Effect of Vitamin C on the Antioxidant and Immune Response of Male White Shrimp (Penaeus vannamei) Broodstock

This study evaluated the effect of vitamin C (L-ascorbyl-2-polyphosphate) on the physiological condition, biochemical antioxidant activity, immune responses, and gene expression in the reproductive tract, as well as on sperm quantity and quality in male white shrimp Penaeus vannamei broodstock. Four diets containing 42.5% protein, 11.5% lipids, and 23.5% carbohydrates were formulated with L-ascorbyl-2-polyphosphate as a source of vitamin C at the following concentrations: 0.016 g/kg (Basal), 0.322 g/kg (A), 0.628 g/kg (B), and 0.934 g/kg (C). Shrimp fed diet C exhibited the highest SOD and CAT activity and serum cholesterol levels, but the lowest expression of hemocyanin (Hemo) mRNA transcripts (p ˂ 0.05). Shrimp fed diet A showed the highest Hemo mRNA expression and phenoloxidase (PO) activity, while those fed diet B had the highest serum triglyceride levels (p ˂ 0.05). In contrast, shrimp fed diets A and B exhibited the lowest serum cholesterol levels (p ˂ 0.05). There were no differences in sperm quality between the diets. In relation to sperm quantity, the shrimp fed diet B had the highest sperm cell count (2,750,000 cel/mL), and those fed diet A had the lowest (585,000 cel/mL) (p ˂ 0.05). These results indicate that vitamin C influences the reproductive aspects of male P. vannamei broodstock. A dietary inclusion level of 0.628 g/kg promotes optimal physiological, oxidative stress, and immunological conditions for increased sperm cell production, whereas an excessive level may promote oxidative stress.