Effects of dietary geniposidic acid on growth performance, flesh quality and collagen gene expression of grass carp, Ctenopharyngodon idella

This study was conducted to investigate the effects of dietary geniposidic acid ( GA ) on growth performance, flesh quality and collagen gene expression of grass carp ( Ctenopharyngodon idella ). The fish with an initial body weight of 47.1 ± 0.8 g were fed one of the seven diets, including control diet, Eucommia ulmoides ( EU )‐supplemented diet (20 g/kg) and GA ‐supplemented diets (200, 400, 600, 800 and 1,000 mg/kg GA ) for 75 days. The growth performance and muscle proximate composition showed no difference among groups ( p  >   .05). Dietary GA (200–1,000 mg/kg) increased the contents of total collagen and alkaline‐insoluble collagen in skin ( p <  .05), and high supplementation of GA (600–1,000 mg/kg GA ) and EU increased the contents of total collagen, alkaline‐insoluble collagen and total amino acids ( p <  .05), but reduced the lipid level in muscle ( p <  .05). In collagen gene expression, EU and 200–1,000 mg/kg GA increased COL 1A1 expression in muscle and skin ( p <  .05), but the expression of COL 1A2 was increased only by high supplementation of GA (1,000 mg/kg, or 800–1,000 mg/kg) ( p <  .05). In conclusion, dietary GA improved the flesh quality of grass carp, and the supplementation level was estimated to be 600 mg/kg diet.