Comparison of laboratory methods for determining forage digestibility

Digestibility of the organic matter of forage can be estimated by different laboratory methods (in vitro): digestion with rumen fluid or with cell-free fungal cellulase, development of regression equations to predict digestibility from chemical composition. The objective of this article was to compare the in vitro digestibility of four different laboratory methods with the digestibility, which has been determined with sheep (in vivo). Digestibility, measured by the technique using rumen fluid, correlated best with the in vivo digestibility. Established equations for the prediction of the digestibility using the content of cell wall and phenolic compounds were also comparable with in vivo digestibility. The replacement of rumen fluid by cellulase corresponded less with the in vivo digestibility.