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Modélisation systémique de la digestion dans le rumen : comparaison des modèles existants, modélisation des flux d'amidon, approche thermodynamique des fermentations

Abstract : Nutritional and zootechnical responses of ruminants to diets largely depend on responses at the rumen level. The objective of this study was to bring new prospects to progress in rumen modeling, pioneered in the early seventies. To tackle this work, we decided to favor a systemic modeling approach based on various organizational levels: from organs to nutrients flows and down to mechanisms of cellular regulation. The first part of this study was devoted to compare current rumen models. Indeed, few comparative validations had been undertaken until now. The results pointed out that models share common principles but have also their own characteristics. Their main weakness was their inability to predict the end-products of fermentation (volatile fatty acids, gas, microbial matter) in a satisfactory way. We investigated two directions to progress in this area. The first one deals with the representation of starch digestion; this carbohydrate substrate explains the most variation in ruminal digestion rates of a diet. We developed a model predicting starch flows to better quantify and explain observed variation. This study was conducted from quantitative databases related to in situ and in vivo flows. Results for variation within experiments were entirely satisfactory. However, variation among experiments remained large and was difficult to explain. The second direction was based on the application of thermodynamic laws to microbial metabolism. The objective was to improve the prediction of end-products of fermentation. This original approach of fermentation includes both modeling and experimental work. Results allowed some properties resulting from thermodynamic principles to be identified and strengthened interest in the subject. This work has contributed to some progress on rumen modeling, especially on the modeling of starch flows. It also opens a promising new field of knowledge that deserves further attention.
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https://pastel.archives-ouvertes.fr/pastel-00000448
Contributor : Ecole Agroparistech <>
Submitted on : Monday, February 9, 2004 - 8:00:00 AM
Last modification on : Tuesday, March 17, 2020 - 2:46:26 AM
Long-term archiving on: : Friday, September 10, 2010 - 3:21:12 PM

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Anne Offner. Modélisation systémique de la digestion dans le rumen : comparaison des modèles existants, modélisation des flux d'amidon, approche thermodynamique des fermentations. Sciences du Vivant [q-bio]. INAPG (AgroParisTech), 2003. Français. ⟨NNT : 2003INAP0015⟩. ⟨pastel-00000448⟩

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