Author(s): R D Walker, R E Lichtenwalner
The effect of reconstitution on protein solubility and in situ protein digestibility of three sorghum selections was evaluated. The proteins in sorghum were classified into five fractions based on their solubility in different solutions. Grain type and reconstitution significandy affected percent soluble protein. Waxy sorghum contained significandy more soluble protein than did the nonwaxy or hetero-yellow sorghum. Reconstitution decreased the total amount of soluble protein, and significandy altered the percent of soluble protein within fractions. Reconstitution tended to shift a greater percentage of the protein from the alcohol soluble and glutelin classes to the water soluble class. Mean apparent ruminal protein digestibility ranged from 40.2 to 84.9% for the five protein classes. Digestibility of water soluble protein was significandy higher than other classes of proteins. Proteins in waxy grain were significantly more digestible than nonwaxy proteins. Reconstitution did not significandy affect total ruminal protein digestibility. In situ digestibility of total protein was of the same general magnitude as apparent protein digestibility for the entire ruminant alimentary tract. These data suggest the major portion of sorghum proteins are digested in the rumen.