Mathematical modeling of digestion and nutrient absorption in pigs

A simple simulation model of digestion and absorption in pigs was developed. The structure of the model is a set of four anatomical compartments for DM: stomach, two portions of small intestine, and the large intestine. In each of these anatomical compartments, subcompartments correspond to the major biochemical components of feed and their products of degradation. The major degradation and absorption events are considered as well as the effect of microbial activity in the large intestine. The total number of compartments is 44. The numerical integration with a time step of 1 min allows prediction of kinetic features of digestion phenomena such as absorption patterns and transit flows. First validation of the model shows that the global dynamic behavior of the model is realistic and promising. However, some additional factors must be considered for improved accuracy, in particular the susceptibility of the feed components to enzymatic degradation. The outputs of such a model could be used as inputs for metabolic or growth models running with time steps smaller than the 24-h basis often used in nutrition.