The University of Arizona

Vegetation, cattle, and economic responses to grazing strategies and pressures.

W.A. Manley, R.H. Hart, M.J. Samuel, M.A. Smith, J.W. Waggoner, J.T. Manley

Abstract


Rotation grazing strategies have been proposed to increase stocking capacity, improve animal gains, and improve forage production and range condition. We compared continuous or season-long, 4-pasture rotationally deferred, and 8-paddock time-controlled rotation grazing on mixed-grass rangeland near Cheyenne, Wyo. from 1982 through 1994. Stocking rates under light, moderate and heavy grazing averaged 21.6, 47.0, and 62.7 steer-day ha-1; grazing pressures were 11.0 to 90.1 steer-day Mg-1 of forage dry matter produced. We estimated above and below-ground biomass, botanical composition and basal cover. Bare ground and cover of warm-season grasses, forbs, and lichens were greater under heavy stocking; cover of litter, western wheatgrass, and total cool-season graminoids were greater under light stocking. Stocking rate and grazing strategy had no effect on above-ground biomass and little effect on below-ground biomass. Under heavy stocking, percent of above-ground biomass contributed by forbs increased, especially under time-controlled rotation grazing, and that of western wheatgrass decreased. Otherwise, effects of grazing strategy, level vs. slope, and north vs. south slope on vegetation were insignificant. Steer average daily gain decreased linearly as grazing pressure increased (r2 = 0.44); grazing strategies had no significant effect. When cattle prices are favorable, the stocking rates that are most profitable in the short run may be high enough to reduce range condition.

Keywords


optimization;ground cover;producer prices;beef;liveweight gain;continuous grazing;root systems;rain;stocking rate;forbs;rotational grazing;steers;Wyoming;grazing intensity;biomass;plant litter;botanical composition;grasses

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