Forage quality, mineral constituents, and performance of beef yearlings grazing two crested wheatgrasses

In the central Great Plains, crested wheatgrasses (Agropyron cristatum (L.) Gaetner and A. desertorium (Fischer ex Link) Schultes] are best utilized for early spring and late fall grazing. The principal objective of this study was to determine if beef (Bos taurus L.) yearlings grazing 'Ruff' (A. cristatum) during the spring grazing season had higher average daily gains and gains per hectare than cattle grazing `Nordan' (A. desertorum). These cultivars were evaluated in grazing trials (four replications) in eastern Nebraska in 1985, 1986, and 1987. The 0.8-ha pastures were seeded in the fall of 1983 on a Typic Argiudoll soil and were fertilized annually with 68 to 90 kg N ha-1. Grazing was for 6 wk each spring by yearling steers with a beginning average weight of 250 kg. Averaged over 3 yr, Ruff produced higher gains per hectare than Nordan (272 vs 245 kg ha-1) probably because it produced more herbage because of its better persistence. At the end of the trial, the averge basal cover of Ruff and Nordan were 21 and 6%, respectively. Three-year mean average daily gains were Ruff = 1.28 vs. Nordan = 1.34 kg d-1, which were unexpected, because Ruff generally had higher forage quality as measured by an array of parameters. Ruff forage had a higher, less desirable grass tetany ratio [K/(Mg +Ca)) than Nordan (2.6 vs. 2.3) averaged over 3 yr. Cattle grazing Ruff had lower blood serum Mg levels than cattle grazing Nordan (15.4 vs. 16.2 mg L-1, both of which were below the hypomagnesemia threshold of 18 mg L-1. This condition may have reduced intake and animal gains. These results indicate the need for evaluating pasture and range grass cultivars under grazing conditions

Forage quality, mineral constituents, and performance of beef yearlings grazing two crested wheatgrasses

In the central Great Plains, crested wheatgrasses (Agropyron cristatum (L.) Gaetner and A. desertorium (Fischer ex Link) Schultes] are best utilized for early spring and late fall grazing. The principal objective of this study was to determine if beef (Bos taurus L.) yearlings grazing 'Ruff' (A. cristatum) during the spring grazing season had higher average daily gains and gains per hectare than cattle grazing `Nordan' (A. desertorum). These cultivars were evaluated in grazing trials (four replications) in eastern Nebraska in 1985, 1986, and 1987. The 0.8-ha pastures were seeded in the fall of 1983 on a Typic Argiudoll soil and were fertilized annually with 68 to 90 kg N ha-1. Grazing was for 6 wk each spring by yearling steers with a beginning average weight of 250 kg. Averaged over 3 yr, Ruff produced higher gains per hectare than Nordan (272 vs 245 kg ha-1) probably because it produced more herbage because of its better persistence. At the end of the trial, the averge basal cover of Ruff and Nordan were 21 and 6%, respectively. Three-year mean average daily gains were Ruff = 1.28 vs. Nordan = 1.34 kg d-1, which were unexpected, because Ruff generally had higher forage quality as measured by an array of parameters. Ruff forage had a higher, less desirable grass tetany ratio [K/(Mg +Ca)) than Nordan (2.6 vs. 2.3) averaged over 3 yr. Cattle grazing Ruff had lower blood serum Mg levels than cattle grazing Nordan (15.4 vs. 16.2 mg L-1, both of which were below the hypomagnesemia threshold of 18 mg L-1. This condition may have reduced intake and animal gains. These results indicate the need for evaluating pasture and range grass cultivars under grazing conditions

Establishment of Big Bluestem and Illinois Bundleflower Mixtures with Imazapic and Imazethapyr

Weeds interfere with establishment of native grasses and legumes. A study was conducted to determine the influence of imazapic1 [(±)- 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]- 5-methyl-3-pyridinecarboxylic acid] and imazethapyr [2-[4,5-dihydro- 4-methyl -4 - (1- methylethyl) -5 -oxo-1H- imidazol -2 - yl]5- ethyl -3- pyridinecarboxylic acid] on weed control and establishment of ‘Pawnee’ big bluestem (Andropogon gerardii Vitman var. gerardii Vitman) and Illinois bundleflower [Desmanthus illinoensis (Michx.) MacMill.] planted in three binary mixtures of 220:110, 165:165, and 110:220 pure live seed (PLS) m-2. Mixtures were seeded at cropland sites near Clay Center, Mead, and Lincoln, NE. Imazapic and imazeth- apyr were applied at 70 g a.i. ha-1 before planted species emerged. Imazapic or imazethapyr did not reduce dry matter yields of annual grass weeds, where herbicides were applied in April 1996 at Mead and Clay Center. Both grass and broadleaf weeds were controlled at Lincoln, where herbicides were applied in early June 1996. The herbicides usually improved big bluestem yields and total forage yields in 1996 and 1997 at all sites. Illinois bundleflower yields at Lincoln, where imazapic and imazethapyr were applied, were greater than 3.0 Mg ha-1 in 1996 and 1997. In 1997, Illinois bundleflower did not survive at Mead and yielded less than 0.5 Mg ha-1 at Clay Center, regardless of weed control treatment or seed mixture. Imazapic and imazethapyr can improve the establishment of big bluestem and Illinois bundleflower mixtures