• Forage intake by beef steers grazing winter wheat with varied herbage allowances

      Redmon, L. A.; McCollum, F. T. III.; Horn, G. W.; Cravey, M. D.; Gunter, S. A.; Beck, P. A.; Mieres, J. M.; San Julian, R. (Society for Range Management, 1995-05-01)
      Two grazing trials were conducted in separate years on a 5.86 ha winter wheat (Triticum aestivum var. Chisholm) pasture divided into 10 experimental paddocks. Paddocks were differentially grazed with beef steers to produce an array of different herbage mass levels, expressed as kg dry matter (DM)/ha. Each experimental paddock was then continuously stocked with 3 beef steers during each 7-day forage intake trial. Daily forage intake, expressed as kg organic matter (OM)/100 kg body weight (BW), was estimated from fecal output (Cr2O3 dilution) of the beef steers and in vitro organic matter disappearance of esophageal masticate collected from each paddock. Estimated daily gain was calculated from forage intake and net energy values calculated from organic matter disappearance data. Forage intake, organic matter disappearance, and estimated daily gain were related to daily herbage allowance, expressed as kg DM 100 kg BW-1 day-1, and herbage mass utilizing a quadratic equation with a plateau function. As herbage allowance increased, organic matter disappearance improved (Y = 62.18 + 1.08 herbage allowance -.022 herbage allowance2; r2 = .64, MSE = 5.06) as did forage intake (Y = 1.3 + .12 herbage allowance -.003 herbage allowance2; r2 = .52, MSE = .07), and estimated daily gain (Y = -.059 + .12 herbage allowance -.003 herbage allowance2; r2 = 59, MSE = .07). Plateaus were achieved at herbage allowance between 20 to 24 kg DM 100 kg BW-1 day-1. Results of this study indicate forage intake and estimated daily gain declined severely as herbage allowance fell below 20 to 24 kg DM 100 kg BW-1 day-1. This data may provide a threshold herbage allowance for initiation of energy supplementation programs for growing cattle on wheat pasture.
    • Grain supplementation on bluestem range for intensive-early stocked steers

      Owensby, C. E.; Cochran, R. C.; Brandt, R. T.; Vanzant, E. S.; Auen, L. M.; Clary, E. M. (Society for Range Management, 1995-05-01)
      A 4-year study was conducted on Kansas Flint Hills bluestem range to monitor animal gain, grass, and forb standing biomass following grazing, plant population dynamics, and in 2 years, subsequent feedlot performance of steers under intensive-early stocking supplemented with increasing levels of sorghum grain. Each year from 1988 through 1991, crossbred beef steers were stocked at 0.24 ha/100 kg of initial steer weight from 5 May to 1; July. Steers in twice-replicated pastures were given no supplementation, 0.91 kg rolled sorghum grain per head daily, or 1.82 kg rolled sorghum grain per head daily, which corresponded to approximately 0, 0.3, and 0.6% of body weight-1. All steers were implanted with estradiol 17 beta in 1988 and zeranol in 1989-91 during initial processing and had unlimited access to a lasalocid/mineral mixture during the entire trial. In 1989 and 1990, representative groups of steers selected from all treatment/pasture combinations were subjected to a feedlot finishing phase and carcass data were obtained. Grass and forb standing crops were estimated each year at livestock removal in mid-July and again in early October. Pretreatment species composition and basal cover were determined in 1988 and compared to those at the end of the study. In mid-July, when cattle were removed, residual standing biomass of grass increased in direct proportion to increasing level of supplement. Standing biomass of grass at the end of the growing season did not differ among pastures with different supplement levels. Forb standing biomass did not differ among pastures with different supplement levels in July or October. Changes in plant populations among treatments during the course of the study were minimal. During the early portion of the grazing period, sorghum grain supplementation did not significantly influence steer gains, but average daily gain during the latter part of the grazing period increased in direct proportion to increasing level of sorghum grain supplement. Daily gain. feed intake, carcass characteristics, and gain:feed ratio were not different among treatments during the feedlot phase. Although conversion efficiencies may be economically marginal, low-level grain supplementation has the potential to increase the daily gain of cattle grazing early-season tallgrass prairie under an intensive-early stocking program.
    • Grass seedling morphology when planted at different depths

      Ries, R. E.; Hofmann, L. (Society for Range Management, 1995-05-01)
      Depth of planting has been acknowledged in the literature as a factor which modifies grass seedling morphology. However, the type and extent of this modification has not been clearly documented. A growth chamber study was conducted to evaluate the mesocotyl, coleoptile, and leaf internode development of smooth bromegrass 'Lincoln' (Bromus inermis Leyss.), sideoats grama 'Pierre' [Bouteloua curtipendula (Michx.) Torr.], and western wheatgrass 'Rodan' [Agropyron smitilii Rydb.; syn. = Pascopyron smithii Rydb. (Love)] seedlings when planted at 6, 25, 51, 76, and 102-mm soil depths. Environmental conditions within the growth chamber were held constant for all treatments. Mesocotyl, coleptile, and/or leaf internodes did not elongate equally for all planting depths. Shallow-planting lessened elongation while deep planting maximized elongation within the genetic limits possible for each species and individual genotype. When evaluating grass seedling morphology, regardless of species or seed size, planting depth must be great enough to allow inherent genetic expression in the development and elongation of the mesocotyl, coleoptile, and leaf internodes. When planting for a grass stand, the sower should keep in mind that percent emergence for smooth bromegrass, sideoats grama, and western wheatgrass decreased significantly when planted deeper than 26, 8, and 52 mm, respectively. Adventitious root numbers at the coleoptilar node decreased significantly when planting depths exceeded 25, 51, and 51 mm for smooth bromegrass, sideoats grama, and western wheatgrass, respectively.
    • Growth of winterfat following defoliation in Northern Mixed Prairie of Saskatchewan

      Romo, J. T.; Redmann, R. E.; Kowalenko, B. L.; Nicholson, A. R. (Society for Range Management, 1995-05-01)
      An observed increase in winterfat (Ceratoides lanata (Pursh) J.T. Howell) on ungrazed rangeland suggests that this shrub may potentially be an important forage resource in the Northern Mixed Prairie under improved grazing management. The objectives of this study were to: 1) compare density, frequency, and cover of winterfat in a grazed pasture and site that had been protected from grazing for about 30 years; and 2) evaluate regrowth of winterfat following defoliation during the growing season on a clayey range site in Saskatchewan. Density, frequency, canopy cover, and basal cover were significantly greater in the protected range than the grazed pasture. Density (1.1 SE +/- 0.01 plants m-2) and frequency (70% SE +/- 3.6) were about 2-fold greater, while canopy cover (7.0% SE +/- 1.4) and basal cover (1.7% SE +/- 1.5) were 7- to 8-fold greater, in the protected versus grazed range. When defoliated to a 5-cm stubble in May, June, or July plants produced significant amounts of regrowth but not when herbage was removed in August. When defoliated in late July or August current year production the following year was significantly lower than control and earlier defoliations. Current year production peaked in late July and August. Total standing crop was 2- to 4-fold greater in the control than the defoliation treatments because the biomass produced in previous years was removed from clipped plants. Because winterfat produces substantial amounts of new growth following defoliation in May, June, or July it is recommended that this shrub be grazed only once during the growing season to prevent grazing of this regrowth. Plants defoliated in May can potentially produce biomass equal to control the following year whereas plants defoliated in June, July, or August will likely require more than 1 year of rest to recover their annual productivity.
    • Herbage dynamics on 2 Northern Great Plains range sites

      Heitschmidt, R. K.; Grings, E. E.; Haferkamp, M. R.; Karl, M. G. (Society for Range Management, 1995-05-01)
      Quantity and quality of forage produced are primary determinants of level of livestock production derived from grazing lands. Moreover, species composition of herbage is often considered a primary determinant of the ecological condition of rangelands. The broad objective of this study was to quantify the productivity, growth dynamics, and quality of herbage growing on 2 Northern Great Plains range sites and to concurrently relate magnitude and composition of production to the ecological condition of the sites. Using frequent harvest techniques, the 2-year study showed herbage production on the highly productive silty range site averaged 219 g m-2 as compared to 218 g m-2 on the supposedly less productive clay pan range site. The primary reason the clay pan site proved to be as productive as the silty site was attributed to the greater amounts of introduced annual grasses on the clay pan (148 g m-2) than the silty site (104 g m-2). The annual grass component on the clay pan was a near equal mix (71 vs 51 g m-2) of Japanese brome (Bromus japonicus Thunb.) and cheatgrass (B. tectorum L.) whereas the overwhelming dominant on the silty site was cheatgrass (73 g m-2). Western wheatgrass [Pascopyrum smithii Rydh. (Love)] was the dominant perennial grass on both sites averaging 49 g m-2 on the clay pan site and 57 g m-2 on the silty site. There were minimal differences between sites in terms of nutrient quality values (i.e., crude protein, acid detergent fiber, neutral detergent fiber) with results showing clearly that age of tissue was the major factor altering seasonal forage quality values. Range condition analyses revealed the clay pan site was in fair ecological condition and the silty site was in good condition. Study results demonstrate the need for land management agencies to continue to refine productivity estimates as well as adopt new techniques for assessing the ecological condition of rangelands.
    • Influence of an environmental gradient on physiology of singleleaf pinyon

      Jaindl, R. G.; Eddleman, L. E.; Doescher, P. S. (Society for Range Management, 1995-05-01)
      The acquisition of water and regulation of its loss are important to plant 'success' in arid environments. Species existing over a range of environmental conditions should respond physiologically to varying conditions to maximize water use efficiency and avoid low tissue water potentials. Seasonal and diurnal ecophysiological responses of singleleaf pinyon (Pinus monophylla Torr. and Frem.) were investigated along an environmental gradient involving elevation, moisture and temperature in Nevada. The gradient was represented by study sites in black sagebrush (Artemisia nova A. Nels), mountain big sagebrush (Artemisia tridentata ssp. vaseyana Nutt.), and mountain mahogany (Cercocarpus ledifolius Nutt.) communities. Xylem pressure potential, conductance, and transpiration were measured over 2 growing seasons. Xylem pressure potential and leaf conductance ranged from -3.0 to -0.7 MPa and 0.01 to 0.43 cm s-l, respectively, during the study. Carbon isotope discrimination (delta) of needles was determined in August 1990. Differences in delta values were not significant between sites at the lowest and highest elevations but were significant between the driest site (black sage) and the relatively wetter site (mountain mahogany). Leaf conductance was influenced by but not strongly correlated with predawn xylem pressure potentials, relative humidity, and temperature. Generally, there was little difference in water use characteristics of singleleaf pinyon along the environmental gradient in this study. Thus, it appears that singleleaf pinyon's ability to exist over a range of environmental conditions is not a function of variable ecophysiological responses but an opportunistic response to the availability of resources and conditions suitabie for erowth to occur.
    • Influence of temperature on germination of Japanese brome seed

      Haferkamp, M. R.; Palmquist, D.; Young, J. A.; MacNeil, M. D. (Society for Range Management, 1995-05-01)
      Japanese brome (Bromus japonicus Thunb.), an introduced annual grass, is now common in some northern mixed-prairie communities. This species has the potential to alter both the seasonality of standing crop and forage quality. We sought to gain a greater understanding of Japanese brome seed germination by subjecting seed to a series of 55 constant or alternating temperature regimes following 3 to 9 months of dry laboratory storage. Cold and moderate temperature regimes provided optimum germination conditions (defined as not lower than the maximum observed minus one-half its confidence interval at the 0.05 level of probability). Extremely cold or warm temperatures suppressed germination. Germination of afterripened seed over a wide range of temperature combinations, many of which occur during fall in the Northern Great Plains, should enhance establishment and perpetuation of Japanese brome on rangelands.
    • Livestock grazing impacts on interrill erosion in Pakistan

      Bari, F.; Wood, M. K.; Murray, L. (Society for Range Management, 1995-05-01)
      This study was conducted for 2 consecutive growing seasons in a temperate region of Pakistan to determine a residual phytomass level necessary to adequately protect the soil against accelerated interill erosion A rainfall simulator was used to apply rainfall to 48 (1 m square) circular plots arranged in a completely randomized experimental design, with 4 residual phytomass levels and 2 replications. The residual treatment with 3,024 kg ha-l phytomass resulted in the lowest erosion rates, and the treatment with 624 kg ha-l phytomass produced the highest erosion. Standing phytomass was the most important variable affecting erosion with foliar cover and basal cover also highly correlated to erosion.
    • New concepts for assessment of rangeland condition

      Adams, D. C.; Short, R. E.; Pfister, J. A.; Peterson, K. R.; Hudson, D. B. (Society for Range Management, 1995-05-01)
      Range condition score or classification does not tell us, in a general sense, much of what managers and the public want to know about rangelands. Range condition is not a reliable indicator, across all rangelands, of biodiversity, erosion potential, nutrient cycling, value for wildlife species, or productivity. Succession, the basis for the current concept of range condition is not an adequate yardstick for evaluation of rangelands. The Society for Range Management (SRM) established the Task Group on Unity in Concepts and Terminology which has developed new concepts tor evaluation of the status of rangelands. These concepts are based on the premise that the most important and basic physical resource on each ecological site is the soil. If sufficient soil is lost from an ecological site, the potential of the site is changed. The Task Group made three recommendations, which were adopted by the SRM: 1) evaluations of rangelands should be made from the basis of the same land unit classification, ecological site; 2) plant communities likely to occur on a site should be evaluated for protection of that site against accelerated erosion (Site Conservation Rating, [SCR]); and 3) selection of a Desired Plant Community (DPC) for an ecological site should be made considering both SCR and management objectives for that site.
    • Observation: Botanical and other characteristics in Arctic salt-affected coastal areas

      Bruce, L. B.; Panciera, M. T.; Gavlak, R. G.; Tilman, B. A.; Cadle, J. M. (Society for Range Management, 1995-05-01)
      This study was designed to provide information on cover, botanical composition, and frequency of major plant species in a brood-rearing area used by migratory geese south of Howe Island on the Sagavanirktok River Delta near Prudhoe Bay, Alaska. The area is split by the Endicott road and the information was also used to gain preliminary information concerning the effect of the road on goose and caribou activity. Transects on the east and west sides of the access road at the base of the Endicott causeway were established to evaluate occurrences of vegetation, goose fecal pellets, caribou tracks, and coastal debris. The point intercept method characterized plant cover, species frequency, and botanical composition. The recorded occurrence of fecal pellets and tracks on the transects were used as estimates of the presence of geese and caribou. Vegetative cover was 21% west and 38% east of the road near the Endicott causeway base in 1991. The 3 species most prominent west of the road were Carex sub-spathacea Wormsk., Salix spp., and Puccinellia phryganodes (Trin.) Scribn. & Merr. (botanical composition of 26, 23, and 21%, respectively). East of the road, Salix spp. (43%) dominated botanical composition followed by Carex aquatilis Wahlenb. (13%) and Dryas integrifolia M. Vahl (11%). The west and east sides differed botanically. Caribou tracks were observed in 60% of the transects on both sides of the road and goose fecal pellets were more prevalent on the west side (86%) than on the east side (48%). Geese pellets and caribou tracks occurred in different locations in the study area. Goose fecal pellets were from all goose species and may have included more than 1 year.
    • Technical Note: Physical factors that influence fecal analysis estimates of herbivore diets

      Bartolomé, J.; Franch, J.; Gutman, M.; Seligman, N. G. (Society for Range Management, 1995-05-01)
      Microhistological analysis of epidermal fragments in feces is often used to estimate the diet of herbivores but is not generally accepted as a consistently reliable method. Gross errors arise, especially when diets are composed of herbage components with widely different morphological and structural characteristics. The present study investigated the possibility of using such physical characteristics to improve the reliability of the method. Over a 7 day period, 4 rumen-fistulated beef cows were given a fixed diet composed of a shrub, a grass, and a forb component. On the last 2 days, samples of rumen content and feces were taken for analysis of epidermal fragment. Forbs were under-estimated, grasses over-estimated, and shrubs correctly estimated. Correction factors to estimate true diet composition were defined as the biomass represented by the specific epidermal fragments (epidermal weight index) and the degree of degradation to which the epidermis is subjected in the digestion process (epidermal erodibility factor). These factors account for characteristic physical features of the different dietary components and were measured directly or were derived from the calibration experiment. The utility of such factors depends on accurate determination of the component variables and may be overshadowed by sampling error and observer bias in the microhistological identification of epidermal fragments.