Effect of selection for improved body composition on muscle and meat characteristics of broilers from experimental and commercial lines

Meat quality (pH, color, and drip loss) and muscle characteristics (composi tion and metabolic pattern) were compared among four broiler lines: an expe rimental line, a commercial line selected for increased body weight and bre ast yield, and the respective unselected control lines. By comparison to th eir controls, the commercially selected birds exhibited higher body weight and breast yield (127 and 61%, respectively), whereas only breast yield was increased (21%) in the experimental selected line. Commercial selection re sulted in higher protein content and lower moisture in the breast muscle. E xperimental and commercial selection decreased the heme pigment content, wh ich could explain why breast meat of the selected birds was more pale and l ess red. This change in the color did not correspond to a pale, soft, and e xudative (PSE) defect, as the selected birds did not exhibit excessive drip loss. By comparison with their controls, both selected lines showed a lowe r rate and extent of pH decline postmortem, which was consistent with the l ower glycolytic potential they also exhibited. However, no significant chan ges in the metabolic pathways of breast muscle, as measured by enzyme activ ities, could be found to explain differences in rates of pH decline among l ines. This study did not support the idea that selection had a negative imp act on meat quality, despite evidence of modified breast metabolism.