Twenty four Hanwoo bulls(mean initial body weight 1628.1kg) were employed to induce the regression equations on body weight gain and dry matter intake. The diets were fed in a 34 factorial arrangement; three roughage sources(rice straw, hay, corn silage) and four roughage ratios in ration(100, 60, 40, 20%). Bulls were alloted by incomplete turn over design with four replications. Daily body weight gain was greatest in bulls fed the corn silage as a roughage source and the 20% of roughage ratio, respectively. Bulls fed hay or corn silage only as feed kept in their body weight gain during the whole experimental period, however those fed rice straw only were in a negative body gain hereafter fatteningⅠperiod(350kg of body wt.). Dry matter intake per metabolizable body weight was decreased with increasing body weight. Dry matter intake was greatest in bulls fed the corn silage as a roughage source and the 20% of roughage ratio, respectively. The regression equations on daily body weight gain(DG, kg) and dry matter intake(DMI, kg/day) according to body weight(BW, kg) of Hanwoo bulls were derived as follows; DG = －0.842 + 17.5DMI/ DMI = 4.125 + 0.013BW + 1.075DG － 0.045NDF where, NDF is the percentage of neutral detergent fiber in ration.