Comparison of five models used to describe gas accumulation profiles in the gas test method with horse caecal fluid as inoculum

Abstract

The in vivo organic matter digestibility (OMD) in ruminants can be predicted with the gas test method by the amount of gas produced after 24-h fermentation (Menke et al., 1979). Mathematical models can also be used and can provide useful information concerning the kinetics of fermentation. In ruminants, various models have been used to fit fermentation profiles. The early models are based on first-order kinetics with a constant fractional rate of fermentation (Ørskov and McDonald, 1979; Khazaal et al., 1993). Recently, more sophisticated models have been used to describe gas production kinetics obtained from new automated gas production equipment (Theodorou et al., 1995; Cone et al., 1996). The aim of this study was to compare the relevance and the accuracy of five models for describing gas production kinetics and for predicting the organic matter digestibility (OMD) of forages in horses.