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

The current research explored the effects of the ethanolic extract of Myristica fragrans (nutmeg, also known as Joyfol) on the immune resistance, antioxidant activity, and growth performance of Macrobrachium rosenbergii (prawns). After a screening test of 24 readily available spices (using 4 solvents), Myristica fragrans was identified as one of the active spices against Vibrio parahaemolyticus through in vitro, and the appropriate dosage were determined by calculating the LC50 after a toxicity test using brine shrimp. A total of 135 prawns, each with an initial weight of 2.0 ± 0.25 g, were randomly placed in nine fiberglass tanks, with 15 prawns in each. The control group (C) received a baseline diet without nutmeg, while the other groups were given a diet with 0.25 g/kg (0.025%) as treatment 1 (T1) and 0.5 g/kg (0.05%) as treatment 2 (T2) of nutmeg extract with three replications. The prawns were fed at 5% of their body weight daily for four weeks. The results showed that the T1 group (0.25 g/kg diet) significantly outperformed the other groups in growth performance, including higher Final Weight (FW), Average Weight Gain (AWG), Specific Growth Rate (SGR) and the lowest FCR. The T1 group also showed better immune responses with improved Total Haemocyte Count (THC), Differential Hemocyte Count (DHC), Hemolymph Clotting Time (HCT), Superoxide Anion Production, Respiratory Burst activity (RBs) and Pro-phenol oxidase activity (proPO) compared to the control and T2 groups. Ultimately the most effective dose of nutmeg extract for improving growth and boosting immune responses in prawns appears to be 0.25 g/kg. This study highlights the potential of spice-based additives in environmentally friendly aquaculture methods, providing a natural substitute to improve aquatic species health and productivity.

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