Effects of ginkgo leaf extract on growth performance, nutrient utilization, blood biochemical parameters, meat quality, fatty acid profiles, and gene expression in growing rabbits.

The objective of this study was to observe the effects of ginkgo leaf extract (GLE) on growth performance, nutrient utilization, antioxidant activity, carcass yield, meat quality, fatty acid profiles, and gene expression in rabbits. A total of 80 weaned male rabbits were randomly divided into 4 equal treatment groups according to a completely randomized design. The control (CON) group was fed a basal diet, whereas treatments 1 (LG), 2 (MG), and 3 (HG) were fed a basal diet supplemented with 2, 4, and 6 g/kg GLE, respectively. The results indicated that compared with the CON group, the MG treatment group presented significantly (P < 0.05) greater body weight change and average daily gain from 0-42 d. The mortality rate was significantly lower (P < 0.05) in rabbits fed GLE than in those of the CON group. Additionally, the apparent digestibility of acid detergent fibre, hemicellulose, and ash in the rabbits in the MG group was greater (P < 0.05) than that in the CON group. Compared with the CON group, dietary supplementation with GLE significantly increased nitrogen retention. Compared with those in the other three treatment groups, the gross energy (GE) absorption and GE retention in the MG treatment group significantly increased (P < 0.05). Compared with the CON group, the GLE-supplemented groups presented significantly (P < 0.05) increased plasma catalase levels and significantly (P < 0.05) decreased malondialdehyde and total cholesterol contents. Compared with those fed the CON diet, rabbits fed the LG and MG diets presented decreased (P < 0.05) levels of yellowness, drip loss, and shear force in the muscle. Compared with the CON diet, the addition of GLE significantly (P < 0.05) decreased C16:0 and C20:4n6 levels, whereas it significantly (P < 0.05) increased C18:3n3 and n-3 polyunsaturated fatty acid (PUFA) levels. Compared with the CON diet, GLE supplementation significantly increased (P < 0.05) nuclear factor (erythroid-derived 2)-like 2, haem oxygenase 1, superoxide dismutase 1, and glutathione peroxidase 1 levels, whereas it significantly decreased (P < 0.05) kelch-like ECH-associated protein 1 levels. Taken together, these findings suggest that dietary supplementation with GLE could improve growth performance, nutrient utilization, meat quality, n-3 PUFA concentrations, and antioxidant activity in growing rabbits. The optimum level of GLE supplementation in the diet for growing rabbits was 4 g/kg under the conditions of this experiment.