Lorin E. Harris

Nutritive Value of Cheatgrass and Crested Wheatgrass on Spring Ranges of Utah.

T HE abundance of cheatgrass (Bromus tectorum) on the foothill and semidesert ranges throughout the Intermountain and Great Basin region make it of concern to the livestock industry of this area. It is the most abundant forage plant on many spring ranges andperhaps contributes more feed for livestock than any other range species during this period. However, the forage production from cheatgrass fluctuates greatly from year to year, depending upon moisture and growing conditions. Therefore, many believe that cheatgrass should be replaced by native or introduced perennial grasses. The return of native perennials through light grazing is slow and the necessary reductions in livestock grazing might constitute inefficient use of the areas involved. However, on the better soils, cheatgrass ranges can be planted successfully to introduced perennial grasses. During the past twenty years crested wheatgrass has been used rather extensively for this purpose. Yet, in many areas, the soils are low in productivity, and rehabilitation through seeding is hazardous and impractical. Further, the necessity of prior eradication of cheatgrass makes seeding uneconomical in many instances. As a result, a large part of the spring ranges throughout the Great Basin area are supporting cheatgrass with scattered clumps of native grasses and browse plants (Fig. 1). Cheatgrass areas often produce as much forage per acre as crested wheatgrass or native bunch grasses (Hull et al., 1947). However, cheatgrass remains green only a relatively short time during the spring and soon after maturity becomes unpalatable. Sheep normally graze very little on cheatgrass after it becomes dry, but cattle graze dry mature cheatgrass rather extensively during the winter when furnished water and a high protein supplement (Fleming et al., 1942). The palatability of crested wheatgrass for both sheep and cattle likewise decreases markedly as the plant matures. However, the perennial wheatgrass remains green much longer than the annual cheatgrass and in addition maintains an upright stature much better through heavy rains and snows. Even though perennial grasses apparently have many advantages over cheatgrass as a forage cover, it is believed that only a relatively small portion of the cheatgrass area in the Great Basin region will be replaced by perennial bunch grasses (Fleming et al., 1942). Therefore, we must recognize cheatgrass as a source of range feed and manage these areas for maximum forage and livestock production.

Measuring Consumption and Digestibility of Winter Range Plants by Sheep.

EXTENSIVE areas of desert range in the intermountain area are the sole ;source of forage for sheep during the winter grazing season. The diversity in soil, climate, and topography provides a variety of native forage for grazing animals, and the nutritive content of the diet varies widely depending upon environmental conditions, and animal selectivity for various species and parts of plants. Thus, a knowledge of the nutritive qualities of native forage plants is of extreme importance for a better understand-ing and appraisal of the animals diet under range conditions. Most studies of the nutrients supplied by range forage have dealt with chemical analyses of bulk samples of herbage collected from the range. However, chemical content is not a reliable index to availability of the various nutrients and is of limited value unless accompanied by digestibility determinations or balance trials. For this reason a method for determining digestibility of native forage under range conditions was developed and used in obtaining the data presented in this paper.

Seasonal Grazing of Crested Wheatgrass by Cattle.

Thirty-six pastures of crested wheatgrass were grazed in early spring plus early fall; late spring; all spring; early summer; late summer; early fall; and late fall. Summer and fall treatments included grazing with and without supplement. Yearlings made substantial gains in all seasons except during late fall when they lost weight. They finished the entire grazing period with an average gain of 224 lb. Calves gained 249 lb. Yearlings and calves did as well on crested wheatgrass as on forest range, and supplementation provided no additional gain. Cows on supplement gained 125 lb as compared to 50 lb for non-supplemented cows. In years with no fall regrowth, second grazing of crested wheatgrass without supplement produced daily gains in early fall equal to those for single grazing with supplement.