Abstract
Nutrition and other external factors are known to have a marked effect on growth of skeletal muscle through alterations to satellite cells. Satellite cells play an integral role in both prenatal and postnatal skeletal muscle growth of mammals. Changes in maternal nutrition can impact satellite cells which ultimately impacts prenatal skeletal muscle development. Alterations to prenatal skeletal muscle development have a direct impact on growth potential of skeletal muscle in the postnatal animal. Satellite cells are important in postnatal skeletal muscle growth as they support the hypertrophy of existing myofibers. Hypertrophy of existing fibers is the only mechanism of postnatal muscle growth because muscle fiber number is fixed at birth and fiber nuclei have exited the cell cycle. Since fiber nuclei do not divide, additional nuclei required for hypertrophy must be acquired from satellite cells. To date, no research has aimed at determining whether nutrition directly impacts satellite cell populations within skeletal muscle of beef cattle. However, it is well established that nutrition alters circulating levels of various growth factors such as insulin-like growth factor 1, epidermal growth factor, hepatocyte growth factor and fibroblast growth factor. Each of these different growth factors impact satellite cell proliferation and/or activation, indicating that nutrition likely plays a large role in skeletal muscle growth through impacting the satellite cell pool in both prenatal and postnatal growth. Furthermore, other external factors such as anabolic implants, are known to directly impact skeletal muscle growth through effects on the satellite cell pool. Specifically, provision of implants that contain estradiol and/or trenbolone acetate can increase the number of satellite cells by 50%. The relationship between nutrition, growth factors, and satellite cells relative to skeletal muscle growth is an important area of research that warrants further consideration.