Effects of Dietary Vitamin D3 on Growth Performance, Immune Status, and Calcium and Phosphorus Metabolism in Litopenaeus vannamei Under Different Salinity Conditions

Vitamin D-3 (VD3) plays a vital role in various physiological processes in addition to its role in regulating the homeostasis of calcium and phosphorus. The present study was conducted to investigate the effects of dietary VD3 on growth performance, immune status and the metabolism of calcium and phosphorus in Litopenaeus vannamei under the optimal salinity (25) and high salinity (35) conditions. Shrimp (2.1 g +/- 0.1 g) were fed with experimental diets containing 0, 1500, 6000 and 12000 IU kg(-1) VD3 for 30 days under two salinity conditions respectively. The results showed that the growth performance and intestinal health were reduced, while oxidative stress was induced in the shrimp cultured at salinity 35 compared to those in the shrimp cultured at salinity 25. Interestingly, dietary supplementation of 1500 IU kg(-1) VD3 at salinity 35 promoted the growth performance, improved the intestinal health, and enhanced the antioxidant capacity and non-specific immunity in shrimp. In addition, the content of inorganic phosphorus in shrimp serum was affected by dietary VD3 independent of salinity. In contrast, the expressions of calcium transport-related genes, including calmodulin and Ca2+-ATPase, were regulated by salinity, instead of dietary VD3. In conclusion, an appropriate supplementation of dietary VD3 under high-salt condition can promote the growth, alleviate intestinal inflammation, enhance antioxidant capacity and immunity, and contribute to phosphorus metabolism in L. vannamei.