Development of a mechanistic model for rumen digestion validated using the duodenal flux of amino acids

Lescoat, Philippe; Sauvant, Daniel

doi:10.1051/rnd:19950104

Cited by 56 publications

(67 citation statements)

References 37 publications

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“…published models derived either from stoichiometric models and not corrected for the experimental effect or from within-experiment models based on a more aggregated covariable, such as percentage of the concentrate (Lescoat and Sauvant, 1995) or dNDF content (Sauvant, 2003). While rumen pH was an interfering factor for the model based solely on dNDF/dOM, it was not an interfering factor when RSD and DMi were included as additional variables.…”

Section: Discussionmentioning

confidence: 99%

In vivo production and molar percentages of volatile fatty acids in the rumen: a quantitative review by an empirical approach

Nozière

Glasser

Sauvant

2011

Animal

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Despite their major contribution to the energy supply of ruminants, the production of volatile fatty acids (VFA) in the rumen is still poorly predicted by rumen models. We have developed an empirical approach, based on the interpretation of large bibliographic databases gathering published in vivo measurements of ruminal VFA production rate (PR), rates of duodenal and faecal digestion and molar percentages of VFA in the rumen. These databases, covering a wide range of intake levels and dietary composition, were studied by meta-analysis using within-experiment models. We established models to quantify response laws of total VFA-PR and individual VFA molar percentages in the rumen to variations in intake level and dietary composition. The rumen fermentable organic matter (RfOM) intake, estimated from detailed knowledge of the chemical composition of diets according to INRA Feed Tables, appears as an accurate explanatory variable of measured total VFA-PR, with an average increment of 8.03 6 0.64 mol total VFA/kg RfOM intake. Similar results were obtained when total VFA-PR was estimated from measured apparent RfOM (total VFA-PR/RfOM averaging 8.3 6 1.2 mol/kg). The VFA molar percentages were related to dry matter intake and measured digestible organic matter (OM), digestible NDF and rumen starch digestibility, with root mean square error of 1.23, 1.45, 0.88 and 0.41 mol/100 mol total VFA for acetate, propionate, butyrate and minor VFA, respectively, with no effect of pH on the residuals. Stoichiometry coefficients were calculated from the slopes of the relationships between individual VFA production (estimated from measured apparent RfOM and individual VFA molar percentages) and measured fermented fractions. Coefficients averaged, respectively, 66, 17, 14 and 3 mol/100 mol for NDF; 41, 44, 12 and 4 mol/100 mol for starch; and 46, 35, 13 and 6 mol/100 mol for crude protein. Their use to predict VFA molar percentages appear relevant for most dietary conditions, that is, when the digested NDF/digested OM ratio exceeded 0.12. This study provides a quantitative review on VFA yield in the rumen. It contributes to the development of feed evaluation systems based on nutrient fluxes.

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Section: Discussionmentioning

confidence: 99%

In vivo production and molar percentages of volatile fatty acids in the rumen: a quantitative review by an empirical approach

Nozière

Glasser

Sauvant

2011

Animal

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“…Results underlined the fairly good capacity of the Lescoat & Sauvant (1995) model to predict starch digestion in the rumen and ruminal pH. The duodenal flow of microbial N was best predicted by the CNCPS model .…”

Section: Comparison Of Mathematical Modelsmentioning

confidence: 75%

“…More recently, Offner & Sauvant (2004) performed a comparison of three models (Baldwin et al, 1987b;Lescoat & Sauvant, 1995;Russell et al, 1992) on their ability to predict various ruminal parameters and digestive characteristics with observed experimental data covering a wide range of feeding situations. Results underlined the fairly good capacity of the Lescoat & Sauvant (1995) model to predict starch digestion in the rumen and ruminal pH.…”

Section: Comparison Of Mathematical Modelsmentioning

confidence: 99%

Mathematical models in ruminant nutrition

Tedeschi

Fox

Sainz³

et al. 2005

Sci. agric. (Piracicaba, Braz.)

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Mathematical models can be used to improve performance, reduce cost of production, and reduce nutrient excretion by accounting for more of the variation in predicting requirements and feed utilization in each unique production situation. Mathematical models can be classified into five or more categories based on their nature and behavior. Determining the appropriate level of aggregation of equations is a major problem in formulating models. The most critical step is to describe the purpose of the model and then to determine the appropriate mix of empirical and mechanistic representations of physiological functions, given development and evaluation dataset availability, inputs typically available and the benefits versus the risks of use associated with increased sensitivity. We discussed five major feeding systems used around the world. They share common concepts of energy and nutrient requirement and supply by feeds, but differ in structure and application of the concepts. Animal models are used for a variety of purposes, including the simple description of observations, prediction of responses to management, and explanation of biological mechanisms. Depending upon the objectives, a number of different approaches may be used, including classical algebraic equations, predictive empirical relationships, and dynamic, mechanistic models. The latter offer the best opportunity to make full use of the growing body of knowledge regarding animal biology. Continuing development of these types of models and computer technology and software for their implementation holds great promise for improvements in the effectiveness with which fundamental knowledge of animal function can be applied to improve animal agriculture and reduce its impact on the environment. Key words: cattle, feeding, nutrient, requirement, supply MODELOS MATEMÁTICOS NA NUTRIÇÃO DE RUMINANTESRESUMO: Modelos matemáticos podem ser utilizados para melhorar a performance, reduzir os custos de produção, e minimizar a exceção de nutrientes através de melhores estimativas da exigência e utilização de alimentos em vários cenários produtivos. Modelos matemáticos podem ser classificados em cinco ou mais categorias dependendo da sua natureza. Um dos maiores problemas na construção de modelos matemáticos é o nível de agregação das equações. Os passos mais importantes são o estabelecimento do propósito do modelo, determinação da melhor combinação de equações empíricas e teóricas para representar das funções fisiológicas dado a disponibilidade de banco de dados, informações tipicamente encontradas a nível de campo, e os benefícios e riscos associados com o uso do modelo na produção animal. Nesse artigo são discutidos cinco sistemas de alimentação padrão de ruminantes mais utilizados atualmente. Eles compartilham de conceitos de exigência e disponibilidade de energia e nutrientes, mas diferem na estrutura e como esses conceitos são abordados. Modelos animais podem ser utilizados para vários propósitos, entre eles uma simples descrição de observações, estimativa...

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“…for modelling intake [19], digestion and metabolism [3,13,27], reproduction [5] or growth [18,20]). In herd models, not all of these mechanisms are required.…”

Section: Models Of Physiological Functions Within a Multi-agent Simulmentioning

confidence: 99%

Modelling the performance of the beef cow to build a herd functioning simulator

Agabriel

Ingrand²

2004

Anim. Res.

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-This review deals with the representation of the individual animal in herd scale models for cattle. One main problem in these models is to connect two levels of complexity: herd functioning at the farm level and functioning of the individual animal when physiological processes are considered. The text deals first with the representation of the animal and its physiological functions within existing models. Different physiological functions (i.e., growth, intake, lactation and breeding) are rarely modelled in a mechanistic way when used at the herd level, but mostly on an empirical basis, according to classic mathematical laws. The breeding function is the most important one (since it allows for herd renewal) and is frequently modelled as a stochastic process. The body condition score is a relevant indicator of the cow's status, which requires a better representation in individual-based models. Some herd models are presented and discussed and some proposals are presented for a herd functioning model for beef cattle taking into account both animal performance and decisional processes.cattle / herds / cow model / herd models Résumé -Modéliser la performance de la vache dans un simulateur de fonctionnement de troupeau allaitant. Cette revue rassemble les différentes manières d'envisager la représentation de l'animal au sein des modèles de simulation de troupeau. Un des problèmes majeurs est en effet de bien faire correspondre deux niveaux de complexité potentielle : celle du fonctionnement du troupeau au sein de l'exploitation agricole, et celle du fonctionnement de l'animal selon la finesse de description des mécanismes biologiques. Ce texte envisage d'abord la manière dont l'animal et ses différentes fonctions physiologiques sont prises en compte dans les modèles existants. Les fonctions de l'animal (croissance, ingestion, lactation) sont rarement modélisées de façon mécaniste, mais plutôt sur la base d'ajustements empiriques selon des lois mathématiques classiques. La reproduction a une place prépondérante car elle gère la dynamique du troupeau simulé. Elle se modélise le plus souvent de façon stochastique. La note d'état est un indicateur fiable des performances individuelles de la vache qu'il faudrait bien savoir représenter pour développer de meilleurs modèles individuels. Ensuite, les modèles développés à l'échelle du troupeau sont présentés et discutés, pour au final, formuler des propositions pour le développement d'un simulateur individu centré intégrant la modélisation du fonctionnement de l'animal en relation avec les décisions de l'éleveur.bovins allaitants / troupeaux / modèle vache / modèle troupeau * Corresponding author: aga@clermont.inra.fr 348 J. Agabriel, S. Ingrand

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Development of a mechanistic model for rumen digestion validated using the duodenal flux of amino acids

Cited by 56 publications

References 37 publications

In vivo production and molar percentages of volatile fatty acids in the rumen: a quantitative review by an empirical approach

In vivo production and molar percentages of volatile fatty acids in the rumen: a quantitative review by an empirical approach

Mathematical models in ruminant nutrition

Modelling the performance of the beef cow to build a herd functioning simulator

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