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United States Department of Agriculture

Agricultural Research Service

Research Project: OPTIMIZING THE BIOLOGY OF THE ANIMAL-PLANT INTERFACE FOR IMPROVED SUSTAINABILITY OF FORAGE-BASED ANIMAL ENTERPRISES

Location: Forage-Animal Production Research

Title: Effects of grazing intensity and chemical seedhead suppression on steers grazing tall fescue pastures

Authors
item Goff, Ben -
item AIKEN, GLEN
item Witt, William -
item Burch, Patrick -
item Sleugh, Byron -

Submitted to: American Forage and Grassland Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: November 10, 2011
Publication Date: January 9, 2012
Citation: Goff, B.M., Aiken, G.E., Witt, W.W., Burch, P.L., Sleugh, B.B. 2012. Effects of grazing intensity and chemical seedhead suppression on steers grazing tall fescue pastures. American Forage and Grassland Conference Proceedings. CD-ROM.

Interpretive Summary: Tall fescue [Lolium arundinaceum] is a cool-season grass that is commonly found in pastures of the temperate southeastern USA. The application of the herbicide Chaparral™ to suppress the reproductive growth of tall fescue has potential for use within stocker operations. In addition to increasing the nutritive value of the available forage throughout the grazing season, Chaparral increased steer average daily gain (ADG) approximately 45%. There were approximately 47 less days of grazing following herbicide treatment; however, the increase in ADG compensated for loss and resulted in gains per acre comparable to the untreated pastures. Similar results in steer and pasture performance were obtained by using a low grazing intensity, but animal gains would likely decrease due to the forage becoming mature and unpalatable later in season. Carcass quality of steers grazing the Chaparral-treated pastures was also enhanced, with 15 and 17% increases in ribeye area and rump fat thickness, respectively. It should be noted that the inferences of this study are based on data from one growing season and further replication is needed before any definitive conclusions may be made.

Technical Abstract: The first year of a 2 yr grazing study was conducted to evaluate use of Chaparral™ to suppress reproductive growth in tall fescue grazed with low and moderate grazing intensities. Chaparral applications (0 and 2.0 oz/acre) and grazing intensities were arranged as RCBD with three replications. Variable stocking rates were used with three Angus steers per pasture being used as tester animals. Application of Chaparral increased forage nutritive value and improved steer carcass traits as measured by ultrasound. Steers on the Chaparral-treated and low grazing intensity pastures showed an approximate 45% increase (P < 0.05) in average daily gain (ADG), but also showed decreases in carrying capacity (CC) of 47 and 37 fewer days/acre, respectively. Despite this decrease in CC, there was no difference in weight gain per acre (GPA) between either grazing intensity or application of the herbicide (P > 0.68). Because near maximal GPA was achieved with the highest steer ADG, the use of Chaparral to suppress tall fescue growth may prove to be economical for use in stocker operations. However, a second year of data is needed before any definitive conclusions may be made with the application of Chaparral.

Last Modified: 8/27/2014
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