Dietary nutgrass ( Cyperus rotundus ) extract–loaded chitosan nanoparticles: Enhance growth performance, boost immune responses, improve antioxidant capacity, and physiological performance in white leg shrimp ( Litopenaeus vannamei )

Aquaculture has increasingly turned toward plant extracts' usage as functional additives, owing to their rich content of bioactive compounds that enhance growth performance, boost immune responses, and improve antioxidant capacity in cultured species. This study evaluated the effectiveness of Cyperus rotundus extract–loaded chitosan nanoparticles (CE/CNPs) as a phytobiotic feed additive for Litopenaeus vannamei post larvae (initial weight 0.74 ± 0.12 g, N = 450). The extract screening revealed high phenolic and flavonoid contents with strong antioxidant activity. The CE/CNPs were subsequently incorporated into the experimental diets at different levels: 0 mg/kg feed (C, control), 150 mg/kg feed (T1), 300 mg/kg feed (T2), 500 mg/kg feed (T3), and 1000 mg/kg feed (T4) for a 75‐day feeding trial in triplicate. Results showed that shrimp feeding with CE/CNPs, especially the 300 and 500 mg/kg diets, displayed significantly enhanced growth performance, survival, molting frequency, and feed utilization compared to the control. These improvements were supported by higher protease, amylase, and lipase activities. Additionally, increased protein and decreased lipid retention, and favorable proximate composition were detected. Likewise, antioxidant enzymes (SOD, CAT, GPx, GSH) and immune parameters (THC, lysozyme, phagocytosis, PO) were markedly elevated, while MDA was reduced. Additionally, growth‐related genes ( GH, IGF‐I, IGF‐II, Myosin, Paramyosin) were significantly upregulated. Moreover, intestinal morphology showed increased villus height, width, and muscle thickness. Overall, CE/CNPs represent a potent natural nano‐biotic capable of improving growth, health, and production efficiency in L. vannamei aquaculture.