Feed intake, pH, and ruminal ammonia concentration were evaluated in four goats in which omasal digesta was collected by ruminal fistula in order to estimate the ruminal digestion of nutrients. The urinary total nitrogen compounds (N) and the concentrations of N-urea in serum (NUS), milk (NUL), and urine were evaluated in 12 goats assigned to three 4x4 Latin squares. The animals were fed rations composed of 50% of maize silage and 50% of concentrate, containing 11.5, 13.5, 15.5, and 17.5% of crude protein (CP) in the dry matter. With the exception of protein, the intake and total digestibility of the other nutrients were not influenced by the dietary CP levels. Ruminal pH was reduced in the post-prandial period. As the N intake increased, ruminal concentration of ammonia, NUS and NUL concentrations, urinary volume the N balance increased. It was concluded that the level of 13.5%, or 245 grams of CP, is sufficient for goats producing 1.6kg per day and that the method of omasal digesta collection needs to be evaluated in more detail for its validation in goats.
goat; digestion; lactation and nitrogen compounds
