• Cattle and Sheep Diets Under Short-duration Grazing

      Ralphs, M. H.; Kothmann, M. M.; Merrill, L. B. (Society for Range Management, 1986-05-01)
      Studies have shown a negative relationship between stocking rate and animal performance in conventional grazing systems. However, short-duration grazing (SDG) proponents state that stocking rates can be increased and still maintain acceptable animal performance by reducing the length of stay on a pasture. The objective of this study was to determine if sheep and cattle diet quality could be maintained in SDG as stocking rates increased from the level recommended for moderate continuous grazing to 2.67 times the recommended level. Small pastures ranging from 1.68 ha to .47 ha were fenced to give the desired stocking rates. Pastures were grazed 3 days and rested 51 days. Diets were collected from esophageally cannulated sheep and cattle during the 3-day grazing periods. Botanical composition of diets was determined and crude protein and IVOMD were analyzed to estimate diet quality. As live green forage was depleted diet selection shifted to reserve forage resulting in a decline in diet quality as stocking rate increased in pastures where reserve forage was abundant during the cool season. There were few shifts in diet selection and diet quality where vegetation was more homogenous and lacked reserve forage. Grazing pressure declined during the warm season in all pastures due to above-average forage production. Only cattle diets showed a decline in digestibility as stocking rates increased and diet selection switched from mature warm-season grass to reserve forages. Diet quality declined within the short 3-day grazing periods and the decline was greater at the higher stocking rates.
    • Effect of Grazing Stubble Height and Season on Establishment, Persistence, and Quality of Creeping Bluestem

      Kalmbacher, R. S.; Martin, F. G.; Pitman, W. D. (Society for Range Management, 1986-05-01)
      Creeping bluestem (Schizachyrium stoloniferum) was grazed every 60-days to 15 or 30-cm stubble heights during the following 4 periods (seasons): (1) June, Aug., Oct. (JAO); (2) Oct., Dec., Feb. (ODF); (3) Feb., Apr., June (FAJ); (4) year-long (YL). Average diameter (37 cm) of plants grazed in JAO and YL to 15-cm stubble was less (P<0.05) than plants (43 cm) grazed to 30 cm. There was no difference in diameter of plants grazed to 15 and 30-cm stubble in ODF and FAJ (45 cm). Tiller density was influenced by stubble height only in 1982 and 1983 when density for the 15 cm stubble averaged 111/m2 vs. 142/m2 for the 30-cm stubble. Tiller density in 1980, 1982, and 1983 was less (P<0.05) in JAO and YL treatments (109/m2) than in ODF and FAJ (167/m2). Forage dry matter yield in 1979-80 and 1982-83 depended on stubble height and seasons. Average yield at 15-cm height was greater for the FAJ treatment (1,700 kg/ha), similar for JAO (910 kg/ha) and ODF (910 kg/ha) and lowest for YL (660 kg/ha), but yield was similar at all seasons (510 kg/ha) at 30-cm stubble. Crude protein and IVOMD were influenced more by grazing time within a season than by seasons or stubble height. Poorest quality forage was at the beginning of the seasons (especially ODF and FAJ treatments). Best quality came from regrowth. Winter or spring grazing resulted in better stands of creeping bluestem than summer or year-long grazing.
    • Cattle Feeding and Resting Patterns in a Foothills Riparian Zone

      Marlow, C. B.; Pogacnik, T. M. (Society for Range Management, 1986-05-01)
      Cattle impact on riparian areas is dependent upon both their behavior and utilization of streamside vegetation. Development of grazing strategies for riparian environments would be enhanced by an understanding of cattle behavior in riparian and adjacent uplands. Results of a 2-year behavior study indicate that a seasonal trend in cattle use of riparian and upland areas exists. Unless low precipitation limited upland forage quality/production, cattle spent a significant (P<0.05) amount of their feeding time in upland areas during late June and early July. Significant levels of feeding activity (P<0.05) occurred in the riparian zone from late August through September. Resting patterns differed only during the early part of the grazing season when cattle spent significantly more (P<0.05) of their time resting in upland areas. During late July, August, and September, there was no significant difference (P>0.50) in the amount of time spent resting in either zone. Significant differences (P<0.05) occurred only when adverse weather conditions caused cattle to seek shelter in the riparian zone. Because cattle spend a disproportionate amount of their feeding time in the riparian zone during late summer and early fall, impacts could be limited by basing stocking rates for this period only on forage available in the riparian zone.
    • Genetic Progress Through Hybridization of Induced and Natural Tetraploids in Crested Wheatgrass

      Asay, K. H.; Dewey, D. R.; Gomm, F. B.; Horton, W. H.; Jensen, K. B. (Society for Range Management, 1986-05-01)
      Because of restrictions imposed by crossing barriers, crested wheatgrass breeders have usually limited themselves to selection and hybridization within ploidy levels i.e., diploid (2n=14), tetraploid (2n=28), or hexaploid (2n=42) populations. Several procedures have now been devised and evaluated to transfer genetic traits among ploidy levels, and interploidy breeding appears to be a feasible approach in the crested wheatgrass complex. Plant scientists with the USDA-ARS at Utah State University have developed a superior breeding population by hybridizing induced tetraploid Agropyron cristatum (L.) Gaertn. with natural tetraploid A. desertorum (Fisch. ex Link) Schult. The cultivar 'Hycrest' was released from this germplasm base in 1984. Chromosome number of the Hycrest breeding population ranged from 2n=28 to 32 and averaged 30. Chromosome pairing relationships were similar to those observed in natural tetraploids and the cultivar was as fertile as the parental species. Hycrest produced significantly more seeds per spike than 'Nordan,' and ample genetic variability for seed set existed in the population to make additional improvement through selection. Hycrest produced significantly (P<0.05) more forage than Nordan and Fairway in 9 of 12 comparisons at 5 semiarid range sites. The superiority of the cultivar was most noteworthy during and immediately after stand establishment on harsh sites. The need to expand the genetic base of the present population with selected parental materials is recognized.
    • Forage Quality of Winterhardy Lovegrasses

      Voigt, P. W.; Croy, L. I.; Horn, F. P. (Society for Range Management, 1986-05-01)
      Germplasm of Eragrostis curvula and E. lehmanniana was evaluated for in vitro dry matter disappearance (IVDMD), palatability (animal preference among genotypes), and forage vigor (weight/-plant). Our objective was to determine if sufficient genetic variation was present among relatively winterhardy genotypes to develop new lovegrass varieties with improved forage quality. The germplasm was divided into 4 types: curvula, conferta, short chloromelas (SC), and cold-hardy lehmann (CLE). Differences among types were significant for all characteristics studied. Differences within types were found also. The average IVDMD of the more stemmy CLE and SC types was higher than that of the more leafy curvula and conferta types. However, both CLE and SC types were less productive generally than curvula and conferta types and the palatability of CLE types was frequently lower than that of the other types. The more vigorous CLE types tended to be lower in IVDMD and palatability than less productive selections of that type. Chances of selecting an improved lovegrass variety directly from this germplasm are unlikely because few selections were superior to the weeping lovegrass controls. The best CLE and SC selections might be useful in a breeding program for improved forage quality if stemmyness can be decreased in their offspring while IVDMD is increased. Selections of the CLE type should not be widely planted until grazing evaluation proves them to be useful for animal production.
    • A Weather Severity Index on a Mule Deer Winter Range

      Leckenby, D. A.; Adams, A. W. (Society for Range Management, 1986-05-01)
      Temperature, wind, and snow conditions predictably affect the nutrition, behavior, distribution, productivity, and mortality of free-ranging cattle and big game in winter. Indexing of data obtained with commonly available weather instruments to reflect episodes of positive and negative energy balances of free-ranging ruminants could aid scheduling of feeding programs and planning of cover-forage manipulations. Such a weather severity index was developed and tested over 11 winters. Plausible levels of stress and episodes of relative severity were depicted during winters when mule deer exhibited low, moderate, and high mortality. The index curves mirrored over-winter declines of fat reserves probably sustained by mule deer. Lesser weather severity was predicted and measured in a western juniper woodland than in an adjacent rabbitbrush steppe community in southcentral Oregon.
    • Diets and Liveweight Changes of Cattle Grazing Burned Gulf Cordgrass

      Angell, R. F.; Stuth, J. W.; Drawe, D. L. (Society for Range Management, 1986-05-01)
      We investigated effects of fall burning of gulf cordgrass (Spartina spartinae) rangeland on winter diets and liveweight gains of cattle on the Texas Coastal Prairie during 1979-1981. Gulf cordgrass dominated steer diets (21-76%) regardless of burning treatment. However, Texas wintergrass (Stipa leucotricha) on adjacent upland sites accounted for 13 to 36% of animal diets during winter growth periods. Burning increased dietary crude protein content from January to March in all years and increased in vitro organic matter digestibility during February and March. Cattle gained or maintained weights on burned pastures but maintained or lost weight on unburned pastures. Weight gains of animals with access to burned gulf cordgrass, but not Texas wintergrass, equaled gains of animals grazing unburned gulf cordgrass and Texas wintergrass. Burned gulf cordgrass can provide alternative green forage that will improve diet quality of cattle when cool-season species are absent.
    • Effects of Brush Control and Game-bird Management on Nongame Birds

      Gruver, B. J.; Guthery, F. S. (Society for Range Management, 1986-05-01)
      We observed the responses of nongame birds to brush suppression and habitat management for game birds in the Rolling Plains of Texas during 1981-1983. Data from line transects were used to describe density, species diversity, species richness, and equitability. We observed no difference in these variables between untreated sites and sites late sprayed with herbicides in 1969. The density of northern mockingbirds (Mimus polyglottos) was lower on treated than untreated areas, but no other species were affected. Habitat management to favor mourning doves (Zenaida macroura) and bobwhites (Colinus virginianus) was associated with a 54% increase in combined density of nongame birds and a reduction in equitability. Species diversity and species richness were similar on managed and unmanaged sites. On our study area, past herbicide treatment of mesquite (Prosopis glandulosa) and habitat management for game birds were compatible with nongame birds.
    • Effects of Cattle Grazing on Passerine Birds Nesting in Riparian Habitat

      Taylor, D. M. (Society for Range Management, 1986-05-01)
      Nine transects, in areas with different histories of cattle grazing, were established along the Blitzen River in Oregon. Counts of birds and measurements of vegetation were made in the summers of 1981 and 1982. Increased frequency of grazing on an annual basis correlated significantly with decreases in bird abundance, shrub volume, and shrub heights. The longer the time since a transect was last grazed correlated significantly with increases in bird abundance, shrub volume, and shrub heights. Bird abundance increased significantly with increased shrub volume and taller shrub heights. Bird species richness decreased with increased grazing. Bird counts were 5 to 7 times higher on an area ungrazed since 1940 than on 2 areas grazed annually until 1980, and 11 to 13 times higher than on a transect severely disturbed by extensive grazing and dredging activities. Disturbances from camper activities also appeared to reduce bird populations.
    • Effects of Short-Duration and Continuous Grazing on Bobwhite and Wild Turkey Nesting

      Bareiss, L. J.; Schulkz, P.; Guthery, F. S. (Society for Range Management, 1986-05-01)
      We compared effects of short-duration and continuous grazing on nesting cover and success of bobwhites and wild turkeys in south Texas during 1984. Coverage, density, and dispersion of suitable nest sites and loss rates of artificial nests were not affected by grazing treatment.
    • Exposition on the Selection of Appropriate Experimental Design and Statistical Analysis for Pasture Improvement Research

      Stroup, W. W.; Waller, S. S.; Gates, R. N. (Society for Range Management, 1986-05-01)
      Selection of appropriate treatment and experiment designs are essential elements in research. However, the expense and variability associated with pasture renovation studies creates unique problems in the application of standard statistical techniques. Pasture-size renovation studies are restricted by expense, requiring the use of grazing exclosures (subsamples). Treatment design must include an adequate control for treatment comparison. Controls for pasture renovation practices cannot be limited to untreated areas within a grazing exclosure. The true measure response is found in the difference between treated areas and a typical grazed pasture situation. Criteria for exclosure selection (homogeneity) and heterogeneity of the grazed pasture may result in unequal variances or nonnormal error distributions, thus restricting the use of an analysis of variance. The experiment design must recognize the requirements for making reliable inferences. Pasture-to-pasture variability generally demands that pastures should be replicated in renovation studies to allow general inferences. Within pasture variability would support the need for multiple exclosures within each pasture. Costs associated with this kind of research limit the utility of idealized experimental designs. Several alternative experimental designs are discussed. Limitations in interpretation and risks of drawing erroneous or weak conclusions are reviewed.
    • Forage Establishment: Weather Effects on Stubble vs. Fallow And Fall vs. Spring Seedling

      Hart, R. H.; Dean, J. G. (Society for Range Management, 1986-05-01)
      Improved pastures are a valuable forage resource in the Central Great Plains, but ranchers need to know which seeding techniques provide the best chance of successful establishment of such pastures. We compared late fall vs. spring seedings of 5 grasses and 2 legumes in barley stubble or fallow. Four directions of stubble rows were compared for snow catchment and effect on forage establishment. Stubble rows in any direction had little effect on snow catch or establishment, and there was little difference between stubble and fallow. Spring seeding gave better stands than fall seeding in the kind of weather most often encountered in the Central Great Plains. Days from seeding to emergence were controlled by soil temperature and timing and amount of precipitation. Stands were negatively correlated with the time required for emergence.
    • Floral Changes Following Mechanical Brush Removal in Central Texas

      Rollins, D.; Bryant, F. C. (Society for Range Management, 1986-05-01)
      A field study was initiated in May 1981 to monitor the effectiveness of mechanical brush control (chaining) as a method of reclaiming Ashe juniper (Juniperus asheii)-oak (Quercus spp.) dominated rangelands in central Texas. Brush was cleared from 4 sites by double-chaining and the resultant slash was burned. Brush canopy reduction and herbaceous standing crop were monitored for 2 growing seasons following treatment. Total brush canopy at 1 year post-treatment was 80% less than untreated brush stands. Chaining was more effective for Ashe juniper (93% reduction) than for oaks (64-75% reduction). Grass and forb standing crop at 22 months post-treatment was 55% higher on chained sites during all collection months.
    • Fertilization Effects on the Phosphorus Content of Browse Species

      Everitt, J. H.; Gausman, H. W. (Society for Range Management, 1986-05-01)
      A study was conducted in Hidalgo County, southern Texas, to determine the effects of inorganic nitrogen (N) and phosphorus (P) fertilization on the P content of 5 deer browse species. Treatments were 2 rates of N-112 and 224 kg N/ha; 2 rates of P-56 and 112 kg P/ha; 1 fertilizer combination of 224 kg N/ha + 112 kg P/ha; and a nonfertilized control. Plant samples were collected and assayed for P on 5 dates: May, September, and December 1981, and May and October 1982. Neither P or N fertilization influenced P browse content. Results indicated that P deficiencies in the browse plant species studied could not be alleviated by P fertilization.
    • Technical Notes: Evaluation of the Dry-Weight-Rank Method for Determining Species Composition in Tallgrass Prairie

      Gillen, R. L.; Smith, E. L. (Society for Range Management, 1986-05-01)
      The dry-weight-rank (DWR) method for determining species composition of tallgrass prairie vegetation was compared to hand clipping. Species composition estimates for the 2 methods were similar in 3 of 4 trials when true ranking and previously published multipliers were used. Weighting the DWR estimates by plot total weight did not consistently improve the accuracy of the method. Observer errors reduced the accuracy of DWR, emphasizing the need for observer training. DWR estimates were generally less precise than hand clipped estimates for a given sample size but the speed of DWR would allow more samples to be taken resulting in more precise estimates in practice.
    • The Distribution of Halogeton in North America

      Pemberton, R. W. (Society for Range Management, 1986-05-01)
      Halogeton [Halogeton glomeratus (Stephen ex Bieb.) C.A. Mey.], a livestock-poisoning plant from central Asia, occurred in most Great Basin states in 1954. Current distribution of the species was studied by surveying botanists, weed scientists and other specialists in 1980. The survey indicated that halogeton had spread into additional counties in all states occupied in 1954 and into southern California, New Mexico, and east of the Rocky Mountains to Nebraska. The largest infestations continue to be in the Great Basin and Wyoming.
    • The Impact of Experimental Design on the Application of Grazing Research Results: An Exposition

      Brown, M. A.; Waller, S. S. (Society for Range Management, 1986-05-01)
      Funding limitations often restrict pasture replication in grazing research on rangeland. Consequently, subsample error has been used to estimate treatment effects or characterize populations. Assumptions associated with experimental designs which utilize subsample error to make inferences are discussed and an example evaluated. The appropriate experimental unit for inferential grazing research is the pasture. Animals or vegetation sampling within pastures must be considered as subsamples in inferential grazing research. Pasture replication must be used in intensive grazing trials to establish treatment differences or provide adequate characterization. Following intensive trials, extensive, unreplicated trials implemented by private producers can be effective in establishing broad-based applicability. Unreplicated pasture trials may also be used for screening several treatments.
    • Population Recovery of Black-tailed Prairie Dogs Following Control with Zinc Phosphide

      Knowles, C. J. (Society for Range Management, 1986-05-01)
      This study evaluated the efficacy of 2% zinc phosphide grain bait as a control agent for black-tailed prairie dogs (Cynomys ludovicianus) and the rate at which prairie dogs returned to treated areas. Visual counts of prairie dogs closely corresponded to actual population trends and were chosen as the technique to evaluate changes of prairie dog numbers. Treatment of all of 2, and portions of 5, prairie dog colonies with zinc phosphide grain bait between 30 July and 25 August 1978 resulted in an average of 85% (range 65 to 95%) reduction in prairie dog numbers. Best results were obtained in the 2 colonies treated totally. The 2 colonies treated along the perimeter had the lowest percentage decrease in numbers of prairie dogs and were among the treatment types with the fastest population recovery. Prairie dogs returned to pretreatment levels within 1 year posttreatment at 1 colony. After 2 years posttreatment, 3 other colonies were approaching pretreatment population levels. Three to 5 years posttreatment appeared to be needed to obtain pretreatment numbers in the 2 colonies treated totally.
    • Correlation of Rangelands Brush Canopy Cover with Landsat MSS Data

      Boyd, W. E. (Society for Range Management, 1986-05-01)
      Traditional methods of monitoring brush canopies such as ground survey and aerial photography are not cost effective for large areas. This experiment compared photo-estimated brush canopy closure to Landsat MSS derived vegetation indices. Several vegetation indices were found to be highly correlated to brush canopy cover. The vegetation index which was most highly correlated with brush canopy cover was the GB ratio (Kauth and Thomas Greenness/Kauth and Thomas Brightness, r=0.813). These results suggest that brush canopy cover can be quantified through the use of the Landsat MSS data; however, further research is necessary to determine the transportability between sites of green biomass/brush canopy quantification indices.