Effects of Acanthus ebracteatus (Sea Holly) Aqueous Extract as a Functional Feed Additive on Growth Performance, Immune Responses, and Hepatopancreatic Histology in Pacific White Shrimp (Litopenaeus vannamei)

Intensive shrimp aquaculture has led to increased disease outbreaks and a greater reliance on antibiotics, driving the need for sustainable alternatives. This study examined the phytochemical profile, antioxidant activity, and effects of Acanthus ebracteatus (AC) aqueous extract as a natural feed additive on growth performance, and health in Pacific white shrimp (Litopenaeus vannamei). Phytochemical analysis of AC aqueous extracts revealed high concentrations of phenolics (162.1 ± 11.78 mg GAE/g), flavonoids (75.8 ± 2.32 mg RE/g), tannins (38.4 ± 0.78 mg TAE/g), and verbascoside (0.48 ± 0.01% w/w). Strong antioxidant capacity was confirmed with DPPH IC50 of 42.6 ± 11.78 µg/mL, ABTS IC50 of 2.93 ± 0.02 mg/mL, and FRAP value of 1.41 ± 0.08 mmol FeSO4/g extract. A feeding trial was conducted over eight weeks using 300 shrimp randomly assigned to four treatments: control diet and diets supplemented with 1%, 2%, and 3% AC aqueous extract. AC 2% supplementation showed optimal results for growth performance, including improved final body weight, weight gain, and feed conversion ratio. AC 3% treatment maximally enhanced immune responses, significantly elevating catalase, lysozyme, total antioxidant capacity, and hemocyanin, and glutathione peroxidase activity showed a numerical increase in AC-supplemented groups, particularly at the 3% inclusion level, although the differences were not statistically significant. AC 2% supplementation also improved hepatopancreatic histology through oxidative stress modulation and enhanced lipid metabolism. This study provides a comprehensive evaluation of AC aqueous extract by integrating phytochemical characterization, antioxidant profiling, and in vivo assessment of growth, immune response, and hepatopancreatic morphology in Pacific white shrimp.