No abstract

This study indicated that the bite-count and fecal analysis methods give similar results for estimating major components of cattle diets in Texas. The bite-count method could not be used on large, brush-infested pastures with rough terrain; however, the fecal analysis metnod was easily used under such conditions. Other advantages of fecal analyses were: samples were collected with a minimum of field work, diets of wild and domestic animals could be obtained, and bad weather and poor field conditions were not problems. Major disadvantages of the fecal analysis technique were: forages with dense stellate trichomes were overestimated; mesquite beans were retained in the digestive tract for abnormally long periods; the laboratory phase required a trained technician; and the work was tedious.

Highlight: Both honey mesquite density and percent of plants dead the year of aerial spraying with 2,4,5-T proved to be major factors influencing perennial grass production. Sites with sparse honey mesquite stands and very dense stands (over 50% canopy cover) yielded little extra grass after 2,4,5-T application. Heavy mesquite foliage probably prevented adequate leaf coverage with 2,4,5-T in dense stands, and in sparse stands mesquite competed little with the herbaceous plants. Increased perennial grass production of about 540 lb/acre/year would be necessary over a 5-year period to break even with a $4.60/acre aerial applicationof2,4,5-T. With honey mesquite cover of 30%, a plant kill over 80% the year of application was required to provide a 540 lb/acre/year grass increase. However, a 90% kill would provide nearly 750 lb/acre/ year extra perennial grass. Thus, paying particular attention to optimum environmental factors and proper timing for the 2,4,5-T application can pay big dividends.

The problems inherent in managing rangeland where wide fluctuations in forage production and rainfall occur are well known to livestock men on the Great Plains. Annual percipitation at Akron, Colorado, averages about 17 inches and varies from 10 inches to 27 inches. Grazing programs that will minimize the effects of wide forage fluctuations resulting from precipitation flucuations have been the subject of many varied proposals. The most common has been to recommend that ranges be stocked with a basic breeding herd at a rate that is. not detrimental to range land during drought years. Any excess forage produced, in average or above-average years, would be utilized by purchased livestock or by "carried over" yearling livestock. A reliable method for predicting forage production in advance of the grazing season Yolorado Agricultural Experiment Station Scientific Journal Article No. 779. This study was supported in part by Regional Project W-25, Ecology and Improvement of Brush-Infested Ranges.

Sites particularly susceptible to medusahead invasion in the more arid portions of Idaho were either those with well-developed soil profiles, particularly those with high clay content either at or near the surface; or those occupying topographic positions that received additional runoff from adjacent sites. In more mesic climates moderately well developed soils appeared as highly susceptible as the well-developed soils. Conversely, soils with little profile development, particularly those which were well drained, remained dominated by cheatgrass in early seral stages regardless of whether they were in the more arid or mesic areas. The nature of the surface geology as it influenced the soil texture derived therefrom was a valuable aid to identifying sites susceptible to medusahead. Maintaining a good stand of perennial vegetation appeared the best barrier to medusahead invasion in to susceptible soils.