Management Implications , Page 3
|Cows from the hill climber treatment resting on a ridge at the Thackeray Ranch.|
Implications for Riparian Area Management
In critical areas such as riparian zones, stubble heights were 5 inches in pastures grazed by hill climbers and only 3 inches in pastures grazed by bottom dweller cows (Figure 1). The differences in stubble heights observed between treatments in this study would be economically important for many public-land ranchers. A standard for grazing on riparian areas is often forage stubble height of 4 to 5 inches [11, 12]. If stubble heights fall below the standard, livestock are often required to be moved to a new pasture or off the allotment. In this study, pastures grazed by hill climbers had acceptable grazing levels based on this standard, while grazing levels in pastures grazed by bottom dwellers were not acceptable. Forage utilization measurements on upland slopes also suggested that hill climbers used rough terrain more uniformly than bottom dwellers. Forage utilization in pastures grazed by hill climbers was affected less by slope, horizontal distance to water, and vertical distance to water than pastures grazed by bottom dwellers. For example, forage utilization declined by 0.33 percentage points for every degree increase in slope in bottom dweller pastures, and forage utilization only declined 0.25 percentage points for every degree increase in slope in hill climber pastures. These results demonstrate that selection for grazing distribution has the potential to improve conditions of riparian and other sensitive areas that have been heavily grazed in the past and to increase the use of upland slopes that previously received little grazing.
The impact of this proposed practice (selection for distribution) on performance of the herd is an important consideration for ranchers. Research conducted in this SARE project found that the location where cows grazed was not related to their pregnancy rates, weight or body condition score. In addition, cattle that used high and steep terrain had similar calf weaning weights as cows that remained in gentle terrain near water. Selection of animals that spend more time on high upland slopes and culling cows that graze in lower terrain near water should not have any adverse impact on calf growth or reproductive performance of the cows.
Summary and application. When cows with clearly undesirable grazing patterns are identified, culling the animals or separating them from herds that graze rugged pastures should increase uniformity of grazing with more use of upland slopes and less use of bottoms and riparian areas. Multiple observations are needed to characterize the grazing patterns of individual cows. Observations should be recorded in the early morning when cattle are grazing and more emphasis should be made during the first third of the grazing season. Using breeds that were developed in topography and climate that is similar to rangeland conditions of the ranch also should help resolve livestock distribution problems. Although results from this project clearly showed that selection has the potential to solve many issues associated with grazing, much more research is needed before this practice can be widely recommended and implemented.