Effect of dietary glutathione supplementation on the immune responses and the fatty acid and amino acid composition in Chinese mitten crab, Eriocheir sinensis

Abstract

Chinese mitten crab (Eriocheir sinensis) is an important aquatic commercial species in China. Due to the deterioration of the local aquaculture environment, the output and quality of Chinese mitten crab have been heavily influenced. Glutathione (GSH) is a tripeptide, that, when administered via diet, has been shown to improve the growth and enhance immune function in livestock and poultry. However, whether GSH could be developed as a special feed supplement for Chinese mitten crab remains unclear. Therefore, in the present study, a total of 200 crabs were divided into five groups fed with experimental diets supplemented with 0, 300, 600, 900, and 1200 mg/kg of GSH for 65 days. Results showed that supplementation with 600 mg/kg GSH significantly improved growth performance with the percentage of polyunsaturated fatty acids (PUFAs) increasing and the percentage of saturated fatty acids significantly decreasing in the hepatopancreas. Further, crabs fed diets supplemented with 900 mg/kg of GSH enhanced the levels of glutamic acid, glycine, cysteine, serine and alanine compared to the control group. Diets supplemented with 600 or 900 mg/kg of GSH significantly improved the total protein, albumin (Alb), and globulin (Glb) contents in haemolymph. Moreover, crabs fed diets supplemented with 900 mg/kg GSH exhibited the highest myeloperoxidase activity and complement component 3 and 4 levels in the haemolymph, with the highest mRNA expression of immune related genes (alf1, alf2, alf3, crus1 and crus2) observed in the 600 and 900 mg/kg GSH groups. The present study has effectively shown that supplementation of E. sinensis diets with GSH served to enhance physiological and immunological functioning, which would subsequently enhance the overall health of the animal while also improving the economic yield from Chinese aquaculture.