• Diet selection by sheep and goats on Mediterranean heath-woodland range

      Bartolomé, J.; Franch, J.; Plaixats, J.; Seligman, N. G. (Society for Range Management, 1998-07-01)
      The study determined the species components of the diets of small ruminants grazing mountain ranges of the Montseny Biosphere Reserve (Catalunya, NE Spain). Three mixed flocks of sheep and goats, led by shepherds, were monitored for a year. Animals grazed a mountain rangeland composed of Quercus ilex woodland and Calluna-Erica heathland during the day and were returned to their corrals every night. Diet selection was estimated using fecal analysis. Of the 111 species that were identified, 71 were common to both sheep and goat. Of these, 23 were represented in proportions of more than 1% of the annual diet. Even though goats and sheep grazed together, their diets were significantly different (p < 0.0001), the animal factor accounting for 18% to 60% of the total variation among the main diet components. Variation between seasons was also a major (5% to 56%) highly significant factor, while differences between flocks accounted for a significant, but relatively small part (3 % to 10% ) of the total variation in diet. The outstanding difference was the avoidance of the tree, Quercus ilex, by the sheep while the goats selected it throughout the year. Sheep selected graminoids throughout the year while goats tended to avoid them. For the rest there was substantial overlap in species composition between the diet of sheep and goats, especially when analysed over an entire cycle.
    • Effect of hand defoliation on herbicide efficacy in honey mesquite

      Bovey, R. W.; Pace, P. F.; Cralle, H. T. (Society for Range Management, 1998-07-01)
      Greenhouse and field experiments were conducted to evaluate the effect of hand defoliation of honey mesquite (Prosopis glandulosa Torr) before herbicide application on herbicide efficacy. In the greenhouse, the monoethanolamine salt of clopyralid, the butoxyethyl ester of triclopyr, and 1:1 mixtures of clopyralid plus triclopyr were applied as foliar sprays at 140 g ha-1 each on 2-year-old single-stemmed plants averaging 50 cm tall. In the field, the same herbicides were applied as broadcast sprays at rates of 280 g ha-1 on multistemmed trees 1 to 2 m tall. Plants were defoliated prior to herbicide application at 0, 25, and 50% of original foliage. Defoliation at 25 or 50% did not reduce herbicide efficacy compared to nondefoliated plants in the greenhouse or field. The clopyralid:triclopyr mixture was sometimes synergistic in controlling honey mesquite in the greenhouse and field.
    • Fecal NIRS for predicting percent leafy spurge in diets

      Walker, J. W.; Clark, D. H.; McCoy, S. D. (Society for Range Management, 1998-07-01)
      Research on diet selection is limited by inadequate techniques for determining botanical composition of diets. Our objective was to determine if near infrared reflectance spectroscopy (NIRS) of fecal material could be used to quantify the percentage leafy spurge (Euphorbia esula L.) in the diets of sheep (Ovis aries) and goats (Capra hircus). Fecal material representing diets of known percentage leafy spurge was obtained from feeding trials conducted in 1992 and 1994. In 1992, diets containing 87.5, 75, 60, 45, 30, and 15% leafy spurge were fed to 20 sheep and 20 goats. In 1994 10 sheep and 10 goats were fed alfalfa hay (Medicago sativa L.) at 0.5% of their body weight and ad libitum access to leafy spurge hay. Thus, the percent leafy spurge in the diet varied daily. Microhistological analysis was performed on fecal samples from the 1992 trial for comparison with NIRS predictions. Near infrared reflectance spectroscopy evaluations were performed with a scanning reflectance monochromator. Calibrations were done separately for sheep and goats. Samples were divided into calibration and validation sets. Data from the 1994 feeding trial were analyzed to determine the appropriate lag time between diet consumption and fecal spectral characteristics that provided the best prediction. The average of the diet composition 48 and 72 hours prior to the fecal sample provided the best predictions for the 1994 trial. The effect of spectral outliers on prediction accuracy was also evaluated. Spectral outliers were predicted with equal or better accuracy compared to samples that were spectrally similar to the ones from which calibration equations were derived. The NIRS predictions were more accurate than microhistological estimation of leafy spurge in the diet. The final calibration equation had coefficients of simple correlation for validation samples of 0.91 and 0.93 and standard errors of prediction of 4.6 and 4.8 for goats and sheep, respectively. The results of this study showed that NIRS of fecal material can be used to screen large numbers of animals for phenotypic differences in diet selection and for making treatment comparisons.
    • Grazing intensities, vegetation, and heifer gains: 55 years on shortgrass

      Hart, R. H.; Ashby, M. M. (Society for Range Management, 1998-07-01)
      Shortgrass rangeland, dominated by blue grama (Bouteloua gracilis [H.B.K.] Lag. ex Steud), was grazed at 3 intensities, equivalent to mean stocking rates of 16.7, 23.0, and 36.5 heifer-days ha-1, from 1939 through 1994. Few changes in plant communities had been documented by the early 1970's. In 1992-1994, frequency of occurrence, basal and foliar cover, and biomass at peak standing crop (PSC) were determined on the remaining pasture at each grazing intensity, and on 3 ungrazed exclosures. Blue grama and buffalograss (Buchloe dactyloides [Nutt.] Engelm.) increased, and western wheatgrass (Pascopyrum smithii [Rydb.] A. Love) and needle-and-thread (Stipa comata Trin. &Rupr.) decreased, as grazing intensity increased. Redthree-awn (Aristida longiseta Steud.) was most plentiful under light grazing. Basal cover and biomass of forbs were lower under grazing than in exclosures, but differences in biomass were not significant. Shrubs and half-shrubs decreased as grazing intensity increased. Frequency and cover of plains pricklypear (Opuntia polyacantha Haw.) were higher in the exclosures and under light grazing than under moderate or heavy grazing; biomass was 4 to 6 times as high in the exclosures as under any grazing intensity. Heifer gains declined linearly with increasing grazing pressure index. Optimum (most profitable) stocking rate was about 20% higher than that under the moderate grazing intensity, under which biomass production was maintained and shrub and pricklypear remained at low levels. Returns to land, labor, and management were only slightly higher under the optimum stocking rate than under the moderate grazing intensity. The moderate grazing intensity appears to be both profitable and sustainable.
    • Growth responses of warm-season tallgrasses to dormant-season management

      Schacht, W. H.; Smart, A. J.; Anderson, B. E.; Moser, L. E.; Rasby, R. (Society for Range Management, 1998-07-01)
      A study on Conservation Reserve Program (CRP) land was established in southeastern Nebraska to determine the effect of dormant-season management on subsequent-year growth rates and yields of tallgrasses. The purpose of the management practices was removal of standing dead material and litter that negatively impact plant growth and grazing efficiency. Treatments consisted of a control with no residue manipulation and 5 residue manipulation practices including (1) October shredding and leaving residue; (2) October haying; (3) October intensive grazing; (4) March intensive grazing; and (5) spring prescribed burning. The study was conducted in 1994/95 and 1995/96 on a switchgrass (Panicum virgatum L.) monoculture and mixed stand of warm-season tallgrasses dominated by big bluestem (Andropogon gerardii Vitman) and little bluestem [Schizachyrium scoparium (Michx.) Nash]. The manipulation treatments effectively removed standing dead material without reducing yields in the growing season following application. Marked switchgrass tillers on the control plots increased (P < 0.1) in height at a more rapid rate than switchgrass on other treatments until late summer in both years. Rate of morphological development was similar (P > 0.1) for all treatments in 1995 and 1996. Rate of height increase and morphological development in big and little bluestem on the mixed grass site generally was comparable or slower on the manipulation treatments than the control in both years; however, big and little bluestem tillers grew relatively rapidly at the end of the 1995 growing season. Because the manipulation treatments generally did not increase tiller growth rates of the dominant grass species, potential harvest dates would be similar to those of untreated areas.
    • Herbage characteristics and performance of steers grazing old world bluestem

      Coleman, S. W.; Forbes, T. D. A. (Society for Range Management, 1998-07-01)
      Old World bluestem (OWB; Bothriocloa spp.) are popular in the southern Great Plains but little is known about the relationships between forage characteristics and animal productivity. The influence of differences in herbage mass and sward height of OWB on rate of gain during the summer grazing season was examined during 2 years at El Reno, Okla. Soils were fine, silty Pachic Haplustolls of the Dale series. Swards of caucasian [B. caucasica (Trin.) C. E. Hubb.] and 'Plains' [B. ischaemum var ischaemum (L.) Keng.] OWB were maintained at different levels of forage mass (low, medium, and high) by continuous variable stocking and were grazed from mid- May to late September by steers with an initial weight of about 225 kg. Weight gains were depressed in late August, but in 1985 gains recovered due to late season rains. Season-long gains averaged 0.61 kg day-1 in 1984 and 0.69 kg day-1 in 1985. Daily gains of steers increased linearly with increased herbage mass (P < 0.05), but slopes were different due to a year X species interaction. Daily gains peaked at a herbage height of 41 cm in 1984, but increased linearly throughout the range of the data (75 cm) in 1985. Individual animal gains decreased linearly with increasing stocking rate such that maximum gain per hectare was achieved at about 5 animals ha-1 (standard 500 kg). The data suggest that maintaining higher herbage mass and height of OWB forage improves animal performance and support the practice of intensive early grazing and removing cattle by late July when rate of gain declines.
    • Identifying Montana hunter/rancher problems and solutions

      Swensson, E. J.; Knight, J. E. (Society for Range Management, 1998-07-01)
      A 1 year survey was developed to identify conflicts and solutions to conflicts between hunters and ranchers. A questionnaire was mailed to randomly selected groups of 1,000 hunters and 989 ranchers in Montana. One-third of the questionnaire was different for the 2 groups and consisted of questions relating to background information. The other two-thirds was identical between the groups and presented questions related to perceived problems and solutions, big game populations, importance of private and agricultural land to wildlife and hunter/rancher representation. Thirty-five percent of the hunters and 42% of the ranchers responded to the survey. The top 3 conflicts between hunters and ranchers as identified by hunters were too little access to private land, driving off roads, and trespassing. The top 3 solutions selected by hunters were greater consideration and appreciation by ranchers, better communication between groups, and better boundary identification. The top 3 problems identified by ranchers were driving off roads, trespassing, and too many hunters. The top 3 solutions selected by ranchers were stiffer penalties for violators, better communication between groups, and greater consideration and appreciation by hunters. Both hunters and ranchers ranked driving off roads and trespassing in their top 3 problems and ranked better communication and greater consideration and appreciation in their top 3 solutions. Hunters and ranchers have different (P < 0.01) views of who represents them in hunter/rancher related issues. Forty-seven percent of the hunters responding believe they represent themselves or have no representation; whereas, 57% of the ranchers responding indicated they are represented by livestock producer groups. Results of this survey indicate that hunters and ranchers have similar concerns and better communication will help alleviate conflicting interests.
    • Morphological development of 2 warm-season grasses in the Nebraska Sandhills

      Hendrickson, J. R.; Moser, L. E.; Moore, K. J.; Waller, S. S. (Society for Range Management, 1998-07-01)
      Morphological development of grasses has numerous implications to rangeland management including the timing and amount of herbivory. The objective of this study was to quantify the developmental morphology of prairie sandreed [Calamovilfa longifolia (Hook.) Scribn.] and sand bluestem [Andropogon gerardii var. paucipilus (Nash) Fern.] tiller populations. Tiller populations of these 2 grasses were studied for 2 years in the Nebraska Sandhills. Plant development was evaluated using a growth staging system which quantifies the development of tiller populations. A morphological growth index for each species was calculated from either the weighted average of tiller numbers reported as mean stage count (MSC) or tiller weight reported as mean stage weight (MSW) and correlated with the independent variables of growing degree days (GDD) and day of year (DOY). Correlation coefficients with the independent variables were greater than 0.97 for MSC and MSW within years and greater than 0.90 between years. Greater rainfall and warmer temperatures in 1991 increased the number of tillers in the more advanced morphological stages in prairie sandreed, but tiller weight rather than tiller number increased in more advanced stages of sand bluestem. A majority of the harvested tillers were vegetative throughout the sampling period but by the end of the growing season, a wide range of morphological stages were present. The use of grazing to prevent the formation of culmed tillers in these grasses may be unnecessary because of the high proportion of vegetative tillers and the wide range of morphological stages available for selection by livestock.
    • Nitrogen fertilization of a native grass planting in western Oklahoma

      Gillen, R. L.; Berg, W. A. (Society for Range Management, 1998-07-01)
      Native warm-season grass mixtures have been established on the Southern Plains under the USDA Conservation Reserve Program. We studied responses to N fertilizer on such pastures in western Oklahoma over a 4-year period. Experimental pastures were previously cultivated fields with loamy soils seeded to a mixture of native warm-season grasses. Fertilizer treatments were 0 and 35 kg N ha-1 year-1 as ammonium nitrate. Pastures were intensively grazed from early June to early August over 4 years. Stocking rates averaged 52 and 104 AUD ha-1 for the 0 and 35 kg N ha-1 treatments, respectively. These stocking rates are heavy for seasonal grazing in this region. Responses measured included forage mass and nutritive value before and after grazing, plant basal area, and livestock performance. Precipitation was variable but generally favorable over the study period. Peak forage mass was increased by N fertilization (2,480 versus 4,030 kg ha-1; P < 0.01), producing 45 kg forage per kg N applied. Nitrogen fertilization increased crude protein concentration in June (8.2 versus 10.3%; P < 0.05) and August (4.1 versus 4.6%; P < 0.05), but had inconsistent effects on in vitro dry matter digestibility. Total vegetative cover and basal cover of blue grama (Bouteloua gracilis (H.B.K.) Lag. ex Griffiths) increased in the fertilized pastures. Average daily steer gain was not different between treatments (0.96 versus 1.02 kg hd-1 day-1) even though stocking rates were substantially higher on fertilized pastures. Steer gain ha-1 was increased by fertilization (83 versus 176 kg ha-1, P < 0.01). This resulted in a fertilizer N use efficiency of 2.7 kg steer gain per kg N applied. Nitrogen fertilization combined with intensive summer grazing provided a net return of 0.65 to 0.94 per kg N applied.
    • Nitrogen fertilization, botanical composition and biomass production on mixed-grass rangeland

      Samuel, M. J.; Hart, R. H. (Society for Range Management, 1998-07-01)
      Many studies have reported nitrogen (N) fertilization of rangeland, but few have reported changes in botanical composition, which may be as important as changes in forage production, or were continued for as long as 14 years. We determined frequency of occurrence of over 90 plant species in 1976-1988 under rates of 0, 22, or 34 kg N ha-1 applied in spring or fall to mixed-grass rangeland in southeast Wyoming; frequency of 23 species will be reported. We also determined total biomass production and production of major species and species groups in 1982-1988. Blue grama Bouteloua gracilis (H.B.K.) Griffiths] frequency decreased during years 5 through 7 because of the interaction of N and drought. The effects of long-term application of N decreased blue grama in year 12 and beyond. Nitrogen fertilization increased frequency of western wheatgrass [Pascopyrum smithii (Rydb.) A. Love] in all years except the driest year of the study. Needleleaf sedge [Carex eleocharis Bailey] decreased because grazing had been removed from the study area; this occurred sooner and to a greater extent on fertilized than on unfertilized plots. Fourteen other perennial species were quite variable in response to the 3 rates and the 2 seasons of application. Frequency of 6 annual species fluctuated greatly among years and treatments. Nitrogen fertilization did not increase average forage production enough to be profitable for cattle production.
    • Prediction of leaf:stem ratio in grasses using near infrared reflectance spectroscopy

      Smart, A. J.; Schacht, W. H.; Pedersen, J. F.; Undersander, D. J.; Moser, L. E. (Society for Range Management, 1998-07-01)
      Leaf:stem ratio of grass stands is an important factor affecting diet selection, quality, and forage intake. Estimates of leaf:stem ratios commonly are based on a labor intensive process of hand separating leaf and stem fractions. Near infrared reflectance spectroscopy (NIRS) has been used successfully to predict forage quality and botanical composition of vegetation samples. The objective of this study was to evaluate the use of NIRS to predict leaf:stem ratios in big bluestem (Andropogon gerardii Vitman), switchgrass (Panicum virgatum L.), and smooth bromegrass (Bromus inermis Leyss.). A total of 72 hand-clipped samples of each species was taken from seeded monocultures in eastern Nebraska throughout the 1992, 1993, and 1994 growing seasons. Leaf:stem ratio was determined first for each sample and then the entire sample was ground. Samples were scanned by a Perstorp model 6500 near infrared scanning monochromator. Three calibration equations were developed based on using 18, 36, and 54 (1/4, 1/2, and 3/4 of total samples, respectively) samples. These 3 calibration equations were used to determine the number of samples necessary to achieve an r2 of 0.70 or higher for each data set. Big bluestem and switchgrass had coefficients of determination (r2) of less than or greater than 0.69 for all calibration equations except for the equation using only 18 samples of big bluestem r2 = 0.60). Smooth bromegrass had a r2 ranging from only 0.06 to 0.14 for the calibration equations regardless of the number of samples used. Near infrared reflectance spectroscopy was a rapid means of estimating leaf:stem ratios in monocultures of big bluestem and switchgrass but it was not suitable for smooth bromegrass.
    • Soil depth assessment of sagebrush grazing treatments using electromagnetic induction

      Bork, E. W.; West, N. E.; Doolittle, J. A.; Boettinger, J. L. (Society for Range Management, 1998-07-01)
      Depth to a root restricting layer affects both soil moisture and nutrient availability, resources strongly correlated to plant cover and production. We evaluated the potential of 2 electromagnetic induction meters (EM38 and EM31) for non-destructively assessing soil depth to bedrock in 2 long-term seasonal sagebrush steppe sheep grazing treatments with different vegetational compositions. Apparent conductivity readings, measured with the EM38 and EM31 in both the horizontal (H) and vertical (V) dipole orientations, were positively related to soil depth. Apparent conductivity measured with the EM31H (r2 = 0.78) and EM38V (r2 = 0.75) were the best predictors of depth. Soil depth distributions were similar between grazing treatments based on Kolmogorov-Smirnov (K-S) tests of the EM38H apparent conductivity (P = 0.47) and EM38V apparent conductivity (P = 0.56). In constrast, K-S tests for the EM31H apparent conductivity (P = 0.09) and EM31V apparent conductivity (P < 0.01) indicated the fall-grazed treatment had a larger area in which soil depth exceeded 150 cm. Because less than 2% of each grazing treatment was predicted to have soils deeper than 150 cm, however, overall site differences between the 2 treatments appeared to be minor. Therefore, the vegetational differences between the treatments have probably resulted more from differences in the seasonality of grazing rather than ecological site characteristics as reflected in soil depth. Maps of soil depth indicated both treatments consisted of intermittent shallow and deep soils, created by several parallel basalt pressure ridges. Results suggest electromagnetic induction can effectively assess the spatial variability of soil depth and could aid in selecting sites for rangeland monitoring or manipulation.
    • Spatial memory and food searching mechanisms of cattle

      Laca, E. A. (Society for Range Management, 1998-07-01)
      Uneven distribution of grazing negatively impacts rangelands through over- and under utilization of resources. The goal of this study was to quantify the role of experience on search pattern and foraging efficiency of cattle. Steers (Bos taurus x B. indicus) were exposed once daily during 15-20 min. sessions to 3 food-distribution treatments: VR (variable-random, food locations were changed randomly and daily), CR (constant-random, food locations were randomly set at the beginning and remained the same throughout the experiment), and CC (constant-clumped, food locations were constant and clumped in groups of 5). Pelleted feed was available in 20 out of 64 feeders arranged in 8 rows and 8 columns, with neighboring locations 5 m apart. Encounter rate of food locations was partitioned into search speed, total number of visits per unit distance walked, ratio of different (not previously visited within the session) locations to total visits (including revisits), and ratio of food locations to different locations visited. Intake rate increased (P < 0.01) as animals gained experience, but more slowly in variable-random than constant-clumped and constant-random. Residence time at food locations declined (P < 0.01) with increasing experience. Intake rate was negatively affected (P < 0.01) by search time per food location, which in turn was determined by the steers' ability to remember food locations. Steers in constant random and constant clumped used long-term spatial memory to return to food locations, and ignored areas where no food was found (P < 0.01). Conversely, steers in variable random used a strategy based on avoidance of locations already visited within sessions. Thus, in constant random and constant clumped food search was more efficient (P < 0.01) and concentrated in certain areas, whereas in variable random it was less efficient and more evenly distributed over the whole area. The results of this study suggest that impeding spatial memory could improve grazing patterns.
    • Temperature effects on regrowth of 3 rough fescue species

      King, J. R.; Hill, M. J.; Willms, W. D. (Society for Range Management, 1998-07-01)
      Three species of rough fescue, alpine rough fescue (Festuca altaica Trin.), mountain rough fescue (F. campestris Rydb.), and plains rough fescue (F. hallii (Vasey) Piper) were grown for 12 weeks under 5 temperature regimes — 7:3, 12:8, 17:13, 22:18, and 27:23 degrees C — and defoliated 3 times to 3.5 cm at 4-weekly intervals in a growth cabinet study. Final plant dry mass and harvestable biomass production were greatest at 17:13 degrees C for alpine rough fescue and plains rough fescue, and at 12:8 degrees C for mountain rough fescue. Harvestable biomass plateaued or declined at the final harvest in all species for temperatures above 12:8 degrees C. Tiller numbers increased at successive harvests. Biomass per tiller declined markedly at the final harvest of alpine rough fescue at all temperatures. Regrowth in alpine rough fescue was markedly reduced at temperatures either above or below the optimum. The results indicate that mountain rough fescue and plains rough fescue are better able to regrow following defoliation at temperatures below or equal to their optima, than at temperatures above their optima. This provides greater understanding of field responses in both species where frequent defoliations are more deleterious after the April/May period when temperatures are above optimal.
    • Using a grazing pressure index to predict cattle damage of regenerating tree seedlings

      Pitt, M. D.; Newman, R. F.; Youwe, P. L.; Wikeen, B. M.; Quinton, D. A. (Society for Range Management, 1998-07-01)
      This research investigated the potential for using cattle grazing pressure (AU Mg-1 ha-1) and stocking rate (Animal Unit Days ha-1) for predicting basal scarring and browsing of lodgepole pine (Pinus contorta Dougl.) seedlings on cutblocks in southern British Columbia from 1989 to 1992. Cattle browsing on lodgepole pine seedlings occurred almost exclusively during the first 2 years of grazing. Browsing increased (P < 0.05; r2=0.71) with increasing stocking rate only during the first year of grazing. Browsing increased with increasing grazing pressure in 1989 (P < 0.05; r2= 0.38) and 1990 (P < 0.05; r2 = 0.39). Basal scarring peaked during the second year of grazing, but was correlated (P < 0.05; r2 = 0.79) with stocking rate only during the first year of grazing. Increasing grazing pressure was associated with higher (P < 0.05) basal scarring during all 4 years of the study, and likely better predicts trampling damage than does stocking rate, particularly during the first year of grazing. Basal scarring during 1989 generally increased to > 10% of sample trees when grazing pressure exceeded 12.0 AU Mg-1 ha-1. This threshold grazing pressure value of 12.0 AU Mg-1 ha-1, however, cannot likely be extrapolated directly to other sites. Grazing pressure values and associated basal scarring are unquestionably influenced by many factors (e.g., pasture size, kind of grazing animal, forage species, tree height, water availability, topography, and weather patterns during the grazing period). Nonetheless, our work provides evidence that grazing pressure provides a useful index for predicting the potential for trampling damage of lodgepole pine seedlings by cattle.
    • Viewpoint on objectives, boundaries, and rangeland carrying capacity

      Scarnecchia, David L. (Society for Range Management, 1998-07-01)
      This paper de-analyses a recent paper by Roe (1997, J. Range Manage., 50:467-472) entitled Viewpoint: On Rangeland Carrying Capacity. This response to that paper: (1) examines and demonstrates the importance of defining objectives and boundaries in management, science, management science and art, (2), reaffirms an earlier, objective-based concept of carrying capacity applicable to general systems and to models of them, and (3) implores minimal use of unnecessary jargon in range management science.
    • Viewpoint: Applying riparian buffers to Great Plains rangelands

      Dosskey, M. G. (Society for Range Management, 1998-07-01)
      Better management of riparian areas has been promoted by public agencies for almost 2 decades. Recently, however, efforts have been intensified because serious conservation concerns remain. To achieve mandated conservation goals for water quality and wildlife will require widespread acceptance and application of recommended riparian practices. Success of riparian programs in the Great Plains will require recognition of differences between the interests of public agencies and those of private landowners and the development of an approach to riparian management that can accommodate both.