Seed Characteristics of Different Varieties of Grain Sorghum

Eight varieties of grain sorghum representing four different seed classes (Waxy, Waxy-BR, Normal, Normal-BR) were wet-milled to study seed composition (percent starch, bran and germ, peripheral endosperm cells-PEC and gluten). Starch recovery was high and similar for all varieties except the Waxy 1126 and Normal-BR ROKY 78. Depression in starch recovery was reflected in the other fractions, particularly the bran and germ. Protein recovery in each fraction was variable but total protein recovery was fairly constant except for a decreased response in Soft Endo (Normal-BR). In vitro dry matter disappearance (DMD) studies perform~d on the purified isolatedstarchsuggested only small differences in ruminal starch digestibility between varieties. These studies suggest some differences in wet-milling composition, but that the in vitro digestibility of purified starch differs little among varieties. Hence, differences in digestibility of finely ground sorghum grains are probably not influenced much by digestibility differences in the starch "per se", but by factors (such as protein content and compostion, tannin content, etc.) which may affect digestive access to the starch in the grain. Gross compositional differences (e.g. percent starch, percent protein, etc.) may also be important, however, in influencing nutritive value.