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Construction and evaluation of a digestive model (Systali project)

The Systali project (CI) mobilizes 5 teams including the Joint Research Unit MoSAR, which has 6 participants in the project. MOSAR has contributed with the following: 1) the construction of three large databases on digestion and nutrition of ruminants, 2) their interpretation by meta-analyzes, 3) integration of hundreds of regression equations into a mechanistic model of digestion, 4) half of these equations built into a program called “Systool” for calculating energy and protein values of rations from INRA feed tables, 5) these calculations provide feedback to reassess feed requirements and build nutrient responses to diets.

Cows in a stable. © INRA
By Sylvie André
Updated on 01/13/2015
Published on 01/13/2015

Context and challenge: The feed unit systems must be periodically revised in a more or less complete way in order to incorporate the latest research results and to meet the needs of farmers and industries. Thus, new challenges have accumulated in recent decades: maximizing feed efficiency, minimizing releases of certain components capable of altering the environment (N, P , CH4 ... ), providing products whose composition is adapted to their further transformation, improving health and welfare of animals, etc. Therefore, it was important to build new systems of feed units able to explain and predict the multiple responses of animals to dietary changes and feeding practices. For this, a new approach has been initiated, it consists in collecting and processing databases of many results in INRA laboratories or published in the literature.

Results: At the Joint Research Unit MoSAR three original databases were built: "Bovidig" based on the quantitative digestion in cattle (496 articles, and 2,136 treatments), "Rumener" based on calorimetric measurements on different types of ruminants (188 art and the 1193 tr), and the "Caprinut" base that includes results of the unit in goats or obtained from the literature (99 art and 471 tr). These bases were treated with meta-analyses to describe the main digestive quantitative phenomena.  Over 100 intra-experiment regression equations were extracted from these bases. At MoSAR , these equations have been incorporated into a mechanistic model of digestion in order to verify and ensure consistency. About half of the regression equations were included in the "Systool" program targeted to calculate UF values and PDI rations from INRA feed tables or from specific user data. Such a program is needed to integrate the phenomena of digestive interactions. The results of these calculations are being reintegrated into databases to reassess the energy and protein requirements of the animals and to determine their responses to dietary practices.

The main equations of the digestive model were presented at international conferences in 2013 (EAAP, Nantes; ISEP, Sacramento) and in various French meetings (3R congress; 2013 AFZ-INRA meeting). In addition, they have been the subject of publications that are currently in French, considering the main target users. English translations are in progress.

Perspectives: This contribution will allow progress towards further developments of the Systali project, which will be focused on the needs and animal responses.

The new proposed systems are intended not only for the French livestock sector but also for users in other countries of Europe and the World.

Scientific contact(s):


Sauvant D., Nozière P., 2012. Modèle intégratif du tube digestif intégrant les interactions digestives, les flux de nutriments d’intérêt et compatible avec les systèmes UF et PDI. Renc.Rech.Rum., 19, 181-184.

Chapoutot P., Nozière P., Sauvant D., 2013. "Systool", a new calculator for the new French "Systali" project. In: Book of abstracts No 19. 64th Ann. Meet. Eur. Fed. Anim. Sci., Nantes,France, 138.

Sauvant, D., Nozière, P. 2013, Integrative model of the digestive tract including the interactions involved in energy and protein digestion in Ruminants, 317-318.EAAP publication n°134.

Nozière P., Giger-Reverdin S., Chapoutot P., Sauvant D., 2013. Quantification des interactions digestives chez les petits ruminants, résultats préliminaires. Renc. Rech. Rum., 20, 41-44.

Sauvant D., Nozière P., 2013, Rénovation des unités alimentaires des ruminants : les principales relations utilisées pour le calcul des apports alimentaires. Renc. Rech. Rum., 20, 33-40.

Sauvant D., Nozière P., 2013. La quantification des principaux phénomènes digestifs chez les ruminants : les relations utilisées pour rénover les systèmes d’unités d’alimentation énergétique et protéique. INRA Prod. Anim., 26, 4, 327-346.

Sauvant D., Nozière P., 2014. A quantified review of the main digestive processes in ruminants: contribution to renewed energy and protein feed evaluation systems. Animal, submitted.