Digestibility and energy value of maize silage : laboratory methods for prediction

Abstract

The aim of this paper is to evaluate the methods available at the present time in French laboratories that predict the nutritional quality of maize forage for feeding or selection. The equations suggested at the 1966 Nantes congress by INRA-Theix using pepsine cellulase digestibility associated to crude protein are at the present time the most precise for predicting the net energy value of the whole maize plant for feeding. However half of the total variation of the "in vivo" digestibility is not explained by these relations. The narrow relationship between "in vivo" organic matter digestibility and undigested cell wall contents illustrates the weight of nutritional cell wall quality. The prediction of cell wall quality with the help of the DINAG and DEPAR criteria is described. In selection, these two criteria are very interesting for the prediction of "in vivo" cell wall digestibility, even though they are less precise than enzymatic dry matter digestibility for the prediction of "in vivo" organic matter of the whole maize plant. At the present time, the interest of these criteria for the prediction of indigestibility is being investigated at INRA.