CASE STUDY: Effect of cattle and sheep grazing on stocking rate and botanical composition of subirrigated pasture

Changes in commodity pricing and environmental concerns are changing animal agriculture throughout the United States. Adopting multispecies grazing as an alternative production system could result in improved forage utilization, increased animal performance, and reduced production costs, and thereby improve the financial stability of livestock operations. This study focused on the Silver Spur Ranch near Saratoga, Wyoming, a historical cattle ranch where sheep grazing is being integrated into irrigated and rangeland pastures. The overall objectives of this study were to evaluate the effect of multispecies grazing on changes in botanical composition and nutrient availability following grazing in subirrigated pasture. Forage DM followed the general dietary patterns of animals that were last stocked in the pasture. There were fewer forbs in the north pasture, where sheep grazing followed cattle grazing, and fewer graminoids in the south pasture, where cattle grazing followed sheep grazing. Relative depletion of CP and digestible DM was highest for forbs grazed by sheep after cattle. At the end of the first grazing period, the small north pasture (cattle grazing) had 9.7 d of grazing remaining at the current stocking rate. However, at the end of the second grazing period (sheep following cattle), the small north pasture had 14.7 d of grazing remaining. This represents a 52% increase in days of grazing remaining over the first period. The small south pasture (sheep followed by cattle) had little change from the first grazing period to the second (13.4 vs. 13.0 d).