The Influence of Eicosapentaenoic Acid on Macrobrachium rosenbergii Broodstock: Ovarian Development, Antioxidant Status, and Lipid Metabolism

Lipids are essential for crustacean reproduction, supporting broodstock growth and ovarian development. However, studies of n‐3 highly unsaturated fatty acids (HUFAs), particularly eicosapentaenoic acid (EPA), on the growth and ovarian development of prawn broodstock remain limited. Accordingly, five experimental diets containing EPA concentrations of 0.12%, 0.79%, 1.46%, 2.21%, and 2.78% were formulated to examine their effects on ovarian development and broodstock health in the giant freshwater prawn Macrobrachium rosenbergii (initial weight: 9.32 ± 0.52 g) and to determine dietary EPA requirements during ovarian maturation. The results were as follows: (1) no significant differences in survival rate were observed among groups. Weight gain (WG) initially increased and then declined, reaching the highest values in the 1.46% EPA group, although differences among treatments were not significant. In contrast, hepatopancreas index decreased significantly with increasing dietary EPA ( p < 0.05). (2) Dietary EPA significantly altered hepatopancreatic fatty acid composition. Saturated fatty acid (SFA) levels showed no significant differences, whereas monounsaturated fatty acids (MUFAs) decreased significantly ( p < 0.05). In contrast, polyunsaturated fatty acids (PUFAs) and HUFA increased significantly with higher dietary EPA ( p < 0.05), peaking in the 2.78% EPA group. (3) Antioxidant parameters, including total antioxidant capacity (T‐AOC), total superoxide dismutase (T‐SOD), and glutathione peroxidase (GSH‐Px), followed a pattern of initial increase followed by decline with higher EPA levels ( p < 0.05). Malondialdehyde (MDA) content showed the opposite trend, reaching its lowest level in the 1.46% EPA group ( p < 0.05). (4) Ovarian histology revealed that the 1.46% EPA group exhibited a higher proportion of mature oocytes, with most females reaching ovarian development stages III–IV, and this group also showed the highest gonadosomatic index (GSI). Steroid hormone secretion was significantly affected by dietary EPA ( p < 0.05). (5) At the molecular level, EPA inhibited the expression of genes related to lipid synthesis in the hepatopancreas ( p < 0.05) and promoted fatty acid β ‐oxidation, but excessive EPA caused irreversible hepatopancreatic damage. Polynomial regression analysis of steroid hormone secretion indicated that 1.32% and 1.50% dietary EPA supported maximum progesterone (PROG) and 17 β ‐estradiol (E2) levels, respectively. Overall, a dietary EPA level of 1.46% was found to promote broodstock growth, enhance antioxidant capacity, accelerate fatty acid β ‐oxidation, stimulate steroid hormone secretion, and provide sufficient energy for ovarian development in the giant freshwater prawn.