This research was carried out to evaluate the intake, total and ruminal digestibilities, microbial efficiency synthesis, nitrogen balance (NB) and ruminal parameters of beef heifers, fed sugarcane treated or not with calcium oxide (CaO - 1.0%) and different concentrate levels (CL), in feedlot. Six animals (170.0 kg BW) were allotted to a 6 × 6 Latin square design in a 2 × 3 factorial arrangement (sugarcane in nature treated or not with 1.0% CaO and three CL 0.0, 0.5 and 1.0% BW). No interaction was observed between forage and CL for nutrients intake and total digestibilities. With exception for DM and NDF intakes (% BW) and of EE and NDF total digestibilities, sugarcane treated with CaO prejudice the intake and digestibility of others nutrients. NDF intake was unaffected by CL, however the intake of the other nutrients showed a positive linearly behavior as CL increased. The total apparent digestibilities of nutrients linearly as CL increased. Ruminal digestibilities were unaffected by sugarcane treated with CaO. The increase of CL showed a positive linear behavior for DM, OM, CP, NDF ruminal digestibilities. There was no effect of sugarcane treated or not CaO on microbial nitrogen and microbial DM, which increased as CL increased in the diet. The lesser nitrogen retention was observed in animals fed sugarcane treated with CaO. Sugarcane treated with 1.0% CaO, fed after 24 hours of storage, prejudice the intake of most nutrients. Nitrogen balance and CL up to 1.0% BW improve DM intake, digestibility of most nutrients and nutrient balance.
digestibility; intake; microbial efficiency; pH; ruminal ammonia
