One hundred and twenty 4-week-old broilers were randomly assigned to one of the three dietary treatments including control (none), oxidized oil (5% of diet) and antioxidants (500 IU vitamin E and 200 ppm BHT) and fed for 2 weeks. Blood samples were collected 1day before slaughter and breast muscles were sampled immediately after slaughter. Degree of lipids and protein oxidation in blood and breast muscle, and meat quality parameters were determined. Compared to control group, broilers fed diet with oxidized oil significantly increased lipid oxidation in both blood (P \u3c 0.05). Dietary oxidized oil tended to increase carbonyl content in blood and muscle (P \u3c 0.05). Addition of antioxidants significantly decreased lipid oxidation in both blood and muscle samples and arrested protein oxidation in muscle (P \u3c 0.05). Meats from oxidized oil treatment showed higher drip loss at days 1 and 3 and lower water holding capacity at day 1 than control group (P \u3c 0.05). No significant difference was found about drip loss and water holding capacity between control and antioxidant treatments. The rate of pH decline in breast meat from oxidized oil treatment was significantly higher than that of control between 0 and 1 hour after slaughter (P \u3c 0.05). However, dietary treatments did not show significant effects on body weight gain, feed consumption and feed efficiency of live birds, and cooking loss and color of breast meat. This suggested that degree of oxidation in diet increased the oxidation in blood and muscle, and the oxidative stress in live birds were related to the variations in quality parameters including pH decline, drip loss, and protein and lipid oxidation of broiler breast meat.
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