The experiment was carried out to study the effects of fiber levels (38.7 and 57.2% NDF), composed of elephantgrass silage and chopped sugarcane and two protein sources, a high (soybean meal) and low (blood meal and corn glúten meal) ruminal degradable protein, on the ammonia nitrogen concentration (N-NH3) and on the ruminal pH of steers. Four rumen fistulated Brow-Swiss steers, with 316 kg of average initial weight, were randomly allotted to a 4 x 4 Latin square design. The steers were full fed diets containing two levels of fiber and two sources of protein with different ruminal degradable protein. The highest means of N-NH3 concentrations in the ruminal fluid were observed with the diets with soybean meal as protein source, independently of the fiber level, with values of 0.18 mg of N-NH3/mL of ruminal fluid. The minimum values of N-NH3 in the ruminal fluid were appropriate to the microbial growth in all the experiment diets. The smallest mean of pH value in the ruminal fluid was observed in diets with low fiber, with value of 6.27, and the minimum value of pH in the ruminal fluid was in the range of maximum microbial growth, as well as maximum ruminal digestion, in all the experimental diets.
concentration; fiber; levels; nitrogen ammonia; protein; pH; sources; steers
