Dry matter digestibility of roughages and concentrates determined “in vitro” procedures

Abstract

The aim of this work was to compare the values of in vitro dry matter digestibility of six classes of concentrates and roughages feeds, determined by the two-stage technique carried in individual digestion tubes or using an automatized equipment of fermentation (filter bag technique, FBT). In the second digestion stage of the technique it was also evaluated the effect of pepsin acid solution and the reflux with neutral detergent solution on the in vitro dry matter digestibility. For both studies the experimental design was completely randomized with a 2 x 6 factorial arrangement (in vitro procedures x food classes). The IVDMD values determined in tubes were close to those found by others authors and lower than those obtained by the filter bag technique. Standard deviation of in vitro dry matter digestibility means were, in general, lower when the individual tubes method were used. The procedure using reflux with neutral detergent was less expensive and time-consuming, and yield similar results when compared to those using the acidified pepsin digestion methodology. The apparent overestimated values of in vitro dry matter digestibility observed in the filter bag technique suggests that the recommendation of the automatized equipment will be dependent of new studies, with emphasis to the material used to make the incubation bags.