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

Abstract An eight-week feeding trial was conducted to evaluate the effects of soy isoflavone and soy saponin on growth performance, intestinal structure, intestinal immunity and gut microbiota community of rice field eel Monopterus albus (initial weight 20.12\xa0±\xa00.15\xa0g). Six isonitrogenous and isolipidic experimental feeds were formulated, including a positive control (55% fish meal, FM), a negative control (28.6% fish meal, 37.2% soybean meal, SBM) and basic diet group (28.6% fish meal, 22.6% soy protein concentrate, SPC), the rest was supplemented with soy isoflavone (40%, 2.5\xa0g / kg, SI), soy saponin (≥98%, 2\xa0g / kg, SS) and their mixed in basic diet (SI\xa0+\xa0SS). Compared with FM, growth performance, intestinal immune indices (acid phosphatase, alkaline phosphatase, complement 3, complement 4 and immunoglobulin M), intestinal villus height and intestinal muscular thickness and mRNA (occludin-like, claudin 12, tight junction protein ZO-1-like, tight junction protein ZO-2-like, interleukin-10, transforming growth factor beta 1, transforming growth factor beta 2) expression intestine of M. albus fed SBM diet were significantly decreased (P