Effect of Nutmeg (Myristica fragrans) on the Growth and Resistant Capacity of Prawn (Macrobrachium rosenbergii) against Vibrio parahaemolyticus infection

This study assessed the impact of dietary Myristica fragrans (MF) extract on the growth, immune function, body composition, and disease resistance in juvenile prawn Macrobrachium rosenbergii. Fifteen prawns (2.1 ± 0.25 g) in each tank were given either a control diet or diets with 0.025% (T1) or 0.05% (T2) MF extract. Each treatment was done in three tanks (total n = 135 prawns) and the prawns were fed 5% of their body weight every day for eight weeks. Vibrio parahaemolyticus (106 CFU/mL) was used to challenge M. rosenbergii after the feeding experiment, and they were observed for 14 days post challenge. Prawns fed the T1 diet showed significantly improved growth performance (FW, AWG, SGR, PER, and FCR), higher protein and ash content, and elevated digestive enzyme activities (amylase and protease) compared to the control and T2 groups. Immune parameters (THC, HCT, RB, proPO, SOD, and superoxide anion generation) exhibited a significant elevation in the MF-supplemented groups, both prior to and following bacterial exposure. Post-infection, T1 had the highest survival (86.4%), T2 reached 72.85%, and the control suffered complete mortality (100%) by day 14. These findings indicate a dose-dependent response, with the lower inclusion level (0.025%) being more effective than the higher dose. This study provides preliminary evidence for the optimized use of MF extract in enhancing growth and innate immunity of M. rosenbergii under Vibrio challenge conditions. However, its application as a replacement for synthetic additives requires further validation.