Effects of Dietary Isoflavone Supplementation on Meat Quality and Oxidative Stability During Storage in Lingnan Yellow Broilers

To investigate the effects of a synthetic isoflavone (SI) on meat quality and oxidative stability, 1 500 43-d-old Lingnan yellow male broilers were randomly assigned to five dietary treatments: diets supplemented with 0, 10, 20, 40, or 80 mg SI kg(-1), fed ad libitum for a period of 3 wk. After refrigerated storage, a* value of the meat increased with dietary SI supplementation using 10 and 40 mg kg(-1) level (P<0.05), L* value decreased (P<0.05), and 40 mg kg(-1) increased the pH (P<0.05). Supplementation with SI, at all levels, increased water holding capacity (P<0.05) and decreased lactic acid content of meat (P<0.05). The concentration of malondialdehyde at 72 h decreased linearly (P=0.005) and quadratically (P=0.004) with increasing levels of SI. Dietary SI at 20 and 40 mg kg-1 levels enhanced total superoxide dismutase activity in meat (P<0.05). Meat pH quadratically decreased as the storage time increased (P<0.05), with the highest value at 24 h (P<0.05). Lactic acid and malondialdehyde concentrations of meat increased over time, with value at 96 h being far higher than at earlier times (P<0.05). Supplemental SI linearly and quadratically increased the mRNA abundance of glutathione peroxidase (GPX) (P=0.001 and P=0.002) and catalase (CAT) (P=0.003 and P=0.006) in breast muscle. The results from this study indicate that dietary supplementation with SI can improve meat quality during refrigerated storage by decreasing lipid peroxidation and enhancing oxidative stability and, for male broilers from 43 to 63 d of age, the optimal level of SI was 40 mg kg(-1).