This study evaluated the effects of varying proportions of finger millet (Eleusinecoracana) and pearl millet (Pennisetumglaucum) straw silage, supplemented with poultry litter, on the chemical composition, nutrient intake, digestibility, and nitrogen utilization of growing Yankasa rams. Five experimental diets were formulated by substituting finger millet straw with increasing levels of pearl millet straw at 0, 18.75, 35.5, 56.25, and 75%, while maintaining poultry litter as a constant basal supplement. Chemical analysis revealed that dry matter and fiber fractions (crude fiber, acid detergent fiber, and neutral detergent fiber) increased progressively with higher pearl millet straw inclusion, while crude protein and ether extract contents declined. Nitrogen-free extract (NFE) peaked at moderate inclusion levels (T2 and T3) before decreasing. Nutrient intake and digestibility were significantly (P < 0.05) influenced by dietary treatments; rams fed moderate inclusion levels exhibited superior feed intake and nutrient digestibility. Nitrogen balance data indicated improved retention and utilization efficiency in rams fed the T2 and T3 diets, whereas higher inclusion levels (T4 and T5) increased nitrogen loss and reduced retention. In conclusion, incorporating pearl millet straw silage at 18.75–35.5% in combination with poultry litter enhances nutrient utilization and performance in growing Yankasa rams. Conversely, excessive inclusion levels reduce diet quality due to elevated fiber content and diminished protein availability. For optimal performance, a pearl millet straw inclusion level of 18.75–35.5% is recommended.