Tributyrin‐supplemented high‐soya bean meal diets of juvenile black sea bream, Acanthopagrus schlegelii : Study on growth performance and intestinal morphology and structure

An 8-week growth trial was conducted to evaluate the effects of different levels of tributyrin supplementation in a high-soya bean meal diet on juvenile black sea bream (11.30 ± 0.16 g). The positive control (PC) diet contained 45% fishmeal and 20% soya bean meal, while the negative control (NC) contained 12% fishmeal and 45% soya bean meal. Graded levels of tributyrin were added to the NC diet at 0.05% (TB 0.05), 0.1% (TB 0.1), 0.2% (TB 0.2), 0.4% (TB 0.4) and 0.8% (TB 0.8). Ultimately, the fish fed the PC diet had a higher weight gain and specific growth rate than the fish fed other diets. The fish fed the NC diet had the lowest growth, and TB 0.05–TB 0.2 diets increased growth performance while TB 0.4–TB 0.8 diets caused reduction in growth. Dietary tributyrin supplementation improved protease activity and enhanced antioxidant capacity. Compared with the fish fed the NC diet, the fish fed the tributyrin-supplemented diets had improved gut morphology and structure, and the results were similar to those of the fish fed the PC diet. Furthermore, the analysis of the dose response with second-order polynomial regression indicated that the optimum tributyrin supplementation for juvenile black sea bream is 2.24 g/kg in the 45% soya bean meal diet.