Influences des régimes et de leur fermentation dans le rumen sur la production de méthane par les ruminants

Abstract

This work is based on the study of several databases to extract predictive models of CH 4 production based on diets and ruminal fermentations. Methanogenesis is described with the main principles of the stoichiometry and thermodynamics of ruminal fermentation. It appears a particularly positive relationship between CH 4 production and the ratio of acetic/propionic in rumen liquor (Ac/Pr). Changes in the profile of the volatile fatty acids (VFA) and of CH 4 production reflect phenomena of adaptation of the rumen microbes to the amount of available energy. Among the various criteria for predicting the food production of CH 4, the digestible organic matter (DOM) is an interesting parameter to be considered: it is closely linked to the rumen fermentable OM, therefore CH 4, and the energy value of food. However, the ratio CH 4/DOM also varies depending on dietary factors that also affect the ratio Ac/Pr in the rumen: the feeding level, forage quality, the dietary concentrate and fat. A final section is devoted to the study of mechanistic models that are based on the principles of stoichiometry of VFA, these models constitute a step towards integrated modeling of all phenomena and digestive fermentation in the rumen.