In the Intermountain West where summer precipitation does not generally occur, grasses normally mature early in the summer. When mature, grasses usually have rather poor nutritional quality. Mule deer and pronghorn seldom use mature grasses in their diets during fall, winter and early spring for this reason. Elk will utilize them but nutrient content of the grasses will not meet the nutritional requirements of elk. Controlled grazing with livestock provides a potential method of improving both protein and energy content of grasses as well as improving the palatability of them for mule deer, pronghorn and elk.
Livestock grazing in the spring when grasses are in the boot stage, just as the seed heads are forming in the sheaths of the plants, removes most of the plant material. This forces the grass plants to begin again. As this regrowth develops, soil moisture is being depleted. If timing is correct there is insufficient soil moisture available to complete the growth cycle of the grass and the plants will go into dormancy in an immature stage. This immature stage is higher in nutrient content than if the plants were allowed to complete their life cycle and produce seed. The lack of reproductive stems also improves the palatability of the grasses to wild ungulates. This same management strategy can also be used to enhance the growth of desirable shrubs like bitterbrush. The trick is to remove the livestock when sufficient soil moisture remains to provide regrowth of the grasses or additional growth by shrubs. This system must not be used annually, as the grasses need to be rested every other year and allowed to complete their life cycle.
A multiple pasture grazing system that provides both rest and deferment as well as spring use treatments will provide high quality conditioned grasses for wildlife use later in the year, rest for regaining vigor and seed production of the grasses, and seasonal forage for livestock during spring and early summer. Forage produced in the rested pasture will also be available for use by wildlife. The deferred pasture will be used by livestock after soil moisture is low enough so that spring regrowth will not occur. However, if fall rains occur, regrowth may develop at this time and be readily available to wildlife.