Myopathy occurrence and meat quality in broiler chickens: effect of genotype, gender, and light program

To evaluate the effect of genotype (Cobb vs. Ross), gender and light program (14L:10D vs 18L:6D) on myopathy occurrence and meat quality, 800 chickens were reared under controlled conditions. At commercial slaughter (44 d of age), 192 P. major (24 per group) were examined for white striping (WS), wooden breast (WB), and meat quality. Chi-square test and PROC MIXED of SAS were used to evaluate differences in myopathy occurrence and meat quality among groups, respectively. The genotype did not affect myopathy (on average WS: 76.9%; WB: 6.26%), but some meat traits changed (cooking losses: 27.0 vs. 29.3%; shear force: 2.29 vs. 2.55 kg/g in Cobb vs. Ross; P<0.01). Females were less affected by WS (70.5 vs. 83.3%; P<0.05) and WB (3.13 vs. 9.38%; P<0.10) than males and showed lower ultimate meat pH (5.92 vs. 5.98; P<0.01), cooking losses (26.4 vs. 29.9%; P<0.001), and shear force (2.26 vs. 2.58 kg/d; P<0.01). Under 14L:10D, chickens were less affected by WS (64.6 vs. 89.5%; P<0.001), and showed lower meat shear force (2.20 vs. 2.64 kg/g; P<0.05) and fat content (1.87 vs 2.29%; P