Individual Animal Selection Has the Potential to Improve Uniformity of Grazing on Foothill Rangeland

Uneven grazing distribution is a concern in rugged topography, because resources may be adversely impacted if livestock concentrate in gentle terrain near water. A study was conducted to determine if removing cattle with undesirable distribution patterns has the potential to increase uniformity of grazing. Before the study, 2 herds of cattle were observed by horseback observers during early mornings to establish terrain use patterns of individual animals. Cows were ranked on slope use and observed vertical and horizontal distance to water. Based on these rankings, cows were assigned to 1 of 2 treatments, hill climbers (observed on steeper slopes and farther from water) or bottom dwellers (used gentler slopes near water). Hill climber and bottom dweller cows grazed similar, but separate, pastures at 2 ranches during the 3-year study for a total of 8 comparisons. Based on a normalized and integrated index of terrain use from visual observations, hill climber cows used steeper and more distant areas from water (P = 0.06) than bottom dwellers. Hill climber cows tracked by global positioning system collars used steeper and more distant areas from water than bottom dwellers (P 0.09) during the first 4 weeks of the 6 weeks that pastures were grazed based on a normalized index of terrain use. Forage utilization was more uniform (P < 0.05) across slopes and varying horizontal distances to water in pastures grazed by hill climbers than by bottom dwellers. Stubble heights in riparian and coulee bottom areas were higher (P = 0.01) when grazed by hill climber cows (13.3 cm) than by bottom dwellers (8.1 cm). This study demonstrates that cattle with divergent grazing patterns when observed in the same pasture continue to use different terrain when separated, and it suggests that individual animal selection has the potential to increase uniformity of grazing.