Prediction of the rumen passage rate of dietary starch

The “Voeding op Maat” project investigates if and how the current protein feed evaluation system for dairy cattle (the DVE system) can be improved. In the DVE system, the degradation (Kd) and passage (Kp) in and through the rumen are important parameters for predicting the fermentation of the different components (e.g. Protein, Starch (ST), Fibers, Sugar) in the rumen. The present report investigates the passage rate of potentially rumen-fermentable starch (Kp-D-ST) through the rumen and the degradation rate of washable starch (Kd-W-ST) in the rumen. This was done by fitting different models to a dataset of digestion experiments. The dataset consisted of data from the scientific literature of experiments in which rumen fermentation of ST was measured for European diets. The tested models examined the influence of different factors (feed intake, forage vs. concentrate, concentrate ratio, and starch particle size) on the prediction of Kp-D-ST and Kd-W-ST. This study found that simple models had a better goodness-of-fit than more complex models. This report can serve as a basis for further decision-making regarding the updating of the existing DVE system.