The University of Arizona

Evaluating grazing strategies for cattle: deer and cattle food partitioning.

I.M. Ortega, S. Soltero-Gardea, F.C. Bryant, D.L. Drawe

Abstract


We studied resource partitioning between cattle and deer (Odocoileus virginianus Boddaert) within replicated treatments of continuous and short-duration grazing at heavy and moderate stocking rates. We recorded food habits using the bite-count technique with tame white-tailed deer, and the esophageal fistula technique with steers. Through use of canonical discriminant analysis, we found diets of cattle and deer to be distinct (p< 0.05) from each other in every treatment throughout the sampling period. Overall, deer used mostly forbs (72%) whereas cattle primarily used grasses (60%) and forbs (39%). We also evaluated sensitivity to pasture conditions created by cattle grazing by comparing diets across treatments, especially during the summer months (May through September) and the second winter, which was affected by drought. Out of a possible 48 treatment combinations compared, deer selected different diets 21 times whereas cattle selected different diets 16 times. Deer were more sensitive than cattle to grazing treatments. Cattle were most sensitive to treatments during the first summer and second winter. Deer were the least sensitive to the grazing treatments during spring, when their diets were similar across all treatments. We recommend moderate stocking rates to reduce dietary overlap between cattle and deer and continuous grazing or less intensive grazing systems to create an environment where deer can select greater amounts of forbs.

Keywords


interspecific competition;browse plants;continuous grazing;Odocoileus virginianus;stocking rate;species differences;forbs;rotational grazing;cattle;Texas;seasonal variation;botanical composition;grasses;feeding preferences

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