Four grams substrate, 100 ml buffer and 50 ml of rumen fluid filtered through cheesecloth were incubated in a water bath (39 C) for 4 hours. Gas produced was measured every 30 min by a water displacement apparatus. All determinations were in triplicate. Ground sorghum grain was used as the control substrate. Coffee grounds replaced ground sorghum grain at concentrations of 5, 10, 25, 50 and 100%.