Influence of Beef Cattle Stocking Density on Utilization of Vegetative Communities in a Late-Spring, Early-Summer Native Bunchgrass Prairie

This study evaluated the influence of cattle stocking density on the use of botanical communities on a native bunchgrass prairie. In each of two years, 192 cow-calf pairs and 48 yearling heifers were randomly selected for the following grazing treatments- 1) control, no livestock grazing; 2) low stocking, 0.36 animal units (AU) ∙ ha-1; 3) moderate stocking, 0.72 AU ∙ ha-1; and 4) high stocking, 1.08 AU ∙ ha-1 for a 42-day grazing period. Thirty-six monitoring sites were established uniformly along a grid in each paddock. Standing crop and relative preference data for cattle collected from the treatment area were used to develop the following vegetation community classifications- 1) > 20% introduced; 2) > 40% native bunchgrass with > 50% Idaho fescue (Festuca idahoensis); 3) > 40% native bunch grass with < 50% Idaho fescue; 4) > 50% Forb; and 5) other. Utilization for each community type was collected at the end of the grazing period. High stocking density paddocks had higher utilization across all vegetation classifications compared to other stocking densities (P ≤ 0.04). Moderate stocking density paddocks were utilized 11.5% more than low paddocks, however, utilization of introduced vegetative communities, Idaho fescue dominated bunchgrass communities, and forb dominated communities did not differ in use (P ≥ 0.13). Use of monitoring to actively adjust stocking densities based on differential community utilization may improve the sustainable grazing of sensitive communities because conventional stocking rate calculations based on total productivity do not account for the selective grazing behavior of cattle.