Tall Wheatgrass and Western Wheatgrass Used for Complementary Cool‐Season Forage Systems

Core Ideas Western wheatgrass provides greater individual animal gain potential than tall wheatgrass in the spring. Deferred grazing of rangelands can potentially reduce late season animal performance. Native rangelands with a significant cool‐season grass component provides high early season animal gain potential similar to complementary cool‐season forage.Seeded monocultures of tall wheatgrass [ Thinopyrum ponticum (Podp.) Z.‐W. Liu & R.‐C. Wang] and western wheatgrass [ Pascopyrum smithii (Rydb.) Á. Löve] have demonstrated good yield potential and persistence in plot studies within the southern Great Plains region. These cool‐season grasses have potential to serve as a complementary forage in a grazing system with warm‐season dominated mixed‐grass rangelands, but few studies have included their use under such systems to provide animal data. Multiparous cows with calves at side were stocked on one of three replicated grazing systems: (1) native mixed‐grass rangelands from April to October [NR‐only], (2) seeded tall wheatgrass from April to mid‐June followed by native mixed‐grass rangelands from mid‐June to October [(TW)NR], or (3) seeded western wheatgrass from April to mid‐June followed by native mixed‐grass rangelands from mid‐June to October [(WW)NR]. Cows grazing native rangelands or western wheatgrass typically had greater spring body weight gain than cows grazing on tall wheatgrass. Spring calf gains on the native rangeland system were similar to calf gains on western wheatgrass, but were greater than calf gains on tall wheatgrass. For the total growing season, cows only on native rangeland had greater total body weight gain than the western wheatgrass and tall wheatgrass complementary systems in two and three of the five years, respectively. Calf body weight gain for the entire growing season was similar in most years. Deferred grazing in the native rangeland portion of the complementary cool‐season grass systems allowed indigenous western wheatgrass composition to increase over time. Benefits of the seeded cool‐season grasses were masked by the deferred grazing of the native rangeland component and the relatively high beginning proportion of indigenous western wheatgrass in the native rangeland‐only system.