Abstract: 【Objective】 LED (light emitting diodes) as light sources was used in this study to investigate the effect of intermittently monochromatic light stimuli during the embryogenesis on breast muscle growth, chemical composition, and meat quality of male broiler chicks.【Method】 Fertile broiler eggs (Arbor Acres, n=1 480) were preweighed and randomly assigned into one of the three treatment groups in 3 modified incubators: 1) monochromatic green light group (560 nm, n=490), 2) monochromatic blue light group (480 nm, n=490) and 3) control group (in dark condition, n =500). Light intensity was 15 lx at the eggshell level, and was intermittent at 15 min on and 15 min off. After hatching, 120 male chicks from each group were placed in 6 replicates with 20 birds each. All the birds were housed under normal white light (30 lx at bird-head level) with a light schedule of 23L﹕1D.【Result】 No significant differences in the hatchability, birth weight and feed intake among all groups were observed (P＞0.05). Compared to birds in blue or dark group, BW in green light group was significantly increased at 21 d and 42 d of age (P＜0.05). The breast muscle weight and breast muscle percentages in birds incubated under green light were significantly elevated by 38.3 g, 0.67%, and 44.6 g, 0.78% than those in the dark condition or blue group at 42 d of market age (P＜0.05), respectively. In green light group, feed conversion ratio during 0-42 d was lower than that in the dark condition or blue group (P＜0.05). No significant differences in the contents of breast moisture, CP, crude fat or crude ash among all groups were observed (P＞0.05). There was a trend toward green light stimuli increasing drip loss (P=0.10) and cooking loss (P=0.07). In addition, blue light induced a higher b* value of 24-h meat color than that in the dark condition or green light group (P=0.05).【Conclusion】Intermittently green light (15 lx) stimuli during the embryogenesis enhanced the posthatch BW of male broilers, increased breast muscle growth, and improved feed conversion ratio, but did not cause any significant changes in breast chemical composition, or any noticeable changes in overall meat quality characteristics except for a decreasing trend in water-holding capacity.

Key words: broiler embryo, monochromatic light, breast muscle, chemical composition, meat quality