Fibrolytic enzyme supplements for increasing the digestibility of legume forages and grain feeds for ruminants, a method of treating legume forages and grain feeds with fibrolytic enzymes, and feed compositions consisting of feed materials treated with a mixture of fibrolytic enzymes are provided. The enzyme supplements do not pre-digest the feed material but assist in the colonization of feed particles in the rumen by ruminal microbes. The fibrolytic enzyme supplements consist of mixtures of cellulase and xylanase in certain preferred ratios and levels which are dependent on the feed material to be treated. The cellulase and xylanase are dissolved in a buffer solution and sprayed onto dry legume forages or grain feeds. The feed material is then incubated for at least three hours to allow the enzymes to be absorbed into and adhere to the feed material. The resulting feed compositions remain stable for at least one year against predigestion. When cellulase and xylanase are applied to legume forages and grain feeds in certain ratios, levels and in accordance with the methods of the present invention, synergistic effects between the enzymes occur, providing large improvements in digestibility of feed materials at low enzyme levels.