VARIOUS LIGHT-SOURCE TREATMENTS AFFECT BODY AND SKELETAL-MUSCLE GROWTH BY AFFECTING SKELETAL-MUSCLE SATELLITE CELL-PROLIFERATION IN BROILERS

In this study we addressed the effect of various monochromatic light t reatments on muscle growth and satellite cell proliferation in broiler s (Gallus domesticus). Broilers were reared under green (560 nm), blue (480 nm) and red (660 nn) monochromatic lights and white light as a c ontrol from day one until 35 days of age. At five days of age, satelli te cells were prepared from the experimental chicks. The number of sat ellite cells per gram of breast muscle and total number of satellite c ells derived from the experimental broilers was substantially higher i n the groups reared under green and blue light, compared to the red an d white light groups. Growth hormone receptor gene expression was also higher in the former groups. High correlation was found between the b reast muscle weight observed on day 35 and the number of satellite cel ls per gram of breast muscle (r = 0.915) and total number of satellite cells (r = 0.833), derived from the experimental chicks as early as l ive days of age. In addition, the protein/DNA ratio found in breast mu scle at 35 days of age was significantly lower in chicks that were rea red under green and blue lights. The lowest ratio which was found in t he green group and was twice as low as in the control group, indicates the highest number of nuclei in the former group. As satellite cells are the only source of additional nuclei in skeletal muscles of postna tal animals, our results suggest that the higher muscle weight found i n the green and blue light groups was due to increased satellite cell proliferation during the first days of age. (C) 1998 Elsevier Science Inc. All rights reserved.