Cattle Range Site Preference Using GPS/GIS Technology R.K. Lyons, R.V. Machen, and C. Nicklas position of each animal within 5-10 Furthermore, some areas within the BOTTOM LINE yards of their actual location after Rumple-Comfort soil were favored differential correction. Collars were over the total area occupied by this ! Strong cow preference for soil also equipped with an ambient soil type. For example, in the April types could increases grazing temperature sensor and vertical and trial, Map Sites 3 and 4 which were pressure. horizontal motion sensors. Field within the Rumple-Comfort soil type observations were conducted to accounted for 38% of the total ! Rock cover greater than 30% interpret data from the motion position fixes and 50% of the almost completely deterred cow use. sensors. Motion data provides an Rumple-Comfort position fixes. indication of whether cows were These two map sites made up about ! Brush management decisions grazing or resting. Data was collected 9% of the pasture area available should consider rock cover. during five six-day trials at 15-minute during the April trial. Distribution intervals for a total of about 576 patterns for the April trial are position fixes per cow per trial. illustrated in Figure 1. In the Mid- ArcView Global Information August trial, Map Site 4 alone Introduction System (GIS) software was used to accounted for 48% of the total project cow position fixes onto digital position fixes and 80% of the fixes Research has demonstrated that aerial photographs. ArcView was also within the Rumple-Comfort soil. This cattle and other grazing livestock do used to quantify use of areas within map site made up about 12% of the not always distribute themselves pastures in terms of position fixes per pasture area available during the Mid- evenly across a pasture and, therefore, acre. Within pastures, brush density, August trial. do not evenly use the forage within rock cover, and distance to water When analyzed over the whole the pasture. The purpose of this study were measured within areas of use range of rock cover (almost zero to 48 was to examine cattle distribution and non-use. Overall use between the percent), rock cover was the only patterns, to find reasons for these two major soil types on the study variable of the three considered (rock patterns, to find potential solutions ranch was analyzed statistically using cover, brush density, and distance to for these distribution problems, and to analysis of variance. Effects of rock water) that explained cow use of show these patterns pictorially to cover, brush density, and distance to areas. This one variable explained 63 illustrate grazing distribution water were analyzed using regression percent of the variation in cow use concepts in Extension publications analysis. (Figure 2). Essentially no use and at educational events. occurred above 30 percent rock Results and Discussion cover. Experimental Approach Below 10 percent rock cover, On average, almost 3 times as both rock and brush helped explain This study was conducted on a many position fixes (p=0.01) were cow use when considering total ranch in the eastern Edwards Plateau. located in the Rumple-Comfort soil (grazing and non-grazing) position Four mature cows were fitted with type as in the Comfort soil type fixes per acre, grazing position fixes, Lotek 2000 Global Positioning (Table 1). Within each of the five and non-grazing position fixes. In System (GPS) Collars. These collars trials, position fixes per acre were addition, when only grazing position were capable of estimating the significantly greater for the Rumple- fixes were considered, distance to Comfort soil type (Table 1). water negatively influenced cow use. UREC-02-026 Interestingly, brush density had a Table 1. Comparison of average differentially corrected position fixes per acre positive influence on cow use when for cows within the Rumple-Comfort and Comfort soil types. rock cover was below 10 percent. A strong preference for the Position Fixes/acre Rumple-Comfort over the Comfort soil type was exhibited by cows in Trial Rumple- Comfort Probability this study. In addition, there were Comfort preferred areas within the Rumple- Comfort soil type. These preferences Overall 1.25 0.43 0.01 can lead to overuse. Fencing preferred areas separately is a Mar-Apr 2.61 O.97 <0.0001 potential means of preventing April 0.64 0.16 0.0156 overuse. If separate fencing is not feasible, other options include May 1.08 0.24 <0.0001 rotational grazing and reduced stock densities and stocking rates. Mid-Aug 0.89 0.48 0.002 Rock cover above 30 percent Late-Aug 1.01 0.32 0.0001 appeared to almost completely deter cow use of an area. In contrast, brush appeared to have a positive influence on cow use when rock cover was below 10 percent. This observation may seem confusing. However, most dense brush also tended to be associated with dense rock. Therefore, at lower brush densities and low rock cover, cows were probably attracted to the brush for shade and grazing. While dense brush is a deterrent to grazing by cows, results from this study indicate that brush management decisions related to increasing grazing for cows also needs to include consideration of rock cover. Figure 1. Grazing distribution patterns within the For example, in this study, some of Rumple-Comfort (RC) and Comfort (CR) soil types for the highest rock cover was in an open the April trial. area close to water. However, this area had very few position fixes. 100 Therefore, even if brush were r2=0.63 80 removed from heavily wooded areas Relative Use, % associated with high rock cover, these 60 areas would probably receive little cow use. Heavily wooded areas 40 associated with high rock cover are probably best left for wildlife habitat. 20 Because these kinds of areas provide 0 little potential benefit to cows, they should not be included when -20 considering the cow carrying 0 10 20 30 40 50 capacity. Rock Cover, % Figure 2. Relationship between rock cover and cow use. Rock cover explained 63% of the variability.
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