Marine Diatom Skeletonema costatum Dietary Supplementation Improves Growth, Immunological Responses, Antioxidant Activities, Gene Expressions, and Digestive Enzymes of Shrimp Litopenaeus vannamei

This work highlighted the impact of dry concentrations (0, 1, 2, and 4 g/kg diet) of the marine diatom species Skeletonema costatum (SK_0%, SK_0.1%, SK_0.2%, and SK_0.4%, respectively) as an aquafeed additive on the postlarvae of Pacific whiteleg shrimp (Litopenaeus vannamei). During an 8-week feeding trial, the impact of S. costatum on growth, digestive enzymes, antioxidant activities, immunity-associated gene expressions, and immunological responses of Pacific white shrimp was investigated. The protein, lipid, and carbohydrates of S. costatum were 33.50%, 35.95%, and 11.87%, respectively. Shrimp reared in group SK_0.4% exhibited a significant improvement in growth performance indicators, compared to the other groups. The results showed that, compared to the control group (SK_0%), shrimp-fed S. costatum supplemented groups (SK_0.1%, SK_0.2%, and SK_0.4%) showed significantly (p  < 0.05) higher amylase activities. Compared to the control group (SK_0%), shrimp-fed S. costatum groups (SK_0.1%, SK_0.2%, and SK_0.4%) demonstrated major significant (p < 0.05) improvement in catalase and superoxide dismutase values. Shrimp reared in group SK_0.4% showed a significant (p < 0.05) improvement in lipase and lysozyme activities. The increasing levels of S. costatum dietary supplementation significantly (p < 0.05) increase the relative gene expression of the p53-like protein isoform delta (p53) gene. SK_0.4% revealed a major significant (p < 0.05) increase in the relative gene expression of the prophenoloxidase (PPO1) and peroxiredoxin (Prx) genes. This study highlights the potential of S. costatum as a promising aquafeed additive enhancing growth performance and immunity of Pacific whiteleg shrimp health, opening the way for more sustainable shrimp aquaculture practices.