In order to estimate fecal production and digesta flow of cattle, three assays were carried out using indigestible NDF and ADF as internal markers, applying in vitro and in situ incubation procedures, as well as chromium oxide as an external marker. The experiment was a randomized block design in a factorial arrangement. Indigestible NDF and ADF contents exhibited high variation despite the methodology employed (in vitro or in situ). These results indicate that, eventually, 144-h incubation time does not reproduce the indigestible total fraction. The estimates of fecal production and duodenal digesta flow, calculated in function of the marker used, presented a variable behavior according to the roughage, which implies its effect on the marker concentration. Regarding important criteria involved in their determination, these internal markers can be used as predictors of the evaluated parameters.
ADF indigestible; chromium oxide; in situ incubation; in vitro incubation; markers; NDF indigestible
