Evaluation of caper (Capparis spinosa) extract supplementation on growth performance, antioxidant activity, innate immunity, immune-related gene expression, and resistance to Vibrio parahaemolyticus in Litopenaeus vannamei

Capparis spinosa L. (caper) is a drought-resistant shrub valued for its therapeutic, pharmaceutical, and culinary properties. This study evaluated the biological activities of its aqueous (AQE) and methanolic (MEE) extracts on growth performance, innate immunity, antioxidant activity, immune-related gene expression, and resistance to Vibrio parahaemolyticus in Litopenaeus vannamei . Aqueous and methanolic extracts were prepared and analyzed, demonstrating that the methanolic extract of C. spinosa (MEE) exhibited significantly stronger antioxidant activity (P < 0.05) in terms of total phenolic content (TPC), ferric reducing antioxidant power (FRAP), and DPPH scavenging activity than the aqueous extract (AQE). According to HPLC analysis, RP-HPLC for phenolic component characterization in C. spinosa L. extractions identified 16 phenolic compounds; sinapic acid predominated in MEE, while only trace gentisic and benzoic acids were noticed in AQE, with all the other phenolics being absent from AQE. Overall, MEE exhibited substantially higher phenolic content than AQE. For feeding/challenge test: A three-month nourishment experiment was performed to investigate the impact of supplementing the diet with AQE and MEE of C. spinosa at concentrations of 1.0, 2.0, and 3.0% kg -1 feed. Juvenile shrimp 1.66 ± 0.55 g (N = 2100) were randomly distributed into 21 fiberglass tanks (250 L), with three replicates per treatment, and fed the experimental diets. Diets containing higher MEE levels (3.0% kg -1 ) significantly (P