Modelling options for analysing ruminal ammonia-N concentration profiles

In this communication we descuss mathematical models that can be used to describe ammonia-N concentration profiles in the rumen of animals post-feeding. The unimodal pattern of ammonia-N profile following a single meal is modelled and analysed. Animals fed twice daily show bimodal patternswhere each component is separated due to the time interval between feeding times. Thus the selected model can be fitted to each peak separately. Various modelling options are explained and illustrated. There are three categories of models discussed: (1) summarising models to generate data for treatment comparisons, (2) kinetics-based models that furnish parameter estimates and meaningful functions thereof which can be used for treatment comparisons and (3) empirical models to generate quantitative information for further analysis. More complete information was obtained while analysing ammonia-Nprofiles using kinetics-based models such as the critical exponential and summarising models such as the single Gaussian