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Evaluation of four intermediate wheatgrass populations under grazing

Moore, K.J., Vogel, K.P., Kolpfenstein, T.J., Masters, R.A., Anderson, B.E.
Agronomy journal 1995 v.87 no.4 pp. 744
Thinopyrum intermedium subsp. intermedium, cultivars, variety trials, crop quality, forage, beef cattle, liveweight gain, steers, nutritive value, in vitro digestibility, population, Nebraska
The grazing season in the central and northern Great Plains could be extended by use of adapted cool-season grass pastures for spring and fall grazing to augment the native warm-season range. A grazing trial was conducted to evaluate the forage quality of four intermediate wheatgrass [Thinopyrum intermedium (Host) Barkw. & D.R. Dewey] populations for use in forage-livestock systems. The cultivars Slate and Oahe and two populations selected for improved IVDMD, 'Manska' and NE TI 1, were evaluated. Each population was seeded in the fall of 1987 in three replicated 0.4-ha pastures arranged in a randomized complete block design. Pastures were stocked with three beef yearlings for 28 d in spring 1989 and 42 d in spring 1990 to provide a stocking rate of 7.5 steers ha-1. Duration of grazing was shorter in 1989 because of inadequate soil moisture. Average daily gain (ADG) and gain per hectare were higher (P less than or equal to 0.10) in 1989 than 1990, despite the lower (P less than or equal to 0.10) forage availability and lesser number of grazing days in 1989. Steers grazing Manska in 1989 gained 1.59 kg d-1, compared with 1.42, 1.27 and 1.43 for Oahe, Slate, and NE TI 1, respectively. There were no differences (P > 0.10) in ADG or gain per hectare among populations in 1990. The improvement in ADG resulted in 30 to 65 kg more gain per hectare from Manska compared with the other populations in 1989. These results demonstrate the excellent quality of intermediate wheatgrass for grazing livestock and the impact that modest improvements in forage quality can have on animal performance.