Experiments were conducted to determine: 1) the fermentation characteristics and in vitro dry matter digestibility (IVDMD) of corn (<i>Zea mays</i>) stover treated with different sources of N; 2) digestibility, N utilization and palatabi1ity in sheep fed corn stover treated with different N sources; and 3) fermentation characteristics and nutrient utilization by sheep of sorghum (<i>Sorghum bicolor</i> L., Moench) forage treated with urea an poultry litter. In a small silo study, corn stover was ensiled untreated or after treatment with 3% aqueous NH₃, 50% and 75% poultry litter, 5.8% urea alone or with 10% cattle waste, 1.5% urease powder or 5% soybeans (<i>Glycine max</i>), DM basis. All treatments resulted in substantial increases (P < .01) in CP of corn stover. Lactic acid was detected in substantial levels only in the stover which was untreated and treated with 50% poultry litter. Ammonia and urea treatments decreased NDF content of stover by 4 to 7 percentage units. Increases (P < .01) of IVDMD of 9 to 14 percentage units resulted from treatment with NH₃ or urea. Use of urease sources did not enhance IVDMD. / Ph. D.