Were evaluated sodium bicarbonate.-F1- and urea.-F2.- (two factors), each factor at two inclusion levels (F1 and F2: 0 and 1%), and its effect on intake and digestibility in rations with byproduct of the fermentative process of starches and / or molasses (mixture of yeast and unfermented material).-LD.-, sugarcane molasses and ammoniated sugar cane tops for lamb. Eight crossbred lamb (19.31±5.96 kg/lamb) was included in a 2x2 factorial in a 4x4 Latin square design. Treatments were combinations of LD (14% in T1, 13.8% for T2, T3 and T4) and molasses (26% in T1, 25.8% for T2, T3 and T4), with or without urea, and / or sodium bicarbonate to 1% w/u, and source of fiber were used 60 % of ammoniated sugar cane tops in all treatments. The supply of rations was gradually adjusted to 7% dry matter (DM) of body weight (28±8.66% rejection of the offer), digestibility was measured by total collection for seven days adaptation period preceded of seven day. Differences (p<0.01) for intake where intake had the highest T2 and T4 the lower (1239 vs 1066 gDM/animal/day) in the digestibility of organic matter (p<0.01) were found where T4 reached one 72% while the T2 was the lowest with 57.35%. The coefficients of digestibility of hemicelluloses, acid detergent fiber, neutral detergent fiber and were different (p<0.01) and were higher in the same T1. The results showed that T4 was the best treatment, urea and sodium bicarbonate can be used effectively with agro-industrial byproducts in lambs in confinement.