DefinePK

Abstract

ABSTRACT There are weight and size differences in skeletal muscles of fast- (FG), and slow- growing (SG) chickens, however, the underlying molecular mechanisms responsible for the differences in post-hatch muscle development are unclear. Here, we report on the identification of several candidate genes that may modulate myofiber growth and thus explain some of the differences in the skeletal muscle phenotype of FG and SG chickens. We collected pectoralis major (PM) and gastrocnemius muscles (GM) on d 1, 7, 28, 49, and 70 post-hatch, and measured the weights of the muscles, diameter and, a density of myofibers, and the expression abundances of MyoD, MyoG, IGF-1, and Pax7. The body weight of FG was heavier than SG from d 7 to 70. Their muscle weights and myofiber diameters of FG were also greater than SG (P < 0.05). The expression of MyoG was affected by chicken population, age, and muscle-type. It was the heaviest in PM for FG on d 28, compared with other combinations. The expression of Pax7 mRNA paralleled changed in myofiber density, whereas the expression profiles of MyoG and MyoD were similar to the developmental changes in myofiber diameter. Overall, body weight and muscle expansion of SG chickens were less than FG chickens. MyoG was the possible gene controlling myofiber development as its expression abundances were associated with the muscle development profiles in the SG and FG chickens, respectively.