Growth, physiological, biochemical, and molecular responses of Pacific white shrimp Litopenaeus vannamei fed different levels of dietary selenium

This study investigated the effects of different levels of dietary selenium (Se) on the growth, antioxidant capacity, hepatopancreas health, and transcriptional-level responses of Litopenaeus vannamei. Sodium selenite was added to basal diet formulations at 0, 0.2, 0.4, and 0.8 mg/kg, with final Se concentrations of 0.13, 0.20, 0.45, and 0.81 mg/kg, respectively. Shrimp were fed the experimental diets for 8 weeks, after which the following parameters were measured: growth performance, antioxidant enzymes activity, ALT, AST activity, endoplasmic reticulum stress and transcriptome. Shrimp fed the 0.45 and 0.81 mg/kg Se diets (P < 0.05) showed the highest weight gain, shrimp fed the 0.13 mg/kg Se diet had the highest hepatosomatic index (P < 0.05), and the endoplasmic reticulum stress related genes were down-regulated (P < 0.05) in shrimp fed the 0.45 mg/kg Se diet. Antioxidant enzyme activity (SOD, CAT, and GPx) was enhanced with the increase in the Se level. The transcriptome results showed that glycine, serine, and threonine metabolism, the pentose phosphate pathway, and ascorbate and aldarate metabolism were enriched in shrimp fed the 0.45 mg/kg Se diet, while focal adhesions, gap junctions, tight junctions, and adhesion junctions were found in shrimp fed the 0.13 and 0.81 mg/kg Se diets. Co-expression analysis showed that genes PINK1 and Innexin (among others), were involved in the influence of Se levels on shrimp. Our results suggested that Se supplementation improved the growth and antioxidant capacity of L. vannamei by promoting the biosynthesis of glutathione and enhancing the activity of antioxidant enzymes. However, high levels of dietary Se can cause endoplasmic reticulum stress and hepatopancreas tissue damage.