Nine ruminally cannulated Nellore steers (300.0 ± 30kg of BW and 18 ± 2 mo of age) were used in a 3x3 Latin Square experimental design to evaluate the effect of different sources of forage in diets with crude glycerin (80.64% of glycerol) on DM, CP, NDF and NFC intake and digestibility. The treatments were different sources of forage (fixed 15% of NDF from forage; fNDF): corn silage, sugar cane and sugar cane bagasse, in diets with 10% (DM) of crude glycerin. For this study intake, refusals and total feces collection were recorded for 3 d, experimental periods were 17 d (14 d for adaptation, 3 d for intake and total digestibility. Data were analyzed as a triple Latin square design with 3 treatments and 3 animals in 3 simultaneous triplicates using the PROC MIXED procedure of SAS. The least squares means were generated and compared (P < 0.05) using Tukey’s test. There was no difference on DM and CP intake among diets. On the other hand, the intake of NDF increased (P < 0.05) in animals fed corn silage which did not differ from animal fed with sugar cane bagasse. Furthermore, animals fed with sugar cane bagasse decreased NFC intake (P < 0.05). Animals fed with corn silage increased DM and NDF digestibility compared with the other diets (P < 0.05). Additionally, an increase on CP digestibility was observed in animals feed with sugar cane bagasse, which not differed from animals fed with corn silage (P < 0.05). NFC digestibility increased in animals fed with sugar cane (P < 0.05). Different sources of forage included in 15% of fNDF in diets with crude glycerin (10% DM) altered intake and digestibility.