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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #113825
Title: VEGETATION AND LIVESTOCK RESPOND TO BROME REMOVAL WITH ATRAZINE

Author
item Haferkamp, Marshall
item Heitschmidt, Rodney
item Grings, Elaine
item Macneil, Michael

Submitted to: Research Update for Fort Keogh Livestock and Range Research Laboratory
Publication Type: Other
Publication Acceptance Date: 10/1/1999
Publication Date: N/A
Citation: HAFERKAMP, M.R., HEITSCHMIDT, R.K., GRINGS, E.E., MACNEIL, M.D. VEGETATION AND LIVESTOCK RESPOND TO BROME REMOVAL WITH ATRAZINE. RESEARCH UPDATE FOR FORT KEOGH LIVESTOCK AND RANGE RESEARCH LABORATORY. p. A.8.1-4. 1999.

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 progresses from spring to fall in the Northern Great Plains. One might question how much of this decline is simply due to maturation of plant, and how much of this decline may be due large amounts of early maturing annual bromes in the forage standing crop. We studied the biological impacts of brome presence on rangeland and livestock performance by comparing brome infested rangeland to similar sites on which brome had been suppressed with fall applications of atrazine. Brome suppression increased crude protein content in July (7.1% vs. 9.1%) and August (6.0% vs. 7.1%). 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 to 2.3 pounds per head per day and 62 to 72 pounds per acre.

Technical Abstract: 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 progresses from spring to fall in the Northern Great Plains. One might question how much of this decline is simply due to maturation of plant, and how much of this decline may be due large amounts of early maturing annual bromes in the forage standing crop. We studied the biological impacts of brome presence on rangeland and livestock performance by comparing brome infested rangeland to similar sites on which brome had been suppressed with fall applications of atrazine. Brome suppression increased crude protein content in July (7.1% vs. 9.1%) and August (6.0% vs. 7.1%). 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 to 2.3 pounds per head per day and 62 to 72 pounds per acre.