The objectives of this work were to evaluate the effects of five dietary concentrate levels (25,0; 37,5; 50,0; 62,5 and 75,0%) on the efficiency of microbial synthesis, the ruminal ammonia concentrations and pH, nitrogenous compounds balance, and the digest passage rate. Five rumen, abomasum and ileum fistulated F1 Limousin x Nellore bulls, with an average initial body weight of 279 kg, were used in a 5 x 5 Latin square design. Ruminal liquid samples were obtained before and 2; 4; […]