Jerry L. Holechek

Evaluation of Different Calculation Procedures for Microhisological Analysis.

This study evaluated 3 procedures for calculating dry weight composition of forage mixtures when microhistological analysis was used. Dividing the frequency of each species by the total frequencies of all species gave a slightly more accurate representation of dry weight composition than converting frequency to relative density or using actual density. The frequency addition procedure is much quicker than either procedure

Training Needed for Quantifying Simulated Diets from Fragmented Range Plants

A procedure is described that results in rapid training of observers for microhistological analysis. Observers trained using this procedure were able to evaluate accurately 6 handcompounded diets comprised of semidesert plant species. The accuracy of microhistological analysis was examined by using the 4 trained observers to evaluate 26 additional hand-compounded diets containing various combinations of 30 different grasses, forbs, and shrubs from semidesert range. The relationship between relative density (estimated percent by weight composition) and actual percent by weight composition was close to unity for species in each forage class individually or in combination. However this relationship would probably have been different if the observers had not used known diets to evaluate their accuracy and make corrections. It is recommended that all technicians using microhistological analysis regularly check their accuracy with handcompounded diets.

Grazing influences on watering point vegetation in the Chihuahuan desert.

Long-term influences of livestock grazing on vegetation around watering points was studied on 2 upland Chihuahuan desert ranges in southcentral New Mexico using regression analysis. One range had been conservatives stocked since the 1950s while the other was more heavily stocked. About 45% of the climax vegetation occurred on the heavily stocked range compared to 70% on the conservatively stocked range. During 3 years of study, both ranges were stocked conservatively so annual utilization of the key forage grasses was 30-35%. Regression analyses showed black grama (Boueteloua eriopoda Torr.), mesa dropseed (Sporobolus flexuosus Thurb, Rybd.), threeawn (Aristida sp.), and total perennial grass standing crop increased as distance from water increased on the good condition range (P < 0.05). However, black grama and threeawn standing crop showed no association with distance from water on the fair condition range. Broom snakeweed (Xanthocephalum sarothrae Pursh.), the primary poisonous plant found on both ranges, was associated (r2 = 0.35) with distance from water only on the good condition range in April. Poisonous plants other than broom snakeweed decreased as distance from water increased with the exception of the fair condition range in October. No livestock losses from poisonous plants were noted on either range over the 3 years. We attribute this to the present conservative stocking rates. Our study supports the recommendation that downward stocking rate adjustments be made for the zone more than 1,600 m from water.

Evaluation of fecal indices to predict cattle diet quality.

A study involving 6 feeds of widely varying chemical properties fed to 6 steers in a Latin square design was conducted to evaluate the potential of fecal chemical characteristics for predicting ruminant nutritional status. Forage intake, diet in vivo digestibility %, and diet nitrogen % were used as dependent variables and fecal nitrogen %, nucleic acid %, nonflber bound nitrogen %, ether extract %, neutral detergent fiber %, acid detergent fiber %, acid detergent lignin %, water soluble material %, and acid/pepsin disappearance % were used as independent variables in regression equations. Forage intake and diet in vivo digestibility could not be accurately predicted from any single variable or combination of independent variables. Fecal acid/pepsin disappearance was the independent variable most highly correlated with forage intake (r = .63) and diet in vivo digestibility (r = .33). Diet nitrogen % was highly correlated with fecal nitrogen % (r = .81) and fecal acid pepsin disappearance % (r = .83). Combined data from this and other studies give a generalized regression equation that shows potential for detecting nitrogen deficiencies in steer diets from fecal N % (organic matter basis) when steer diets contain low levels of soluble phenolics. When steer fecal nitrogen % drops below 1.7%, dietary nitrogen deficiencies should be

Cattle diets in the Blue Mountains of Oregon. II. Forests.

Esophagerlly flstulated cows were used on forested range in northeastern Oregon to collect diet samples which were then analyzed by the microhlstological technique. Grasses, forbs, and shrubs averaged 61,16,and 23% of the diet, respectively. Composition of diets differed among years and with seasonal advance. Idaho fescue and elk sedge were the most important forage species consumed. Forbs were used heavily in the early part of the grazing season before maturation. Browse comprised as much as 47% of the diet when green grass was unavailable. Cattle were opportunistic grazers and did not limit their selection to grass species. On forested ranges cattle diets varied among grazing periods within each year as well as among years. Knowledge of dietary habits of livestock and game animals is valuable to the range manager in determining if competition exists among different range animals and in balancing livestock and game numbers with available forage. Also, a knowledge of species consumed tells a manager what the key species are and helps explain changes in diet quality and animal performance (Holechek et al. 1981). At present information concerning cattle diets on forested range in eastern Oregon is limited to utilization studies reported by Pickford and Reid (1948), Harris (1954), Miller and Krueger (1976), and Skovlin et al. (1976). Pickford and Harris (1948), Harris (1954), and Skovlin et al. (1976) conducted their research at the Starkey Experimental Range and Forest in northeastern Oregon. Results from all three studies showed that bluebunch wheatgrass (Agropyron spicufum), Idaho fescue (Festuca iduhoensis). prairie junegrass (Koeleriu cristata), elk sedge (Carex geyeri), Sandberg bluegrass (Pea sandbergii). and pinegrass (Calumugrostis rubescens) were the primary forage species considering availability and utilization. Pickford and Reid (1948) reported that grass was the primary forage class consumed by cattle but forbs were readily utilized in June and early July. Shrubs, particularly common snowberry (Symphoricarpos albus), also received heavy use during some periods although shrubs comprised a small amount of the available forage. Harris ( 1954) observed that over a 9-year period bluebunch wheatgrass was the forage species most heavily used by cattle followed by prairie junegrass, Idaho fescue, elk sedge, and pine. grass. Skovlin et al. (1976) also found that bluebunch wheatgrass was an important forage species. Elk sedge and pinegrass, however, contributed the most forage. In all three of the previously discussed investigations, Sandberg bluegrass (Poa sandbergii) was one of the most common forage species present but utilization Authors were, respectively, graduate research assistant: associate professor rangeland msources, Oregon State University, Eastern Oregon Agricultural Research Center, Union. Oregon; professor, project leader, U.S. Dep. Agr. Rangeand wildlife Habitat Laboratory, La Grandc, Oregon; and leader, rangeland resources progran+ Oregon State University, Corvallis, at the time of the research. J.L. Holechek 1s currently assistant professor of range science, Division of Animal and Range Sciences, New Mexico State University, Las Cruces, New Mexico 88003. This report is Oregon State Agricultural Experiment Station Technical Paper Number 5490. This research was jointly funded by the Eastern Oregon Agricultural Research Center, Oregon State University and the Pacific Northwest Forest and Range Experiment Station, United States Forest Service, U.S. Dep. Agr., and was part ofthe PNWFRES Project 1701 entitled,“Theinfluenceofcattlegrazmgmethods and big game on riparian vegetation, aquatic habitat and fish populations.” levels were much below those for bluebunch wheatgrass, prairie junegrass, Idaho fescue, and elk sedge. Pickford and Reid (1948) observed cattle during the grazing season and reported a preference for grasslands. Forest areas were generally utilized by mid-summer. However, Harris (1954) stated that cattle used forest areas all summer when heat and/or flies became intense, although a preference for grassland areas were shown. In these studies cattle grazed an 8500-ha range area divided into two pastures and grazed under deferred rotation. The objectives of this study were to restrict cattle to forest ranges and determine important dietary constituents, estimate changes in diet with season progression and to observe annual differences in dietary constituents. Experimental Site and Procedure The study was conducted on a portion of the Starkey Range described by Holechek et al. (1981). In 1976, two 230-ha pastures were established on a range having a common grazing history. The vegetation and terrain of the two pastures was similar. Vegetation is representative of the ponderosa pine-Idaho fescue (pinus ponderosa-Festuca idahoensis), ponderosa pine-common snowberryelk sedge (Pinus ponderosa-Symphoricurpos albusCurex geyeri), Douglas fir-ninebark (Pseudotsuga menziesiiPhysocarpus malvuceus), and Douglas fir-common snowberryelk sedge (Pseudotsuga menziesii-Symphoricarpos albus-Curex geyeri) associations originally described by Daubenmire and Daubenmire (1968). Percent cover of important forage species on the pasture was determined and presented in Table I. Because the vegetation composition on the two pastures was identical,, cover data were pooled across pastures. Scientific and common names in Table 1 and the text follow Garrison and Skovlin (1976). Cattle grazing was conducted on the pastures in 1976, 1977, and 1978 under a two pasture-one herd rest rotation grazing system. This involved grazing one pasture all season long in 1976 and resting the other pasture. In 1977 grazing was initiated on the pasture rested in 1976. At mid-season cattle were moved to the other pasture. In 1978, the pasture rested in 1976 was grazed while the other pasture was rested the entire season. Grazing was initiated on June 20and concluded on October JOinall three years of study. Diet samples were collected with four esophageally fistulated cows in all three years of study. Eighteen head of yearling heifers and four fecal collector steers were also grazed on the pastures. Data on diet quality, forage intake, and livestock performance are given in Holechek et al. (198 1). Two collections were made every other week with thet ftstulated animals. The grazing season was divided into four 28-day periods to show trends in dietary botanical composition. These were June 20 to July 18 (late spring), July 19 to August 15 (early summer), August 16 to September 12 (late summer), and September 13 to October 10 (fall). Sixteen esophageal fistula samples were collected during each period. Diet samples were analyzed for botanical composition by the Sparks and Malechek (1968) method. Where applicable, regresJOURNAL OF RANGE MANAGEMENT 35(2), March 1992 239 Table 1. Percent cover of the primary forage species and their percent by weight contribution to cattle diets. Snecies Percent Percent cover’ in diet* Bluebunch wheatgrass (Agropyron spicatum) Elk sedge (Carex geyeri) Pinegrass (Calamogrostis rubescens) One-spike danthonia (Danthonio unispicota) Idaho fescue (Festuca idahoensis) Western fescue (Festuco occidentalis) Kentucky bluegrass (Poa prorensis) Sandberg bluegrass (Poa sandbergii) Total grasses Western yarrow (Achilles millefolium

Relationships Between Chihuahuan Desert Perennial Grass Production and Precipitation

Abstract Perennial grass production on the Chihuahuan Desert Rangeland Research Center in south-central New Mexico was correlated with precipitation characteristics over a 34-year period. Total December through September precipitation was highly correlated (r = +0.77, n = 34) with perennial grass production. Practical generalized indices were developed that could be broadly applied by managers for predicting perennial grass production from precipitation characteristics. Perennial grass production and precipitation data on 3 separate pastures were collected over a 6-year period to evaluate the reliability of models to predict perennial grass production. Simple linear, 2-variable, quadratic, and polynomial regression models gave perennial grass production estimates that were well correlated with actual values (r = +0.85 to +0.91, n = 17) across the 3 pastures. The quadratic regression model (Y = 4.04 − 0.24X + 0.012 X2, X = December through September precipitation, Y = forage production, n = 34, r = 0.85) gave the most accurate predicted values. Our quadratic regression model should be of practical use to ranchers and range managers on Chihuahuan Desert upland rangelands receiving 200–300 mm annual precipitation, with loamy to sandy loam soils and in mid- to late-seral ecological condition. These conditions match those generally found on Chihuahuan Desert Uplands. We consider our quadratic regression model to be highly useful over large areas to ranchers in southern New Mexico, southeastern Arizona, southwestern Texas, and north-central Mexico.

Forb and shrub influences on steer nitrogen retention.

Two experiments with steers were conducted to evaluate the influence of native forbs and shrubs on nitrogen utilization by cattle. Diets in Exp. 1 were blue grams (Bouteloua gracilis [H.B.K.])(BG), BG plus 23% alfalfa (Medicago sativa) hay (ALF), BG plus 42% forbs and BG plus 41% shrubs. Diets in Exp. 2 included barley (Hordeum vulgare L.) straw, and straw plus either 42% ALF, 63% forbs, or 62% shrubs. Forbs used in our study were scarlet globemallow (Sphaeralcea coccinea Nutt.) and leatherleaf croton (Croton pottsii Lam.). Shrubs included fourwing saltbush (Atriplex canescens [Pursh.]) and mountain mahogany (Cercocarpus montanus Raf.) Forb and shrub mixtures were 50:50 of each species. Blue grams and straw basal diets contained 7.6 and 3.5% CP, respectively. Diets containing ALF, forbs, and shrubs were isonitrogenous (10.5% CP) in both experiments. In Exp. 1, no differences (P>.10) were observed among treatments for N retention (g/d). In Exp. 2, N retention was least (P .05), and intermediate for the forb diet. Inclusion of forbs or shrubs with low-quality forage diets was, in most instances, comparable to inclusion of ALF. Our results indicate that maintaining palatable forbs and shrubs on rangelands should reduce the need to supply cattle with protein during periods when grasses are dormant.

Influence of two native shrubs on goat nitrogen status

In vivo digestibility trfnls were conducted in metrbolism stalls at New Mexico State University to evaluate the influence of leaves of true mountain mahogany (Cercocurpus montanus Raf.) and fourwing saltbush (A tr@w cunescens [Pursh.] Nutt.) on nitrogen retention and digestibility hy Angora goats. Each of the 2 shrubs were fed at 3% and 6% (air dry basis) of the diet along with prairie hay that was comprised mostly of blue grama (Bouteloua grucilis [H.B.K.] Lag. Ex. Griffhhs). High and low shrub diets contained about 12% and 8% crude protein, respectively. Nitrogen retention did not differ (IQO.05) among mountain mahogany and fourwing saltbush diets; however, goats fed the 60% shrub level had greater (P<O.OS)nitrogen retention than did those fed the 3% level. Mountain mahogany diets had a greater soluble phenolic/tannin content than fourwing saltbush diets, but this did not appear to influence nitrogen retention. Forage organic matter intakes averaged 2.% of body weight and did not differ (890.05) among the 4 treatments. Total fecal output of nitrogen (g/d) was highly correlated (1-2 = .71, n = 15) with nitrogen retention. Hence, total fecal nitrogen output may be useful as an indicator of grasing ruminant protein status. Digestible protein (70) and dietary crude protein concentrations were associated poorly with nitrogen retention in our study. Blood serum analysis showed no toxicosis problem for any of the 4 dietary treatments. We concluded that leaves from fourwing saltbush and true mountain mahogany have potential to he an effective source of protein for range livestock consuming low-quality grasses.

Comparison of Big Sagebrush Vegetation in Northcentral New Mexico under Moderately Grazed and Grazing Excluded Conditions

Vegetation canopy cover on upland and lowland sites inside and outside a ZZyear-old exciosure in big sagebrush (At-tern& tridentutu trident&z) range was evaluated by sampling for canopy cover. The area outside the exciosure had received moderate use of grazabie forage by cattle in the late winter and spring for the past 22 years. The two sites did not show a consistent response to grazing. Big sagebrush canopy cover was higher inside the exciosure on the upland site and higher outside the exciosure on the lowland site. Big sagebrush dominated the canopy cover both inside and outside the exciosure on both sites and relatively little understory was present. Forbs were nearly absent from the area, which is atfributed to a past history of heavy sheep grazing. Elimination of grazing had little effect on vegetation composition on both sites studied. Because of its size (approximately 50 million hectares) the big sagebrush (Artemisia tridentata) range type is of considerable importance in the western United States. Major provinces within the big sagebrush range type include the following: Columbia River (Hironaka 1979); the Great Basin (West 1979); the high plains of Montana, Wyoming and the Dakotas (Johnson 1979); and the Colorado plateau (West 1979). The Colorado plateau province of southwestern Colorado and northwestern New Mexico has had the longest history of livestock grazing, which dates back to the seventeenth century (Carlson 1969). Because of both widespread and heavy grazing in the nineteenth and early twentieth centuries by first sheep and later cattle (Wooten 1908), little is known about the original vegetation. Our review of the literature shows the Colorado Plateau has received the least study of the four big sagebrush provinces. Information concerning successional changes that result from reduction or removal of livestock grazing pressure is not available for this province. Exclosures can be a useful tool to the range manager for evaluating and interpreting both short-term and long-term grazing influences of domestic and wild animals (Daubenmire 1968). Moderate to light grazing appears to be beneficial to most range plant communities (Holechek 1980) although further study is needed. Changes in vegetation that result from grazing management are difficult to separate from those that result from changes in climate unless ungrazed areas are available for comparison with grazed areas within the same pasture. The objective of this study was to compare the vegetation canopy cover of different moderately grazed basin big sagebrush (Artemisia tridentata tridentata) sites in northcentral New Mexico with that of the same sites when they had received 22 years of protection. Authors are associate professor of range ecology and graduate research assistant. Department of Animal and Range Sciences, New Mexico State University, Las Cruces 88003. This report is article 900. Agricultural Experiment Station, New Mexico State University, Las Cruces 88003. Manuscript received October 10, 1981. JOURNAL OF RANGE MANAGEMENT 36(4), July 1963 Methods The study area was located 40 km northwest of Taos, N. Mex., in a 25-35 cm precipitation zone at 1800-2,000-m elevation. Most (65%) of precipitation occurs in the spring and summer; July and August are months of peak rainfall. Soils of the area belong to the order aridisol and the suborder argid due to their high clay content. Soil texture ranges from a clay loam on lowland sites to a silty clay loam on upland sites. Soil depth averages about 170 cm on lowland sites and 140 cm on upland sites. Vegetation is heavily dominated by big sagebrush (Artemisia tridentata tridentata) with an understory of primarily blue grama (Bouteloua gracilis) on the upland sites and western wheatgrass (Agropyron smithii) on the lowland sites. Other species found on the study area included fourwing saltbush (Atriplex canescens), galleta (Hilaria jamesii), common winterfat (Ceratoides lanata), cactus (Opuntia sp.), scarlet globemallow (Sphaeralcea coccinea), Russian thistle (Salsola kali), broom snakeweed (Xanthocephalum sarothrae), summer cypress (Kochia seoparia), ring muhiy (Muhlenbergia torreyi), and crested wheatgrass (Agropyron cristaturn) (Stephenson 1982). Forbs are almost entirely absent with the exception of well-traveled roadsides. The pasture selected for study is controlled by the Bureau of Land Management. We believe it is typical of big sagebrush ranges in northern New Mexico in terms of precipitation, soils, vegetation, grazing history, and grazing management. It is characterized by relatively flat roiling terrain (uplands) with slight depressions (lowlands) caused by waterdrainage. Uplands compriseabout 80% of the area with lowlands comprising about 20%. During the past 25 years the study pasture had been grazed by cattle at a moderate stocking rate (30 to 50% use of current years growth) during the late winter and spring until early June. in 1958 an exclosure of approximately 16 ha was built with woven wire to prevent use by both livestock and game animals. It was located in a “key area”as discussed by Stoddart et al. (1975). The western half of the exclosure was on a lowland site and the eastern half was on a upland site. A modification of the line-intercept procedure of Canfield (1941) was used tosamplevegetationcanopycoverin August 1981. For sampling canopy cover, a stick of Im in length incremented in millimeters was used instead of an extended line. Eight transects were randomly selected based on consecutive numbering of fence posts at the west and east ends of each exclosure. Ten-meter buffer areas immediately inside and outside the ends of each exclosure were omitted from sampling to avoid influences of the fence. Each transect involved IO subunits of 5m in length. Cover was sampled for all 10 subunits of each transect by perpendicular orientation of the meter stick to the left side at the end of each subunit. Two observers independently sampled each location. The number of jackrabbit pellets intercepting the meter stick was recorded for all subunits. A one-way completely randomized design with observers as subsamples was used to evaluate experimental results (Steel and Torrie 1960).

Honey mesquite influences on Chihuahuan desert vegetation

Research has been lacking on the influence of honey mesquite (Prosopis glandulosa Torr.) on forage production in the Chihuahuan desert. In 1964 honey mesquite was controlled (65% kill) with the herbicide, Monuron, on portions of the New Mexico State University College Ranch. Both herbicide treated and nontreated areas occur within the same pasture on similar soils and have similar grazing histories (continuous grazing, conservative stocking rate). This has resulted in areas with moderate and low levels of mesquite (16% and 9% mesquite canopy cover, respectively). We evaluated relationships among forage standing crop, vegetation canopy cover, mesquite density, mesquite height, mesquite diameter, and mesquite volume on areas with low and moderate mesquite levels in fall 1992 and spring 1993. Regression analyses showed forage standing crop and canopy cover generally were not (P > 0.10) associated with mesquite height, mesquite diameter, canopy volume, and mesquite density on either low or moderate mesquite areas. Honey mesquite canopy cover on the non-treated area was nearly double that on the treated area. Data from long term permanent transects (1968-1992) showed no differences (P > 0.10) in total forage production between low and moderate mesquite areas in fall of 1992. On these transects mesquite increases in cover and density were over 3 times greater on the low compared to moderate mesquite areas in the 1982 to 1992 period. Our data indicate mesquite density and cover increase rapidly after herbicidal mesquite control even under conservative stocking. However at canopy cover levels below 17% honey mesquite appeared to have little effect on forage production. Potential maximum canopy cover of mesquite on these types of sites is about 37%. Our data show that under proper stocking both mesquite and perennial forages grasses can increase concurrently on desert grassland ranges. We recognize that the outcome of our study may have been modified with higher mesquite densities, different soil characteristics or a lack of desirable understory species.