|Bohnert, David - OREGON STATE UNIVERSITY|
Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 14, 2007
Publication Date: January 26, 2008
Citation: Ganskopp, D.C., Bohnert, D. 2008. Rangeland nutritional patterns and cattle distribution. Society for Range Management Meeting Abstracts.Building Bridges:Grasslands to Rangelands. Symposium Remote Sensing and GIS - What can they do for you? Technical Abstract: Several animal and environmental characteristics affect livestock distribution on rangelands. An understanding of mechanisms governing livestock distribution can help land and livestock managers avoid or ameliorate potential deleterious grazing effects. This research tested hypotheses that foraging cattle seek nutritionally superior portions of sagebrush/steppe rangeland pastures. Plots were sampled across three 800+ ha pastures in early June 2004. Samples were weighed and herbage analyzed for CP, NDF and ADF, and in situ digestibility. GIS was used to rasterize forage quantity and quality attributes. Four GPS collared cattle grazed each pasture for 15 days, and quantity/quality data were queried with GIS to ascertain composition of pastures and sites used by cattle. Sites within 50 m of water were excluded from analyses. Grazing cattle preferred areas with higher than average CP and digestibility and locales with lower than average NDF and standing crop. Distribution was unaffected by ADF. Intuitively, we expected greater concentrations of cattle on sites supporting the highest levels of CP. With 84% of the study area meeting or exceeding 7.5% CP, however, there was likely no physiologic need for stock to seek small areas of exceptionally high CP. Cattle probably avoided areas with high herbage mass due to dense standing dead material making green forage inaccessible or undesirable. Findings suggest cattle respond to forage quantity/quality spatial dynamics at landscape scales. We propose many of the seasonal shifts in distribution patterns of cattle, like midsummer movements from grassland to forest sites, or late season shifts to riparian areas, are simply a response to changing nutritional patterns at landscape scales. Management programs altering the nutritional status of the landscape could be used to affect desirable changes in cattle distribution. Potential tools include: prescription grazing, prescribed burns, mowing, reclamation with desirable forages, and/or fertilization programs.