Dietary fermented soybean meal replacement alleviates diarrhea in weaned piglets challenged with enterotoxigenic Escherichia coli K88 by modulating inflammatory cytokine levels and cecal microbiota composition

BACKGROUND: Impaired gut microbiota leads to pathogenic bacteria infection, pro-inflammatory response and post-weaning diarrhea. Enterotoxigenic Escherichia coli (ETEC) K88 is a major cause of post-weaning diarrhea in weaned piglets. Fermented soybean meal (FSBM) could relieve diarrhea, alleviate inflammatory response, and modulate gut microbiota of weaned piglets. We used ETEC K88-challenged weaned piglet model to investigate the effects of FSBM on the growth performance, inflammatory response and cecal microbiota. Twenty-four crossbred piglets (6.8 ± 0.5 kg; 21 ± 2 days of age) were allotted into 2 treatment fed the diets with or without FSBM (6% at the expense of soybean meal). Six weaned piglets in each diet treatment were challenged by ETEC K88 (1 × 10(9) CFU/piglets) on day 15. The experimental period lasted for 20 days. RESULTS: The ETEC K88 challenge decreased (p < 0.05) fecal consistency and plasma interleukin-10 (IL-10) concentration, while increased (p < 0.05) average daily feed intake (ADFI) and plasma tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin 6 (IL-6) concentrations. After ETEC K88 challenge, dietary FSBM replacement increased (p < 0.05) final body weight (BW), average daily gain (ADG), ADFI, and fecal consistency, but decreased feed conversion ratio (FCR). The plasma IL-10 concentration of weaned piglets fed FSBM was higher (p < 0.05), while IL-1β, IL-6 and TNF-α concentrations were lower (p < 0.05). Dietary FSBM replacement attenuated the increase of plasma TNF-α concentration and the decrease of ADG induced by ETEC K88 challenge (p < 0.05). High-throughput sequencing of 16S rRNA gene V4 region of cecal microbiota revealed that ETEC K88 challenge increased (p < 0.05) Campylobacter relative abundance on genus level. Dietary FSBM replacement resulted in higher (p < 0.05) relative abundances of Bacteroidetes and Prevotellaceae_NK3B31_group, and lower (p < 0.05) relative abundances of Proteobacteria and Actinobacillus. Furthermore, dietary FSBM replacement relieved the increase of Escherichia-Shigella relative abundance in weaned piglets challenged by ETEC K88 (p < 0.05). CONCLUSIONS: Dietary FSBM replacement improved growth performance and alleviated the diarrhea of weaned piglets challenged with ETEC K88, which could be due to modulation of cecal microbiota composition and down-regulation of inflammatory cytokines production.