Abstract: We used four ruminally cannulated steers (350±3 kg) to evaluate the effect of season on chemical composition, intake, kinetic, digestibility and ruminal fermentation of diet selected during grazing. Data were analyzed as a randomized complete block design with months as the block and season of year as treatment. Time-sequence data than pH, ammonia Nitrogen (NH3N) and Volatile Fatty Acids (VFA) were analyzed as repeated measures within a randomized block design. The Dry Matter Intake (DMI), Organic Matter Intake (OMI), Digestible Energy (DE), Metabolizable Energy (ME) and passage rate (Kp) of diet were affected by season (p<0.05). The Crude Protein (CP) and NH3N concentration were higher in the rain season (p<0.01). The content of NDF was different in seasons (p<0.01). Similar, acetate, propionate and butyrate concentrations were different (p<0.01). Changes in chemical composition, intake, kinetic, digestibility and ruminal fermentation observed in this study appeared to be related to season.