Effect of Lactobacillus reuteri Postbiotics on Growth Performance and Intestinal Health of Escherichia coli-Infected Broilers

Avian pathogenic <i>Escherichia coli</i> (<i>E. coli</i>) impairs poultry production and causes substantial economic losses. This study investigated the effects of <i>Lactobacillus reuteri</i> postbiotics (LR) on growth performance and intestinal health of broiler chickens challenged with <i>E. coli</i>. A total of 180 one-day-old Arbor Acres+ broilers were allocated into three groups (six replicates per group and 10 chicks each replicate): CTR, control group; <i>E. coli</i>-infected group, orally challenged with a mixture of <i>E. coli</i> O₁, O₂, and O₇₈ at a dose of 10⁹ CFU/mL; LR <i>+ E. coli</i>-infected group, challenged with <i>E. coli</i> and fed a basal diet supplemented with 100 mg/kg LR. The results showed that dietary LR significantly improved the average daily gain (ADG) in the LR + <i>E. coli</i> group compared to the <i>E. coli</i>-infected group from days 1 to 18 (<i>p</i> < 0.05). However, no significant differences in average daily feed intake (ADFI) or feed conversion ratio (FCR) were observed among the CTR, <i>E. coli</i>, and LR + <i>E. coli</i> groups. Infection with <i>E. coli</i> led to lower total antioxidant capacity in jejunum and activity of total superoxide dismutase in ileum. Moreover, dietary LR significantly alleviated the down-regulation of <i>Mucin2</i> and <i>Aquaporin-3</i> gene expression in jejunum and ileum caused by <i>E. coli</i> infection and up-regulated the gene expression of <i>Claudin-1</i> and <i>Zonula occludens</i> 1 in the ileum. In addition, dietary LR treatment led to the up-regulation of <i>interleukin-10</i> mRNA transcripts in the jejunum. Further analysis demonstrated that dietary supplementation with LR reshaped the ileal flora of birds challenged with <i>E. coli</i> via elevating the relative abundance of <i>Romboutsia</i> and <i>Bacteroidota</i>, while reducing the abundance of <i>Candidatus_Arthromitus</i> and <i>Escherichia-Shigella.</i> In conclusion, dietary LR supplementation improved the expression of intestinal barrier and anti-inflammatory genes and reshaped the intestinal flora in <i>E. coli</i>-infected broilers.