Intact and steam-flaked grains of maize, wheat and rice (with whole hulls) were analyzed for chemical composition, starch gelatinization degree (SGD) and in vitro fermentation characteristics to investigate the influence of cereal type and steam-flaking (SF) processing on their nutritive values. The treatments were arranged in a 3×2 factorial design. Obvious differences (P<0.001) in chemical composition and energetic values were observed among the different cereal types. SGD and gas production (GP) rate was significantly increased (P<0.001) by SF processing. SF processing also increased (P<0.01) the proportion of propionic acid and decreased the acetic:propionic acid ratio in vitro. Steam-flaking also increased organic matter digestibility and the energetic value of the cereal grains, especially rice. Based on these results, rice probably is more amendable to SF processing than maize and wheat. In conclusion, it is feasible to partially substitute maize grain with wheat or rice in ruminant diets, and steam-flaking can significantly improve the nutritional value of wheat and rice grains.