A cow-calf vs yearling substitution ratio for shortgrass steppe

Abstract

Managers often deal with the problem of herd replacement of one animal class by another. A preliminary study suggested that steers could be substituted for cow-calf pairs on shortgrass steppe on a weight:weight basis. This ratio was tested on 2 pairs of pastures, one dominated by native shortgrass steppe and the other by a seeded stand of sideoats grama (Bouteloua curtipendula (Michx.)Torr.). The pasture sizes were set so the cow-calf pastures were 1.8 times larger than the steer pastures to allow equal herd sizes for the 2 classes of animals. Adequacy of stocking was determined by equalizing utilization. The actual stocking ratios of 1.79 steers to 1 cow-calf pair on the native pastures and 1.78 steers to 1 cow-calf pair on the seeded pastures resulted in no significant differences in utilization or standing crop of remaining forage after the grazing season ended. Season-long, the 90% confidence bounds of the steer-weight:pair-weight ratio was 0.981-1.035 and 0.968-0.985 for native and seeded pastures, respectively. This ratio provides an acceptable initial stocking rate guide for those wishing to change from cow-calf to steer operations, or vice versa, on the shortgrass steppe.