Simulations from modified U-system approach compared with relative concentrations obtained by metabolome and amino acid analyses. The red and blue dots represent relative concentrations (see Materials and Methods) of lysine and threonine supplementation experiment with coefficient of variations less than or more than 20%, respectively, which are obtained by metabolome (upper boxes) and amino acid (middle boxes) analyses. Red lines represent simulations from the modified U-system approach. The normalized peak intensities of lysine and threonine-supplemented samples and control samples are shown as red dots and black dots, respectively (lower boxes). a, threonine (X26); b, lysine (X93); c, glutamate (X37); d, aspartate (X78).