The Effects of Dietary Tributyrin Supplementation on Growth Performance, Antioxidant Capacity, Immune Function, and Intestinal Health of Fat Greenling (Hexagrammos otakii)

The objective of the current research was to evaluate the influence of dietary tributyrin (TB) inclusion on the growth performance and physiological well-being of Hexagrammos otakii. Juvenile fish (initial weight 24.01 ± 1.35 g) were fed one of six isonitrogenous and isolipidic diets containing graded levels of TB (0–1.5 g/kg) for 90 days. Supplementation significantly enhanced the weight gain and specific growth rates. The optimal level of 0.9 g/kg TB improved muscle nutritional quality, muscle texture, and intestinal morphology. This dosage also significantly increased hepatic and intestinal antioxidant capacity, elevating superoxide dismutase (SOD), catalase (CAT), and total antioxidant capacity (T-AOC), while reducing malondialdehyde (MDA) content. Furthermore, dietary TB at 0.9 g/kg reduced plasma and hepatic triglycerides and total cholesterol, and elevated key plasma immune parameters, including complement components (C3, C4) and phosphatase activities (ACP, AKP). Intestinal health was further enhanced, as evidenced by increased digestive enzyme activities (amylase, lipase, chymotrypsin) and improved microbial diversity, marked by a proliferation of beneficial bacteria. In conclusion, dietary TB supplementation at 0.9 g/kg optimally promotes growth, improves muscle and intestinal health, and enhances antioxidant and immune functions in H. otakii.