with ETEC challenge, respectively. The other five dietary treatments were supplemented with either 1% or 2% Glu or Asp, or 50 mg/kg of Carbadox, and were challenged with ETEC. All pigs except for NC were challenged with F18 ETEC orally for three consecutive days at the dose of 1010 CFU/dose/day. The study period lasted for three weeks, with a 7-day adaptation period and 14 days post-inoculation (PI). Pig body weights, feed consumption, and fecal score were recorded throughout the experiment. Fecal samples were collected on d 2, 5, 10, and 14 PI to confirm the presence and dynamics of β-hemolytic coliforms. Blood samples were collected on d 0 before ETEC inoculation, and on d 2, 5, and 14 PI to analyze white blood cell profile. All data were analyzed with ANOVA using the PROC MIXED of SAS with pig as the experimental unit. Frequency of diarrhea was analyzed by Chi-Square analysis. Compared with PC, pigs supplemented with 1% Glu, 2% Asp, or Carbadox had greater (P < 0.05) average daily weight gain and gain:feed ratio from d -7 to 5 PI and d 0 to 5 PI. Pigs fed with 1% Glu had reduced (P < 0.05) percentage of β-hemolytic coliforms in feces on d 14 PI than PC. Compared with PC, pigs fed with NC, 1% Asp, 2% Asp, or Carbadox had decreased (P < 0.05) severity of diarrhea (32.47% vs. 16.23 to 24.68%). The counts of white blood cells, neutrophils, lymphocytes, and monocytes were increased (P < 0.05) on d 2 PI and peaked (P < 0.05) on d 5 PI, and were reduced (P < 0.05) on d 14 PI. Pigs fed with 1% Glu had least (P < 0.05) neutrophils:lymphocytes ratio on d 2 PI, while pigs fed with 2% Glu had greatest (P < 0.05) neutrophils:lymphocytes ratio on d 5 PI among all treatments. In conclusion, results of the present study indicate that dietary supplementation of 1% Glu or 2% Asp enhanced growth performance of ETEC challenged weaned pigs at early stage. Supplementation of 1% or 2% Asp also mitigated severity of diarrhea. Both amino acids modulated the systemic immunity of weaned pigs, which needs to be further investigated.