WASHINGTON — Grazing is an agricultural term to describe the natural behavior of cattle moving across pastures and rangelands as they consume different plants. Surprisingly, grazing cattle are selective about where and which plants they will eat, and land managers consider grazing distribution an essential factor in deciding how to manage their herds, including how to prevent overgrazing for conserving biodiversity of the land.
The U.S. Department of Agriculture’s Agricultural Research Service (USDA-ARS) collaborated with various universities and the Long-Term Agroecosystem Research (LTAR) network to examine the influence of topography on grazing distribution that can inform land managers in the selection of efficient grazing strategies.
Livestock managers desire information on several factors affecting grazing distribution before implementing land management strategies. With this in mind, researchers at USDA-ARS completed a cross-site collaboration study with university-operated experiment stations and four LTAR funded sites, with the primary goal of determining how factors like landscape topography and water availability affect cattle grazing distribution. The data collected at all sites creates a benchmark for understanding how environment can drive the spatial patterns of animal use in pastures under several management practices and across numerous ecosystems covering arid, semiarid, and sub-tropical environments.
The study collected data from seven rangeland sites in Florida, Nebraska, New Mexico, Colorado, and Idaho and used collars equipped with global positioning system (GPS) technology to measure cattle movement and activity. This technology was successfully used in prior studies completed by scientists David J. Augustine and Justin D. Derner, from the Rangeland Resources and Systems Research Unit, at Fort Collins, CO and Cheyenne, WY.
“The information collected from the GPS-collars allowed us to develop a broad-scale analysis of how topography in these seven rangeland sites in North America determines livestock grazing distribution,” said E.J. Raynor, Research Associate Ecologist within the Rangeland Resources & Systems Research Unit at Fort Collins, CO at the time of study and currently with the Pasture Systems & Watershed Management Research Unit in University Park, PA. “By studying how livestock grazing occurs on different parts of the landscape like flat plains, lowlands, open slopes, and upland, we developed models that can be used to predict distribution of grazing cattle. One observation from these models is cattle prefer to graze low-lying locations in drier regions and more elevated locations in wetter regions, where flooding likely reduces selection.” The USDA-ARS LTAR Grazinglands working group of scientists is optimistic that this study will set the stage for similar collaborative efforts, including plant community composition, forage production, and livestock weight gains to provide insights into sustainable livestock management strategies across diverse rangeland ecosystems.
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