Summary The addition of at least 200lb. of nitrogen per acre to bromegrass and orchardgrass increased the crude protein, TDN, and gross energy above that of the bromegrass and orchardgrass fertilized with no more than 25lb. of nitrogen per acre. This high rate of application also significantly increased the apparent digestion coefficients of protein and energy of the bromegrass and orchardgrass rations above those of the low-N rations. The apparent digestion coefficients of fiber of the grasses were significantly increased above those of the comparison roughage alfalfa. These hays were fed to dairy heifers during two digestion trials. The addition of 15g. of urea per pound of orchardgrass hay which was not fertilized with nitrogen resulted in the low-N hay having a protein equivalent equal to the protein content of the high-N hay. The apparent digestion coefficients of the protein and fiber, and TDN of the low-N-plus-urea ration were not only significantly greater than the low-N ration but were significantly greater than the high-N and alfalfa rations. The application of nitrogen as a fertilizer to bromegrass, or as a feed component in the form of urea to orchardgrass hay, increased the apparent digestion coefficients of protein and fiber, and the TDN of the hay rations.