Escape and rumen degradable protein fractions in warm-season grasses

Crude protein (CP) is routinely used to quantify protein concentration of forages. The CP concentration varies with forage species, plant part, plant maturity, and management practices. Ruminants derive their amino acid supply from microbial protein synthesized in the rumen, undegraded proteins, and amino acids that escape ruminal degradation. Rumen escape protein is the nondegraded or protected dietary proteins, amino acids, and peptides. A minimum rumen ammonia or CP level is needed for basal microbial protein synthesis. Therefore, it is essential to supply rumen degradable proteins in combination with high escape protein forages when rumen degradable protein of warm-season forage diets may be deficient. Protein degradation can be estimated by in vitro, in situ, or in vivo methods. Numerous attempts have been made to modify procedures for estimating forage protein degradation. Newer, innovative techniques such as sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunochemical techniques are being used more frequently to characterize forage proteins.