Comparison of markers and collection methodology for fecal production and digesta flow estimates in bovine

It was aimed to compare the internal markers, indigestible neutral detergent (NDFi) and acid fiber (ADFi), and ADFi with chromic oxide to estimate the dry matter fecal production and nutrients digestibility of bovine diets, in two collections schemes (2 or 6 days). For the comparison among internal markers, 32 Nelore growing bulls, with 240 kg, were maintained under feedlot, receiving diets with different concentrate levels (20, 40. 60 and 80%). For the comparison among internal and external marker, five 165 kg Nelore growing bulls, fistulated in the rumen, abomasum and ileum, were used. The design was in blocks with four treatments and five collection periods. The treatments consisted of four concentrate levels (20, 40. 60 and 80%). The roughage used was Tifton 85 bermudagrass hay. The apparent digestibility of dry matter (DM) was smaller, when was estimated by oxide chromic, however DM digestibility in the rumen and intestines did not differ among markers. When the collection methodology was compared (6 days vs. 2 days), there was no difference for all studied variables, showing that the alternative methodology (2 days of colleciton) can be used with safety for the estimates of fecal production and DM flows in the abomasum and ileum.