Deliverable D3.2 A simulation model to evaluate the digestive use of compound feeds and nutrients in monogastric animals

Regarding the context of animal production, monogastric livestock systems have to be more sustainable. For this, an increase in the efficiency of feed utilization is necessary. This requires a better understanding and prediction of the nutritional value of the feeds. Many experimental data provide the digestibility of nutrients in various conditions. However, very few studies describe the digestive mechanisms along the digestive tract and for all the nutrients contained in the diet. However, it seems very important to be able to identify the reasons why a diet is digested more efficiently than another and what the causes of differences in digestibility are in the digestive system. Consequently, a modeling approach seems a good way to integrate information available, be able to represent the digestive processes and predict the digestibility. 

The work performed aimed at developing a model representing the transit, hydrolysis, fermentation and absorption/excretion of the main nutrients along the digestive tract. A similar structure was adopted for pig and poultry and only selected model parameters were adapted for each species. Parameters for pigs come from existing models and were then modified for the broiler based on biological knowledge and literature data. The transposition of a digestive model for pigs to a broiler has been done step by step to preserve the genericity and make only those modifications that are really needed. Modifications were driven either for biological reasons or to improve the predictive capacity of the model. For now, a generic model has been developed for growing pigs and broilers.

Objectives

The aim of the project was to develop a generic, dynamic and mechanistic model to represent transit and digestion in pigs and poultry and to integrate factors of variation of the nutritional value of feed in complex diets fed to animals at different physiological stages.

Rationale

Modelling is an appropriate tool to integrate knowledge, to represent biological mechanisms and to test hypotheses. It is also a very useful approach to understand how a biological system works and to predict responses of animals in various conditions (e.g. species, physiological status, diet composition). Several models have been developed to represent the digestive process in pigs but this type of model is scarce in poultry. Considering many similarities in feeds used for both species and that the main digestive functions can be represented in a same way, it seemed logical to use the same generic model concept to be able to carry out comparative studies on the digestive use of feeds and nutrients.