Influences of dietary Eucommia ulmoides extract on growth, flesh quality, antioxidant capacity and collagen-related genes expression in grass carp (Ctenopharyngodon idellus)

Abstract

The study investigated the effects of dietary Eucommia ulmoides extracts on growth, flesh quality and collagen-related genes expression of grass carp (Ctenopharyngodon idella). Eucommia ulmoides bark extract (EBE) and Eucommia ulmoides leaf extract (ELE) were individually supplemented into basal diet (control) at an inclusion of 4 g/kg, and then the three diets were fed to grass carp (59.7 ± 0.3 g) for 60 days. The results indicated that dietary ELE significantly increased weight gain (+4.22 %), and decreased feed conversion ratio (-4.05 %) (P < 0.05), while EBE did not significantly affect the growth performance of grass carp. Compared to the control, dietary ELE significantly increased apparent digestibility coefficient of dry matter, crude protein and intestinal digestive enzyme activity (P < 0.05), and the contents of calcium, total collagen, heat-insoluble collagen and free amino acids level (including delicious amino acids) in flesh were also significantly increased (P < 0.05). In both extracts groups, the flesh centrifugal loss, steaming loss, drip loss24h, protein carbonyl and malondialdehyde were significantly lower, and superoxide dismutase and glutathione peroxidase activities were significantly higher than the control (P < 0.05). No significant differences in the amount of saturated, monounsaturated and polyunsaturated fatty acids in flesh were found among the three groups, but docosapentaenoic acid (DPA), docosahexaenic acid (DHA), n-3 polyunsaturated fatty acids and n-3/n-6 ratio in flesh were significantly increased by dietary EBE and ELE (P < 0.05). In collagen-related genes expression, the ELE supplementation significantly promoted the expression of collagen type I (COL1A1, COL1A2), proline hydroxylase, lysine oxidasein in muscle, while the expression of matrix metalloproteinase-2 and matrix metalloproteinase-9 was significantly decreased (P < 0.05). In conclusion, dietary ELE improved the growth, muscle antioxidant capacity and flesh quality of grass carp.