This research was carried out to evaluate the effect of different levels of concentrate in the diet on the contents of dry matter (DM), neutral detergent fiber (NDF), acid detergent fiber (ADF) and crude protein (CP) of the digesta, in the distinct sections of the gastrointestinal tract (GIT) of the dairy calves. Thirty-two young bulls were used, half Holstein and the other half crossbred Holstein-Zebu, were slaughtered with an average age of six months and 190 kg LW final after fasting of 16 h. The diets, ad libitum fed, were constituted of coast-cross hay and different dietary concentrate levels (ground corn, soybean meal, limestone and mineral salt), levels: 45.0, 60.0, 75.0 and 90.0% . There were no differences between Holstein calves and crossbred Holstein-Zebu in this study. The DM content in the reticulum-rumen and small intestine did not differ; in the large intestine there was a crescent linear effect, and in the omasum and abomasum, a quadratic effect on the concentrate levels in the diet. The NDF and ADF contents maintained constant in the reticulum-rumen, and in the other sections of GIT there was a crescent linear effect. In the reticulum-rumen and large intestine, the CP contents maintained constant; in the omasum, abomasum and small intestine there was a crescent linear effect, and the highest CP contents were found in the small intestine.
dairy calf; concentrate level; nutrient; gastrointestinal tract
