• Vegetation response to increased stocking rates in short-duration grazing

      Ralphs, M. H.; Kothmann, M. M.; Taylor, C. A. (Society for Range Management, 1990-03-01)
      Short-duration grazing (SDG) has been purported to increase forage production and utilization compared to other grazing systems, and thus can sustain higher stocking rates. This study was designed to determine if standing crop could be maintained as stocking rates increased. Four stocking rate treatments ranging from the recommended rate for moderate continuous grazing to 2.5 times the recommended rate were applied in a simulated 8-pasture SDG system. There was little change in frequency and composition of short-grasses over the study, but mid-grass frequency and composition both declined. Standing crop of all major forage classes declined as stocking rates increased. However, the rate of decline was less than proportional to the increase in stocking rate during the growing season. By fall, standing crop was inversely proportional to stocking rate, leading us to conclude that standing crop could not be maintained at the higher stocking rates. Low standing crop in the fall indicated a potential shortage of forage at the high stocking rates during the winter.
    • Value of multiple fecal indices for predicting diet quality and intake of steers

      Leite, E. R.; Stuth, J. W. (Society for Range Management, 1990-03-01)
      The relationship of fecal nitrogen fractions and condensed tannins dietary crude protein, in vitro organic matter digestibility, and intake of steers was assessed to determine the suitability of these multiple fecal indices for predicting quality of animal diets under free-roaming conditions. Research was conducted on the Texas A&M Native Plant and Animal Conservancy near College Station, located in the Post Oak Savannah region of Texas. Regression equations were used to evaluate relationships between dietary intake and quality to fecal variables. Dietary crude protein, digestible organic matter, organic matter intake, crude protein intake, and digestible energy intake were determined from previous studies. Corresponding fecal samples were analyzed for absolute output, proportions, and concentrations of nitrogen and selected fractions of fecal organic matter, as well as fecal condensed tannins, proportions of fecal monocot and dicot fragments, and fecal organic matter. In general, no fecal parameter by itself had a high correlation with dietary variables when expressed on a proportion or concentration basis. A combination of fecal indexes accounted for more variation in dietary parameters than fecal nitrogen. Fecal nitrogen fractions did not improve the predictive power of multiple variable models. Equations predicting dietary crude protein (%) and crude protein intake yielded the highest coefficients of determination (R2 = .57 and .51, respectively). Multiple fecal indices used in this study were of limited value in predicting diet quality and intake.
    • Trampling effects from short-duration grazing on tobosa-grass range

      Weigel, J. R.; Britton, C. M.; McPherson, G. R. (Society for Range Management, 1990-03-01)
      Emergence of broadcast-seeded kleingrass (Panicum coloratum L. 'Selection 75') was compared for 2 seasons in short-duration grazed (SDG) areas and ungrazed exclosures in the Texas Rolling Plains in order to test the hypothesis that short duration grazing (SDG) increases seedling emergence. Kleingrass emergence was similar between treatments in both years. Emergence was unrelated to percent foliar cover of preexisting vegetation. Soil strength was greater in grazed areas in both years, but showed evidence of recovery between years. Trampling under short-duration grazing provided no beneficial effect on kleingrass emergence or soil strength in either year.
    • Tiller defoliation patterns under short duration grazing in tallgrass prairie

      Gillen, R. L.; McCollum, F. T.; Brummer, J. E. (Society for Range Management, 1990-03-01)
      Simulated 8-pasture short duration grazing systems were studied in 1985-86 to determine the effect of grazing schedule and stocking rate on defoliation patterns of individual grass tillers of big bluestem (Andropogon gerardii Vitman) and little bluestem (Schizachyrium scoparium (Michx.) Nash). Treatments consisted of 3 grazing schedules (2, 3, or 4 rotation cycles per 152-day grazing season) and 2 stocking rates (1.3 and 1.8 times the recommended normal). Grazing schedule and stocking rate did not affect the percent tiller height reduction per grazing period except for the combination of 2-cycle grazing and heavy stocking which increased percent height reduction. Percent tiller height reduction per grazing period decreased over the grazing season for the 3 and 4-cycle grazing schedules. Grazing schedule and stocking rate had little effect on the height at which tillers were defoliated. Increasing the number of grazing periods reduced the percentage of tillers defoliated per grazing period but increased the cumulative defoliation frequency over the grazing season. Grazing schedule did not affect the percentage of tillers ungrazed over the entire grazing season. Big bluestem was consistently defoliated more intensely and frequently than little bluestem.
    • Survival of juvenile basin big sagebrush under different grazing regimes

      Owens, M. K.; Norton, B. E. (Society for Range Management, 1990-03-01)
      Basin big sagebrush (Artemisia tridentata Nutt ssp tridentata Beetle) often invades rangelands seeded to introduced grass species. Livestock grazing may enhance the invasion but the effects of grazing intensity on invasion rates are not known. To investigate invasion rates, individual big sagebrush plants were marked and observed for mortality over a 4-year period within a short duration grazing (SDG) cell and continuous season-long grazed pastures. Over the course of the experiment, the survival of juvenile big sagebrush was higher in the SDG cell. However, there were no differences in survival between grazing treatments during the first year of the study. In subsequent years, declining tiller numbers and density of individual crested wheatgrass plants may have decreased the competitive pressure on juvenile big sagebrush under SDG. The intensity of grazing did not affect which individual juveniles survived. Plants with more than 50 cm2 canopy area had the highest survival rates of all big sagebrush in both grazing treatments. Plant density, which ranged from 1 to 30 plants m-2, did not affect plant survival in either of the grazing treatments. Big sagebrush survival in the SDG cell was higher in a rhizomatous grass community than in a tussock grass community.
    • Stratification, freezing, and drying effects on germination and seedling growth of Altai wildrye

      Romo, J. T. (Society for Range Management, 1990-03-01)
      Altai wildrye (Leymus angustus (Trin.) Pilger) is recommended for late season forage and stabilization or improvement of salt affected land in the northern Great Plains. Establishment from seeding is erratic, perhaps due to environmental extremes that occur in the seedbed. Objectives of this study were to evaluate the effect of temperature and moisture variation on germination, solute leakage from seeds, and etiolated growth of seedlings of this perennial grass. Seeds were subjected to 5 preincubation treatments: stratification (5 degrees C) (STR); stratification plus drying (30 degrees C) (STR-D); stratification plus freezing (-10 degrees C) (STR-FR); cool-dry storage (5 degrees C) (COOL); and laboratory storage (LAB). After pretreatment, seeds were incubated at 10 and 20 degrees C in a gradient of osmotic potentials ranging from 0.0 to -1.59 MPa. Solute leakage from seeds and seedling growth were also assessed following pretreatment. Germination was higher and more rapid over the range of osmotic potentials at 20 degrees C than at 10 degrees C with germination poorest in STR-FR. In the absence of water stress, leakage of solutes was 21% lower from stratified seeds than unstratified seeds; leakage at -0.48 MPa was similar across pretreatments. Compared to the other pretreatments, root and shoot growth of seedlings following STR-FR were reduced 34 and 76% at -0.48 MPa. Negative effects of STR-FR were reflected in restricted germination and growth, but not in solute leakage. Results of this study and others suggest that efforts to minimize temperature extremes in the seedbed could improve germination and seedling growth of Altai wildrye.
    • Stocker cattle performance and vegetation response to intensive-early stocking of Cross Timbers rangeland

      Mccollum, F. T.; Gillen, R. I.; Engle, D. M.; Horn, G. W. (Society for Range Management, 1990-03-01)
      A 4-year study was conducted on Cross Timbers range in north-central Oklahoma. Conventional seasonlong grazing (SLS) of stocker cattle was compared to intensive-early season stocking (IES). Stocking density was increased 2-fold on the IES system but stocking rate was the same relative to SLS. Grazing treatments were applied in a manner that allowed each pasture to be grazed under each management system. Midseason standing crop of grazed residue was lower under IES but there was no difference in end-of-season standing crop. In July, tallgrass residue and forb residue were lower on IES pastures while residue of little bluestem and other grasses was not affected by grazing treatment. End-of-season standing crop of tallgrass residue was similar because of late-season regrowth under IES and continued defoliation under SLS. Distribution of utilization was not improved by IES. Cattle gains (kg/head) during the early-season were similar for both grazing programs. Total beef production was increased 19% by IES as a result of increased stocking density. Our results indicate that IES can be utilized to improve cattle production from Cross Timbers ranges.
    • Sand shinnery oak as forage for Angora and Spanish goats

      Villena, F.; Pfister, J. A. (Society for Range Management, 1990-03-01)
      Little information is available on goat nutrition and diet selection on shrub-dominated ranges. This study examined the botanical and nutritive composition of Angora and Spanish goat diets, and forage intake when grazing on sand shinnery oak (Quercus havardii Rydb.) range in west Texas during June, July, and August, 1986. A digestion trial evaluated the nutritive value of shinnery oak diets for goats. Angora and Spanish goats consumed similar amounts of shinnery oak, grass, and forbs. Their diets had similar levels of crude protein (CP), fiber, and in vitro digestibility. Consumption of oak by goats increased from 31% of diets in June to 55% in August. Dietary CP levels averaged 8.1 to 9.4% during the summer. In vitro digestibility of diets varied from 44 to 53% during the summer, with lower values during July and August. Spanish goats had higher forage intakes during July and August compared to Angora goats. Digestible energy (DE) intake (Mcal/-day) did not differ between breeds, but increased during the summer. The digestion trial was conducted using 0, 25, and 50% shinnery oak with alfalfa hay. Apparent organic matter digestibility (OMD) declined linearly with increasing levels of oak; the same decline was noted for apparent CP and neutral detergent, but not acid detergent, fiber digestibility. Extrapolated OM and CP digestibilities for 100% oak were 38% and 17%, respectively. Voluntary OM intake did not differ among diets. CP and DE intakes declined linearly as dietary oak levels increased. Fecal N increased and urinary N decreased linearly with increasing levels of oak in diets. We found no evidence of intoxication from shinnery oak in grazing or pen-fed goats. Shinnery oak can contribute substantially to the nutrition of goats foraging on these ranges, but some supplemental feeding may be necessary.
    • Relationship of photosynthetic rate and edaphic factors to root carbohydrate trends in honey mesquite

      Wan, C.; Sosebee, R. E. (Society for Range Management, 1990-03-01)
      Total nonstructural carbohydrate (TNC) concentration in honey mesquite (Prosopis glandulosa var. glandulosa) roots and its relation to current photosynthetic rate and selected soil parameters were examined on 2 upland soils. Root carbohydrate recharge rates were generally greater in trees on a sandy loam site than those on a clay loam site during the spring rainy season because of higher photosynthetic rates and more apparent root growth. Recharge rate was greater on the clay loam site during midsummer, which was related to higher soil water potential. Root carbohydrate recharge was less sensitive to a moderate water stress (dawn xylem water potential ranged from -1 to -1.6 Mpa) than was photosynthesis; but it was more sensitive to severe water stress (dawn xylem water potential ranged from -1.9 to 2.4 MPa) than was photosynthesis. Effective control of honey mesquite with foliar-applied herbicides is determined by photosynthetic rates and TNC trends as they are influenced by both soil temperature and soil water content. Higher photosynthetic rates and greater amounts of root TNC are related to higher soil temperature and higher soil water content.
    • Mid-winter protein, phosphorus, and digestibility of Chrysothamnus nauseosus subspecies

      Bhat, R. B.; Welch, B. L.; Weber, D. J.; McArthur, E. D. (Society for Range Management, 1990-03-01)
      Little has been done to evaluate the mid-winter crude protein, phosphorus, and in vitro digestibility of subspecies and accessions of rubber rabbitbrush (Chrysothamnus nauseosus ssp.) For those few studies that have been conducted, subspecies and accessional variation was not addressed. This study tested the hypothesis that certain subspecies and accessions of rubber rabbitbrush grown in a common garden on homogeneous soil would exceed other subspecies and accessions in crude protein, phosphorus, and in vitro digestibility. Also, the level of these traits for the various subspecies and accessions of rubber rabbitbrush were compared to other species of winter forages. Significant differences for all 3 traits occurred among subspecies and accessions. Some accessions of rubber rabbitbrush were ranked high in crude protein, phosphorus, and digestibility in comparison to other species of winter forages. Enough variation exists among subspecies and accessions that a selection program could result in the development of superior forms of rubber rabbitbrush to be used as a winter forage.
    • Interpretation of environmental gradients which influence sagebrush community distribution in northeastern Nevada

      Jensen, M. E. (Society for Range Management, 1990-03-01)
      Sagebrush stands on the Humboldt National Forest, northeastern Nevada, were classified by two-way indicator species analysis (TWINSPAN) into 15 community types. Detrended correspondence analysis (DECORANA) was used to ordinate samples and plant species and characterize environmental gradients regulating community structure. Regression of soil attributes with sample ordination scores suggested that the plant communities respond to a complex gradient involving soil depth, water holding capacity, mollic epipedon thickness, clay content, and effective rooting depth. Soil chemical properties which displayed significant correlations with sample ordinations included pH, base saturation, calcium, total nitrogen, organic matter, and phosphorus. These soil properties are considered to either directly influence or indirectly reflect the available soil moisture of a site. The transition from black sagebrush (Artemisia nova Nels.) to low sagebrush (A. arbuscula Nutt.), basin big sagebrush (A. tridentata Nutt. ssp. tridentata) and mountain big sagebrush (A. tridentata Nutt. ssp. vaseyana) stands along DECORANA Axis 1 appeared to represent a gradient of increasing available soil moisture. Elevation and aspect were not correlated with sample ordination scores. This lack of correspondence is presumably due to various soil properties (e.g., depth, rock content, texture) which modify the direct effects of elevation and aspect on available soil moisture.
    • Influence of range site on diet selection and nutrient intake of cattle

      Launchbaugh, K. L.; Stuth, J. W.; Holloway, J. W. (Society for Range Management, 1990-03-01)
      It is common in range science to base stocking rate estimates on range sites as units of forage production. However, little is known about how diet composition, quality, and intake may differ by range site. This study examines the influence of 2 range sites on the diet selection and nutrient intake of cattle. A sandy loam (SL) and a clay loam (CL) range site were compared in 4 seasonal, trials on an Acacia dominated, mixed-brush savanna on the Texas Rio Grande Plains. Diet composition and quality, and nutrient intake of cattle were determined throughout each 16-21 day trial using esophageally fistulated cattle and daily dosing with ytterbium acetate. The range sites differed widely in proportions of grass, forb, and browse biomass. Cattle generally selected similar diets and adjusted diets to increasing grazing pressure and decreasing forage availability in a similar manner regardless of site, except in fall when cattle selected more browse on the SL site where herbaceous forage was severely limited. Fecal output of cattle differed between sites only in fall when cattle on the SL site had lower fecal output than cattle on the CL site. Cattle on the site of lower herbaceous mass (SL site) generally achieved higher diet quality and nutrient intake during the growing season, when herbaceous forage was readily available because of greater access to green forage. Therefore, the SL site yielded higher diet quality at low grazing pressure during the growing season. Conversely, the CL site, because of its greater herbaceous mass, yielded higher nutrient intake in the fall and at high levels of grazing pressure.
    • Evaluation of a continuous-release ytterbium bolus

      Estell, R. E.; Freeman, A. S.; Galyean, M. L.; Wallace, J. D. (Society for Range Management, 1990-03-01)
      Four ruminally cannulated steers were used in a 4 X 4 Latin square design to determine the efficacy of a continuous-release bolus containing Yb203 for estimation of fecal output. One bolus was placed in the reticulum of each steer at the beginning of the experiment. Four diets were fed, including alfalfa, alfalfa treated with a commercial preservative, and each of the 2 alfalfa hays in a 50:50 mixture with concentrate. Each period of the Latin square consisted of 15 d for adaptation to diets, followed by 5 d of total fecal collection. Fecal output was estimated from marker concentration in grab (0800, 1700, and 0800 + 1700) and composite (from total collection) fecal samples using 3 methods of dose calculation (manufacturer-formulated release, 160 mg Yb/d; trial average, based on bolus weight change over entire trial; and period average, based on bolus weight change during the week preceding and week of sampling period). Percentage of actual fecal output estimated by each calculation method was not affected by diet (P>.10). Calculated Yb release from the week before and the week of collection provided estimates of fecal output that were not different (11% overestimation;P>.10) from total collection, while estimates using formulated or trial average dose differed (P<.10; 37 and 34% overestimation, respectively). Across dose calculation method, actual fecal output was overestimated by 31, 27, and 29% from 0800, 1700, and 0800 + 1700 grab samples, respectively. Estimates based on composite fecal samples overestimated actual fecal output by 22% averaged across dose method. Composite fecal samples and dose based on period average provided the best estimation of actual fecal output (9% greater than total collection values). Regardless of method of dose calculation or fecal sampling method used, estimates were variable and greater than total collection values.
    • Establishment and survival of Illinois bundleflower inter-seeded into an established kleingrass pasture

      Dovel, R. L.; Hussey, M. A.; Holt, E. C. (Society for Range Management, 1990-03-01)
      The introduction of perennial legumes into warm-season grass pastures has been shown to improve both forage quality and animal performance. Illinois bundleflower (Desmanthus illinoensis (Michs.) MacM.) appears to have potential for pasture and range interseeding. This study investigated establishment methods and the competitive ability and longevity of this species when interseeded into kleingrass (Panicum coloratum L.) swards. Sabine Illinois bundleflower was drilled or broadcast into a mature kleingrass pasture either intact or suppressed by disking, paraquat (1-dimethyl-4-4 dipyridinium dichloride), or mefluidide (N-[2,4 dimethyl-5 (trifuromethyl) sulfonyl-amino-phenyl]acetamide). Seed was sown in broadcast plots at 6.8 kg PLS/ha compared to 3.4 kg PLS/ha in drilled plots. Establishment data were only collected for 1 year. The establishment year had a wetter than normal spring. Treatment effects on legume establishment could differ substantially from those found in this study in drier years. Both paraquat and disking treatments resulted in good establishment of the legume (greater than 10 seedlings m-2 in the establishment year). With the exception of disked plots, broadcasting at twice the rate of drilled plots resulted in similar seedling legume densities between the 2 seeding methods. Illinois bundleflower proved to be quite competitive under the conditions of this study. The legume component increased from 14% in the establishment year to 52% by the third year after establishment. Individual Illinois bundleflower plants survived for the 4 years of the study. Interseeding increased total plot yield in the second, third, and fourth years after establishment. Interseeded plots produced more biomass than noninterseeded plots 1, 2, and 3 years after interseeding.
    • Diet composition of Angora goats in a short-duration grazing system

      Taylor, C. A.; Kothmann, M. M. (Society for Range Management, 1990-03-01)
      Botanical and chemical compositions of Angora goat (Capra hircus) diets, determined with esophageally cannulated animals, were studied with and independent of a cattle-sheep-goat herd in a short-duration grazing (SDG) system. The study site consisted of 2 pastures in a 14-pasture, 1-herd SDG system. Each collection period in both pastures began when 44 animal units of livestock moved into either pasture 1 or 2. This methodology allowed a comparison of diet selection with and without grazing pressure. Goats selected more grass during the summer and fall than during the winter and spring. Browse was preferred over grass and forbs. Generally, higher crude protein values tended to be associated with large amounts of browse and forb selection. In vitro digestibility was highest in April and lowest in August. Crude protein was highest in April and lowest in November. Under this particular stocking rate (.19 animal unit years/ha) and weather conditions, we concluded that increased grazing pressure, caused by a 4-day graze period in a SDG system, had little effect on goat nutrition.
    • Conditioned taste aversion: potential for reducing cattle loss to larkspur

      Lane, M. A.; Ralphs, M. H.; Olsen, J. D.; Provenza, F. D.; Pfister, J. A. (Society for Range Management, 1990-03-01)
      Barbey larkspur (Delphinium barbeyi L. Huth) is a palatable poisonous plant that causes a large number of cattle deaths on mountain rangelands. The objective of the study was to determine whether or not cattle could be conditioned to avoid eating larkspur. Five heifers were conditioned to avoid eating larkspur by intraruminal infusion of lithium chloride whenever they consumed larkspur in a pen feeding trial. Five control heifers were likewise infused with distilled water. Following the conditioning, the heifers were taken to mountain rangeland in central Utah and observed in 1986 and 1987. The non-averted heifers consumed larkspur throughout the 1986 field trial, while the averted heifers generally consumed little larkspur. The aversion from the previous summer persisted as the averted heifers refused to eat larkspur in the first grazing trial in 1987. During the second grazing trial in 1987, the averted heifers were placed in a pasture with non-averted heifers to determine if social influences would affect learned aversions. A rapid breakdown of the aversions was observed and the averted heifers continued consuming larkspur after being separated from non-averted heifers.
    • California's privately owned oak woodlands: Owners, use, and management

      Huntsinger, L.; Fortmann, L. P. (Society for Range Management, 1990-03-01)
      Social science research is an important tool for guiding development of education programs for owners of private rangelands. California oak woodland, a productive and extensive range type in California that is undergoing rapid changes in use and management, is the focus of this study. Results indicate that landowners with different property size differ demographically, make different uses of their land, and have distinctly different attitudes toward oak management and living in the oak woodland. Owners of smaller properties, on the increase in rural California, do not earn their living from their land, and will respond best to resource education programs that they believe will contribute to bettering the quality of life they seek by residing in the oak woodland. Owners of larger properties, the traditional clientele of advisory agencies, will more likely respond to programs that protect and enhance earnings from their property. Still, even a third of the owners of the largest (over 5,000 acres) properties earn the majority of their income from sources other than their lands. To be effective, range-oriented education programs and policies must track the changing composition of rural populations, and the changes in attitudes, needs, and interests that accompany demographic shifts.
    • Biases in relative estimates of dietary mineral status from esophageal extrusa

      Pinchak, W. E.; Greene, L. W.; Hunt, L. J. (Society for Range Management, 1990-03-01)
      An experiment was conducted to determine whether or not the effects of forage type and time into feeding period precluded use of esophageal extrusa to estimate relative dietary mineral status of cattle. Four esophageally fistulated Angus-Hereford X Jersey crossbred steers (340 to 545 kg.) were alternately fed Coastal bermudagrass hay (Cynodon dactylon) (BGH) and fresh green-chopped. TAM 105, wheat (Triticum aestivum) (GCW). Extrusa was sampled at 5 and 20 minutes into the feeding period. Significant additions of Na, P, and K occurred in the extrusa of both forages. Ash, Mg, and Ca concentrations were higher in the extrusa of BGH. Calcium, Zn, and N concentrations were similar in extrusa of both forages. Changes in Na, P, ash, Ca, and Mg concentrations were as expected; however, the changes in K, Cu, and Zn disagree with published results. Previous research suggested K, N, Ca, Cu, and Mg content of the diet could be estimated from esophageal extrusa. The current experiment indicated dietary Cu, Mg, and K content of diets could not be extrapolated from extrusa concentrations of these minerals. Forage type had significant effects on the extent and form of change in the associated extrusa. The magnitude of these effects precludes use of esophageal extrusa for relative comparisons among plant communities within and among seasons, if selected forages are markedly different in maturity, moisture content, and physical form. Time into feeding period had no detectable effect on amount or percent of change in extrusa from the forage.
    • Above-ground phytomass dynamics in a grassland steppe of Patagonia, Argentina

      Defossé, G. E.; Bertiller, M. B.; Ares, J. O. (Society for Range Management, 1990-03-01)
      Aerial phytomass and litter dynamics of a grassland steppe in Patagonia, Argentina, were studied at either monthly or bimonthly intervals for 2 years. This area is characterized by a cold and wet winter (June to September) and a warm and dry summer (December to March). The growing season extends from September to April, with moist spring and fall periods interrupted by a midsummer drought. Festuca pallescens (St. Yves) Parodi produced about 95% of the total annual phytomass. Peaks of green phytomass were recorded in spring-summer of the first growing season (33.6 +/- 2.9 g m-2) and in early spring (35.0 +/- 2.4 g m-2) and fall (32.7 +/- 2.7 g m-2) of the second growing season. Less abundant forage grasses were Poa ligularis Nees ap Steudel, Bromus setifolius Presl., Hordeum comosum Presl., and Rytidosperma virescens (Desvaux) Nicors. Shrubs and forbs represented less than 2% of the total annual phytomass of this grassland. The relationships between phytomass production of the main species and some environmental variables are discussed. These results contribute to the knowledge of above-ground phytomass dynamics and forage availability throughout seasons of this grassland in Patagonia, and are part of the data necessary for proper range management planning. This information will permit the designing of appropriate grazing schedules by balancing the number of grazing animals to the forage resources available.