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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #106022
Title: SUPPRESSION OF ANNUAL BROMES IMPACTS RANGELAND: ANIMAL RESPONSES

Author
item Haferkamp, Marshall
item Grings, Elaine
item Heitschmidt, Rodney
item Macneil, Michael
item KARL, MICHAEL - USDI-BLM

Submitted to: Journal of Range Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2001
Publication Date: 3/15/2001
Citation: HAFERKAMP, M.R., GRINGS, E.E., HEITSCHMIDT, R.K., MACNEIL, M.D., KARL, M.G. SUPPRESSION OF ANNUAL BROMES IMPACTS RANGELAND: ANIMAL RESPONSES. JOURNAL OF RANGE MANAGEMENT. v. 54. p. 663-668. 2001.

Interpretive Summary: Annual bromes have invaded thousands of acres in the Northern Great Plains. Many studies have shown a decline in weight gains of stocker cattle as the grazing season progresses from spring to fall in the Northern Great Plains. One might question how much of this decline is simply due to maturation of plants, and how much of the decline may be due to presence of large amounts of early maturing annual bromes in the forage standing crop. We studied the impacts of the presence of brome on livestock performance by comparing brome infested rangeland to similar sites on which brome had been suppressed with fall application of atrazine. Brome suppression and environment affected plant species in diets, diet quality, and livestock performance. Brome suppression reduced percentage of annual grasses in diets from 14.2% to 9.6%. Annual grasses were replaced by a variety of species (western wheatgrass, forbs, and blue grama) with specific replacement depending upon year and month. Steer gains were increased from 2.0 to 2.3 pounds per head per day and 62 to 72 pounds per acre.

Technical Abstract: Presence of annual bromes (Bromus spp.), introduced annual weedy grasses, can alter seasonal patterns of forage production and quality and require management changes for efficient use of infested rangelands. We determined biological impacts of the presence of brome by comparing livestock performance on brome infested rangeland to similar sites on which brome had been suppressed by fall applications of atrazine [6- chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine] at 0.56 kg ha**-1 in 1992 and 1993. Each replicate (12ha) was stocked with 8 crossbred steers from mid-May to mid-September 1993 and 1995 and to mid- August 1994. Brome suppression and environment affected plant species in diets, diet quality, and livestock performance. Brome suppression reduced percentage of annual grasses in diets from 14.2% to 9.6%. Annual grasses were replaced by a variety of species {western wheatgrass [Pascopyrum smithii Rydb. (Love)], forbs, and blue grama [Bouteloua gracilis [H.B.K.] Lag. ex Griffiths]}, with specific replacement depending upon year and month. Steer gains were increased from 0.92 to 1.04 kg head**-1 day**-1 and 69 to 81 kg ha**-1 with brome suppression.