Effects of dietary protein levels on the growth, ovarian development and biochemical composition of swimming crab (Portunus trituberculatus)

Abstract:

The study was designed to investigate the effects of dietary protein levels on the growth, ovarian development, and biochemical composition of the swimming crab Portunus trituberculatus [initial body weight of (10.98±0.28) g]. Four experimental diets, which were isoenergic and islipidic, were formulated to contain different protein levels (30%, 34%, 38%, and 42%, defined as diets 1~4, respecitvely). These diets were fed to pond-reared P. trituberculatus females for a 120-day culture experiment. The results showed that: The dietary protein levels had no significant influence on the growth of pond-reared P. trituberculatus females. Diet 3 had the highest gonadosomatic index (GSI) and total edible yield (TEY). The crude protein contents in the ovary and hepatopancreas increased significantly with the increasing dietary protein (P<0.05). Among the four treatments, diets 1 and 3 had the highest crude protein contents in the muscles (P<0.05). Similarly, an increasing trend was found for the total lipid contents in the ovary with the increasing levels of dietary protein (P<0.05). Diet 1 had the highest total lipid contents in the hepatopancreas and muscles, while the lowest total lipid content was found for diet 2 (P<0.05). The contents of total essential amino acids (∑EAA) and non-essential amino acids (∑NEAA) in the muscles of diets 1 and 3 were significantly higher than those of the other two treatments (P<0.05). These results indicate that the appropriate protein level in the diet of adult P. trituberculatus females is approximately 40.16%. The results show that an appropriate dietary protein level could improve ovarian development and muscle nutrition, which provides a reference for the formulation of a diet for P. trituberculatus inhabiting a pond.