Abstract:

The aim of this experiment is to investigate the improvement effect and mechanism of Lycium barbarum flavonoids (LBFs) on the muscle quality of meat ducks. Two hundred one-day-old male Cherry Valley ducks were randomly divided into four groups, with six replicates per group and ten ducks per replicate. The control group was fed a basal diet, while the experimental groups were fed the basal diet supplemented with 250, 500, or 1 000 mg ·kg^-1 of LBFs for 42 days. After slaughter, the quality of the breast muscle, intramuscular fat content, ROS levels, and antioxidant capacity were measured. The results showed that, regarding meat quality, compared with the control group, dietary 500 and 1 000 mg ·kg^-1 of LBFs significantly reduced cooking loss, drip loss after 24 hours post-slaughter, shear force values, improved meat color (redness), and increased pH_{24 h} (P < 0.05) in the breast muscles of ducks. Dietary 500 mg ·kg^-1 of LBFs had no sigaificant effect on the relative area of lipid droplets or the triglyceride content in the breast muscle (P>0.05). In terms of antioxidant function, compared with the control group, dietary 500 and 1 000 mg ·kg^-1 of LBFs significantly increased the activities of glutathione peroxidase (GSH-Px) and total superoxide dismutase (T-SOD), or decreased reactive oxygen species (ROS) and malondialdehyde (MDA) contents (P < 0.05) in the breast muscles. There were no significant differences in catalase (CAT), total antioxidant capacity (T-AOC), and glutathione (GSH) contents among the groups (P>0.05). Dietary 500 mg ·kg^-1 of LBFs significantly reduced the fluorescence intensity of ROS (P < 0.05) in the breast muscles. Dietary 500 and 1, 000 mg ·kg^-1 of LBFs significantly increased the relative mRNA expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2), superoxide dismutase 1 (SOD1), and heme oxygenase-1 (HO-1), and 500 mg ·kg^-1 of LBFs also significantly increased the relative mRNA expression level of NAD(P)H quinone oxidoreductase 1 (NQO1) (P < 0.05) in the breast muscles. There were no significant differences in the relative mRNA expression levels of CAT or GSH-Px among the groups (P>0.05). Dietary 500 and 1 000 mg ·kg^-1 of LBFs significantly increased the relative protein expression levels of Nrf2 and HO-1, and decreased the relative protein expression level of Kelch-like ECH-associated protein 1 (Keap1) (P < 0.05) in the breast muscles. In conclusion, dietary LBFs can improve duck meat quality by enhancing muscle water-holding capacity and pH, improving meat color, and reducing shear force. This improvement is likely closely related to the activation of the Nrf2/HO-1 signaling pathway, thereby enhancing antioxidant function. Under the conditions of this experiment, an appropriate level of LBFs supplementation is 500 mg ·kg^-1.

Key words: Lycium barbarum flavonoids, meat ducks, meat quality, antioxidant, Nrf2/HO-1 signaling pathway