Abstract
Five native grasses and one sedge of the Stipa-Bouteloua prairie, three introduced grasses collected at five stages of growth, and four shrubby species collected at three stages of growth were analyzed for proximate chemical constituents.The amounts of phosphorus and digestible and crude protein of all species decreased with maturity, while the cellulose increased. Introduced grasses generally contained more crude protein than native grasses. Shrubby species were higher in crude protein and phosphorus than native grasses. No consistent trend was observed in relative total ash and calcium content at progressive stages of development. The estimated nutritive value index was high for all grasses and low for two Artemisia species. The seasonal declines in crude protein and phosphorus suggest that protein and phosphorus supplements are desirable for range cattle during the fall, winter, and early spring.