Dietary Fagopyrum dibotrys Extract Supplementation: Impacts on Growth Performance, Immune Response, Intestinal Morphology, and Microbial Community in Broiler Chickens Infected with Escherichia coli O157

This study explored the efficacy of dietary <i>Fagopyrum dibotrys</i> extract (FDE) in mitigating <i>Escherichia coli</i> O157 (<i>E. coli</i>) infections in broilers. A total of 240 one-day-old male Shengze 901 broilers were randomly allocated to four groups (with 10 broilers per group): CON (basal diet), COLI (basal diet + <i>E. coli</i> challenge), FDE (basal diet + 500 mg/kg FDE), and FDEC (basal diet + 500 mg/kg FDE + <i>E. coli</i> challenge). The results showed that <i>E. coli</i> challenge reduced the average daily gain (ADG) and average daily feed intake (ADFI), increased the feed conversion ratio (FCR) and cecal <i>E. coli</i> load, impaired the intestinal mucosa, and induced intestinal inflammatory responses (<i>p</i> < 0.05). FDE supplementation improved growth performance, increased duodenal villus height and villus/crypt ratio; reduced serum interleukin (IL)-1β, tumor necrosis factor-α (TNF-α), diamine oxidase (DAO), and endotoxin levels; and lowered cecal <i>E. coli</i> counts (<i>p</i> < 0.05). Molecularly, FDE supplementation upregulated Occludin, Claudin-1, and ZO-1 gene expressions, and downregulated jejunal TLR4 and MyD88 mRNA levels. Microbiome analysis revealed that FDE increased the relative abundance of <i>Faecalibacterium</i> and alleviated the <i>E. coli</i>-induced reduction in <i>Clostridia_UCG-014</i>. In conclusion, dietary supplementation with 500 mg/kg FDE could mitigate colibacillosis-related intestinal damage and inflammatory responses.