Supplementing tributyrin to cottonseed protein concentrate‐based diets can improve growth performance, lipid metabolism and distal intestinal immunity in hybrid grouper ( Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂)

Abstract

An 8-week trial was performed to evaluate tributyrin effects on growth, disease resistance, lipid metabolizing, distal intestinal inflammation-, tight junctions- and apoptosis-related gene expressions caused by high-level cottonseed protein concentrate (CPC) substitution of fishmeal. Fish were fed one fishmeal (50% fishmeal) and six CPC diets (27.5% fishmeal and 25.2% CPC). Seven isonitrogenous (48.0%) and isolipidic (9.0%) were formulated to contain 0.0 (FM), 0.0 (S00), 0.2 (S02), 0.4 (S04), 0.8 (S08), 1.6 (S16) and 3.2 (S32) g/kg tributyrin. Fish (initial body weight: 7.3 ± 0.0 g) were randomly assigned to 21 300-L fiberglass buckets. Results indicated that optimal tributyrin improved weight gain (WG), specific growth rate (SGR), feed utilization, reduced serum triglyceride and total cholesterol levels. Based on Vibrio alginolyticus challenge test, supplementation with 0.4–3.2 mg/kg tributyrin significantly improved percent survival. Optimal tributyrin enhanced distal intestinal development by increasing fold height/intestinal diameter ratio and goblet cell number, and upregulated jam1, claudin3 and ZO-1; and upregulated TGF-β1, hepcidin, downregulated TNF-α, IL-1β, caspase-2 and caspase-8 mRNA levels. Generally, optimal tributyrin could improve growth performance, disease resistance, hepatic lipid metabolism capacity, distal intestinal immunity and tight junctions. Based on SGR, dietary optimal tributyrin supplementation in hybrid grouper was estimated to be 790.0 mg/kg.