Dietary myo-inositol supplementation enhances growth performance and salinity stress tolerance in giant freshwater prawn (Macrobrachium rosenbergii)

Abstract

Salinity intrusion driven by climate change poses a growing challenge to freshwater prawn aquaculture, necessitating nutritional strategies to enhance stress tolerance and production sustainability. This study evaluated the effects of dietary myo-inositol supplementation on growth performance, feed efficiency, physiological resilience, environmental indicators, and economic outcomes of Macrobrachium rosenbergii juveniles cultured under varying salinity conditions. Two consecutive 30-day feeding trials were conducted. Experiment 1 assessed graded myo-inositol inclusion levels (0, 0.35, 0.45, and 0.55%) under freshwater (0 ppt) and low-salinity (10 ppt) conditions. Experiment 2 validated the optimal inclusion level (0.55%) across a broader salinity gradient (0, 6, and 12 ppt), with additional evaluation of ionic regulatory and stress-related biomarkers. Myo-inositol supplementation significantly improved growth, biomass production, and feed conversion ratio, with the highest and most consistent benefits observed at 0.55% inclusion across all salinities. Enhanced carcass protein and lipid deposition accompanied improved feed utilization. Physiologically, myo-inositol reduced hemolymph glucose and Ca²⁺Mg²⁺-ATPase activity, while increasing total antioxidant capacity, indicating lower metabolic stress and reduced ionic regulatory energy demand. Feed-efficiency–adjusted CO<inf>2</inf>-equivalent intensity was estimated using feed conversion ratios and published emission factors to reflect feed-related environmental performance; however, these values represent proxy estimates and not direct measurements or full life-cycle assessment (LCA) of greenhouse gas emissions. Importantly, improved feed efficiency translated into substantial reductions in feed-adjusted CO<inf>2</inf>e intensity and significantly higher economic returns. These findings demonstrate that dietary myo-inositol functions as an effective osmoprotective and metabolic modulator, supporting climate-resilient, low-salinity freshwater prawn aquaculture while simultaneously improving environmental and economic sustainability.