Tributyrin enhances growth and intestinal health in green mud crab (Scylla paramamosain) through butyrate-driven metabolic regulation.

Tributyrin (TB), a derivative of butyric acid, is considered a promising feed supplement to regulate growth and intestinal barrier function in livestock and aquatic animals. However, its application in the green mud crab (Scylla paramamosain) has not been extensively investigated. Therefore, this study aimed to investigate the regulatory mechanism of TB on growth performance, intestinal barrier function, butyrate metabolism, digestive enzyme activity, and carbohydrate-lipid metabolism in the green mud crab. A total of 144 crabs (10.68 ± 0.03 g) were divided into four groups with three replicates of 12 crabs each and hand-fed either a basal diet (Con) or diets containing 0.05%, 0.10%, and 0.20% TB for nine weeks. Results revealed that compared with Con, supplementation with 0.20% TB significantly promoted growth performance in the green mud crab (P < 0.05), including final body weight and percent weight gain. Additionally, TB supplementation significantly improved intestinal health by upregulating the mRNA relative expression of intestinal physical-barrier genes, including zo-1 (P = 0.031), pt-1 (P = 0.010), pt-44 (P < 0.001), mlck (P = 0.033), and claudin (P = 0.006) and reducing diamine oxidase (DAO) activity (P = 0.001); TB supplementation also enhanced lipase activity in the stomach, lipase, amylase, and protease activities in the hepatopancreas, and lipase and protease activities in the intestine (P < 0.05); TB supplementation significantly activated butyrate metabolism, including upregulation of hadh (P = 0.001) and acads (P = 0.006) mRNA relative expression, and downregulation of acadl (P = 0.001) mRNA relative expression, increased adenosine triphosphate (ATP) (P = 0.002) contents and nicotinamide adenine dinucleotide reduced/nicotinamide adenine dinucleotide+ (NADH/NAD+) (P < 0.001) downregulated transcriptional expression related to glycolysis (pygl, gk, pfk, hk, and pk), and upregulated mRNA relative expression related to gluconeogenesis (gys, g6pase, pdh, pc, and pepck) (P < 0.05); furthermore, TB induced lipid deposition in the hepatopancreas by upregulating lipid synthesis genes (fas, 6pgd, g6pd, and acc) at the transcriptional level and increasing the area of lipid droplets in hepatopancreas tubules (P = 0.001). Overall, current results indicated that TB could enhance growth in the green mud crab through coordinated improvements in digestive enzyme activity, intestinal health, and tissue-specific metabolic regulation.