Prediction of rumen passage rate of neutral detergent fiber (NDF)

The “Voeding op Maat” project investigates whether 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, Fiber (NDF), sugar) in the rumen. The present report investigates the prediction of the passage rate of potential rumen fermentable NDF (Kp-D-NDF) through the rumen. This was done by fitting different models to a dataset of digestion experiments. The dataset consisted of data from scientific literature of experiments in which the rumen fermentation of NDF was measured on European rations. The models tested examined the influence of various factors (Kd of NDF, feed intake, forage vs. concentrate and concentrate ratio) on the prediction of Kp-D-NDF. The model that takes into account the effect of feed intake provided the best prediction of the Kp-D-NDF. However, that model produces unexpected results at higher feed intakes. The present report can serve as a basis for further decision making on how to build an improved DVE model.