Dietary Supplementation With <i>Ulva</i> sp. and Garlic Extracts Enhances Growth, Immune Response and Digestive Enzyme Activity in Pacific Whiteleg Shrimp ( <i>Litopenaeus vannamei</i> )

The present study investigated the effect of dietary supplementation with ethanolic extracts of Ulva sp. and garlic (Allium sativum) on the growth performance, muscle composition, digestive enzyme activity and immune response of Pacific whiteleg shrimp (Litopenaeus vannamei). A60-day feeding trial was conducted using seven experimental diets, including a control and diets supplemented with varying concentrations of Ulva sp. extract (0.5, 1.0 and 2.0 g/kg) and garlic extract (2.0, 4.0 and 6.0 g/kg). Phytochemical analysis confirmed the presence of bioactive compounds such as flavonoids and phenolics in Ulva sp. and alkaloids, saponins and phenolic acids in garlic extract. Shrimp fed Ulva sp. extract showed significant improvements in crude protein content, essential amino acid composition and digestive enzyme activity, particularly protease and lipase activities, suggesting enhanced nutrient utilisation. Conversely, garlic extract supplementation resulted in increased fat content, indicating increased fat deposition, alongside a marked upregulation ofimmune-related genes, including Penaeidin3, Penaeidin4, HSP70 and proPO, highlighting its immunostimulatory potential. The combined findings suggest that Ulva sp. extract optimally enhances protein deposition and digestive efficiency, whereas garlic extract strengthens immune responses, making both promising functional feed additives for sustainable shrimp aquaculture. Future research should explore their synergistic effects and long-term benefits in commercial farming applications.