Document Type

Thesis - Open Access

Award Date

1990

Degree Name

Master of Science (MS)

Department

Animal Science

First Advisor

Al F. Schlundt

Abstract

Grazing management is a "first order" approach to range improvement (Gartner 1987). The goal to improve range condition can be part of basic management decisions regarding stocking rate, kinds of livestock and season of use. Numerous "systems" of grazing management have been developed to achieve range improvement. Most recently, intensive grazing systems have been promoted as a method of increasing grazing efficiency and improving range condition (Savory and Parsons 1980); however, these grazing systems often require intensive livestock management and large capital investments. Furthermore, research results of the long-term benefits of intensive grazing systems are inconclusive (Holechek et al. 1989). A less intensive approach to grazing management for range improvement might be a more appropriate alternative (Schlundt and Krcil 1986). On many ranches fencing already exists to support implementation of a simple grazing management scheme. However, in eastern South Dakota, ranchers often do not use their pastures in a manner that improves the range resource. They commonly leave animals on the range throughout the growing season without providing for any strategic grazing deferment or rest. Frequently, they do not remove livestock until the grass has been grazed to ground level. Some provide supplemental and substitute feeds at this point to maintain the animals. Such abusive management results in rangeland dominated by shortgrass sods and decreased forage productivity. Commercial cattlemen have the option of improving range condition and increasing ranch productivity by simply combining groups of animals and implementing a deferred-rotation (DR) grazing system, while incurring little or no additional investments (Schlundt 1985). This study was designed to compare traditional continuous, season-long grazing (CSL) as a control treatment with DR grazing as a low-cost solution to achieve gradual range improvement. It was modeled after a typical stocker-steer operation in eastern South Dakota in which a rancher normally purchases "green" yearling steers in the spring and markets them in the fall (Schlundt 1985). The range involved was a wetland/upland mosaic characteristic of the Prairie Pothole Region of the Northern Great Plains. Under continuous grazing, livestock tend to favor and overgraze wetter range sites on this type of range, thereby lowering range condition (Engle and Schimmel 1984). The study included CSL grazing and 2 types of DR grazing schemes that provided warm- and cool-season deferments for range plants. One DR grazing scheme was based on a fixed annual rotation date, and the second was based on the phenology and subsequent livestock use of warm-season grasses. The management goals of the DR grazing schemes were to enhance the warm - season decreaser component of the plant community with its forage production and nutritive qualities, and maintain a desirable mixture of both warm-season and cool-season grass species. This thesis contains results of 2 years (1985 and 1986) of experiments that occurred within a larger study, which had long-term objectives relating to range condition trends as affected by the grazing treatments. The short-term objectives and associated null hypotheses (H) for the smaller study covered by this thesis included: Objective 1. Evaluate stocker-steer gains for CSL and 2 DR grazing schemes on prairie pothole rangeland. H1.1 Steers will gain equally under CSL and DR grazing. H1.2 Steer gains will remain constant throughout the grazing season, regardless of grazing treatment. Objective 2. Measure forage production and utilization during the grazing season on the dominant range site. H2.1 Forage use by steers will be equal for CSL and DR grazing. H2.2 Steers will be equally selective in grazing under CSL and DR grazing. The main focus of this study revolved around practical questions for farmers and ranchers who have limited land and capital resources but who would benefit from improved grazing management. However, the results of this research should also contribute to the scientific information base concerning grazing management, particularly for grazing management of prairie pothole rangeland.

Library of Congress Subject Headings

Grazing -- Prairie Pothole Region
Range management

Format

application/pdf

Number of Pages

120

Publisher

South Dakota State University

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