model

evaluation

intake regulation

Prediction

body condition score

dairy cows

The objective of this work was the evaluation of a feed intake regulation model for dairy cows described in a previous paper. Sensibility analysis revealed that the model is sensible mainly to those parameters defining the upper limit of NDF rumen digesta. The level of sensibility varies with the energy content of the diet evaluated and with the time in the lactation cycle where the sensibility analysis is done. A total of 17 treatments from a series of experiments were used to compare experimentally observed feed intake and body condition score (BCS) of dairy cows with model predictions of these variables. Feed intake, either throughout the whole lactation period or as an average for a certain period of it, is predicted by the model with an acceptable degree of accuracy for most of the treatments. Typical curves of feed intake are predicted by the model for most of the treatments. Accuracy of prediction of BCS depends on the treatment being evaluated. However, losses of BCS are predicted at the beginning of the lactation period followed by a gradual increase in BCS. The interplay between energy transactions and rumen digesta load constitutes an acceptable framework on which mechanistic models of feed intake regulation can be developed.