A Model to Interpret Gas Accumulation Profiles Associated with In Vitro Degradation of Ruminant Feeds

The time course of cumulative gas production obtained during in vitro incubation of forages in rumen fluid can be described by the model {1-exp[-b(t-T)-c(√t-√T)]}. per offers a kinetic derivation of this model and demonstrates how its parameters can be used to calculate the extent of degradation in the rumen. Application of the model is shown using data from a study of Gliricidia tropical forage trees. The effects of incorporating the concepts of microbial degradation by surface erosion and by complete invasion into the derivation are also examined and the resultant gas accumulation curves compared with experiment. The comparison lends support to the theory that fibrolytic rumen bacteria degrade by erosion and rumen fungi degrade by invasion.