Dietary cholesterol enhances osmoregulation, antioxidant defenses and immune response of Litopenaeus vannamei to alleviate the macromolecular damage induced by salinity stress

Cholesterol is an important essential nutrient for crustaceans. This experiment investigated the effects of dietary cholesterol on the osmoregulation, antioxidant defense, immune response and salinity stress resistance of Pacific white shrimp (Litopenaeus vannamei). Six diets (Chol 1.0, Chol 1.4, Chol 1.8, Chol 2.2, Chol 2.6, and Chol 3.0) with cholesterol levels of 0.1%, 0.14%, 0.18%, 0.22%, 0.26% and 0.30% were prepared and fed on shrimp (1.27 ± 0.18 g) for 56 d, followed by the low salinity stress experiment for 144 h. Sampling was conducted at 56 d and 24, 72, 144 h during salinity stress. At 56 d, cholesterol enhanced the growth performance of L. vannamei by promoting transport and absorption of endogenous lipid. Dietary 0.22%–0.30% cholesterol could enhance the antioxidant defense and immune response of shrimp. After salinity stress, Na+, Cl− and K+ ion concentrations and osmolality in hemolymph were decreased significantly (P