Effects of Dietary Starch Supplementation on Muscle Metabolism and Antioxidant Capacity, Fatty Acid and Amino Acid Composition of Juvenile Yangtze Sturgeon (Acipenser dabryanus).

The metabolic adaptation of endangered Yangtze sturgeon (Acipenser dabryanus) to dietary carbohydrates remains unclear. This study investigated how graded corn starch levels (0%, 10%, 20%, 30%) affected digestive capacity, immunity performance, nutrient metabolism and muscle quality in juveniles (216.6 ± 10.2 g) during an 8-week trial. Digestive (lipase, amylase) and glycolytic enzymes (GK, HK, G6PDH) activities rose with starch levels, correlating with elevated glycogen storage (muscle: 8.4 mg/g; liver: 24.6 mg/g) (p < 0.05). Antioxidant capacity increased at 20%-30% starch (p < 0.05), while 30% starch reduced muscle PUFA content and increased n - 6/n - 3 ratio, elevating atherogenic (IA) and thrombogenic (IT) indices. Essential amino acid ratios and flavor-enhancing amino acids decreased with starch inclusion, with valine as the first limiting amino acid. These findings demonstrate that 20%-30% starch could enhance metabolic and immune performance but required balancing with lipid deposition and nutritional quality considerations for sustainable Yangtze sturgeon aquaculture.