@article {JRN55387, title = {Diet selection of raramuri criollo and angus x hereford crossbred cattle in the Chihuahuan Desert}, journal = {Journal of Arid Environments}, volume = {205}, year = {2022}, month = {7/4/2022}, pages = {104823}, abstract = {Strategies to help producers cope with unpredictable forage production associated with low and variable precipitation patterns on arid rangelands are needed, particularly if global warming trends continue as projected. One option is to identify cattle biotypes compatible with less productive shrubby landscapes. One such biotype is the Raramuri Criollo (RC) from the Copper Canyon of northern Mexico. This small-framed animal exhibits travelling behaviors that allow it to exploit vegetation at a greater distance from water, although it is unknown whether RC have dietary preferences that differ from European breeds typically raised in the southwestern U.S.A. We examined diet selection of RC vs. desert adapted Angus x Hereford (AH) crossbreds typical of the region using DNA metabarcoding to determine the proportion of plant species in fecal samples. Fecal samples were collected from 10 cows of each breed in two adjacent pastures during two seasons (growing and dormancy; four weeks per season) for three consecutive years. Dominant plant species in fecal samples of both cattle breeds were Atriplex canescens (four-wing saltbush), Hoffmannseggia glauca (hog potato), Hopia obtusa (vine mesquite), Setaria leucopila (plains bristlegrass), Sporobolus spp. (S. contractus, S. flexuosus, and S. giganteus), Pleuraphis mutica (tobosa), and Bouteloua eriopoda (black grama), which is consistent with previous studies in the region using different techniques for assessing dietary plant composition of other breeds of cattle. Only a few differences were detected between breeds. Compared to AH, fecal samples from RC tended to contain a higher proportion of mesquite and Yucca spp. (P < 0.07) and less Ephedra spp. (P < 0.06). The only grass species that differed between breeds was black grama (P < 0.05), with AH fecal samples containing about twice as much as RC cows (\~{}8\% vs. 4\%). This finding could have important implications for conservation of black grama in the Chihuahuan Desert.}, keywords = {beef cattle, diet selection, DNA metabarcoding, Raramuri Criollo}, doi = {10.1016/j.jaridenv.2022.104823}, url = {files/bibliography/22-016.pdf}, author = {Richard E. Estell and S. Nyamuryekung{\textquoteright}e and D. K. James and S. Spiegal and Andr{\'e}s F. Cibils and Amy L. Gonzalez and Matthew M. McIntosh and Kirsten B. Romig} } @article {JRN55335, title = {The genesis of the Jornada criollo cattle program}, journal = {Journal of Arid Environments}, volume = {193}, year = {2021}, month = {6/11/2021}, abstract = {Many rangelands in the southwestern United States have experienced increased shrub cover and lower and more variable forage resources during the past 100 years. Criollo cattle are descendants of cattle brought to the Americas by European explorers that spread throughout North and South America. These cattle were displaced in many areas as British breeds became popular, but isolated populations remained that had undergone natural selection for nearly 500 years. Scientists at the Jornada Experimental Range in Las Cruces, New Mexico introduced Raramuri criollo genetics from the Tarahumara region of Chihuahua, Mexico to the research herd about 15 years ago in an effort to capitalize on their ability to thrive in harsh landscapes of the Chihuahuan Desert. They hypothesized that this smaller framed animal might be more suited to extensive shrubby landscapes and exert a lower environmental footprint than cattle of European descent. Preliminary observations during the early years of this project suggested that behavioral characteristics of this biotype could potentially be used to improve utilization of extensive rangelands with restricted water distribution. Raramuri criollo generally traveled farther per day and farther from water than Angus x Hereford crossbreds typically raised on these rangelands. Approximately five years ago, the Jornada expanded this program by joining forces with scientists from New Mexico State University, Mexico, and South America. Several studies were initiated that encompassed aspects of behavior, distribution, habitat and ecological site use, maternal behavior, diet selection, heat tolerance, and performance of Raramuri criollo cattle. Many of the results from these collaborations are reported in this special issue.}, keywords = {beef cattle, criollo cattle, Heritage beef cattle}, doi = {10.1016/j.jaridenv.2021.104563}, url = {files/bibliography/21-047.pdf}, author = {Richard E. Estell} } @article {JRN54922, title = {Controlling one-seed juniper saplings with small ruminants: What we{\textquoteright}ve learned}, journal = {Rangelands}, volume = {40}, year = {2018}, month = {10/2018}, pages = {129-135}, chapter = {129}, abstract = {

Protein supplements and polyethylene glycol increased juniper intake by small ruminants in all seasons except fall, when PSM concentrations were greatest. Terpenes were affected by season and sapling size, and were related to juniper intake by small ruminants. Small sapling browsing occurred most frequently in summer. Debarking of branches on taller saplings was greatest in spring. Ten years later, juniper kill ranged from 5-14\%. Growth suppression was still evident after 10 years; browsed saplings averaged 13 cm shorter than controls. Strategies to target grazing of one-seed juniper are more likely to succeed if aligned with periods when PSM are lowest.

}, keywords = {goats, phenology, plant secondary metabolites, protein supplementation, sheep, targeted grazing}, doi = {doi.org/10.1016/j.rala.2018.07.002}, url = {/files/bibliography/18-018.pdf}, author = {Richard E. Estell and Andr{\'e}s F. Cibils and S. A. Utsumi and Stricklan, D. and Butler, E. M. and Fish, A. I. and Amy Ganguli} } @article {JRN54560, title = {Defoliation of Flourensia cernua (tarbush) with high-density mixed-species stocking}, journal = {Journal of Arid Environments}, volume = {130}, year = {2016}, month = {04/2016}, pages = {62-67}, chapter = {62}, abstract = {

Interest in shrub use by livestock is increasing along with the rising demands placed on rangelands worldwide. Historically, Flourensia cernua (tarbush) has increased in the Chihuahuan Desert but receives limited use by cattle. Cattle, sheep and goats co-grazed eight 0.6 ha tarbush-dominated paddocks during two periods for up to nine days during two consecutive years. Cumulative tarbush defoliation across periods and years averaged 75.6\%, with a mean increase of 9.3\%/day (P \< 0.0001). Defoliation of individual shrubs varied from 5 to 99\% in 1989 and 0 - 100\% in 1990, indicating highly variable palatability among individual plants. Sheep lost 2.3 - 5.5 kg/hd (P \< 0.0001) across periods and years when forced to browse tarbush. In 1989, goats gained (P . 0.0345) 0.6 kg/hd in period 1, but the gain in period 2 was not significant (P . 0.2934). During 1990, goats lost 3.1 kg/hd (P . 0.0001) across periods. High-density mixed-species stocking of small areas for short time periods resulted in extensive tarbush use, primarily due to browsing by sheep and goats. Targeted use of tarbush for short time intervals may increase use of this highly nutritious forage and potentially serve as a form of biocontrol for this shrub.

}, keywords = {biocontrol, browsing, cattle, goats, sheep, shrubs}, doi = {10.1016/j.jaridenv.2016.03.013}, url = {/files/bibliography/16-008.pdf}, author = {Richard E. Estell and D.M. Anderson and D. K. James} } @article {JRN54522, title = {Effect of light intensity and wavelength on concentration of plant secondary metabolites in the leaves of Flourensia cernua}, journal = {Biochemical Systematics and Ecology}, volume = {65}, year = {2016}, month = {04/2016}, pages = {108-114}, chapter = {108}, abstract = {

Flourensia cernua (tarbush) is a shrub that has encroached into grasslands in many areas of the northern Chihuahuan Desert and contains high levels of carbon-based secondary compounds. Concentrations of secondary compounds are affected by numerous biotic and abiotic influences, including amount and wavelength of solar radiation. However, responses to shade and ultraviolet light restriction are inconsistent among plant species and compound class. We conducted a three-year study to evaluate the effect of shade and UV light restriction on total phenolic and terpene concentrations in tarbush. Sixty plants were randomly assigned to one of three treatments (control, UV light restriction, or 50\% incident light restriction). Mean concentrations of total phenolics and total volatiles in tarbush were 82.4 and 12.5 mg/g DM, respectively. Total phenolics did not differ between UV-restricted and control plants, but were lower in shaded plants than the other treatments (P \< 0.05).\  Total volatiles tended to be greater for the UV-restricted treatment than control plants (P= 0.056), with shaded plants not different from either treatment. Treatment effects were detected for 18 individual compounds (P \< 0.05). Our results partially support the hypothesis that UV restriction and shading alter carbon-based secondary chemical concentrations.

}, keywords = {Flourensia cernua, phenolics, plant secondary metabolites, shade, terpenes, ultraviolet light}, doi = {10.1016/j.bse.2016.02.019}, url = {/files/bibliography/16-006.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D. K. James} } @conference {JRN54441, title = {Effect of light intensity and wavelength on concentration of antiherbivory compounds in Flourensia cernua leaves}, booktitle = {Joint Annual Meeting ADSA - ASAS}, year = {2015}, month = {07/2015}, publisher = {Journal of Animal Science}, organization = {Journal of Animal Science}, address = {Orlando, FL}, abstract = {

Shrub encroachment negatively affects forage production and rangeland health in many semi-arid regions. Flourensia cernua (tarbush) has increased in the northern Chihuahuan Desert at the expense of grasslands. Our previous studies have shown a negative relationship between tarbush terpene concentrations and livestock herbivory. Concentrations of secondary compounds are affected by many biotic and abiotic factors, including amount and wavelength of solar radiation. A 3-year study was conducted to examine the impact of shade and UV light restriction on phenolic and terpene concentrations in tarbush. Our hypothesis was that UV restriction and partial shade would reduce carbon based secondary compounds. Sixty plants were randomly selected and assigned to 3 treatments (control, UV light restriction, or 50\% incident light restriction) in a randomized complete block. Frames covered with clear plastic film (UV blocking treatment), black shade cloth (50\% shade treatment) or frame only were placed over 20 plants each. Leaves were collected from each plant in late September each year and freeze-dried for total phenolic analysis (Folin-Denis method) or frozen for leaf surface terpene analysis (extracted with ethanol and identified and quantified with GCMS). Data were analyzed using repeated measures linear mixed effects models with treatment as the fixed effect and year as a repeated effect. Means were separated by LSD. Mean concentrations of total phenolics and total volatiles in tarbush were 82.4 and 12.5 mg/g DM, respectively. Tarbush leaves contained 102 individual terpenes (includ{\textlnot}ing 19 unknowns). No year x treatment interactions were detected for any variable (P \> 0.05). Total phenolics did not differ between controls and UV restricted plants, but were lower for shaded plants than the other 2 treatments (P \< 0.05). Total volatiles were higher for the UV restriction treatment than controls (P \< 0.05), with shaded plants not differing from either treatment. Treatment effects were detected for 18 compounds (P \< 0.05). Shade reduced total phenolics as predicted, but did not affect total volatiles. In contrast to our expectations, UV restriction had no effect on total phenolics, and increased total volatile concentrations.\  Journal of Animal Science Supplement 93: Suppl. x3$\#$ W185/J:684.

}, author = {Richard E. Estell and E.L. Fredrickson and D. K. James} } @conference {JRN54508, title = {Impacts of projected mid-century temperatures on thermal regimes for select specialty and fieldcrops common to the southwestern U.S.}, booktitle = {American Geophysical Union Fall Meeting}, year = {2015}, month = {12/2015}, publisher = {AGU}, organization = {AGU}, address = {San Francisco, CA}, abstract = {

The impacts of projected temperature increases in agricultural ecosystems are complex, varying by region, cropping system, crop growth stage and humidity. We analyze the impacts of mid-century temperature increases on crops grown in five southwestern states: Arizona, California, New Mexico, Nevada and Utah. Here we present a spatial impact assessment of common southwestern specialty (grapes, almonds and tomatoes) and field (alfalfa, cotton and corn) crops. This analysis includes three main components: development of empirical temperature thresholds for each crop, classification of predicted future climate conditions according to these thresholds, and mapping the probable impacts of these climatic changes on each crop. We use 30m spatial resolution 2012 crop distribution and seasonal minimum and maximum temperature normals (1970 to 2000) to define the current thermal envelopes for each crop. These represent the temperature range for each season where 95\% of each crop is presently grown. Seasonal period change analysis of mid-century temperatures changes downscaled from 20 CMIP5 models (RCP8.5) estimate future temperatures. Change detection maps represent areas predicted to become more or less suitable, or remain unchanged. Based upon mid-century temperature changes, total regional suitable area declined for all crops except cotton, which increased by 20\%. For each crop there are locations which change to and from optimal thermal envelope conditions. More than 80\% of the acres currently growing tomatoes and almonds will shift outside the present 95\% thermal range. Fewer acres currently growing alfalfa (14\%) and cotton (20\%) will shift outside the present 95\% thermal range by midcentury. Crops outside present thermal envelopes by midcentury may adapt, possibly aided by adaptation technologies such as misters or shade structures, to the new temperature regime or growers may elect to grow alternate crops better suited to future thermal envelopes.

}, author = {Richard E. Estell and Brody-Lopez, Nathan and Jake Dialesandro and Caitriana Steele and A. Rango} } @article {JRN53932, title = {The changing role of shrubs in rangeland-based livestock production systems: Can shrubs increase our forage supply?}, journal = {Rangelands}, volume = {36}, year = {2014}, month = {04/2014}, pages = {25-31}, chapter = {25}, abstract = {

Projected global increases in ruminant numbers and loss of native grasslands will present a number of challenges for livestock agriculture. Escalated demand for livestock products may stimulate interest in using shrubs on western rangelands. A paradigm shift is needed to change the role of shrubs in rangeland ecosystems. Progress has occurred in identifying mechanisms to increase shrub use, but more solutions are needed to convert woody plants into red meat. Strategies for increasing shrub use could be important for rural communities to adapt to changing climate and shrub cover and for the livestock industry to adapt to predicted growth.

}, keywords = {cattle, goats, grasslands, secondary plant metabolites, sheep, woody plants}, url = {/files/bibliography/14-009.pdf}, author = {Richard E. Estell and Kris Havstad and Andr{\'e}s F. Cibils and D.M. Anderson and Scott T. Schrader} } @article {JRN53927, title = {Is differential use of Juniperus monosperma by small ruminants driven by terpenoid concentration}, journal = {Journal of Chemical Ecology}, volume = {40}, year = {2014}, month = {02/2014}, pages = {285-293}, chapter = {285}, abstract = {

We examined the relationship between volatile plant secondary metabolite concentrations and Juniperus monosperma herbivory by small ruminants. Two groups of animals (10 goats or 5 goats plus 4 sheep) browsed 16 paddocks (20 x 30 m) containing one-seed juniper for six days during two seasons. Juniper leaves were sampled from 311 saplings on the same day they were browsed. Saplings were categorized by size (short [\< 0.5 m], medium [0.5-1.0 m] or tall [\> 1.0 m]) and browsing intensity (light [\< 33\%], moderate [33-66\%] or heavy [\> 66\%]). Juniper bark was also collected from 12 saplings during spring. Total estimated terpenoid concentrations in leaves and bark were 18.3 \± 0.3 and 8.9 \± 0.8 mg/g, respectively, and the dominant terpene in both tissues was a-pinene (11.1 \± 0.2 and 7.6 \± 0.7 mg/g, respectively). Total terpenoid concentration was greater (P \< 0.001) in spring than summer (20.6 \± 0.5 vs. 16.7 \± 0.3 mg/g, respectively) and lower (P \< 0.001) in short saplings than medium or tall saplings (16.5 \± 0.6 vs. 19.8 \± 0.4 and 19.5 \± 0.4 mg/g, respectively). Total concentration also differed (P \< 0.001) among the three defoliation categories (16.1 \± 0.4, 18.7 \± 0.5, and 21.2 \± 0.6 mg/g for heavy, moderate, and light, respectively). The smallest subset of terpenes able to discriminate (P \< 0.001) between heavy and light browsing intensity categories included eight compounds ([E]-\ß-farnesene, bornyl acetate, \&$\#$39;-eudesmol, endo-fenchyl acetate, y-cadinene, a-pinene, cis-piperitol, and cis-p-menth-2-en-1-ol).

}, keywords = {goats, herbivory, one-seed juniper, Oxygenated terpenes, Resource availability hypothesis, sheep, targeted grazing, terpenes}, doi = {10.1007/s10886-014-0389-1}, url = {/files/bibliography/14-006.pdf}, author = {Richard E. Estell and S. A. Utsumi and Andr{\'e}s F. Cibils and D.M. Anderson} } @proceedings {JRN53998, title = {Relationship between one-seed juniper terpene concentration and herbivory by small ruminants}, volume = {91}, year = {2013}, month = {07/2013}, pages = {553}, publisher = {Journal of Animal Science}, address = {Indianapolis, IN}, abstract = {

Plant secondary metabolite affect the amount of use by herbivores for serveral woody species.\  We examined the relationship between terpenoid concentrations and Juniperus monosperma herbivory by small ruminants.\  The study was part of a larger effort in which goats (n = 10) or mixed species (5 goats and 4 sheep) were allotted to 16 plots (20 \× 30 m) containing one-seed juniper for 6 d during 2 seasons at 2 stocking rates. Juniper leaves were sampled from 311 saplings on the same day they were browsed. Saplings were categorized by size (small [\<0.5 m], medium [0.5-1.0 m] or tall [\>1.0 m]) and browsing intensity (low [\<33\%], moderate [33-66\%] or heavy [\>66\%] herbivory). Juniper bark was also collected from 12 saplings during spring. Leaves and bark were analyzed for terpenoids with gas chromatography-mass spectrometry. Terpene data were pooled across species and stocking rate and ANOVA was conducted for season, sapling size, and herbivory level. The volatile profile of one-seed juniper leaves and bark consisted of 65 and 55 compounds, respectively. Total estimated terpenoid concentrations in leaves and bark were 18.3 \± 0.3 and 8.9 \± 0.8 mg/g, respectively, and the dominant terpene in both tissues was \α-pinene (11.1 \± 0.2 and 7.6 \± 0.7 mg/g, respectively). Total terpenoid concentration was greater (P \< 0.001) in spring than summer (20.6 \± 0.5 vs. 16.7 \± 0.3 mg/g, respectively) and lower (P \< 0.001) in small saplings than medium or tall saplings (16.5 \± 0.6 vs. 19.8 \± 0.4 and 19.5 \± 0.4 mg/g, respectively). Total concentration also differed (P \< 0.001) among all 3 browsing categories (16.1 \± 0.4, 18.7 \± 0.5, and 21.2 \± 0.6 mg/g for heavy, moderate, and light herbivory, respectively). Approximately 42\% of the variation in browsing intensity could be explained (P \< 0.001) by 12 compounds ([E]-\β-farnesene, cis-sabinene hydrate, bornyl acetate, \γ-eudesmol, germacrene A, \γ-cadinene, \α-pinene, [Z]-\β-ocimene, terpin-4-ol, cispiperitol, cis-p-menth-2-en-1-ol, and camphene hydrate). Our results indicate that the terpene profile of one-seed juniper is related to sapling size, season, and degree of use by sheep and goats.

}, keywords = {goat, sheep, terpene}, author = {Richard E. Estell and S. A. Utsumi and Andr{\'e}s F. Cibils and D.M. Anderson} } @article {49847, title = {Within-plant distribution of volatile compounds on the leaf surface of Flourensia cernua}, journal = {Biochemical Systematics and Ecology}, volume = {48}, year = {2013}, month = {01/2013}, pages = {144-150}, chapter = {144}, abstract = {

We are using Flourensia cernua as a shrub model to study the role of terpenes on intake by livestock. Two experiments were conducted to examine distribution of volatile chemicals within a plant in an effort to minimize sample variability. In Exp. 1, leaves (current year\&$\#$39;s growth) were collected from 20 tarbush plants. Two leaders were sampled from each of three positions (outer canopy, subcanopy, and basal) in all four quadrants (based on ordinal direction). In Exp. 2, 10 leaders of current year\&$\#$39;s growth were removed from another 20 plants. Leaders were collected from the outer canopy of each quadrant and separated into thirds before removing leaves, thereby creating three leaf age categories. Volatile compounds were extracted with ethanol and analyzed with gas chromatography/mass spectrometry. Ninety-four chemicals (including 15 unknowns) were present on the leaf surface of F. cernua. Although 14 and 21 compounds differed (P \< 0.05) among quadrants in Exp. 1 and 2, respectively, no consistent quadrant effect was detected in either study. Leaf position differed (P \< 0.05) for 52 chemicals in Exp. 1 but outer canopy and subcanopy leaves differed for only 10 compounds. In Exp. 2, 63 compounds differed among leaf age categories. Immature leaves contained greater concentrations of 46 chemicals (P \< 0.05) than moderate or mature age categories, but moderate and mature leaves differed for only seven compounds. Estimated total concentration (i.e., cumulative concentration of all compounds) was not affected by leaf position but varied among leaf age categories (P \< 0.05; immature \> moderate \> mature). Differences in leaf position were attributed about equally to mono- and sesquiterpenes, whereas leaf age was affected to a greater extent by sesquiterpenes. Leaf position and maturity both affect terpene concentration and sampling variability for tarbush. However, little difference was detected between subcanopy and canopy positions. Thus, by avoiding basal sprouts and sampling from the mid-point of current year\&$\#$39;s growth, sampling variation should be minimal.

}, keywords = {Flourensia cernua, leaf age, plant secondary metabolites, terpenes, volatiles, within-plant distribution}, doi = {10.1016/j.bse.2012.11.020}, url = {/files/bibliography/13-002.pdf}, author = {Richard E. Estell and D. K. James and E.L. Fredrickson and D.M. Anderson} } @article {49882, title = {Increasing shrub use by livestock in a world with less grass}, journal = {Rangeland Ecology and Management}, volume = {65}, year = {2012}, month = {11/2012}, pages = {553-562}, chapter = {553}, abstract = {

Much of the world\&$\#$39;s rangelands are dominated by woody species. Competing land uses and continued encroachment of woody species into non-woody dominated rangelands have reduced grasslands in many parts of the world. Land use conversions to fuel and feed global populations, especially for increasing numbers of middle class people seeking broader, meat-based diets, will certainly continue. Halting and/or reversing further encroachment of woody species into grasslands is slow, expensive, and in some cases, not possible. Yet, global livestock numbers continue to increase to meet the growing demand for red meat and other livestock products. How do we reconcile a world with less grass and the concurrent increased demand for forages to feed livestock, either in extensive rangeland production systems or intensive confined feeding systems? Strategies and mechanisms are needed to safely enhance shrub use by ruminants in order to capitalize on a presently underutilized forage resource. Such strategies could provide important means for rural communities to adapt to changing land cover and climate.

}, keywords = {animal behavior, cattle, genetics, goats, plant secondary metabolites, sheep}, doi = {10.2111/REM-D-11-00124.1}, url = {/files/bibliography/12-031.pdf}, author = {Richard E. Estell and Kris Havstad and Andr{\'e}s F. Cibils and E.L. Fredrickson and D.M. Anderson and Scott T. Schrader and D. K. James} } @conference {49943, title = {Distribution of antiherbivory compounds in Flourensia cernua}, booktitle = {American Society of Animal Science Joint Annual Meeting}, year = {2011}, month = {07/2011}, publisher = {Journal of Animal Science}, organization = {Journal of Animal Science}, address = {New Orleans, LA}, abstract = {Flourensia cernua is serving as a shrub model to study the influence of terpenes on intake by livestock at this location. Two studies (n=20 plants per study) were conducted to examine within plant distribution of volatile compounds to improve sampling protocol. Leaves from 3 positions (outer canopy, subcanopy, and basal) were collected from 4 quadrants (based on ordinal direction) in Exp. 1. Leaves were removed from 2 leaders of current year\&$\#$39;s growth for each position in each quadrant. In Exp. 2, 10 leaders of current year\&$\#$39;s growth were collected from the outer canopy in each quadrant and 3 leaf age categories were formed by separating leaders into thirds and removing leaves. Chemicals were extracted from 5 leaves in duplicate with ethanol and analyzed with gas chromatography/mass spectrometry. Data were log transformed and analyzed by univariate ANOVA and means were separated using Tukey\&$\#$39;s HSD. Ninety-three volatile compounds (including 15 unknowns) were present on the leaf surface of F. cernua. Only 7 compounds (including 3 unknowns) in Exp. 1 and 9 in Exp. 2 differed (P\<0.05) among quadrants, and no consistent effect of quadrant was observed in either study. In Exp. 1, 31 compounds differed (P\<0.05) among leaf positions, but outer canopy and subcanopy leaves did not differ for any compound. Basal leaves contained greater concentrations than outer canopy and subcanopy leaves for 10 compounds, and less than the other 2 positions for 10 compounds. Thirty-two compounds differed for leaf age in Exp. 2, with immature leaves containing greater concentrations than mature leaves for 30 compounds and greater than the middle age category for 26 compounds (P\<0.05). Total concentration (cumulative concentration of all compounds) did not differ among leaf positions but differed for leaf age (greater in immature than mature leaves; P\<0.05). Compounds that differed in Exp. 1 were represented about equally by mono- and sesquiterpenes, whereas compounds affected by leaf age were predominantly sesquiterpenes (only 3 of 32 were monoterpenes). Both leaf position and age affect terpene concentrations and sampling variability in this shrub.}, keywords = {chemical distribution, leaf age, terpenes}, author = {Richard E. Estell and E.L. Fredrickson and D. K. James and D.M. Anderson} } @article {JRN52696, title = {Coping with shrub secondary metabolites by ruminants}, journal = {Small Ruminant Research}, volume = {94}, year = {2010}, month = {10/2010}, pages = {1-9}, chapter = {1}, abstract = {

Rangelands throughout the world contain varying but often substantial proportions of shrubs. Shrubs are generally heavily chemically defended, and herbivores must either contend with their plant secondary metabolites (PSM) or avoid a significaant component of the available forage. Browsing ruminants are exposed to thousands of chemicals in infinite combinations and concentrations that are constantly changing both temporally and spatially. The success with which a herbivore navigates this complex environment is in part attributed to its ability to cope with PSM. Plant secondary metabolites can affect a number of physiological and metabolic processes (e.g., altered microbial activity, reduced digestion, compromised acid/base balance, toxicity), although negative consequences to the herbivore range from harmless to lethal, depending factors such as dose, animal species, plane of nutrition, and physiological state. Herbivores have a variety of intertwined mechanisms to cope with consumption of PSM, ranging from physiological (e.g., salivary proteins, detoxification pathways) to behavioral (e.g., avoidance, regulation of intake below critical threshold, cautious sampling, altering size and pattern of feeding bouts, diet switching, consuming diverse and/or complementary diets). Secondary compounds may affect requirements for nutrients (e.g., protein, minerals, and glucose) and water, and may alter basal metabolic rate. Energy requirements may also increase to accommodate increased travel to water and supplementation sites to counter these negative effects, particularly on arid rangelands.

}, keywords = {foraging behavior, herbivory, intake, plant secondary metabolites, ruminants, secondary chemistry, shrubs}, doi = {10.1016/j.smallrumres.2010.09.012}, url = {/files/bibliography/10-033.pdf}, author = {Richard E. Estell} } @article {50026, title = {Measurement of monoterpenes and sesquiterpenes in serum, plasma, and rumen fluid from sheep}, journal = {Animal Feed Science and Technology}, volume = {158}, year = {2010}, pages = {104-109}, abstract = {Studies involving the consumption, metabolism, and elimination of terpenes by small ruminants consuming terpene-laden shrubs as well as those exploring the potential for natural products as rumen modifiers could benefit from a procedure that measures terpenes in both blood and rumen fluid and that is suitable for either serum or plasma. The objective of this study was to modify an existing procedure for plasma utilizing solid phase extraction/gas chromatography, and extend its use for measurement of structurally diverse mono- and sesquiterpenes in three fluids (serum, plasma, and rumen fluid) from sheep. Generally, terpene recovery was lower from rumen fluid than from serum or plasma, although the extent and direction of differences varied among chemicals. Fourteen terpenes (camphene, {\ss}-pinene, a-terpinene, p-cymene, cis-{\ss}-ocimene, 1,8-cineole, {\textquoteright}-terpinene, terpinolene, linalool, camphor, longifolene, {\ss}-caryophyllene, a-humulene, and caryophyllene oxide) were recovered from serum at approximately 100\%. Recovery from rumen fluid was lower than for serum or plasma for most terpenes, but eight terpenes (p-cymene, 1,8-cineole, cis-sabinene hydrate, terpinolene, borneol, terpin-4-ol, a-terpineol, and caryophyllene oxide) were recovered at near 100\%. Yet, 15 terpene recoveries were below 75\% (tricyclene, a-pinene, camphene, sabinene, {\ss}-pinene, myrcene, 2-carene, 3-carene, a-terpinene, cis-{\ss}-ocimene, limonene, {\textquoteright}-terpinene, longifolene, {\ss}-caryophyllene, and a-humulene). Oxygenated monoterpenes were typically recovered in greater quantities and hydrocarbon monoterpenes were least effectively recovered with this method. The procedure is suitable for measurement and recovery adjustment of terpenes from serum, plasma, and rumen fluid of sheep.}, keywords = {plasma, recovery, rumen fluid, ruminants, serum, sheep, shrub, terpene}, url = {/files/bibliography/10-04.pdf}, author = {Richard E. Estell and S. A. Utsumi and Andr{\'e}s F. Cibils} } @conference {50027, title = {Quantifying terpenes in rumen fluid, serum, and plasma from sheep}, booktitle = {Journal of Animal Science}, volume = {88}, year = {2010}, pages = {58}, abstract = {Determining the fate of terpenes consumed by browsing ruminants require methods to quantify their presence in blood and rumen fluid. Our objective was to modify an existing procedure for plasma terpenes to quantify 25 structurally diverse mono- and sesquiterpenes in serum, plasma, and rumen fluid from sheep. The terpenes examined were tricyclene, α-pinene, camphene, sabinene, β-pinene, myrcene, 2-carene, 3-carene, α-terpinene, p-cymene, limonene, 1,8-cineole, cis-β-ocimene, γ-terpinene, cis-sabinene hydrate, terpinolene, linalool, camphor, borneol, terpin-4-ol, α-terpineol, longifolene, β-caryophyllene, α-humulene, and caryophyllene oxide. Terpenes were extracted with SPE columns and quantified using gas chromatography (n = 8 per terpene/fluid combination). Data were analyzed with the MIXED procedure of SAS with fluid as the independent factor, and means were separated by LSD in the event of a significant F test (α = 0.05). Recovery estimates were 100{\textpm} 5\% for 14, 7, and 4 terpenes from serum, plasma, and rumen fluid, respectively. Recovery from plasma and serum differed for 12 terpenes (P < 0.05), although typically differences were <10\%. Recovery from rumen fluid differed (P < 0.05) from both serum and plasma for 16 compounds (lower in each case except linalool). Recovery did not differ (P > 0.05) among the 3 matrices for only 2 compounds (p-cymene and terpinolene). Greater recovery was generally observed for oxygenated terpenes than hydrocarbon compounds, particularly for monoterpenes. This procedure is applicable to a wide array of terpenes in fluids from sheep, but differential recoveries among terpenes and fluids require that estimated concentrations of each analyte be corrected for recovery using that specific compound in the same matrix collected under the same set of experimental conditions, and that caution be exercised in generalizing responses among different compounds with this procedure.}, keywords = {daily gain, mesquite, steers}, url = {/files/bibliography/10-011.pdf}, author = {Richard E. Estell and S. A. Utsumi and Andr{\'e}s F. Cibils} } @article {50204, title = {Effects of cis-beta-sabinene hydrate, and monoterpene adn sesquiterpene mixtures on alfalfa pellet intake by lambs}, journal = {Journal of Animal Science}, volume = {86}, year = {2008}, month = {June 2008}, pages = {1478-1484}, abstract = {

The transition of grasslands to shrub-dominated scrubland reduces livestock productivity and contributes to impoverished human conditions in arid and semiarid regions worldwide. Many shrubs increasing in dominance contain secondary compounds that deter herbivores. Knowledge concerning the effects of specific compounds on herbivore diets is limited but may provide useful insights into desertification. Flourensia cernua is a dominant shrub in the northern Chihuahuan Desert that contains an abundance of terpenes. Four experiments were conducted to determine the effects of individual terpenes (cis-\â-ocimene and cis-sabinene hydrate; Exp. 1 and 2) or mixtures of monoterpenes (borneol, camphene, camphor, 1,8-cineole, limonene, myrcene, and \á-pinene; Exp. 3) or sesquiterpenes (\â-caryophyllene, caryophyllene oxide, \á-copaene, and \á-humulene; Exp. 4) on intake of alfalfa pellets by lambs. Forty-five lambs (9 lambs/treatment) were individually fed treated alfalfa pellets for 20 min each morning for 5 days. Five treatments (0X, .5X, 1X, 2X, and 10X; multiples of the concentrations of the same terpenes in Flourensia cernua) were applied to alfalfa pellets (637 g, DM basis) in an ethanol carrier. Experiments were preceded by a 10-d adaptation period to untreated pellets. Except during the 20-min test, lambs were maintained outdoors and fed untreated alfalfa pellets (total mean intake = 4.7\% of BW, DM basis). Day \× treatment interactions were detected (P\< 0.04) in Exp. 1 and 4, due to greater intake for 0X than other treatments on day 1 (Exp. 1) and lower intake for the 10X treatment on day 1 and 2 (Exp. 4). A trend for decreased intake (g/kg BW) as concentration of the sesquiterpene mixture increased was observed in Exp. 3 (P = 0.093 for the linear contrast). Although there was a tendency for the sesquiterpene mixture to decrease intake, cis-\â-ocimene, cis-sabinene hydrate, and the monoterpene mixture did not appear to affect intake by lambs. Thus, sesquiterpenes may exert antiherbivory properties under certain conditions that may contribute to shrub dominance with extended periods of livestock foraging.

}, keywords = {alfalfa pellets, lambs, monoterpene, sesquiterpene}, doi = {10.2527/jas.2007-0699}, url = {/files/bibliography/08-009.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and M.D. Remmenga} } @article {50327, title = {Effects of Eugenol, Alpha-Terpineol, Terpin-4-ol, and methyl eugenol on consumption of alfalfa pellets by sheep}, journal = {Small Ruminant Research}, volume = {73}, year = {2007}, month = {Septembe 10, 200}, pages = {272-276}, abstract = {Many secondary compounds are typically present in unpalatable shrubs on rangelands in the western United States. However, the relationship between intake by livestock and concentration of individual chemicals has been examined for very few of these compounds. Four experiments were conducted to examine effects of individual volatile compounds on intake of alfalfa pellets by lambs. Forty-five lambs (9 lambs/treatment) were individually fed alfalfa pellets with eugenol, {\textquoteright}-terpineol, terpin-4-ol, or methyl eugenol applied at one of five concentrations in an ethanol carrier. Treatments were multiples (0, 0.5, 1, 2, and 10X) of the concentration (X) of each compound on the leaf surface of Flourensia cernua. Treatment solutions were sprayed on alfalfa pellets (0.64 kg.lamb-1.d-1, DM basis), and consumption was measured during a 20-min interval for five days. A day effect (P < 0.001 for both linear and quadratic contrasts) was detected for intake in all four experiments, but no day x treatment interactions were observed (P > 0.05). The day effect was generally due to lower intake on day 1, except for the methyl eugenol experiment, in which lambs consumed more pellets on day 1. No treatment effects were observed (P > 0.05) for any of the four chemicals tested; thus, eugenol, {\textquoteright}-terpineol, terpin-4-ol, and methyl eugenol were not related to intake of alfalfa pellets by lambs under the conditions of this study.}, keywords = {diet selection, Herviory, intake, sheep, terpenes}, url = {/files/bibliography/07-026.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and M.D. Remmenga} } @conference {50326, title = {Effects of individual terpenes and terpene mistures on intake of lambs}, booktitle = {American Society of Animal Science}, volume = {85}, number = {Suppl. 1}, year = {2007}, month = {July 9, 2007}, pages = {287-288}, abstract = {Rangeland degradation due to shrub encroachment is a major concern to livestock producers and land managers in the western United States and in arid and semiarid regions worldwide. Most invasive shrubs contain secondary compounds that reduce their consumption by herbivores, but knowledge concerning the effects of specific compounds is limited. Four experiments were conducted to determine the effects of individual terpenes or mixtures of monoterpenes or sesquiterpenes on intake by lambs. After a 10-day adaptation period with untreated alfalfa pellets, lambs were individually fed treated alfalfa pellets for 20 min. each morning for 5 days. Five treatments (0X, .5X, 1X, 2X, and 10X; multiples of the concentrations of the same terpenes in Flourensia cernua) were applied to alfalfa pellets (637 g, DM basis) in an ethanol carrier. Except during the 20-m,in test, lambs were maintained outdoors and fed untreated alfalfa pellets (total mean intake = 4.7\%) in Exp. 1 and 4 because of greater intake of OX than other treatments on day 1 and lower intake for the 10XZ treatment on day 1 and 2. A trend for decreased intake (g/kg BW) as concentration of the sesquiterpene mixture increased was observed. Although there was a tendency for a sesquiterpene mixture to decrease intake, and the monoterpene mixture did not appear to affect intake by lambs.}, keywords = {alfalfa, alfalfa pellet, intake, lambs, shrubs, terpene}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and M.D. Remmenga} } @conference {50438, title = {Antiherbivory Compounds on the Leaf Surface of Intact and Resprouted Tarbush}, booktitle = {2006 Joint Annual Meeting, American Society of Animal Science, American Dairy Science Association}, volume = {J. Animal Sci. Vol. 84, J. Dairy Sci. Vol. 89}, number = {1}, year = {2006}, month = {July 9-13, 2006}, pages = {22}, address = {Minneapolis, Minnesota}, abstract = {Shrub encroachment into desert grasslands of the southwestern United States is a serious problem, resulting in loss of forage and rangeland productivity. Flourensia cernua (tarbush) is one such shrub contributing to the decline of Chihuahuan Desert grasslands. Our previous research has shown tarbush consumption by sheep and goats to be negatively related to leaf surface concentration of individual terpenes and epicuticular wax. Concentrations of antiherbivory compounds such as terpenes change with plant age and phenology. Our objective was to alter the vegetative state and potential palatability of tarbush by clipping intact plants and generating resprouts. We hypothesized resprouts would invest fewer resources into antiherbivory compounds and therefore have lower concentrations of volatile chemicals such as terpenes than intact plants. Ninety tarbush plants were randomly selected, and all biomass within 10 cm of the soil surface was removed from 45 plants during winter dormancy. Leaves were collected the following summer during active growth from the canopy of intact controls and resprouts. Leaf surface volatiles were extracted in ethanol and analyzed by gas chromatography-mass spectroscopy to determine their identity and concentration. Data were transformed to natural logarithms and subjected to univariate analysis of variance and stepwise discriminate analysis. Of the 87 compounds present on tarbush leaves, 35 were greater in canopy samples and 16 were greater in regrowth samples based on univariate analysis (P < 0.05). Mean concentration of total volatiles on canopy leaves tended to be less (P = 0.0622) than that of regrowth (3642 vs 4684 {\textquoteright}g/g DM). Nine compounds in the discriminate analysis explained 95\% of the variation between canopy and regrowth samples. In contrast to our hypothesis, lower cumulative concentration of volatile compounds in canopy than regrowth samples suggests repsrouts may be less vulnerable to herbivory than old growth tarbush. However, animal studies are needed and effects on other classes of secondary compounds must be examined.}, keywords = {regrowth, shrub, terpene}, author = {Richard E. Estell and E.L. Fredrickson and M.D. Remmenga} } @article {50439, title = {Introduction to special issue - Landscape linkages and cross scale interactions in arid and semiarid ecosystems}, journal = {Journal of Arid Environments}, volume = {65}, year = {2006}, month = {April 2006}, pages = {193-195}, abstract = {The conversion of grasslands to shrublands in arid and semiarid ecosystems is a serious global problem. Although a great deal of research has been conducted on these conversions, we lack a complete understanding of the processes underlying the transitions. More importantly, our ability to predict when and where desertification will occur and our ability to manage landscapes to prevent degradation and restore degraded landscapes is limited. Research being conducted at the Jornada Experimental Range (JER) is addressing these problems in a new, synthetic way. Since 1981, scientists affiliated with the Jornada Basin Long-Term Ecological Research site in collaboration with scientists from the JER and New Mexico State University generated a number of new ideas and concepts regarding the processes governing desertification that changed our thinking about how these systems operate. Our focus now emphasizes cross-scale spatial and temporal heterogeneity in vegetation patterns and dynamics that have been difficult to explain using traditional approaches. The realization that our current knowledge often cannot explain the existing variability among land units led to the development of a conceptual model by JER scientists that considers nonlinear dynamics and connections among land units across scales. This cross-scale landscape ecology approach will further our understanding of critical processes occurring in arid regions globally and will provide insight to help identify mechanisms to address the pressing issue of desertification.}, keywords = {arid, cross scale, desertification, ecosystems, invasion, landscape, linkages, semiarid, shrub}, doi = {10.1016/j.jaridenv.2005.04.001}, url = {/files/bibliography/06-006.pdf}, author = {Richard E. Estell and E.L. Fredrickson and Debra C. Peters} } @article {50440, title = {Plant-Animal Interactions}, volume = {10}, number = {1}, year = {2006}, month = {April 10, 2006}, pages = {3}, publisher = {Jornada Basin Long-Term Ecological Research Program}, address = {Las Cruces, NM}, abstract = {Shrub invasion into desert grasslands is an ongoing concern for ecologists and land managers. These shrubs typically contain chemicals that make them unpalatable for livestock and wildlife. Tarbush is a shrub that has invaded productive soils in the northern Chihuahuan Desert. For several years, we have been using tarbush as a model invasive shrub to explore the chemicals involved in plant-animal interactions. From a chemical standpoint, not all tarbush are alike. Sheep and goats select some tarbush plants and avoid others based on the concentration of volatile chemicals on the leaves. When we removed these chemicals using organic solvents, lambs ate more tarbush. Furthermore, when we removed these chemicals from tarbush and added them to a palatable food, animals ate less. We are now examining effects of individual compounds to determine if specific chemicals are critical drivers of diet selection. To date, we have tested effects of 23 volatile chemicals (primarily terpenoids) on intake by lambs, and two more compounds are currently being examined. Only four chemicals (camphor, alpha-pinene, camphene, and caryophyllene oxide) reduced the amount of food eaten. By learning which specific compounds drive diet selection, we hope to ultimately be able to manipulate browsing behavior of livestock and other herbivores.}, keywords = {jornada trails, plant-animal interactions}, url = {jornadalter/site/pubs/newsletr/jornv10i1.pdf}, author = {Richard E. Estell} } @article {50544, title = {Effect of previous exposure of sheep to monoterpene odors on intake of alfalfa pellets treated with camphor or alpha-pinene}, journal = {Small Ruminant Research}, volume = {58}, year = {2005}, note = {This is not a duplicate; ARIS No. 151564 has same title but is an abstract submitted for a meeting. }, month = {April 1, 2005}, pages = {33-38}, abstract = {Lambs were subjected to odors of two monoterpenes (camphor and alpha-pinene) that decreased intake in a previous study to determine if exposure during feeding modified their effects on subsequent intake. Two experiments were conducted using a split-plot design and with 36 ewe lambs (mean BW = 23.1 and 42.2 kg in Exp. 1 and 2, respectively) group-fed alfalfa pellets (3.8\% of BW, DM basis) in enclosed portable buildings for 2 h each morning for 56 d. Nine lambs were randomly assigned to each of four buildings, and 25 g of camphor (Exp. 1) or 50 ml of alpha-pinene (Exp. 2) were placed in a mesh-covered container in the center of the feeder in two buildings immediately before feeding. After the 8-wk exposure period (phase 1), lambs were individually fed alfalfa pellets (640 g, DM basis) for 20 min each morning for 10 d (5-d adaptation, 5-d collection) in a metabolism building (phase 2). Treatments were sprayed on alfalfa pellets at levels representing the concentration of that chemical in Flourensia cernua or at 10-fold that concentration. Controls received the ethanol carrier only. During phase 2, lambs were fed in three groups (n = 12), stratified such that one lamb from each building received each treatment in each group. Lambs were housed as one group and fed alfalfa pellets at 4.7\% of BW (DM basis) except during the 20-min tests. No interactions with day were detected for intake during adaptation or collection periods for either chemical (P > 0.05); therefore, data were pooled across day. Exposure to the volatile aroma for 8 wk had no effect on intake during the subsequent 10-d interval for either monoterpene (P > 0.05). Moreover, intake during the collection period was not affected by treatment concentration (P > 0.05). Neither concentration of the terpene applied to alfalfa pellets nor previous exposure to the volatile aroma from camphor or alpha-pinene altered feed intake under the conditions of this study.}, keywords = {herbivory, intake, monoterpenes, olfaction, sheep}, url = {/files/bibliography/05-022.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @conference {50545, title = {Effects of eugenol, terpin-4-ol, alpha-terpineol, and methyl eugenol on consumption of alfalfa pellets by sheep}, booktitle = {2005 Annual Meeting of American Society of Animal Science}, volume = {83 (Suppl. 1)}, year = {2005}, month = {July 24, 2005}, pages = {274}, address = {Cincinnati, OH}, abstract = {Secondary compounds present in shrubs on rangelands in the western United States are often aversive to livestock. However, effects of many of these compounds on intake have not been individually tested. Four experiments were conducted to examine effects of individual terpenes on alfalfa pellet intake by lambs. Forty-five lambs (9 lambs/treatment) were individually fed alfalfa pellets sprayed with either eugenol, terpin-4-ol, alpha-terpineol, or methyl eugenol at one of five concentrations in an ethanol carrier. Treatments (0, 0.5, 1, 2, and 10X) were multiples of the concentration (X) of a specific terpene on the leaf surface of Flourensia cernua. Terpenes were applied to alfalfa pellets (0.64 kg.lamb1.d1, DM basis), and consumption was measured during a 20min interval for 5 d. Lambs were adapted to handling and individual pen feeding for 10 d and were maintained and fed alfalfa pellets in one group (except during 20 min tests) at a mean total daily intake of 3.9\% of BW (DM basis). A day effect (P< 0.0001) was detected for intake in all four experiments, but no day x treatment interactions were observed (P> 0.05). The day effect was generally due to lower intake of alfalfa pellets on day 1, except for the methyl eugenol experiment, in which lambs consumed more pellets on day 1. No treatment effects were observed (P> 0.05) for any of the four chemicals tested; thus, none of these chemicals were strongly related to intake of alfalfa pellets by lambs under the conditions of this study.}, keywords = {herbivory, intake, terpene}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and M.D. Remmenga} } @article {50547, title = {Effects of gamma-terpinene, terpinolene, alpha-copaene, and alpha-terpinene on consumption of alfalfa pellets by sheep}, journal = {Journal of Animal Science}, volume = {83}, year = {2005}, month = {August 15, 2005}, pages = {1967-1971}, abstract = {Although plant secondary chemistry influences shrub consumption by free-ranging ruminants, the effects of many specific compounds on herbivory have not been examined. We conducted four experiments to examine effects of individual terpenes on alfalfa pellet intake by lambs. Forty-five lambs (9 lambs/treatment) were individually fed alfalfa pellets sprayed with either gamma-terpinene, terpinolene, alpha-copaene, or alpha-terpinene at one of five concentrations in an ethanol carrier. Treatments (0, 0.5, 1, 2, and 10X) were multiples of the concentration (X) of a specific terpene on the leaf surface of Flourensia cernua. Terpenes were applied to alfalfa pellets (0.64 kg.lamb-1.d-1, DM basis), and consumption was measured during a 20-min interval for 5 d. A day effect (P \< 0.02) was detected for gamma-terpinene on intake (P \< 0.0001 for both linear and quadratic contrasts). A treatment effect (P \< 0.02) was observed for alpha-copaene with intake on the 2X treatment lower than other treatments. No effect of terpinolene or alpha-terpinene on intake was detected in this study. None of the chemicals tested were strongly related to intake of alfalfa pellets by lambs under the conditions of this study. http://jas.fass.org/cgi/reprint/83/8/1967}, keywords = {diet selection, herbivory, intake, sheep, terpenes}, url = {/files/bibliography/05-013.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and M.D. Remmenga} } @proceedings {50546, title = {Livestock Research on the Jornada Experimental Range}, year = {2005}, month = {April 7-8, 2005}, pages = {100-102}, publisher = {NMSU College of Agriculture and Home Economics}, address = {Alamogordo, NM}, abstract = {The role of phytochemistry in diet selection by livestock on arid rangelands is being examined at the Jornada Experimental Range (JER) because shrub encroachment into arid and semiarid rangelands is a serious problem for livestock producers. Palatability of these shrubs is often low due to high concentrations of secondary chemicals. Our previous research has shown that crude extracts of tarbush (Flourensia cernua) applied to alfalfa pellets dramatically decreased intake by lambs. However, little is known about how specific compounds affect herbivory. Only 4 of the 19 terpenes we have examined reduced intake when tested individually (camphor, alpha-pinene, caryophyllene oxide, and camphene). Secondly, we are examining ways to control livestock in large pastures with fewer fences. Directional Virtual Fencing (DVF{\texttrademark}) is being tested as a mechanism to contain livestock and improve grazing distribution. This system uses ramped sound and electric shock administered on either side of an animal to keep it within a Virtual Paddock (VP{\texttrademark}) using minimum stress. With GPS data obtained from animals, we determined that cattle and sheep bonded to cattle (i.e., a flerd) could be controlled using DVF{\texttrademark}. A third study examines grazing behaviors of Mexican criollo cattle. Criollo cattle have coevolved with the arid and semiarid regions of North America for approximately 450 years and may have adaptations to arid environments that may be useful for livestock producers. We imported cattle from the Chinipas region of Chihuahua to the JER and compared distance traveled by these animals to Angus x Hereford cattle in a 3000-acre pasture with good forage conditions. Chinipas cattle traveled 7.9 {\textpm} 0.7 miles per day and covered a larger area of the pasture than Angus x Hereford cattle, which traveled 6.0 {\textpm} .4 miles. These data support observations that criollo cattle travel further and use steeper slopes than British or Continental breeds.}, keywords = {history, JER, Jornada Experimental Range, remediation}, url = {/files/bibliography/05-052Proc.pdf}, author = {Richard E. Estell and D.M. Anderson and E.L. Fredrickson} } @conference {50649, title = {Effects of {\~a}-terpinene, terpinolene, {\'a}-copaene, and {\'a}-terpinene on consumption of alfalfa pellets by sheep}, booktitle = {2004 Joint Annual Meeting, American Dairy Science Association/American Society of Animal Science/Poultry Science Association}, volume = {Vol. 82 (Suppl. 1)}, year = {2004}, month = {July 25, 2004}, pages = {34}, publisher = {Journal of Animal Science}, organization = {Journal of Animal Science}, address = {St. Louis, MO}, abstract = {Secondary chemistry influences shrub consumption by free-ranging ruminants. However, effects of many specific terpenes on herbivory have not been examined. Four experiments were conducted to examine effects of individual terpenes on alfalfa pellet intake by lambs. Forty-five lambs (9 lambs/treatment) were individually fed alfalfa pellets sprayed with either {\~a}-terpinene, terpinolene, {\'a}-copaene, or {\'a}-terpinene at one of five concentrations in an ethanol carrier. Treatments (0, .5, 1, 2, and 10X) were multiples of the concentration (X) of a specific terpene on the leaf surface of Flourensia cernua. Terpenes were applied to alfalfa pellets (0.64 kg{\textperiodcentered}lamb-1{\textperiodcentered}d-1, DM basis), and consumption was measured during a 20-min interval for 5 d. Lambs were adapted to handling and individual pen feeding for 10 d and were maintained and fed alfalfa pellets in one group (except during 20-min tests) at a mean total daily intake of 3.9\% of BW (DM basis). A day effect (P <0.02) was detected for intake with {\~a}-terpinene (P <0.0001 for both linear and quadratic contrasts). A treatment effect (P <0.02) was observed for {\'a}-copaene, with intake on the 2X treatment lower than other treatments. No effect of terpinolene or {\'a}-terpinene on intake was observed during the 20-min interval. None of the chemicals tested were strongly related to intake of alfalfa pellets by lambs under the conditions of this study.}, keywords = {alfalfa pellet intake, intake, lambs, sheep, terpenes}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @conference {50768, title = {Effect of previous exposure of sheep to monoterpene odors on intake of alfalfa pellets treated with camphor or alpha-pinene}, booktitle = {Joint Annual Meeting of the American Dairy Science Association, the American Society of Animal Science, and the Mexican Association of Animal Production}, volume = {81}, number = {Suppl. 1}, year = {2003}, month = {June 22-26, 2003}, pages = {353}, address = {Phoenix, AZ}, abstract = {Lambs were exposed to aromas of two monoterpenes that had previously been found to decrease intake to determine if exposure during feeding modified effects of these terpenes on subsequent intake. Two experiments were conducted using a split-plot design. Thirty-six ewe lambs (mean BW = 23.1 and 42.2 kg in Exp. 1 and 2, respectively) were group-fed alfalfa pellets (4\% of BW, DM basis) in enclosed portable buildings (3.0 x 3.7 m) for 2 h each morning for 56 d. Nine lambs were randomly assigned to each of four buildings, and the appropriate chemical (25 g of camphor in Exp. 1 or 50 ml of alpha-pinene in Exp. 2) was placed in a mesh-covered container in the center of the feeder in two buildings immediately before feeding (two buildings served as controls). After the 8-wk exposure period, lambs were individually fed alfalfa pellets (640 g, DM basis) for 20 min each morning for 10 d (5-d adaptation, 5-d intake measurement) in a metabolism building. Treatments were sprayed on alfalfa pellets at levels representing the concentration of that chemical in Flourensia cernua or at 10-fold that concentration. Controls received ethanol carrier only. Lambs were fed in three groups (n = 12), stratified such that one lamb from each building was placed on each treatment in each group. Lambs were housed as one group and fed alfalfa pellets at 5\% of BW (DM basis) except during the 20-min tests. No day effect was detected for intake with either chemical (P> 0.05); therefore, data for collection periods were pooled across day. Exposure to the volatile aroma for 8 wk had no effect on intake during the 10-d interval for either monoterpene (P> 0.05). Moreover, intake during the 10-d interval was not affected by treatment concentration (P> 0.05). Neither concentration of the terpene applied to feed nor previous exposure to the volatile aroma from camphor or alpha-pinene altered feed intake under the conditions of this study.}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @proceedings {50767, title = {Rangeland research on the Jornada Experimental Range}, year = {2003}, month = {March 27-28, 200}, pages = {87-91}, address = {Farmington, NM}, abstract = {The mission of the Jornada Experimental Range is to develop new technologies for the management and remediation of desert rangelands. A few studies in progress that relate directly to this mission are summarized below. One major focus is to develop methodologies for controlling livestock distribution on rangelands. A study is in progress to evaluate the potential of virtual fencing as an alternative to conventional fencing for real-time control of animal movement. A small solar-powered unit worn by the animal uses signals from GPS satellites to determine animal location and a GIS database to define a virtual boundary. When an animal penetrates this boundary, a cue is applied to encourage the animal to move away from the virtual boundary. Preliminary data indicate this low-stress technology can be used to control animal movement. Protein supplementation during conditions of low quality forage is another practice that may be used to control animal movement. Preliminary data indicate that protein supplementation affects beef cow distribution patterns with non-supplemented animals exhibiting greater dispersal and supplemented cows remaining near supplementation areas. These studies have implications for improving forage utilization and livestock management, as well as excluding livestock from ecologically sensitive areas. A third study in progress involves quantification of carbon storage in plants and soils on arid rangelands. This research combines direct field measurement of CO2 fluxes, soil carbon analysis, and modeling. The project will examine how carbon storage might change naturally over time or be influenced by management practices. Initial results suggest rangelands may serve as a significant long-term repository for carbon when shrubs store large amounts of carbon belowground in their extensive woody root systems. Also, aerial photography is being examined as a tool to reconstruct the remediation treatment history of rangelands. Many treatments have been implemented during the last 100 years in an effort to slow shrub invasion, but over time, land management agencies have been disbanded or reorganized and paper records have been lost, resulting in poor documentation of type and extent of treatment, methods used, and evaluations of success. Nationwide aerial photography begun by USDA and other agencies as early as 1930 is a valuable source of information for establishing past management histories and vegetation response to treatments on rangelands. Treatments imposed on the Jornada during early research projects (e.g., root plowing during the 1970{\textquoteright}s, ponding dikes constructed in 1975, and manual shrub removal in 1936) are still evident in aerial photographs today. Combining aerial photography and remaining conventional records with present day field measurements greatly increases the total information available regarding the management history and most effective remediation approaches for use today.}, keywords = {cattle growers, course, livestock, rangeland, research, research notes}, url = {/files/bibliography/03-003.pdf}, author = {Richard E. Estell and D.M. Anderson and E.L. Fredrickson and Kris Havstad and K. A. Mitchell and A. Rango} } @conference {50857, title = {Effects of camphene, myrcene, caryophyllene oxide and beta-pinene on consumption of alfalfa pellets by sheep}, booktitle = {2002 Joint Meeting, American Society of Animal Science/American Dairy Science Association}, volume = {80}, number = {1}, year = {2002}, month = {July 21-25, 2002}, pages = {331}, address = {Quebec City, Canada}, abstract = {Four experiments were conducted to examine effects of individual terpenes on alfalfa pellet intake by lambs. Forty-five lambs (nine lambs/treatment) were individually fed alfalfa pellets sprayed with either camphene, myrcene, caryophyllene oxide, or beta-pinene at one of five concentrations in an ethanol carrier. Treatments (0, .5, 1, 2, and 10X) were multiples of the concentration (X) of a specific terpene on the leaf surface of Flourensia cernua. Terpenes were applied to alfalfa pellets (.64 kg.lamb-1.d-1, DM basis) and consumption was measured during a 20-minute interval for 5 d. Lambs were adapted to handling and individual pen feeding for 10 d and were maintained and fed alfalfa pellets in one group (except during 20-minute tests) at a mean total daily intake of 4.7\% of BW (DM basis). Camphene and caryophyllene oxide tended to decrease intake (linear contrasts were P = .0651 and P = .0504, respectively), while myrcene and beta-pinene exerted no effect on consumption of alfalfa pellets by lambs during the 20-minute interval. Camphene and caryophyllene oxide may be involved in the differential herbivory of individual tarbush plants by livestock.}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @article {50859, title = {Effects of four mono- and sesquiterpenes on consumption of alfalfa pellets by sheep}, journal = {Journal of Animal Science}, volume = {80}, number = {12}, year = {2002}, month = {December 1, 2002}, pages = {3301-3306}, abstract = {Effects of individual terpenes on alfalfa pellet intake by lambs were examined in four experiments. Forty-five lambs (9 lambs/treatment) were individually fed alfalfa pellets sprayed with either camphene, myrcene, caryophyllene oxide, or beta-pinene at one of five concentrations (one terpene per experiment). Treatments (0, .5, 1, 2, and 10X) were multiples of the concentration (X) of a specific terpene in tarbush. Terpenes were applied to alfalfa pellets (.64 kg.lamb-1.d-1, DM basis) and consumption wa measured during a 20-min interval for 5 d. Lambs were maintained and fed alfalfa pellets in one group (except during 20-min tests) at a mean total daily intake of 4.7\% of BW (DM basis). Camphene and caryophyllene oxide tended to decrease intake (linear contrasts were P = .0651 and P = .0504, respectively), while myrcene and beta-pinene exerted no effect on consumption of alfalfa pellets by lambs during the 20-min interval. Camphene and caryophyllene oxide may be involved in the differential herbivory of individual tarbush plants by livestock.}, keywords = {alfalfa pellets, consumption, individual terpenes, sheep}, doi = {10.2527/2002.80123301x}, url = {http://jas.fass.org/cgi/reprint/80/12/3301}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @conference {50858, title = {Effects of individual terpenes on intake by lambs}, booktitle = {Society for Range Management, New Mexico Section Winter Meeting}, year = {2002}, month = {January 8-10, 20}, pages = {5}, address = {Las Cruces, NM}, abstract = {Effects of individual terpenes on alfalfa pellet intake by lambs were examined. Forty-five lambs were individually fed alfalfa pellets treated with either camphene, myrcene, caryophyllene oxide, or beta-pinene at one of five concentrations. Treatments (0, .5, 1, 2, and 10X) were multiples of the concentration (X) of a specific terpene on Flourensia cernua leaves. Terpenes were applied to alfalfa pellets (.64 kg DM/lamb) and intake during a 20-minute interval was measured for 5 days. Lambs were adapted to handling and individual pen feeding for 10 d and were group-fed alfalfa pellets (4.7\% of BW). Camphene and caryophyllene oxide tended to decrease intake (linear contrasts were P = .0651 and P = .0504, respectively), while myrcene and beta-pinene had no effect on alfalfa pellet consumption during the 20-minute interval. Camphene and caryophyllene oxide may be involved in the differential herbivory of individual tarbush plants by livestock.}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @article {50985, title = {Extracts of Flourensia cernua reduce consumption of alfalfa pellets by sheep}, journal = {Journal of Chemical Ecology}, volume = {27}, number = {11}, year = {2001}, month = {November 1, 2001}, pages = {2275-2285}, abstract = {

Effects of three extracts (hexanes, ether and ethanol) from tarbush on intake of alfalfa pellets by lambs were examined in 2 experiments. Forty-five ewe lambs were fed 1 of 5 treatments for 5 days. Treatments were alfalfa pellets (CON) or alfalfa pellets plus ethanol carrier (CAR), hexanes extract (HEX), ether extract (ETH), or ethanol extract (ETOH). Extracts were applied to alfalfa pellets at the same concentration as in an equivalent amount of tarbush in experiment 1 and at 10-fold dilutions of that concentration in experiment 2. Treatments were isolated from 36 kg of tarbush leaves using a sequential extraction with hexanes, diethyl ether and 100\% ethanol. Extracts were obtained in batches (3 kg of leaves in 7 liters of solvent) with constant mixing (22 hr per solvent), filtered, solvents removed using a rotary evaporator and residue resuspended in ethanol. Lambs received 640 g of alfalfa pellets each morning and intake was monitored during a 20-min interval. In experiment 1, mean intake by lambs during the 20-min interval was 361, 393, 204, 212 and 228 g for CON, CAR, HEX, ETH and ETOH, respectively (SEM = 28.9). All 3 extracts decreased intake (P \< .0001) compared to CON or CAR. Intake did not differ among the 3 extracts (HEX, ETH and ETOH) nor between the 2 controls (CON and CAR). Mean intake did not differ among treatments in experiment 2 (468, 455, 389, 381 and 431 g for CON, CAR, HEX, ETH and ETOH, respectively; SEM = 30.5; P = .187). Because all 3 extracts decreased intake of alfalfa pellets at concentrations normally encountered in intact plants, several compounds are probably responsible for the low palatability and differential use of tarbush typically exhibited by livestock.

}, keywords = {alfalfa pellets, consumption, fluorensia cernua extracts, sheep}, doi = {10.1023/A:1012235121852}, url = {/files/bibliography/01-021.pdf}, author = {Richard E. Estell and M.R. Tellez and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @article {51068, title = {Effect of individual terpenes on consumption of alfalfa pellets by sheep}, journal = {Journal of Animal Science}, volume = {78}, number = {6}, year = {2000}, month = {June 1, 2000}, pages = {1636-1640}, abstract = {

We examined effects of five individual terpenes on alfalfa pellet intake of lambs. In each experiment, 45 lambs were individually fed alfalfa pellets sprayed with either p-cymene, alpha-humulene, 1,8-cineole, 3-carene, or sabinene at one of five concentrations. Treatment levels (0, .5, 1, 2, and 10X) were multiples of the concentrations (X) of specific terpenes in tarbush that were related to differential herbivory by livestock in previous studies. Treatments were applied to alfalfa pellets (.64 kg/lamb/d, DM basis), and consumption during a 20-min interval was measured for 5 d. Lambs were adapted to handling and pen feeding for 10 d, and were maintained and fed alfalfa pellets in one group (except during 20-min tests) at a mean total daily intake of 4.7\% of BW (DM basis). None of the five compounds examined decreased pellet consumption during the 20-min interval. These five mono- and sesquiterpenes do not appear to be responsible for differential herbivory of individual tarbush plants by livestock.

}, keywords = {alfalfa pellets, herbivory, individual terpenes, lambs, sheep}, url = {/files/bibliography/00-008.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @conference {51067, title = {Fluorensia cernua extracts decrease intake of alfalfa pellets by sheep}, booktitle = {2000 Joint Meeting, American Society of Animal Science/American Dairy Science Association}, volume = {78}, number = {Suppl. 1}, year = {2000}, month = {2000}, pages = {113}, publisher = {Journal of Animal Science}, organization = {Journal of Animal Science}, abstract = {

Our objective was to evaluate the effects of 3 extracts (hexane, ether and ethanol) isolated from tarbush on intake of alfalfa pellets by sheep. In each of 2 experiments, 45 ewe lambs received 1 of 5 treatments for 5 d. Treatments were alfalfa pellets (CON) or alfalfa pellets plus ethanol carrier (CAR), hexane extract (HEX), ether extract (ETH) or ethanol extract t(ETOH). Treatments were isolated from tarbush leaves (36 kg) using a sequential extraction of hexane, diethyl ether and 100\% ethanol. Extractions (3 kg of leaves in 7 L of solvent, constant mixing, 22 h per solvent) were filtered, solvents removed using a rotary evaporator and resuspended in ethanol. Lambs were offered 640 g of alfalfa pellets (DM basis) and intake was monitored during a 20-min interval each morning. Extracts were applied to alfalfa pellets at the same concentration as in tarbush in Exp. 1, and at 10-fold dilutions in Exp. 2. Lambs were adapted to handling and individual pen feeding for 10 d and maintained and fed alfalfa pellets (4.7\% of BW, DM basis) as one group except during 20-min tests. All 3 extracts reduced intake by lambs in Exp. 1 ( P \< .0001) compared to CON or CAR. Mean intake during the 20-min period was 361, 393, 204, 212 and 228 g for CON, CAR, HEX, ETH and ETOH, respectively (SEM=28.9). Intake did not differ between CON and CAR, nor among HEX, ETH and ETOH. Mean intake in Exp. 2 was not different (468, 455, 389, 381 and 431 g for CON, CAR, HEX, ETH and ETOH, respectively; SEM =30.5; P =.187). Three fractions containing mixtures of compounds of increasing polarity were equally effective in decreasing intake of alfalfa pellets at concentrations encountered in intact tarbush plants; thus, several compounds are probably involved in the low palatability of this shrub exhibited by livestock.

}, keywords = {alfalfa pellets, extracts, Fluorensia cernua, intake, sheep, tarbush, treatments}, author = {Richard E. Estell and M.R. Tellez and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @proceedings {51066, title = {Rangeland research in the Chihuahuan Desert}, year = {2000}, month = {03/2000}, pages = {80-81}, abstract = {

The mission of the Jornada Experimental Range is to develop new technologies for the management and remediation of desert rangelands. We are developing a manual for monitoring rangeland health. Several indicators have been examined and a number of these indicators have proven useful for monitoring purposes, e.g., size of unvegetated patch, perennial grass cover rand soil surface stability. We have worked with individual ranchers in New Mexico to test these methods and have established pilot projects on state lands to demonstrate their application to management. We are also studying prescribed burning of arid rangeland as a tool to improve degraded rangelands. The fire treatment was applied to study sites in 1999 and initial responses to fire and grazing effects will be measured in 2000. We will evaluate effects of fire on ecological processes and post-fire grazing and identify post-fire guidelines for recovery of key species in grazed Chihuahuan Desert grassland. One of our major research objectives is to develop new technologies for controlling distribution of livestock grazing rangelands. Few options presently exist for monitoring animal location and controlling animal movement to a specific area at a particular time. A method and apparatus have been developed that may allow for management of grazing livestock without ground-based fencing. The device worn by an animal incorporates a global positioning system and a geographic information system database to determine and control individual animal movements. We are field testing the ability of a third generation prototype to contain an animal in an area using bilaterally applied sensory cues. This technology could allow producers to reduce management costs, improve utilization of forage and protect ecologically sensitive areas.

}, keywords = {cattle growers, Chihuahuan Desert, livestock, rangeland research, research notes}, url = {/files/bibliography/562.pdf}, author = {Richard E. Estell and D.M. Anderson and J.R. Barrow and E.L. Fredrickson and Kris Havstad and Jeffrey E. Herrick and Debra C. Peters} } @conference {51139, title = {Effects of terpenes on intake of alfalfa pellets by sheep}, booktitle = {91st National Meeting of the American Society of Animal Science}, volume = {77(1)}, year = {1999}, month = {July 21-23, 1999}, pages = {207}, address = {Indianapolis, IN}, abstract = {Five experiments were conducted to examine influences of terpenes on intake of alfalfa pellets by sheep. Five mono- and sesquiterpenes that were related to tarbush (Flourensia cernua) consumption by livestock in previous studies using multivariate analysis were examined individually. Average concentrations of selected compounds (C) were 5, 25, 50, 100, and 10 micro g/g of tarbush DM for para-cymene, alpha-humulene, 1,8-cineole, 3-carene, and sabinene, respectively. During each experiment, 45 individually penned lambs received one of five treatments (multiples of C: 0X, .5X, 1X, 2X, or 10X) for five consecutive days. Treatments were applied to alfalfa pellets (.64 kg, DM basis) and intake was monitored during a 20 min interval each morning. Lambs were adapted to handling and individual pen feeding for 10 d before experiments began and were maintained and fed alfalfa pellets (4.7\% of BW, DM basis) as one group except during 20 min tests. No linear or quadratic responses of intake to treatment level were detected (P > .05 for any of the five compounds. These five terpenes had little influence on consumption of alfalfa pellets, suggesting these compounds are not responsible for differential herbivory of individual tarbush plants by livestock.}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @proceedings {51140, title = {Rangeland research in the Chihuahuan Desert}, year = {1999}, month = {1999}, pages = {71-76}, abstract = {The mission of the Jornada Experimental Range is to develop new technologies for the management and remediation of desert rangelands. Effects of stressors such as drought, soil nutrient depletion and shrub competition on grassland/shrubland ecosystems are being examined. A study is in progress to examine responses of desert ecosystems to fire and the influence of cattle grazing during post-fire recovery on these responses. Several plant and soil-based indicators of ecosystem function have been identified that are being incorporated into a manual for use in monitoring rangelands. Low input/trigger site strategies are being developed for remediation of rangelands. Experiments are underway to evaluate application of dairy manure on different plant communities and effects of portable shade on cattle distribution. A study conducted in which lambs were reared in pens with slatted or solid panels indicated lambs reared in simple environments had difficulty learning new food seeking behaviors and were more stressed in new environments. We have begun to examine the use of fluorometry to improve the accuracy and speed of diet analysis. Preliminary research indicated it could be used to distinguish among fecal samples from sheep consuming simple diets. We are studying the relationship of secondary chemistry of desert shrubs and livestock herbivory. Two of the eleven terpenes that were negatively related to tarbush intake in previous studies decreased intake of alfalfa by lambs. Determining which compounds deter herbivory will help establish methods to alter diet selectivity by livestock.}, url = {/files/bibliography/651.pdf}, author = {Richard E. Estell and Kris Havstad and D.M. Anderson and J.R. Barrow and D.P. Coffin and E.L. Fredrickson and Jeffrey E. Herrick and P.W. Hyder} } @article {51212, title = {Effects of volatile compounds on consumption of alfalfa pellets by sheep}, journal = {Journal of Animal Science}, volume = {76}, year = {1998}, month = {1998}, pages = {228-233}, abstract = {

We examined the effects of six volatile compounds on alfalfa pellet consumption by lambs. In each experiment, 45 lambs were individually fed alfalfa pellets sprayed with a selected compound (camphor, limonene, cts-jasmone, {\^a} -caryophyllene, borneol, or -pinene) at one of five concentrations. Treatment concentrations were multiples (0, .5, 1, 2, and 10) of the concentration of a specific compound (X) that was related to differential herbivory of tarbush by livestock in previous studies. Treatments were applied to alfalfa pellets (.64 kg-lamb^-d"1, DM basis), and consumption was measured during a 20-min interval each morning for 5 d. Lambs were adapted to handling procedures and the pelleted diet (without treatments) for 10 d, Lambs were maintained and fed (approximately 4.5 to 5\% of BW as one group except during 20-min tests. A negative linear effect of treatment concentrations on intake was observed for camphor (P \<.02) -pinene (P\< .01), and a quadratic response was detected for borneol (P \<.02). The other three compounds had no discernible effect on consumption. Although volatile compounds generally had only minor influences on consumption, the negative influences of -pinene and camphor concentrations on pellet consumption suggest that these monoterpenes may partially explain differential herbivory of individual tarbush plants by livestock.

}, keywords = {diets, intake, sheep, terpenoids}, doi = {10.2527/1998.761228x}, url = {/files/bibliography/609.pdf}, author = {Richard E. Estell and E.L. Fredrickson and M.R. Tellez and Kris Havstad and Shupe, W. Larry and D.M. Anderson and M.D. Remmenga} } @proceedings {51211, title = {Rangeland research in the Chihuahuan Desert}, year = {1998}, month = {1998}, keywords = {cattle growers{\textquoteright} short course, Chihuahuan Desert, rangeland, research}, author = {Richard E. Estell and D.M. Anderson and J.R. Barrow and A.G. de Soyza and E.L. Fredrickson and Gibbens, Robert P. and Kris Havstad and Jeffrey E. Herrick and M.R. Tellez and Walter G. Whitford} } @article {51213, title = {Relationship of tarbush leaf surface terpene profile with livestock herbivory}, journal = {Journal of Chemical Ecology}, volume = {24}, number = {1}, year = {1998}, month = {January 1, 1998}, pages = {1-12}, abstract = {

Tarbush (Flourensia cernua DC.) is a Chihuahuan Desert shrub with a resinous leaf surface containing terpenes that may affect livestock herbivory. Cattle, sheep, and goats were densely stocked in paddocks containing tarbush in two consecutive years for six to nine days and defoliation of 160 plants was recorded daily. Plants were categorized as exhibiting high or low defoliation. Leaves were collected from these plants the third year for chemical analysis. A selection procedure was used to generate two variable sets closely related to defoliation category. One set contained 14 variables (dry matter, ash, -pinene, sabinene, 3-carene, p-cymene, limonene, camphor, bomeol, cis-jasmone, {\^a} -caryophyllene, alpha-humulene, ledene, and flourensadiol) and the other set contained 14 unidentified compounds. When subjected to multivariate analysis, each group distinguished between the two defoliation categories (P \<0.001 and P \<0.0019 for known and unknown variable sets, respectively). These data support the hypothesis that leaf surface chemistry of individual tarbush plants is related to extent of defoliation by livestock.

}, keywords = {diet selection, Epicuticular wax, Flourensia cernua, leaf surface chemistry, monoterpenes, sesquiterpenes}, doi = {10.1023/A:1022399426352 }, url = {/files/bibliography/608.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @article {51385, title = {Tarbush leaf surface terpene profile in relation to mammalian herbivory}, journal = {Journal of Chemical Ecology}, volume = {24}, year = {1998}, month = {January 1998}, pages = {1-12}, abstract = {

Tarbush (Flourensiacernua DC.) is a generally unpalatable shrub native to the Chihuahuan Desert and with a resinous leaf surface containing several terpenes. Tarbush epicuticular wax concentration has previously been linked to degree of use by livestock in our laboratory. In 1989 and 1990, cattle, sheep, and goats were densely stocked in tarbush-containing paddocks for 6 to 9 days. Degree of use of 20 permanently marked plants in each paddock (8 paddocks, 2 sites, only 10 plants were monitored in 4 of the paddocks the first year) was recorded daily both years. Thus, no destructive sampling of plants was possible. A high percentage of tarbush in diets and differential use of individual tarbush plants were observed in this companion study. In 1991, leaves were collected from these plants (n = 160) during the same stage of maturity. Leaf surface compounds were extracted with ethanol, and mono- and sesquiterpenes were analyzed using gas chromatography/ion trap mass spectrometry. Our objective was to examine whether degree of tarbush use during the high-density study was related to chemistry of the same plants the following year. Plants were separated into three categories after preliminary data evaluation (Category 1: \> 50\% use at period midpoint; Category 2: \< 50\% use at midpoint but \> 50\% use at period end; Category 3: \< 50\% use at period end). Multivariate analysis is being used to examine relationships of individual plant use with dry matter, ash, epicuticular wax, and several individual and subgroups of mono- and sesquiterpenes (oxygenated and hydrocarbon monoterpenes and sesquiterpenes). Preliminary evaluation suggests chemical subgroup variables in 1991 were related to degree of herbivory in 1989 and 1990, although statistical analyses are not complete. Monoterpene hydrocarbons, oxygenated monoterpenes, and oxygenated sesquiterpenes were all sign different for the three use categories. We will determine which individual compounds contribute to these differences. Estimated concentrations of unidentified compounds will also be evaluated. One assumption is that heavy browsing during 1989 and 1990 did not cause plant secondary chemistry changes which persisted in 1991. Of the 120 plants with use data for both years, 66 plants in a given use category for 1989 were in the same category in 1990 and 38 plants were in a higher category. Only 15 plants fell to a lower use category and only 1 plant dropped from Category 1 to 3. Based on these observations, degree of use was reasonably consistent for individual plants across years, suggesting that, at least between 1989 and 1990, if induction occurred, it was short term. Leaf surface chemistry appears to be related to degree of use of individual tarbush plants by livestock.

}, keywords = {Chihuahuan Desert, leaf surface, mammalian herbivory, tarbush, terpene profile}, doi = {10.1023/A:1022399426352}, url = {/files/bibliography/512.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @conference {51273, title = {Effect of volatile compounds on intake of alfalfa pellets by sheep}, booktitle = {Journal of Animal Science}, volume = {75 (Suppl 1)}, year = {1997}, month = {1997}, pages = {203}, abstract = {

Six experiments were conducted to examine influences of volatile plant compounds on intake. Compounds were selected based on apparent relationships of tarbush leaf surface chemistry and livestock herbivory in previous studies. Average concentration of selected compounds (C) was 100, 100, 5, 300, 25, and 100 /{\`\i}g/g of tarbush DM for camphor, limonene, cis-jasmone, {\^a}caryophyllene, borneol, and -pinene, respectively. During each experiment, 45 individually penned lambs were fed one of five treatments (multiples of C: OX, .5X, IX, 2X, or 10X) for five consecutive days. Treatments were applied to alfalfa pellets (.64 kg, DM basis), and intake was monitored during a 20 min interval each morning. Lambs were preadapted to handling procedures and pelleted diet (without treatments) for 10 d before experiments began. Lambs were maintained and fed (approximately 5\% of BW) as one group except during 20 min tests. Borneol treatment resulted in intake differences (P \< .04), with intake for the 2X treatment greater than OX, IX, and 10X treatments (P \<\  .10). A treatment effect was also observed for -pinene (P \< .05), with lower intake for the 10X treatment than OX, .5X, or IX treatments. Camphor tended to affect intake (P \< .08), with lower intake for the 10X treatment than OX or IX treatments (P \< .10). Although volatile compounds generally had little influence on intake patterns, reduced intake with increased -pinene (and a similar pattern for camphor) concentration suggests these monoterpenes may partially explain differential herbivory of individual tarbush plants by livestock.

}, author = {Richard E. Estell and E.L. Fredrickson and M.R. Tellez and Kris Havstad and D.M. Anderson and M.D. Remmenga} } @proceedings {51272, title = {Rangeland research in the Chihuahuan Desert}, year = {1997}, month = {1997}, keywords = {cattle growers{\textquoteright} short course, Chihuahuan Desert, rangeland, research}, author = {Richard E. Estell and D.M. Anderson and J.R. Barrow and A.G. de Soyza and E.L. Fredrickson and Gibbens, Robert P. and Kris Havstad and Jeffrey E. Herrick and M.R. Tellez and Walter G. Whitford} } @article {51324, title = {Chemical composition of Flourensia cernua at four growth stages}, journal = {Grass and Forage Science}, volume = {51}, year = {1996}, month = {1996}, pages = {434-441}, abstract = {

Tarbush (Flourensia cernua DC) is an abundant Chihuahuan Desert shrub but is used sparingly by livestock. Leaves were removed from forty tarbush plants harvested in each of 3 years during four growth stages: (1) early, (2) mid-point, (3) late and (4) curtailed growth (ten plants per growth stage each year). Plants were air dried and all leaves were removed. In vitro dry-matter (DM) disappearance was greater for the early growth stage than other stages (P\<{\textperiodcentered}05). The fibrous fraction increased with maturity, with neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) contents all less for the early growth stage (P\<0-05) than other stages. The latter three growth stages did not differ in NDF or ADF content, but ADL content was lower for the mid-point growth stage than for the two later stages (P\<{\textperiodcentered}05). Calcium content increased with advancing season (P\<0-05), whereas phosphorus concentration exhibited an inverse pattern (P\<{\textperiodcentered}05). Nitrogen (N) content of tarbush was greatest in the early growth stage (P-cO-OS) and declined substantially thereafter. Soluble N content was greater and acid detergent insoluble N (ADIN) content was lower for early growth (P\<{\textperiodcentered}05) than other stages. Insoluble N concentration followed a pattern similar to N, declining with advancing season (P{\textperiodcentered}Q5). When expressed as a fraction of total N, insoluble N decreased and soluble N increased with maturity (P\<{\textperiodcentered}05). Condensed tannin concentration tended (P\<{\textperiodcentered}10) to increase with advancing season. Total phenolic content was lowest for early growth (P \<{\textperiodcentered}05), and did not differ among the other stages. Chemical analysis revealed tarbush to be relatively high in N concentration. Fibre fractions, ADIN, ADL and condensed tannins were all generally low whereas total phenolic content of tarbush was quite high. Early use by livestock would be most advantageous in terms of nutrient availability (N, P and in vitro digestibility) and lowest total phenolic concentration. Year-to-year variability in chemical composition of tarbush appears to be substantial. It remains to be seen whether overriding intake deterrents would be beneficial to livestock, given the high phenolic concentration in tarbush. Tarbush has several characteristics that make it a suitable model for studying plant-animal interactions of desert shrubs.

}, doi = {10.1111/j.1365-2494.1996.tb02078.x}, url = {/files/bibliography/475.pdf}, author = {Richard E. Estell and E.L. Fredrickson and Kris Havstad} } @conference {51323, title = {Nutrient content and antiquality factors in Flourensia cernua at four growth stages}, booktitle = {Journal of Animal Science}, volume = {74 (Suppl. 1)}, year = {1996}, month = {1996}, pages = {199}, abstract = {

Tarbush (Flourensia cernua \ DC) is a rapidly increasing Chihuahuan Desert shrub. Use of livestock to control tarbush is being examined. Whole plants (n=120) were harvested to assess nutrient composition during 3 years across 4 growth stages: early (EG), midpoint (MG), late (LG) and senescent (SG) growth. Plants were air-dried then leaves were removed and freeze-dried. Nitrogen concentration was greatest for EG, lowest for SG, and no different between MG and LG (P \<.05; 3.95, 2.82, 2.77 and 2.62\% of DM for EG, MG, LG, and SG, respectively. Soluble N content was greater and ADIN content was lower for EG (P\<.05) than other stages. Insoluble N declined with advancing maturity (P\<.05). As a fraction of total N, insoluble N decreased and soluble N increased with maturity (P \<.05). IVDMD and was greater for EG than the other stages (P \<.05; 66.8, 61.0, 60.5 and 60.4\% of DM for EG, MG, LG and SG, respectively. Calcium concentration increased and P content decreased with maturity (P \<.05). Concentrations of NDF and ADF were lowest for EG (P \<.05) but did not differ among later growth stages. ADL content was least for EG and less for MG than LG or SG (P \<.05). Condensed tannin content tended (P \<.10) to increase with advancing season. Total phenolics concentration was least for EG (P \<.05)and not different among the other growth stages (6.6, 8.1, 7.9 and 7.6\% of DM for EG, MG, LG and SG, respectively). Nutrients and antiquality variables exhibited patterns normally associated with advancing phenology. Across seasons and years, tarbush was of reasonably high quality (3.0 \% N, 62.2 \% IVDMD, 20.8 \% NDF, 17.0 \% ADF, 1.51 \% Ca and 0.15 \% \ P, DM basis) and low in antiquality factors (0.1 \% ADIN, 6.6 \% ADL and .34 \% condensed tannins, DM basis), with the exception of total phenolics (7.6 \% of DM) and ether extract (13.6 \% of DM).

}, author = {Richard E. Estell and E.L. Fredrickson and Kris Havstad} } @article {51322, title = {Tarbush leaf surface terpene profile in relation to mammalian herbivory}, year = {1996}, note = {NOT A DUPLICATE OF RECORD $\#$474}, month = {1996}, pages = {237-241}, publisher = {US Forest Service}, edition = {Gen. Tech. Rep. INT-GTR}, abstract = {

Cattle, sheep and goats were densely stocked in pad- docks containing tarbush (Flourensia cernua DC) for six to nine days and defoliation of 160 plants was recorded daily during two years. Plants were separated into high, moderate or low defoliation categories. Leaves were collected from plants during the same stage of maturity during the third year. Leaf surface compounds were extracted with ethanol and mono- and sesquiterpenes were ana-lyzed using gas chromatography/ion trap mass spectrometry. A set of 11 variables was identified that appeared most closely related to plant defoliation categories: dry matter, ash, limonene, camphor, borneol, a copaene, B caryophyllene, a pinene, p-cymene, cis-jasmone and caryophyllene oxide concentrations. This group distinguished among all three defoliation categories (P \< 0.03) when subjected to multivariate analysis. These data support the hypothesis that leaf surface chemistry is related to degree of defoliation of individual tarbush plants by livestock.

}, keywords = {diet selection, Epicuticular wax, Flourensia cernua, leaf surface chemistry, monoterpenes, sesquiterpenes}, url = {/files/bibliography/512.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and Kris Havstad and M.D. Remmenga} } @article {51439, title = {Effects of organic solvents on use of tarbush by sheep}, journal = {Journal of Chemical Ecology}, volume = {20}, number = {5}, year = {1994}, month = {1994}, pages = {1137-1142}, abstract = {

Tarbush (Flourensia cernua DC) is a native perennial shrub prevelant in many parts of the Chihuahuan desert. Ruminants have exhibited limited use of tarbus leaves and new leaders as a forage during the summer growing season. Efforts to increase use of tarbush by lambs, through spraying with various organic solvents were unsuccessful. probably because of the highly variable response. However, complete immersion of tarbush in organic solvents (acetone and ethanol) increased (P\< 0.01) tarbush use by ram lambs when compared to unaltered tarbush using organic solvents enhanced acceptability of tarbush to sheep.

}, keywords = {Flourensia cernua, herbivory, leaf surface, organic solvents, sheep, tarbush}, doi = {10.1007/BF02059749}, url = {/files/bibliography/416.pdf}, author = {Richard E. Estell and D.M. Anderson and Kris Havstad} } @article {51438, title = {Relationship of tarbush leaf surface secondary chemistry to livestock herbivory}, journal = {Journal of Range Management}, volume = {47}, year = {1994}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {1994}, pages = {424-428}, abstract = {

Tarbush (Flourensia cernua DC.) is an abundant shrub native to the Chihuahuan desert. Limited use as a forage by ruminants has been observed. The objective of this studey was to eexamine the leaf surface chemistyr of tarbush inrelation to degree of use by ruminants. Mature tarbush leaves were collected on 2 sites during 2 periods approximately 2 weeks apart from plants exhibiting either high (\>45\%) or low (\<10\%) use when browsed by cattle, sheep, and goats confined to a small area (5 plants per use category for each site/period combination). A greater (P\<0.05) concentration of epicuticular wax was detected on the leaf surface of plants used to a lower degree. Epicuticular wax concentration was 8.2 and 10.3\% of the leaf dry matter for high and low used plants, repectively. Several leaf surface compounds were related to period, while site and degree of use were seldom related to individual mon- and sesquiterpenes measure in this study. Camphene and 10 unidentified compounds differed between periods (P 0.10). Two unidentified compounds were related to site (P \< 0.10) and 2 others were related to use (P\<.0.10). In summary, individual leaf surface compounds on tarbush do not appear to greatly affect degree of us of tarbush by livestock, but collectively ( based on epicuticular wax data), these compunds may influence the diet selected by browsing ruminants.

}, keywords = {Epicuticular wax, herbivores, Leaves, livestock, monoterpenes, Plant biochemistry, plants, shrubs, terpenes, terpenoids}, doi = {10.2307/4002991 }, url = {/files/bibliography/418.pdf}, author = {Richard E. Estell and E.L. Fredrickson and D.M. Anderson and W. Mueller and M.D. Remmenga} } @article {51440, title = {Secondary chemistry of the leaf surface of Flourensia cernua}, journal = {Biochemical Systematics and Ecology}, volume = {22}, number = {1}, year = {1994}, month = {1994}, pages = {73-77}, abstract = {

Epicuticular wax accounted for 9.2\% fo the dry weight of whole Flourensia cernua (tarbush) leaves. Leaf surface extracts of tarbush were analyzed for mono- and sesquieterpenoids with gas chromatography/mass spectrometry. Camphene, $\#$ mycrene, 3-carene, limonene, 1,8-cineole, borneol, cis jasmone, $\#$ caryphyllene, caryophyllene oxide and globulol were consistently present in tarbush. Concentrations of several unidentififed compunds were estimated. A great deal of plant to plant variability was detected in leaf surface mono= and sesquietepenoid concentration. Infomation obtained on surface chemistry might be exploited to enhance use of tarbush as a forage for domestic herbivores.

}, keywords = {epicuticular waxes, Flourensia cernua, leaf surface chemistry, monoterpenoids, sesquiterpenoids}, doi = {10.1016/0305-1978(94)90116-3}, url = {/files/bibliography/419.pdf}, author = {Richard E. Estell and Kris Havstad and E.L. Fredrickson and Gardea-Torresdey, J.L.} } @article {51476, title = {Effects of repeated cycles of feed intake shifts on growth, feed efficiency and endocrine profiles of wether lambs}, journal = {Small Ruminant Research}, volume = {10}, number = {2}, year = {1993}, note = {Reprinted with permission from Elsevier, Copyright {\textcopyright} 1993. (http://www.sciencedirect.com/science/journal/09214488)}, month = {March 1, 1993}, pages = {103-118}, abstract = {

Fifteen wether lambs (average BW 28.8 {\textpm} 1.8 kg) were used in a 128-d trial to examine effects of cyclical feeding changes on growth, feed efficiency and endocrine profiles. Control lambs were fed a 40\% concentrate diet (40C) at 1.5 {\texttimes} NEm requirement during period 1 (64 d). Another group (1x/2x) was fed 40C at 1 and 2 x NEm in 4-d intervals during period 1; a third group (70/10) 70\% and 10\% concentrate diets in 4-d intervals during period 1. To achieve dry matter intake comparable to controls, 70/10 lambs were fed at 1.79 (70C) and 1.21 (10C) {\texttimes} NEm. All lambs were placed on the control diet during period 2 (32 d) and increased to 2 x maintenance during period 3 (32 d). During period 2, ADG and gain/feed of control lambs tended to be greater (P\<0.10) than for lambs fed alternating treatments. Liver weight as a percentage of hot carcass weight was greater (P\<0.05) for controls than for lambs fed alternating treatments. Hot carcass weight (P=0.07) and dressing percentage (P=0.09) tended to be greater for the 70/10 treatment than for controls. The 1x/2x treatment lowered (P\<0.05) serum cholesterol compared with other groups on d 65, but not on d 0 or 129. Smaller liver weight per unit of hot carcass weight for lambs in the 1x/2x and 70/10 treatments suggests a possible reduction of maintenance requirements.

}, keywords = {Carcass weight, Endocrine profile, feed intake, growth, Lamb}, doi = {10.1016/0921-4488(93)90054-L}, url = {/files/bibliography/398.pdf}, author = {Richard E. Estell and Kris Havstad and Heird, C.E. and E.L. Fredrickson and Hallford, D.M. and Shupe, W. Larry} } @conference {51477, title = {Evaluation of onions as a feed source for growing wethers}, booktitle = {Journal of Animal Science}, volume = {71(Suppl. 1)}, year = {1993}, month = {1993}, pages = {71}, abstract = {A study was conducted to evaluate cull onions as a feed source for growing wethers. An additional objective was to assess toxicity of dietary onions. Fifty-six polypay x rambouillet wethers (average initial BW of 33 kg) were randomly assigned to one of four dietary treatments: (1) 50\% whole sorghum grain (CON), (2) 33\% sorghum: 17\% onions (17\%), (3) 17\% sorghum: 33\% onions (33\%), and (4) 50\% onions (50\%). The remaining 50\% of the diet (DM basis) was pelleted alfalfa (19\% CP). All wethers were pen fed (7 wethers/pan) and treatments were replicated. Each diet was fed for 6 weeks following a 3-week adaptation period to the control diet. Serum was obtained at the end of weeks 0, 1, 3, and 6 to obtain a serum clinical profile (SMAC-25). Body weight did not differ (P > .05) among treatments during the trial. Average gaily gain tended (P = 0.057) to be lower for the 33 and 50\% treatments during weeks 1 and 2 but did not differ (P > .05) from CON during the remainder of the trial (over all ADG are .13, .17, .14, and .11 kg/d for CON, 17, 33, and 50\% treatments, respectively). Packed cell volume tended to be less (P = .057) for 33 and 50\% groups during weeks 1 and 2 and was less (P < .0001) for the same groups during week 3 (34, 33, 29, and 29\% for CON, 17, 33, and 50\%, respectively). Differences in PCV among treatments were not detected (P > .05) for weeks 4, 5, or 6. Serum LDH was elevated (P < .05) for weeks 3 and 6 in sheep eating diets of 33 or 50\% onions. We conclude that under the conditions of this study, onions can be fed safely to sheep and support weight gains similar to those from sorghum grain.}, keywords = {feed source, onions, wethers}, author = {Richard E. Estell and E.L. Fredrickson and Kris Havstad and Shupe, W. Larry and Saar, L.J.} } @conference {51519, title = {Role of secondary chemistry of tarbush in herbivory by livestock}, booktitle = {Annual Meeting, Society for Range Management}, year = {1992}, month = {1992}, pages = {P096}, abstract = {

Tarbush (Flourensia cemua) is an abundant shrub in the Chihuahuan desert which is used to a limited degree by ruminants. Related current research has demonstrated differential livestock use within this species. We hypothesize that grazing ruminants express selection preference for individual tarbush plants based upon leaf surface concentrations of epicuticular waxes and terpenoids. The objective of this study was to examine the leaf surface chemistry of tarbush in relation to degree of use by ruminants. Samples were collected in the mature leaf stage on 2 sites from plants exhibiting either high (\>40\%) or low (\<5\%) degree of use when browsed by cattle, sheep, and goats confined to a small area (10 plants per use category per site). Use was estimated visually and approximately 50 g of leaves from each plant were removed and placed on dry ice. Epicuticular waxes were determined with a gravimetric procedure, using a chloroform extraction of whole leaves. Leaves were also extracted in ethanol for mono- and sesquiterpenoid analysis with gas chromotography/mass spectrophotometry. The chloroform extraction revealed a greater concentration of epicuticular wax on the leaf surface of plants which were used to a lower degree (P \< 0.02). Epicuticular wax concentration was 9.5 and 12.0\% (organic matter basis) for high and low use plants, respectively. Data will be presented on surface terpenoid concentrations and their relationship to degree of use of tarbush by grazing ruminants. Information obtained on surface chemistry might be exploited to enhance use of tarbush as a forage.

}, author = {Richard E. Estell and E.L. Fredrickson and Kris Havstad and D.M. Anderson} } @conference {51562, title = {Effect of cyclic feeding patterns on growth, serum metabolites and hormones, organ size and carcass traits of wether lambs}, booktitle = {American Society of Animal Science}, year = {1991}, month = {1991}, pages = {No. 839}, edition = {69 (Suppl. 1)}, abstract = {A study using 15 wether lambs (avg wt of 28.8 kg) was conducted (eight 16-d periods, five lambs/treatment) to examine effects of cyclic intake of dry matter or energy density. During the first four periods, controls received a 40\% concentrate diet (40C) at 1.5 x NE., another group (1X/2X) received 40C at 1 and 2 x NE, in 4-d intervals and a third group (70/10) received 70 and 10\% concentrate diets in 4-d intervals. All lambs were fed the control diet during periods 5 and 6 and increased to 2 x maintenance during periods 7-8. Blood samples were collected on d 0, 65 and 129. During periods 5-6, average daily gain and gain:feed ratio of the control group were greater (P < .10) than cyclic treatments. During periods 1-4, a trend existed for the 1X/2X treatment to have higher average daily gain (P = .15) and gain:feed (P = .12) than controls. Liver wt (hot carcass wt basis) was higher (P < .05) for controls. Hot carcass wt (P = .07) and dressing percentage (P = .09) tended to be higher for the 70/10 treatment than controls. Alternated feeding patterns resulted in no major shifts in GH, insulin, triiodothyronine or thyroxine profiles compared with controls. The 1X/2X treatment resulted in lower (P < .05) serum cholesterol than the other groups on d 65 but not on d 0 or 129. Smaller liver wt per unit of carcass wt with the 1X/2X and 70/10 treatment suggests a possible reduction of maintenance requirements.}, keywords = {feeding patterns, growth, lambs, organ mass}, author = {Richard E. Estell and Kris Havstad and Heird, C.E. and E.L. Fredrickson and Hallford, D.M. and Shupe, W. Larry} } @article {51610, title = {Evaluation of a continuous-release ytterbium bolus}, journal = {Journal of Range Management}, volume = {43}, number = {2}, year = {1990}, month = {1990}, pages = {144-147}, keywords = {beef steers, continuous marker, fecal output, ytterbium}, url = {/files/bibliography/90-001.pdf}, author = {Richard E. Estell and Freeman, A.S. and Galyean, M.L. and Wallace, J.D.} } @article {51876, title = {Relationship of rumen fluid diluation rate to rumen fermentation and dietary characteristics of beef steers1,2}, journal = {Journal of Animal Science}, volume = {60}, number = {4}, year = {1985}, month = {1985}, pages = {1061-1071}, keywords = {beef, rumen, steers}, url = {/files/bibliography/85-001.pdf}, author = {Richard E. Estell and Galyean, M.L.} } @proceedings {52001, title = {Verification of a continuous flow fermentation system and effect of dilution rate on rumen fermentation and microbial numbers}, volume = {33}, year = {1982}, month = {1982}, pages = {29-31}, keywords = {fermentation, micorbial, rumen}, url = {/files/bibliography/82-002.pdf}, author = {Richard E. Estell and Galyean, M.L. and Melchor Ortiz and Leighton, E.A.} }