TP 9: Protein and energy value of cereal grains in ruminants as a result of ruminal degradation of crude protein and starch

For the quantitative description of the protein and energy value of cereal grains in ruminants, extent and kinetic of the ruminal degradation of crude protein (XP) and starch are essential characteristics. Several studies have shown that ruminal degradation of crude protein and starch of grains differ between varieties. Before GrainUp, no experimental studies were available that assessed this variation in more detail, or even to predict them with appropriate methods. Using the in sacco method, the kinetic of the degradation of crude protein and starch was determined under standardized conditions. Thereby, firstly a comprehensive data base was created on the ruminal degradation of crude protein and starch from corn, winter wheat, winter barley, and winter triticale. These analyses were complemented with studies on gas formation and its kinetics using the Hohenheim Gas Test for the determination of the digestibility and content of metabolizable energy. These results were validated with those from the digestibility investigations (TP 10). With this method also the contents of utilisable crude protein (nXP) were estimated by means of the ammonia release. Finally, in vitro specific NIRS calibrations for the key figures of crude proein and starch degradation as well as for gas formation and nXP were developed for of grain samples’ screening. Collaboration exists with TP9 and the Z-project, the subprojects 10 and 12 as well as to subproject 11 in methodological point of view. All grain lots used in the digestion experiments of TP 10 are considered in TP 11 as well.

Subproject leaders

Dr. Herbert Steingaß

University of Hohenheim

Prof. Dr. Karl-Heinz Südekum

University of Bonn