Chemical analyses
The total lipids of breast meat in both groups were extracted as described by Folch et al. (1957) and methylated as described by An et al. (1997). The fatty acid composition was measured by gas-liquid chromatography (Agilent 6890 N, Agilent Technology, Santa Clara, CA, USA) using 0.32 mm i.d. ×30 m capillary column (HP- Innowax, Agilent Technology, USA). One micro liter of sample was injected (split 1:10, 260°C) and then carried out at a flow rate of 1.0 mL/min using helium. The initial column temperature was set at 150°C for 1 min and increased to 200°C at 15°C/min and to 250°C at 3°C/min. The flame ionization detector was set at 280°C. The peaks were identified by comparison with standard mixture of fatty acid methyl ester.