Effects of Dietary Soy Isoflavone and Soy Saponin on Growth Performance, Intestinal Structure, Intestinal Immunity and Gut Microbiota Community on Rice Field Eel (Monopterus Albus)

Abstract Background: Soy isoflavone and soy saponin are heat-stable glycosides present in soybean meal, which is the major factor restrict soy protein using in aquatic feed. This study is aimed to conduct that dietary soy isoflavone and soy saponin on growth performance, intestinal structure, intestinal immunity and gut microbiota community on rice field eel (Monopterus albus), and revealed its mechanism.Results: In current study, dietary 1g/kg soy isoflavone, 2g/kg soy saponin and their mixed feed decreased growth of M. albus. Dietary 1g/kg soy isoflavone significantly increased serum alkaline phosphatase (P < 0.05), dietary 2g/kg soy saponin remarkably declined intestinal immunoglobulin M (P < 0.05). Dietary 1g/kg soy isoflavone and 2g/kg soy saponin mixed feed significantly decreased intestinal complement 3, complement 4 and immunoglobulin M, amounts of intestinal goblet cells per root and shannon of gut microbiota (P < 0.05). Dietary 1g/kg soy isoflavone, 2g/kg soy saponin and their mixed feed down regulated intestinal tight junction protein (Interleukin-12, Interleukin-15, Tight junction protein ZO-2-like) and anti-inflammatory (Interleukin-10, Transforming growth factor beta 2) mRNA expression, up regulated pri-inflammatory factors (Interleukin-1 β, Interleukin-6, Interleukin-8, Interleukin-12 and Interleukin-15) mRNA expression.Conclusion: Based on the current results, dietary soy isoflavone and soy saponin could damage the intestinal structure and changes gut bacteria community of M. albus, and destroyed the intestinal barrier, eventually induced intestinal inflammatory occurring, soy isoflavone and soy saponin mixed feed has more serious effect than they single supplemented.