Abstract
<title>Abstract</title> <p>Disease outbreaks pose a major challenge to the aquaculture industry, often resulting in antimicrobial abuse. To address this, enhancing host immunity to naturally combat pathogens offers a sustainable solution. Functional feed additives, including autolyzed yeast and purified β-glucan, have emerged as promising alternatives to antimicrobials, effectively boosting shrimp health and growth performance. This study evaluated the effects of dietary supplementation with autolyzed yeast at 3 Kg/ton (AY3) and 6 Kg/ton (AY6), alongside purified β-1,3/1,6-glucans at 200 g/ton (BG200) and 400 g/ton (BG400), on the growth performance, post-challenge survival against acute hepatopancreatic necrosis disease (AHPND), immune gene expression, and phagocytic activity of Litopenaeus vannamei. Dietary supplementation with BG200 resulted in significantly higher weight gain during the PL12–PL34 stage (P=0.047) and increased survival during the PL34–PL49 stage (P=0.003) compared to the control (Basal Feed, BF) group. Following an immersion challenge with Vibrio parahaemolyticus (AHPND strain), shrimp fed AY6 and BG200 exhibited significantly reduced cumulative mortality (P=0.008 and P=0.002, respectively). Continuous 70-day feeding trials (2 g shrimp) demonstrated the upregulation of immune-related genes (e.g., PO1, PO2, PPAE2, Crustin 1, ALF1, ALF3, Peroxinectin, and HSP70) in the BG200 and BG400 groups. Shrimp fed with AY3 and AY6 induced moderate gene expression responses. Furthermore, phagocytic activity was significantly elevated in the BG400 group (P=0.004). Overall, these results indicate that purified β-glucan exerts a more pronounced impact on growth, immune response, and disease resistance than autolyzed yeast. These findings highlight the potential of dietary β-glucan supplementation to enhance shrimp health and mitigate disease risks.</p>