Substitution of Fishmeal With Soy Protein Concentrate on Growth, Organic Damage, Antioxidant, Transcriptome, and Metabolomics in <i>Macrobrachium rosenbergii</i>

The present study investigated growth performance, body composition, hepatic and intestinal morphology, biochemical indices, transcriptomic responses, and metabolomic profiles in giant freshwater prawn (<i>Macrobrachium rosenbergii</i>) fed six kinds of soy protein concentrate (SPC) diets over an 8-week feeding trial. The six SPC diets were formulated by replacing varying proportions of fishmeal (FM) with SPC, with the final percentage of FM set at 350, 280, 210, 140, 70, and 0 g/kg, respectively, and designated as F35, F28, F21, F14, F7, and F0 diets. Results showed that the final body weight (FBW), weight gain, and specific growth rate (SGR) of prawn fed F35 were greater than those of prawn fed F7 and F0. The crude lipid content of prawn fed F0 was higher than that of prawn fed F28. Notably, increasing SPC substitution levels disrupted hepatopancreas morphology, with structural degradation becoming more pronounced beyond 40% replacement (F21). Compared to F35 group, the F0 significantly decreased the activity of glutathione peroxidase (GSH-PX), and increases the content of malondialdehyde (MDA) and nitric oxide (NO) in hemolymph. Based on the transcriptomics, two differentially expressed genes (DEGs) LOC136825138 and LOC136856310 were consistently observed across all groups. The metabolomics indicated that 77 differentially expressed metabolites (DEMs) across all treatments. A negative correlation was observed between LOC136856310 and eicosapentaenoic acid (EPA), arachidonoyl dopamine, 8Z,11Z-eicosadienoic acid, and vitamin E nicotinate. A comprehensive analysis of both metabolomic and transcriptomic data sets revealed substantial perturbations associated with "alpha-linolenic acid metabolism" and "glycerophospholipid metabolism". In conclusion, elevated levels of dietary SPC had detrimental effects on the growth performance, hepatopancreas health, antioxidant capacity, and immune function of <i>M. rosenbergii</i>. Based on the growth performance, dietary FM level for <i>M. rosenbergii</i> could be reduced to 140 g/kg by using SPC as a sole substitute, with an inclusion of 211 g/kg of SPC in the diet.