This study evaluated the efficacy of α-lipoic acid (LA) in mitigating the adverse effects induced by high plant protein-based replacement of fishmeal in hybrid sturgeon (Acipenser baerii♀ × A. schrenckii♂). Four diets were formulated: a positive control (PC; 50% fishmeal) and three experimental diets with 70% fishmeal replaced by plant protein: NC (0 mg LA/kg), L200 (200 mg LA/kg), and L400 (400 mg LA/kg). Juvenile sturgeon (initial weight 29.38 ± 0.10 g) were fed these diets for eight weeks. The NC group exhibited significantly lower growth performance and feed utilization than the PC group (P<0.05). Although dietary LA supplementation did not significantly improve weight gain or feed conversion ratio (P>0.05), the hepatosomatic index in the L400 group was significantly lower than that in the NC group (P<0.05). The apparent digestibility coefficients (ADC) of nutrients in the NC group were significantly lower than those in the PC group, whereas LA supplementation significantly increased ADC of dry matter and energy (P<0.05), thereby optimizing energy and nitrogen balance. No significant differences were observed in whole-body or hepatic proximate composition among treatments (P>0.05). Serum analysis revealed that the L200 group had significantly lower alanine aminotransferase (ALT) and malondialdehyde (MDA) levels (P<0.05), but higher total glutathione (T-GSH), oxidized glutathione (GSSG), superoxide dismutase (SOD), and catalase (CAT) activities (P<0.05). In the liver, the L200 group showed significantly reduced MDA content (P<0.05) and restored SOD, CAT activities, and glutathione (GSH) concentration to PC-comparable levels. Histological examination indicated more severe hepatocellular vacuolation and nuclear displacement in the NC and L400 groups, and impaired intestinal villus structure in NC; these pathological changes were attenuated by LA supplementation. In summary, dietary LA under high plant-protein feeding did not enhance growth but improved feed utilization, modulated energy/nitrogen retention, enhanced antioxidant capacity, and ameliorated hepatic and intestinal health in hybrid sturgeon.
 

Aquaculture,Diet,Additive,Growth,Health