Now showing items 21-36 of 36

    • Energy Expenditure by Heifers Grazing Crested Wheatgrass of Diminishing Availability

      Havstad, K. M.; Malechek, J. C. (Society for Range Management, 1982-07-01)
      The daily mean energy expenditure of free-ranging heifers grazing crested wheatgrass rangeland was estimated as 161 kcal/kgBW^.75/day using the carbon dioxide entry rate technique (CERT). This was 46% greater than the mean 110 kcal/kgBW^.75/day estimated for stall-fed heifers consuming similar forage. Under laboratory conditions, CERT can provide a mean estimate of energy expenditure that has a standard error of 5% and a coefficient of variation of 20%.
    • Effects of Monoterpenoid Exposure on Ability of Rumen Inocula to Digest a Set of Forages

      Pederson, J. C.; Welch, B. L. (Society for Range Management, 1982-07-01)
      Rumen inoculum collected from wild mule deer on summer, fall, winter, and spring ranges in central Utah was equally effective in digesting alfalfa hay, orchardgrass hay, big sagebrush, curlleaf mahogany, antelope bitterbrush, and hips of sweetbrier rose. Alfalfa hay was the forage most easily digested. Inocula from deer that had not been exposed to big sagebrush and juniper monoterpenoids (essential oils) digested all test forages, including big sagebrush equally as well as inoculum from deer that had been exposed to big sagebrush monoterpenoids. We concluded that rumen microorganisms do not have to adjust to the presence of the monoterpenoids or other dietary changes.
    • Effects of a Nematode on Biomass and Density of Silverleaf Nightshade

      Northam, F. E.; Orr, C. C. (Society for Range Management, 1982-07-01)
      Infective fourth stage larvae of the silverleaf nightshade (Nothanguina phyllobia Thorne) were broadcast on rangeland populations of silverleaf nightshade (Solanum elaeagnifolium Cav.) as a biological control for the weed. Plots were inoculated with nematode-infested dried leaves in April and August of 1977 at two southern High Plains shortgrass prairie locations. One site had been denuded of vegetation 2 years previously. While the August inoculation failed, the April inoculation was successful at both locations: 41% of the plants at the denuded site and 20% of the plants at the shortgrass site became infected with nematodes. At the disturbed site, a difference from the control of 23% in the foiiar biomass and a 42% in the plant density of silverleaf nightshade were attributable to nematode injury. Nematode infection was not observed on any other plant species.
    • Effect of Light, Temperature and Water Stress on Net Photosynthesis in Two Populations of Honey Mesquite

      Hanson, J. D. (Society for Range Management, 1982-07-01)
      Net carbon dioxide assimilation rates (PN) were measured for individuals from two Texas honey mesquite populations grown under controlled water stress, temperature, and light treatments. Maximum (PN) observed for the various tests ranged from 0.69 to 0.82 mg m-2 s-1. Net assimilation rates were significantly lower in the west Texas population than in the east Texas population under high and low water stress. Maximum (PN) at 1.35 mmol m-2 s-1 photon flux density were reached under low water stress at 20 degrees C and 30 degrees C for east and west Texas populations, respectively. The response of (PN) to light was similar to responses reported for other C3 species; and 81 to 99% of the variability in the data was accounted for by using a hyperbolic light response model. Light use efficiency was lower for the west Texas population, and for high temperature and water stress. High temperature and water stress treatments also caused substantial decreases in the estimated theoretical maximum net assimilation rates. Finally, the light saturation point of mesquite varied depending on population and water stress.
    • Effect of Calf Crop on Net Income of a Nevada Range Cattle Operation

      Torell, L. A.; Speth, C. F.; Ching, C. T. K. (Society for Range Management, 1982-07-01)
      This paper examines the effects of calf crop percentages on net income. Calf crop is defined as the ratio of the number of calves born to the number of mature cows and first-calf heifers. Net income is gross cattle sales less operating costs. The results show that high calf crops are not necessarily the most feasible in an economic sense. Rather, ranchers should consider the added costs of achieving a higher calf crop percentage and compare them to the associated added sales. The higher level calf crop is economically feasible only if added sales are greater than or equal to added costs.
    • Effect of Atrazine, Fertilizer, and 2,4-D on Winter Grazing Preferences of Beef Cows on Northcentral Oklahoma Tallgrass Prairie

      Baker, R. L.; Powell, J. (Society for Range Management, 1982-07-01)
      A good condition, tallgrass prairie experimental area was treated with selected combinations of atrazine, 2,4-D, and NPK fertilizer in spring 1975 and 1976. Crude protein contents in November herbage ranged from 3.4% to 6.3% in treated samples. Untreated herbage contained 5.0% crude protein. Nonlactating beef cows were allowed to graze freely on the area during December, 1976. Utilization of herbage ranged from 43% to 87%. Utilization was greatest on NPK areas (82%), 3.4 kg atrazine + NP areas (85%), and 3.4 kg atrazine + NPK areas (87%). Decreaser species comprised a larger percentage of the total production on atrazine + NP, atrazine + NPK, and 2,4-D + NPK areas than on fertilizer-only areas. Tallgrass prairie treated with atrazine and fertilizer or 2,4-D and fertilizer was preferred by beef cows as winter forage over untreated herbage. There was a 15% increase in herbage utilization for every 1% increase in crude protein in the herbage in December.
    • Effect Of 2,4-D on Hymenoxon Concentration and Toxicity of Bitterweed (Hymenoxys odorata) Force-Fed to Sheep

      Calhoun, M. C.; Ueckert, D. N.; Livingston, C. W.; Camp, B. J. (Society for Range Management, 1982-07-01)
      Bitterweed (Hymenoxys odorata) growing at two locations was sprayed with 2,4-D (1.1 kg acid equivalent/ha) during the spring of 1977. Subsequently, plants were collected, dried, and stored when they showed definite signs of herbicide phytotoxicity (epinasty and turgidity). Hymenoxon concentrations were determined on the dried plant material and it was force-fed to penned sheep, in two experiments, to determine the effect of foliar spraying with 2,4-D on bitterweed toxicity. Bitterweed administration decreased voluntary feed intake and increased serum concentrations of urea nitrogen (UN), creatinine (C) and glutamic-oxalacetic transaminase (GOT). Hymenoxon concentrations (air-dry basis) were 2.33 +/- .18% and 1.64 +/- .05%, for unsprayed and 2,4-D sprayed bitterweed, respectively, in Experiment 1 and 1.24 +/- .02% and 1.08 +/- .05%, respectively, in Experiment 2. Spraying bitterweed did not affect feed intake and serum levels of UN, C and GOT and there were not interactions between bitterweed levels and 2,4-D treatments.
    • Cost of Controlling Maturing Western Juniper Trees

      Young, J. A.; Evans, R. A.; Budy, J. D.; Torell, A. (Society for Range Management, 1982-07-01)
      A cost evaluation was conducted of four alternatives for improvements on maturing western juniper (Juniperus occidentalis) woodlands. The alternatives were: (a) the use of picloram (4-amino-3,5,6-trichloropicolinic acid) to kill the trees with no further treatment, with a total cost of $78/ha ($31/acre); (b) picloram with sufficient limbing and/or removal of trees to allow passage of a rangeland drill for seeding at a cost of $448/ha ($179/acre); (c) mechanical clearing and burning of the trees at a cost of $595/ha ($237/acre); and (d) wood harvesting and slash disposal at a cost of $2,080/ha ($832/acre). The picloram and limb, mechanical, and wood-harvesting treatments provide mechanically seedable sites, but of considerably different quality in terms of ease of seeding and chances of seedling establishment. The mechanical treatment requires a large capital investment, while the wood-harvesting treatment requires a large amount of labor. Based on equivalent energy values, the wood-harvesting operation would produce a profit for the landowner who could afford to invest the labor. For a specific woodland, a combination of treatments would be most cost effective.
    • Copper Supplementation of Young Cattle Grazing Improved Meadow Pastures in Southeastern Oregon

      Gomm, F. B.; Weswig, P. H.; Raleigh, R. J. (Society for Range Management, 1982-07-01)
      Yearling cattle grazing improved, tall fescue-legume, meadow pastures showed signs of copper deficiency. Copper supplemented as injected Cuprin or as CuSO4-salt mix reduced the copper deficiency as expressed by blood plasma analyses and animal gains. Yearlings receiving Cu gained 0.10-0.31 kg/hd/day more than the checks. The methods of supplying the Cu were equally effective, but injections raised large lumps on some animals. The interrelationship of Cu and Mo and their relative concentrations in forage are important considerations in livestock nutrition. The forages grown on meadow soils in southeastern Oregon can cause signs that are associated with Cu deficiency in cattle. The sedges and rushes, dominant species in flood meadows, are less likely than grasses and legumes to cause Cu deficiencies because of favorable Cu/Mo ratios. Of the species tested, tall fescue and white clover were most likely to cause deficiencies because of their relatively high concentrations of Mo.
    • Columbia Ground Squirrel in Subalpine Forest Openings in Central Idaho

      Lambeth, R.; Hironaka, M. (Society for Range Management, 1982-07-01)
      Columbia ground squirrels were studied in natural alpine forest openings. Three sites were selected having the same potential but presently with different vegetation due to differing levels of past domestic sheep use. Ground squirrel population was least in the light-use area and increased with vegetation change induced by increased sheep use. Juveniles were most plentiful in the medium-use site and least in the heavy-use area. Up to a point, ground squirrel population increased with plant retrogression. With continued retrogression the community became less suitable to support a healthy population because of less preferred forage species. Lupinus sericeus was the most preferred forb. Other species included Achillea millefolium and Descurania richardsonii, species not generally preferred by sheep. The discussion of sheep-ground squirrel relative impacts also considers metabolic requirement, grazing period and animal density of both grazers.
    • Brush Management Influences the Nutritive Content of Cattle Diets in East-Central Texas

      Kirby, D. R.; Stuth, J. W. (Society for Range Management, 1982-07-01)
      Nutritive content of seasonal diets following mechanical and chemical brush management on east-central Texas rangeland was determined using esophageally fistulated cows. Brush managed pastures had a greater herbaceous standing crop, except during the grazing period in fall the year of treatment, and generally yielded diets higher in crude protein (CP) and in vitro digestible organic matter (IVDOM) than untreated pastures. Mean crude protein content of cattle diets was higher (P is lesser than or equal to 0.05) in all seasons from tebuthiuron-treated pastures, and in summer and fall from pastures which were bulldozed compared to untreated pastures. Mean IVDOM content of cattle diets was higher (P≤0.05) in spring and summer from pastures receiving brush management compared to untreated pastures. Crude protein and IVDOM content of diets decreased in all pastures and seasons between beginning and end of grazing periods, with the exception of higher IVDOM in the spring, suggesting that the cows benefitted by grazing regrowth of herbaceous plants.
    • Botanical Composition of Cattle Diets Grazing Brush Managed Pastures in East-Central Texas

      Kirby, D. R.; Stuth, J. W. (Society for Range Management, 1982-07-01)
      More grass was consumed in all grazing periods on tebuthiuron-treated pastures, and in fall and summer grazing periods on mechanically treated pastures, than on untreated pastures. Cow diets were dominated by grasses, mainly brownseed paspalum and little bluestem, regardless of treatment and season. Similar amounts of forbs were selected from all treatments during all seasons. More woody vegetation was selected from mechanically-treated and untreated pastures than from tebuthiuron-treated pastures. Forbs decreased and woody vegetation increased in diets from spring through fall. Grasses and leaves decreased, whereas woody vegetation and stems increased in the diets from the beginning to the end of the grazing periods. Within grazing periods forb consumption decreased in fall but increased in summer and spring with time spent in pastures. Small amounts of dead forage were consumed at irregular intervals.
    • An Evaluation of Dimension Analysis for Predicting Shrub Biomass

      Murray, R. B.; Jacobson, M. Q. (Society for Range Management, 1982-07-01)
      Fifteen independent variables consisting of circumference, surface area, and volume for various assumed shapes were derived from simple diameter and height measurements. These variables were used in seven models to predict aboveground biomass of leaves, different sizes of live and dead twigs, and combinations of fractions for threetip sagebrush, gray horsebrush, green rabbitbrush, and broom snakeweed. In addition, models based on height and circumference were tested on each species and fraction. A simple linear model with surface area or volume as independent variables and height × circumference models gave the best biomass predictions for these species.
    • Amount and Distribution of Dry Matter, Nitrogen, and Organic Carbon in Soil-Plant Systems of Mesquite and Palo Verde

      Barth, R. C.; Klemmedson, J. O. (Society for Range Management, 1982-07-01)
      Over a 3-year period, soil-plant systems of velvet mesquite and palo verde from the Sonoran Desert were sampled by standing crop, litter, and soil components and analyzed to describe the amount and distribution of dry matter, nitrogen, and carbon in the systems. Honey mesquite was sampled on a limited basis in southern New Mexico. Velvet mesquite averaged about one-third larger in crown area and weight than palo verde, but the two shrubs were similar in the distribution of dry matter, N, and C. Honey mesquite was much smaller and differed in distribution of dry matter, N, and C. Regression analysis showed that dry matter, N, and C in components of shrub systems of velvet mesquite and palo verde varied in a predictable manner and can be estimated with good precision using height, average crown diameter, or crown area of shrubs as the independent variable. Functional analysis showed that soil under palo verde did not accumulate N or C with increase in shrub size, whereas that under velvet mesquite accumulated N at the rate of 11.2 g/m2 per meter of height and C at the rate of 0.11 kg/m2 per meter of height.
    • Alkaloid Affects in Vitro Dry Matter Digestibility of Festuca and Bromus Species

      Fairbourn, M. L. (Society for Range Management, 1982-07-01)
      A field evaluation study was made on eight pasture grass species, 'Latar' orchardgrass (Dactylis glomerata L.), 'Fawn' tall fescue (Festuca arundinacea Schreb.), 'Manchar' bromegrass (Bromus inermus Leyss.), 'Regar' bromegrass (B. biebersteinii Roem and Schult.), 'Garrison' creeping foxtail (Alopecurus arundinacea Poir.), 'Meadow' foxtail (A. pratensis L.), 'Luna' pubescent wheatgrass [Agropyron trichophorum (Link) Richt.], and 'Greenar' intermediate wheatgrass [A. intermedium (Host) Beauv.]. Three harvests of each species were analyzed for in vitro dry matter digestibility (IVDMD) for 1975, 1976, and 1977. Fawn tall fescue and Manchar bromegrass had severely depressed IVDMD values in the second harvest of 1976 and both species and Regar bromegrass had low values for the third harvest of that year. The forages were analyzed for perloline alkaloid by a thin layer chrometography method and the depressed IVDMD values were found in the replicate samples containing perloline. The alkaloid could be toxic to livestock.
    • Acute Toxicity of Mixtures of Range Management Herbicides to Cutthroat Trout

      Woodward, D. F. (Society for Range Management, 1982-07-01)
      Six different paired mixtures of dicamba, picloram, 2,4-D butyl ester, 2,4-D isooctyl ester, and 2,4-D propylene glycol butyl ether ester were tested with cutthroat trout (Salmo clarki). Except for 2,4-D isooctyl ester, the LC50's resulting from mixtures of 2,4-D esters and picloram were lower than LC50's of those herbicides tested individually. Dicamba and 2,4-D isooctyl ester were the least toxic individually and mixtures of dicamba or 2,4-D isooctyl ester with the other herbicides tested did not result in increased toxicity. Our results reflect the importance of using combination exposures in determining the biological significance of the simultaneous occurrence of more than one herbicide in surface waters.