Dietary sodium butyrate administration alleviates high soybean meal-induced growth retardation and enteritis of orange-spotted groupers (Epinephelus coioides)

An 8-week feeding trial was conducted to investigate whether dietary sodium butyrate (SB) administration alleviates growth reduction and enteritis of orange-spotted grouper ( Epinephelus coioides ) caused by high soybean meal (SBM) feeding. The control diet (FM diet) was formulated to contain 48% protein and 11% fat. Soybean meal was used to replace 60% FM protein in FM diet to prepare a high SBM diet (HSBM diet). Sodium butyrate (SB) at 0.1%, 0.2%, and 0.3% were added to HSBM diets to prepare three diets. Triplicate groups of 30 groupers (initial weight: 33.0 ± 0.3 g) were fed one of the diets twice daily, to apparent satiety. HSBM diets had lowered growth rate and feed efficiency vs FM diets ( P < 0.05). Growth rate and feed efficiency were improved by dietary SB administration and were in a dose-dependent manner ( P < 0.05). A similar pattern to the growth rate was observed for plasma LDL-C and gut digestive activity of lipase, trypsin, and protease, but the opposite trend was observed for intestinal contents of D-lactic acid and endotoxin, in response to dietary SB inclusion levels ( P > 0.05). The muscular thickness in the middle and distal intestines in SB-treated diets were higher than that in HSBM diets ( P < 0.05). The mRNA levels of intestinal pro-inflammatory cytokines IL-8 , IL-1β , IL-12 and TNF-α had a decreasing trend, and the mRNA level of intestinal anti-inflammatory cytokine TGF-β1 had the opposite trend, with increasing SB inclusion levels ( P < 0.05). The above results indicate that dietary SB intervention could enhance growth and feed utilization of groupers with SBM-induced enteritis by promoting intestinal digestive enzyme activities, reducing mucosa permeability, maintaining the integrity of intestinal morphology and attenuating the intestinal inflammatory response.