Dietary tributyrin modifies intestinal function by altering morphology, gene expression and microbiota profile in common carp (Cyprinus carpio) fed all‐plant diets

Butyrate has received particular attention as growth and health promoters for aquatic organisms. To investigate the effects of dietary tributyrin (TB) on the intestinal function of common carp (Cyprinus carpio) fed all‐plant diets, five isoproteinic (320 g kg−1) and isolipidic (70 g kg−1) diets were formulated and fed to common carp (initial body weight about 8.1 g) for 8 weeks. The control diet (D1) contained 120 g kg−1 fishmeal and 500 g kg−1 plant protein blend (soybean, rapeseed and cottonseed meal), while the other four diets contained plant protein blend with TB at 0.5 g kg−1 (D2), 1.0 g kg−1 (D3), 2.0 g kg−1 (D4) and 4.0 g kg−1 (D5), respectively. Ultimately, high growth performance and low feed conversion ratios were observed in the fish fed the D1, D4, and D5 diets. Comparing to the D2 group, the intestinal trypsin, lipase, catalase, superoxide dismutase, and lysozyme activities, and the intestinal villi length and density were improved in the D4 and D5 groups (p