LIVESTOCK RESPONSE TO GRAZING SYSTEM AND STOCKING RATE IN TALLGRASS PRAIRIE

Authors: MCCOLLUM, F. - TEXAS A&M UNIVERSITY; Gillen, Robert; KARGES, BROCK - OK STATE UNIVERSITY; HODGES, MARK - OK WHEAT COMMISSION

Submitted to: Journal of Range Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Rotational grazing involves dividing a pasture into several sub-units and grazing these sub-units in sequence with a single herd of cattle. Compared to continuous grazing, where livestock are kept in a single pasture, rotational grazing sometimes improves grazing efficiency, livestock production, and vegetation health. The effects of rotational versus continuous grazing were compared in tallgrass prairie pastures over 6 years. Each grazing system was operated at high, medium, and low stocking rates (the number of animals per unit land area over the grazing season). Yearling steers grazed the units from late April to late September. Precipitation was above average during the study period. Average gain per steer was higher under continuous grazing than rotational grazing. Gains were 10% lower under rotational grazing at a low stocking rate and 20% lower at a high stocking rate. The reduction in weight gain was due to reduced forage intake under rotational grazing. Livestock gain per acre wa also higher with continuous grazing at all stocking rates. Net return per acre increased as stocking rate increased for both grazing systems. Net returns were lower for rotational grazing at all stocking rates and with high or low livestock prices. Variable costs per head would have to decrease by 24-34% under rotational grazing to equalize net returns between the 2 grazing systems. Unless the decline in gain per head can be reduced or eliminated, there is no economic incentive to implement rotational grazing under the conditions of this study.

Technical Abstract: Grazing system and stocking rate effects on performance of yearling beef cattle grazing tallgrass prairies were evaluated over 6 years. Twelve experimental pastures supporting high seral tallgrass prairie were assigned to either a short duration rotational or continuous grazing system. Stocking rates ranged from 51.5 animal-unit-days (AUD) ha-1 to 89.8 AUD ha- -1. Yearling steers grazed the units from late April to late September. Cumulative precipitation was above average during the study period. Live weight gain per head was higher under continuous grazing than rotational grazing. This difference ranged from 10% lower gains under rotational grazing at 52 AUD ha-1 up to 20% lower gains at 88 AUD ha-1. Measurements of steer diets and forage standing crop suggest that the reduction in weight gain was due to reduced forage intake under rotational grazing. Gain per hectare increased with stocking rate and was higher with continuous grazing at all stocking rates. Net return per hectare increased as stockin rate increased for both grazing systems. Net returns were lower for rotational grazing at all stocking rates. High or low livestock prices increased or decreased net returns but did not change the relationship between grazing systems. Variable costs per head would have to decrease by 24-34% under rotational grazing to equalize net returns between the 2 grazing systems. Unless the decline in gain per head can be reduced or eliminated, there would be no economic incentive to implement rotational grazing under the conditions of this study.