Grazing Evaluation of Big Bluestems Bred for Improved Forage Yield and Digestibility

Authors

R. B. Mitchell, USDA-ARSFollow
Kenneth P. Vogel, University of Nebraska-LincolnFollow
T. J. Klopfenstein, University of Nebraska-LincolnFollow
B. E. Anderson, University of Nebraska-Lincoln
R. A. Masters, Dow AgroSciences

Date of this Version

2005

Citation

Mitchell, R.B., K.P. Vogel, T.J. Klopfenstein, B.E. Anderson, and R.A. Masters. 2005. Grazing evaluation of big bluestems bred for improved forage yield and digestibility. Crop Sci. 45:2288-2292.

Comments

U.S. government work

Abstract

Two big bluestem (Andropogon gerardii Vitman) strains (Pawnee C3 and Kaw C3) developed by three breeding cycles for increased forage yield and in vitro dry matter digestibility (IVDMD) were compared with the base populations of 'Pawnee' and 'Kaw' in a 3-yr grazing trial. Pastures were seeded in May 1998 near Mead, NE. Experimental units were three 0.4-ha pastures of each strain or cultivar in a randomized complete block design. Pastures were burned and fertilized with ammonium nitrate at 112 kg N ha^-1 in the spring of 2000, 2001, and 2002 before grazing. Each pasture was continuously stocked with three crossbred yearling steers (Bos taurus) (380 +/- 38 kg) in mid-June 2000, 2001, and 2002 to provide a stock density of 7.5 steers ha^-1. Pawnee C3 and Kaw C3 produced 16 and 7% more average daily gain (ADG), respectively, than the base populations during the 3-yr study. Additionally, Pawnee C3 and Kaw C3 produced 14 and 5% more total body weight (BW) gain ha^-1, respectively, than the base populations. Pawnee C3 ADG was 1.30 kg hd^-1 and produced greater than 455 kg total BW gain ha^-1 during a drought period in eastern Nebraska. Pawnee C3 pastures produced more available forage with higher IVDMD, cell soluble, cell wall digestibility, and lower lignin concentration than forages from Pawnee pastures. Kaw C3 pastures differed from Kaw pastures by producing forage with greater crude protein concentration. These results demonstrate the productivity of big bluestem pastures in the eastern Great Plains and document the positive livestock response to moderate increases in forage IVDMD. The strains bred for increased yield and IVDMD provided as much as 26% more total BW gain ha^-1 at no additional cost. Pawnee C3 was released as the cultivar Bonanza and Kaw C3 was released as 'Goldmine'.