Although insulin per se has been shown to stimulate whole-body protein synthesis in several mammalian species(Davisetal. 2002;O ’Connor et al. 2003), insulin sensitivity may also have a significant role. Recent studies in neonatal piglets (Bergeronetal. 2007) and steers (Gingras et al. 2007) have shown that protein anabolism is upregulated via enhanced insulin sensitivity in animals fed dietary long-chain n-3 polyunsaturated fatty acids. In both studies, the increase in whole-body protein accretion was suggested to be the result of a decreaseinproteinbreakdown,with no alteration in its synthesis. In addition, studies in rodents have shown an amino acid-enhanced sensitivity of skeletal muscle protein synthesis to insulin, allowing for maximal rates of protein synthesis to be achieved at lower insulin concentrations when amino acids are infused concurrently (Garlick and Grant 1988). Taken together, these above studies suggest a dynamic role for insulin, insulin sensitivity and amino acids and collectively they may act synergistically to stimulate protein synthesis.