ABSTRACT
This chapter discusses the enzymology and microbiology of ruminal protein degradation and general aspects of kinetics of ruminal protein degradation. Peptide uptake in microorganisms has been the subject of recent, thorough reviews by J. W. Payne. Peptide transport in ruminal microbes as a whole is probably the result of individual spp. with rapid rates of uptake and other spp. with perhaps little or no ability to transport peptides. The chapter also discusses the methods used to estimate rates and extents of ruminal protein and some aspects of the application of kinetics to determination of extent of ruminal protein degradation. Direct in vivo measurement would appear to be the most desirable approach for determining rates and extents of ruminal protein degradation. The kinetics of ruminal protein degradation are most often described using a first order model, which divides feed N into three fractions: an nonprotein nitrogen fraction, a degradable fraction, and an indigestible fraction.
