Dietary fermented soybean meal replacement alleviates diarrhea in weaned piglets challenged with enterotoxigenicEscherichia coliK88 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. EnterotoxigenicEscherichia 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 x 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-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta) 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-1 beta, IL-6 and TNF-alpha concentrations were lower (p < 0.05). Dietary FSBM replacement attenuated the increase of plasma TNF-alpha 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)Campylobacterrelative abundance on genus level. Dietary FSBM replacement resulted in higher (p < 0.05) relative abundances of Bacteroidetes andPrevotellaceae_NK3B31_group, and lower (p < 0.05) relative abundances of Proteobacteria andActinobacillus. Furthermore, dietary FSBM replacement relieved the increase ofEscherichia-Shigellarelative 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.