Impact of Dietary Vitamin D Supplementation on Growth, Molting, Antioxidant Capability, and Immunity of Juvenile Chinese Mitten Crabs () by Metabolites and Vitamin D Receptor.

Vitamin D (vit-D), as an indispensable and fat-soluble nutrient, is associated with skeletal mineralization and health in mammals. However, such associations have not been well studied in economically important crustaceans. Six levels of vit-D with isonitrogenous and isolipidic diets were used to feed . The range of optimal vit-D requirements is 5685.43-10,000 IU/kg based on growth. The crabs fed 9000 IU/kg vit-D showed the best growth performance. This vit-D dose significantly increased antioxidant capacity in the hepatopancreas and intestine and was optimal for molting and innate immunity via quantitative polymerase chain reaction analysis. Transcriptomics analyses indicate that vit-D could alter protein processing in the endoplasmic reticulum, steroid biosynthesis, and antigen processing and presentation. As shown by the enzyme-linked immunosorbent assay, vit-D could improve vitamin D receptor, retinoic acid receptor, and C-type lectins concentrations. The 1α,25-dihydroxy vit-D content in serum was significantly higher in 3000-9000 IU/kg vit-D. The study suggests that dietary vit-D and its metabolites can regulate molting and innate immunity in crabs.