Effects of dietary methionine and taurine interaction on growth performance, the profiles of amino acids, and protein metabolism of Chinese mitten crab, Eriocheir sinensis

The purpose of this study is to explore the interaction between dietary methionine and taurine levels on growth performance, the profiles of amino acids, protein metabolism, and how taurine spares methionine of Chinese mitten crab (Eriocheir sinensis). The crabs were divided into six groups which were fed six diets formulated with two Tau levels (0 and 0.4%) and three Met levels (0.6%, 0.9% and 1.2%). The results showed that the weight gain rate and specific growth rate were the highest in the crabs fed 0.4% Tau and 0.6% Met. Crabs fed 1.2% Met had the highest survival rate and lowest feed conversion ratio. Furthermore, the hepatopancreas and muscle amino acid content were significantly influenced by the interactive effects of Met and Tau (P < 0.05). Moreover, interactive effects of dietary methionine and taurine were significantly observed in the expressions of amino acid metabolism-related genes (P < 0.05). Additionally, crabs fed 1.2% Met and 0% Tau had the highest activities of cysteine decarboxylase (CSD) and cysteine dioxygenase (CDO). In conclusion, the addition of appropriate amount of taurine to the diet can reduce the requirement of methionine for Chinese mitten crab by regulating the activities of CSD and CDO. At the same time, the addition of methionine and taurine could affect the amino acids metabolism. Therefore, the diet formula of Chinese mitten crab needs to consider the metabolism of sulfur-containing amino acids.