Cogon grass, a weed occasionally used as livestock feed has a limited nutritive value. Improving the utilization of low quality roughages could be by treatment with nitrogen sources, chemical and physical treatment .Thus an experiment was conducted to assess the voluntary intake and digestibility in vivo of cogon silage and urea-treated corn stover as affected by varying ratios of concentrate: Ipil-Ipil leaf meal (ILM) supplementation in goats. The experiment was setup in a Randomized Complete Block Design (RCBD) with four (4) blocks based on sex-period combination with a 2x3 factorial treatment design: factor A with two types of base forage (cogon silage, urea-treated corn stover), and factor B with three (3) ratios of concentrate: ILM as supplement (1.25:0; 0.75:0.50 and 0.50: 0.75 %BW, DM basis). Results revealed a comparable voluntary intake and in vivo digestibility of cogon grass silage and urea-treated corn stover across three types of supplements, and among supplements across types of basal diet. Interaction between kind of basal diet and type of supplement was not significant. It is, therefore advantageous to mix ILM with concentrate at 0.75%:0.50% BW or 0.50:0.75% BW ratio, DM basis, as supplement to either cogon silage or urea treated corn stover rather than given an all-concentrate supplement at 1.25% BW, DM basis, to save on feed cost.