Determining when to rotate livestock under short duration grazing
Mosley, Jeffrey Clyde
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Determining when to rotate livestock from pasture to pasture is a critical decision with short duration grazing (SDG) management on rangeland. Currently, however, grazing managers have few criteria upon which to base this key decision. Responding to this need, this study attempted to develop a practical management indicator. Specific objectives were to identify a potential rotation indicator and then evaluate the efficacy of this indicator. The initial part of this study monitored a 6-pasture SDG system and examined changes within 7-day grazing periods in diet quality, diet composition, forage quality, forage availability, and grazing behavior of 60 yearling steers. Forage availability and grazing behavior were the only parameters that consistently changed (P < 0.10) within grazing periods, but forage availability was not limiting. Accordingly, a rotation indicator does not appear necessary when rangeland is properly stocked. If a useful indicator does exist, forage availability is favored over grazing behavior because it is more readily monitored by grazing managers. The second part of this study evaluated the utility of forage availability as a rotation indicator. Four simulated C-pasture SDG systems were established, each flexibly stocked with 4-9 yearling steers. Livestock in two of the simulated systems were rotated on a fixed schedule of 7 days per pasture. Steers in the remaining two simulated systems were rotated independently according tc forage availability with grazing periods varying from 0-14 days. No general differences (F > 0.10) were detected in forage quality, forage availability, or animal gains between systems rotated flexibly according to forage availability or those systems rotated every 7 days. Therefore, using forage availability to indicate when to rotate livestock under SDG did not prove advantageous under the conditions of this study. Results of this study support recommendations for SDG that 7-day grazing periods are sufficiently short on properly stocked rangeland.