PS10-16. Effects of Short Chain Fatty Acids Derivatives on Local Recruitment of Intestinal Immune Cells and Gene Expression of Weanling Pigs Challenged with F4 and F18 Enterotoxigenic Escherichia coli.

Abstract

The objective of this study was to investigate the effects of monobutyrin, monovalerin, or their combinations on intestinal gene expression and local recruitment of intestinal immune cells of weanling pigs infected with F4 and F18 enterotoxigenic Escherichia coli (ETEC). A total of 176 pigs (7.14 ± 1.12 kg, 88 gilts and 88 barrows, 21 to 24 days old) were housed individually and randomly allotted into 11 treatments (n = 16) in a randomized complete block design with group and sex as blocks. The treatments included a negative control (NC) without ETEC infection, a positive control (PC) with ETEC, and 9 additional groups supplemented with 50 mg/kg carbadox, 2,500 mg/kg zinc oxide (ZnO), 0.10% sodium butyrate, 0.10% or 0.15% monobutyrin, 0.10% or 0.15% monovalerin, a low dose combination (0.05% monobutyrin and 0.05% monovalerin), and a high dose combination (0.075% monobutyrin and 0.075% monovalerin), respectively. The experiment lasted for 28 days, including 7 days’ adaptation and 21 days’ post inoculation (PI). After the adaptation, all piglets except those in the NC group were orally inoculated with 3 mL dose containing equal amount of 5 × 109 CFU F4 and 5 × 109 CFU F18 ETEC for three consecutive days. Sixty-six pigs (n = 6) were euthanized to collect ileum segment on d 5 PI for immunohistochemistry assay. Ileal mucosa were collected to extract RNA for analyzing the expression of genes related to immunity and gut integrity by qPCR. Cell count of macrophage and neutrophil per villi area were measured. Data were analyzed by ANOVA using SAS with a randomized complete block design using pig as experimental unit. On day 5 PI, pigs supplemented with low dose combination had greatest (P < 0.01) macrophage cells/mm2 compared with other treatments. Supplementing 0.10% monobutyrin, 0.10% monovalerin, 0.10% combination and 0.15% combination yielded greater (P < 0.01) recruitment of macrophage cell/mm2 compared with NC. Pigs in antibiotics, ZnO, sodium butyrate, 0.10% and 0.15% monobutyrin had average macrophage cell count per villus comparable (P < 0.01) to that of NC. Pigs supplemented with 0.15% monovalerin and high dose combination had greater (P < 0.05) neutrophil recruitment compared with pigs in NC, PC, antibiotics, and ZnO. Supplementing high dose ZnO, sodium butyrate, 0.10% and 0.15% monobutyrin, and 0.15% combination significantly lowered (P < 0.05) the expression of CFTR compared with PC. Pigs in all supplemented groups had lower (P < 0.05) expression of IL8 than PC, except 0.10% combination group. In conclusion, dietary supplementation of monobutyrin, monovalerin, or their combination may modulate local intestinal immune cell recruitment and ileal mucosal gene expression of weaning pigs infected with ETEC F4 and F18.