This study aimed to evaluate the digestibility and nitrogen balance (NB) of lambs fed sugarcane hydrolyzed under different conditions. Fifteen Ile de France lambs at, on average, 23.5kg of body weight were evaluated. Treatments were: in natura sugarcane (IN), sugarcane hydrolyzed using 0.6% calcium oxide (CaO) under aerobic condition (AER), and sugarcane hydrolyzed using 0.6% CaO under anaerobic condition (ANA). Therefore, a completely randomized design was constituted with five replicates per treatment. Treatments were supplied to animals along with concentrate. Both hydrolysis conditions aimed to alter the sugarcane fermentation pattern, therefore improving fiber digestibility. Lambs were housed in individual pens and fed with diet allowing 10% of refusals. Refusals, feces and urine were sampled daily during five days. They were collected to determine the digestibility and NB. A higher digestibility of neutral detergent fiber corrected for ash and protein (57.05%), organic matter (85.39%), hemicellulose (72.09%), NB (29.46g day-1 and 2.78g kg-0.75 day-1) and rate of nitrogen absorbed (3.00g kg-0.75 day-1) were observed for lambs fed with ANA than for those fed IN (41.17%, 73.76%, 53.80%, 21.39g day-1, 2.00g kg-0.75 day-1 and 2.22g kg-0.75 day-1, respectively). As roughage, ANA in the lamb diet, optimizes the nitrogen balance and is more efficient to improve the digestibility of some nutrients compared to IN. Whereas AER was as efficient as ANA and IN
