Two new varieties of big bluestem prairie grass could boost beef cattle weight by as much as 50 pounds per head, according to the Agricultural Research Service (ARS) and collaborating university scientists.

The beef weight gains come from grazing trials in eastern Nebraska that compared the new releases - named "Bonanza" and "Goldmine" - to the Pawnee and Kaw varieties. The latter two cultivars have been the leading big bluestems in the Central Plains and Midwest for more than 40 years, a reign stemming from their broad adaptability to the regions' diverse growing conditions.

Such adaptability is especially important on marginal cropland used for cow-calf operations where the animals draw nutrients from forage rather than grains, according to Ken Vogel, who leads ARS' Wheat, Sorghum and Forage Research Unit in Lincoln, Nebraska.

Pawnee and Kaw, however, were never specifically bred with forage quality in mind, according to Vogel, a supervisory plant geneticist. Goldmine and Bonanza are said to offer the best of both worlds, combining adaptability with improved forage quality. Vogel began breeding the big bluestems in 1977, and recently field-tested them in collaboration with ARS Lincoln rangeland scientist Robert Mitchell and University of Nebraska-Lincoln researchers Terry Klopfenstein and Bruce Anderson.

In pasture trials from 2000 to 2002, cattle that grazed the new big bluestems gained 18 to 50 pounds more per acre than those that grazed Pawnee and Kaw. The researchers estimate these gains could mean net-profit increases of $15 to more than $35 per acre a year for beef producers. Certified seed of Goldmine and Bonanza will become available in 2006.

ARS is the US Department of Agriculture's chief scientific research agency.