Growth performance, blood biochemistry, gene expression, gonad histology, and sexual parameters in common carp (Cyprinus carpio) fed diets supplemented with Tribulus terrestris extract

This study investigated the effects of dietary Tribulus terrestris extract (0, 100, 1000, or 2000 mg/kg) on growth, health, and reproductive physiology in common carp (Cyprinus carpio). Over 60 days, fish fed 100 and 1000 mg/kg exhibited higher survival rates (P < 0.05), though growth metrics (final weight, FCR, SGR) remained unchanged (P > 0.05). Reproductive indices displayed sex-specific responses: males showed elevated gonadosomatic index (GSI) at 100–1000 mg/kg, while females had increased GSI at 2000 mg/kg (P < 0.05). T. terrestris extract at 1000 mg/kg significantly reduced female GSI (P < 0.05), while no dose increased male testosterone, suggesting species- and sex-specific efficacy. Blood biochemistry revealed dose-dependent effects, including elevated triglycerides (males, 2000 mg/kg; females, 1000–2000 mg/kg), cholesterol peaking at 100 mg/kg (both sexes), and reduced globulin levels (P < 0.05). Liver function markers SGOT and SGPT increased at higher doses (P < 0.05), while alkaline phosphatase (ALP) decreased at 1000–2000 mg/kg, and lactate dehydrogenase (LDH) declined in males at 1000 mg/kg. Gene expression analysis highlighted significant upregulation of ovarian NRF2 (linked to oxidative stress response), whereas GDF9 (critical for folliculogenesis) remained unaffected. Histologically, T. terrestris enhanced spermatogenic maturity (increased spermatocytes/spermatozoa) and delayed ovarian development in females at 1000 mg/kg, correlating with reduced estradiol (P < 0.05). These findings underscore T. terrestris as a multifunctional supplement for modulating male reproductive performance and female sexual maturation in aquaculture, with implications for broodstock management.