Abstract
<title>Abstract</title> <p> This study aims to investigate the effects of Magnolia officinalis extract (MOE) on the growth, immunity and disease resistance of sturgeon. 360 juvenile <italic>Hybrid Sturgeon</italic> were selected and divided into a four experimental groups (0, 100, 300 and 500 mg/kg MOE), with 3 replicates in each group. After 8 weeks of cultivation, growth performance was measured. Subsequently, 10 tail fish from each group were subjected to a 7-day pathogen challenge test by intraperitoneal injection (0.2 mL of 3.30×10⁷ CFU/mL) of the bacterial solution. Specifically, MOE improved growth performance and body composition in sturgeon (P < 0.05). Compared with the HP0 group, MOE supplementation significantly enhanced intestinal antioxidant enzyme and digestive enzyme activities while significantly reducing malondialdehyde (MDA) levels ( <italic>P</italic> < 0.05). Regarding intestinal immunity, MOE upregulated anti-inflammatory cytokines TGF-β1 and IL-10, as well as non-specific immune enzymes ACP, AKP, and LZM, while suppressing the expression of pro-inflammatory cytokines TNF-α, IL-1β, and IL-8 ( <italic>P</italic> < 0.05). Furthermore, MOE significantly increased villus height and width in the duodenum and spiral valve segments, upregulated the relative expression of tight junction proteins Claudin, Occludin, and ZO-1, and elevated the abundance of beneficial gut bacteria Hafnia ( <italic>P</italic> < 0.05). Infection experiments demonstrated that MOE effectively improved sturgeon survival rate, alleviated intestinal pathological damages such as congestion, hemorrhage, and inflammatory cell infiltration, and enhanced immune function and intestinal barrier integrity. In summary, MOE enhances growth performance, antioxidant capacity, and intestinal health in sturgeon, and improves resistance to <italic>Aeromonas hydrophila</italic> infection. </p>