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United States Department of Agriculture

Agricultural Research Service

Title: The Economic Benefit of Increased Yield and Digestibility in a Perennial C4 Grass

Authors
item Mitchell, Robert
item Vogel, Kenneth
item Sarath, Gautam

Submitted to: Grassland International Congress Proceedings
Publication Type: Proceedings
Publication Acceptance Date: February 15, 2005
Publication Date: June 26, 2005
Citation: Mitchell, R., Vogel, K.P., Sarath, G. 2005. The economic benefit of increased yield and digestibility in a perennial C4 grass. p.99. In F. P. O'Mara et al. (ed). Proc. XX Int. Grassland Congress, Dublin, Ireland 26 June- 2 July 2005. Wageningen Academic Publishers. Wageningen, The Netherlands.

Interpretive Summary: : Increasing forage yield and digestibility can increase livestock performance and subsequent profitability of grasslands. Our objective was to compare the economic value of two big bluestem strains developed by three generations of breeding for increased forage yield and digestibility with the base populations from which they were derived. Four big bluestem cultivars (Pawnee, Bonanza, Kaw, and Goldmine) were evaluated. Bonanza and Goldmine were developed by selecting for high yield and digestibility from the Pawnee and Kaw base populations, respectively. Three pastures of each population were fertilized with ammonium nitrate and stocked with three crossbred yearling steers. Steer values were the average Nebraska market price for the representative weight classes in 2000, 2001, and 2002. Breeding for increased yield and digestibility resulted in a 5 to 14% increase in beef production per ha. Selecting for increased yield and digestibility resulted in Bonanza returning 109 more $ ha-1 than Pawnee, and Goldmine returning 39 more $ ha-1 than Kaw. Using cultivars bred for increased yield and digestibility can significantly increase the profitability of the grazing operation.

Technical Abstract: Big bluestem (Andropogon gerardii Vitman) is a warm-season perennial grass native to the tallgrass prairie of North America. Big bluestem provides productive, high quality forage during late spring and summer in the Great Plains, USA. Increasing forage yield and digestibility can increase livestock performance and subsequent profitability of grasslands. The objective of this study was to compare the economic value of two big bluestem strains developed by three generations of breeding for increased forage yield and digestibility with the base populations from which they were derived. Four big bluestem cultivars (Pawnee, Bonanza, Kaw, and Goldmine) were evaluated. Pawnee and Kaw were developed from regional germplasm from USDA Plant Hardiness Zones (HZ) 5 and 6, respectively. Bonanza and Goldmine were developed by three cycles of selection for high yield and high IVDMD from the Pawnee and Kaw base populations, respectively. Grazing trial experimental units were three 0.4 ha pastures of each population, arranged as a randomized complete block design. Pastures were fertilized with ammonium nitrate at 112 kg N/ha. Each pasture was stocked with three crossbred yearling steers (350-400 kg) to provide a stocking rate of 7.5 steers/ha. Steer values were the average Nebraska market price for the representative weight classes in 2000, 2001, and 2002. Breeding for increased yield and digestibility resulted in a 5 to 14% increase in beef production per ha. Three cycles of selection for increased yield and digestibility from the base populations resulted in Bonanza returning 109 more US$ ha-1 than Pawnee, and Goldmine returning 39 more US$/ha than Kaw (Table 1). Using cultivars bred for increased yield and digestibility can significantly increase the profitability of the grazing operation. Bonanza and Goldmine were officially released in 2004 and are being recommended for use in HZ 5 and HZ 6, respectively, of the USA.

Last Modified: 12/21/2014