Immunomodulatory, Antioxidant, and Growth-Promoting Effects of Hylocereus undatus Peel Powder in Pacific White Shrimp (Litopenaeus vannamei).

Abstract

Shrimp aquaculture is a primary supplier of high-quality aquatic protein worldwide. Incorporating natural feed additives can strengthen health and disease resilience in cultured species. This study evaluated the dietary effects of Hylocereus undatus (dragon fruit, HU) peel powder on growth performance, metabolic profiles, digestive capacity, immune response, antioxidant capacity, tissue integrity, and disease resistance against Vibrio parahaemolyticus in Pacific white shrimp (Litopenaeus vannamei). Shrimp with an initial weight of 4.23±0.03 (n = 60 per treatment) were randomly distributed into four dietary groups and fed diets containing varying levels of HU peel powder (0, 2, 4, and 6 g/kg diet; designated as HU0, HU2, HU4, and HU6) for 10 weeks. Dietary supplementation with HU peel powder significantly enhanced growth performance, food conversion ratio (FCR), and survival rate, with the HU6 diet demonstrating peak efficacy (P < 0.05). Fortification with HU improved metabolic profiles by significantly elevating serum total protein, albumin, and globulin concentrations, while markedly diminishing aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities (P < 0.05). Shrimp fed HU-supplemented diets exhibited notable improvements in whole-body proximate composition alongside elevated digestive enzyme activities (amylase, lipase, and protease; P < 0.05) compared with HU0 group. Furthermore, HU supplementation displayed strong immunomodulatory and antioxidant capacity, evidenced by significant increases in total hemocyte count (THC), lysozyme, and nitroblue tetrazolium (NBT) activities, accompanied by upregulation of antioxidant enzyme activities (SOD, CAT, and GPx) and a marked reduction in malondialdehyde levels (P < 0.05). Hepatopancreas structural integrity was improved in all HU-supplemented shrimp compared to the HU0 treatment. At the transcriptomic level, HU-fortified diets significantly upregulated the mRNA expression of prophenoloxidase, lysozyme, CAT, and SOD genes (P < 0.05). Following the V. parahaemolyticus challenge, post-infection survival rates were increased to 55%, 65%, and 80% in the HU2, HU4, and HU6 groups, respectively, compared to 35% in the control group. Overall, these findings demonstrate that H. undatus peel powder serves as an effective functional dietary additive to enhance growth, immunocompetence, and pathogen resistance in L. vannamei, presenting a sustainable feed additives strategy for shrimp aquaculture.