It was aimed to study the efficiency of microbial synthesis and ruminal parameters in bovine. It were used five 165 kg growing no-castrated Nellore bulls, rumen, abomasum and ileum fistulated.A randomized blocks design with four treatments and five collection periods was used. The treatments consisted of four concentrate levels (20, 40, 60 and 80%). The roughage used was Tifton 85' (Cynodon dactylon (L.) Pers.) Bermudagrass hay. The diets were isonitrogen with 15% of crude protein. The microbial marker used was purine basis. The averages for total compound nitrogen in the abomasum and microbial nitrogen were 68.58 and 60.75 g/day, respectively. The amount total rumen carbohydrates degraded (CHODR) was 1.37 kg/day. It was observed for microbial efficiency 392.4 g DM microbial/kg CHODR. The bacterial composition and efficiency microbial synthesis were not affected by the concentrate level of the diets.
concentrate levels; microbial production; ruminal parameters
