This trial evaluated the inclusion of glycerin in high concentrate diets as an ingredient is able to of reducing ruminal metabolic problems. Sixty Nellore cattle (initial BW of 300 ± 50kg) were used in a completely randomized block. Diets consisted of corn silage, corn, crude glycerin (83% glycerol), urea, sunflower meal, soybean hulls and mineral. Finishing diets presented 15% of roughage and 85% of concentrate. The crude glycerin derived from vegetable used is soybean oil and 30% was included in the diets of DM. Four treatments were used: glycerin during adaptation step up and finishing period (1) or glycerin just during adaptation period (2); absence glycerin during adaptation and finishing period (3) or absence of glycerin during adaptation and finishing period (4). The animals were housed in individual pens with free access to water. The diets were offered twice daily at 0800 and 1600h. Hepatic abscesses incidence (HAI) was determined according the presence and severity. At harvest rumenitis incidence (RI) was determined, on the entire washed rumen, using a scale of 0 (no lesions noted) to 10 (severe ulcerative). A fragment of 1 cm² of each rumen was collected from ventral sac. Manually, the number of papillae per cm² of rumen wall (NOP) was determined and 10 papillae were randomly collected from each fragment; scanned, and mean papillae area (MPA) in cm² was measured by software for image analysis. RASA in cm² was calculated as follows: 1 + (NOP*MPA) – (NOP*0.002). The data were analyzed using GLM procedure of SAS statistical software 9.2 and were compared the means by Tukey’s test (5%). No significant (P > 0.05) effect was observed for RI, HAI, MPA and NOP between diets, however there are difference for ASA and PSA (P < 0.05). Diets without glycerin during adaptation showed reduction on absorptive surface area per cm² of rumen wall and lower participation of rumen papillae in the total area of absorptive surface (%). Use of glycerin during adaptation led to greater development of ruminal epithelium, which may represent a new technology to control rumen acidification.