Orientadora: Telma Teresinha Berchielli / Banca: Izabelle Auxiliadora Molina de Almeida Teixeira / Banca: Paulo Henrique Moura Dian / Resumo: Os objetivos foram avaliar diferentes formas de dosagem de indicadores (infusão contínua 24h, e duas doses diária de indicador) e verificar sua precisão e acurácia para estimativa do fluxo duodenal de matéria seca (MS), consumo de concentrado, consumo de volumoso, produção fecal e digestibilidade aparente da MS em bovinos. No experimento 1, seis animais receberam os indicadores Cr-EDTA e YbCl3 através de uma bomba de infusão contínua, via fístula ruminal durante seis dias de adaptação nos dois períodos de 17 dias, enquanto os outros seis animais receberam os mesmos indicadores em duas dosagens diárias (8h e às 19h). No experimento 2, doze animais receberam os indicadores Cr-EDTA, YbCl3, LIPE®LÍQUIDO, FDNi e FDAi, em duas doses diárias que foram utilizados nas estimativas do fluxo duodenal de matéria seca (MS) pelo método de único e duplo indicador. Os indicadores TiO2 e LIPE®LÍQUIDO foram utilizados para estimativa do consumo de concentrado, produção fecal, digestibilidade aparente e os indicadores internos, FDNi e FDAi para estimar consumo de volumoso, produção fecal e digestibilidade. No experimento 1, o delineamento utilizado foi inteiramente casualisado em parcelas subdivididas com dois tratamentos em dois períodos. No experimento 2, o delineamento foi o de blocos em parcelas subdivididas. As médias foram comparadas pelo teste tukey a 5%. No experimento 1 não foram observadas diferenças entre as formas de fornecimento dos indicadores (P>0,05). No experimento 2, a FDNi estimou o fluxo de digesta no duodeno e a produção fecal e o consumo de volumoso. A estimativa do consumo de volumoso através do FDNi e FDAi foram semelhantes ao observado (P>0,05). O TiO2 e LIPE®LÍQUIDO foram acurados na estimativa do consumo de concentrado / Abstract: The objectives of this study were to evaluate by two metabolism trials different ways to dose markers (by continuous infusion for 24 hours and by two doses of marker per day) and also to study the accuracy and reliability of differents markers to estimate duodenal flow of nutrients concentrate intake, roughage intake, fecal production and apparent digestibility of dry matter (DM) in cattle. Twelve crossbred heifers were used in both experiments with average body weight of 361.7kg ± 59 and approximately 24 months of age, cannulated in the rumen and duodenum. In experiment 1, six animals received the markers Cr-EDTA, YbCl3 by continuous infusion via ruminal fistula in two periods of 17 days, while the other six animals received the same markers in twice daily dosing (8 and 7hours). In experiment 2, animals received the twelve markers twice daily during the experimental periods. Markers Cr-EDTA, YbCl3, LIPE®LIQUID, iNDF and iADF were used in the estimation of duodenal flow of nutrients by the method of single and double markers. Markers TiO2 and LIPE®LIQUID were used to estimate concentrate intake, fecal output, digestibility of DM and internal markers, iNDF and iADF to estimate forage intake, digestibility and fecal production. In experiment 1, a split plot design was used with two treatments (supply), six replicates in two periods. In experiment 2, the experimental design was randomized blocks in split plots, where the markers were considered as treatments. In both experiments, the means were compared by Tukey test at 5%. In experiments 1, there were no differences between the ways to supply the marker (P>0.05). In experiment 2, the iNDF was the best variable to predict digest flow in the duodenum and fecal production. iNDF and iADF were not d significantly different when the average intake of roughage were compared with the observed. The TiO2 was not significantly different... (Complete abstract click electronic access below) / Mestre