The in sacco method prediction of the degradation of dietary components in the rumen

Abstract

The "in sacco" method has been widely used to predict feed nitrogen degradation in the rumen. Similar predicting equations have been obtained from several comparisons of "in sacco" and "in vivo" data, validating this method for such use. The use of this method can, however, introduce a bias in the classification of feeds according to the amount of degraded feed nitrogen of the samples in the bags, due to sample processing, microbial colonisation of bag residues, and the difficulty of considering soluble and undegraded nitrogen fractions.

This "in sacco" method has also been used to describe other application fields, such as predicting starch rumen digestion, fill value of forages, or digestive interactions in the rumen. But comparisons of the "in sacco" and "in vivo" data are few, therefore hindering the validation of the "in sacco" method. The modification of the fineness of the sample may be at the origin of a bias when classifying the feedstuffs according to their starch and cell wall degradability in the rumen.