@conference {JRN54493, title = {Mesquite: A long view}, booktitle = {16th Biennial Mogollon Archeology Conference}, year = {2010}, month = {10/2010}, publisher = {16th Biennial Mogollon Archeology Conference}, organization = {16th Biennial Mogollon Archeology Conference}, address = {Las Cruces, NM}, abstract = {Mesquite (Prosopis glandulosa) is among the most successful plants in Northern M{\'e}xico and America{\textquoteright}s arid Southwest. Mesquite optimizes pollinator services and reproductive effort, resulting in seeds that persist in herbivore digestive tracts and soil seed banks for extended periods. An extensive root system fully occupies the soil profile long distances from its base, allowing it to harvest water and nutrients with extraordinary efficiency. Root nodules harbor nitrogen-fixing bacteria allowing mesquite to overcome usual nitrogen limitations. Mesquite survival is determined early, but once established, it is long-lived, often benefiting from hardships killing most plants. So with mesquite{\textquoteright}s superior adaptations and competitive advantage, why has it only recently dominated desert landscapes? An answer may reside in the literature housing the knowledge of anthropologists and archaeologists studying the Jornada Mogollon, and prehistoric peoples of North America{\textquoteright}s warm deserts. Extensive use of mesquite by prehistoric peoples maybe a mechanism for dispersal of desert shrubs during the Holocene and controlling its distribution prior to European influence. A long-view of mesquite demography appears essential for reinterpreting our relationship with mesquite. A relationship that now cost millions of dollars annually to control its abundance and provide for lost ecosystem services.}, author = {E.L. Fredrickson and Curtis H. Monger and Guevada, Eduardo P.} } @conference {50096, title = {Linking biological conservation to healthy rural communities: a case history of the Janos {\textendash} Casas Grandes Biosphere Reserve}, booktitle = {Ecological Society of America}, year = {2009}, note = {Abstract $\#$ 20230}, month = {08/2009}, pages = {COS 103-6}, address = {Albuquerque, NM}, abstract = {

During the late 1930\’s, Aldo Leopold witnessed a striking contrast along the narrow boundary between the United States and Mexico. He later described Mexican ecosystems as a \“lovely picture of ecological health\” and those same ecosystems north of the U.S. - Mexico border as \“so badly damaged that only tourists and those ecologically blind, can look upon them without a feeling of sadness, and regret.\” On this the hundredth centennial of Leopold\’s arrival in the Southwest, the difference has waned but has not completely vanished. Within Mexico\’s Janos \– Casas Grande region lays the largest black-tailed prairie dog complex within North America, reminiscent of past ecosystems just north of the border. Now a Biosphere Reserve, collaborative efforts between Mexican and U. S. scientists are reconstructing the area\’s ecological history and identifying key ecosystem properties maintaining grasslands and essential ecosystem services.

}, keywords = {abstract, biological conservation, Casa Grandes Biosphere Reserve, ESA, Janos}, author = {E.L. Fredrickson and G. Ceballos and List, R. and Barajas, N. and N. F. Sayre and Roacho, E.J.O. and Sierra, C.R. and G.E. Ponce and A.D. Davidson and Melgoza, A. and Jaquez, C. and G. Bezanilla} } @conference {50207, title = {Landscape histories, livestock management, and mesquite expansion in the Chihuahuan Desert of New Mexico}, booktitle = {Society for Range Management Annual Meeting}, year = {2008}, month = {January 26, 2008}, pages = {2188}, address = {Louisville, KY}, abstract = {During the past 125 years the northern Chihuahuan Desert has undergone a significant shift from desert grasslands to desert shrub conditions, with mesquite (Prosopis glandulosa) dramatically increasing in dominance during this period. The transition from desert grasslands is viewed as deleterious, decreasing forage availability for both wildlife and livestock while negatively impacting air, water, and soil processes that support ecosystem services important to rapidly growing, human populations. Causes leading to this transition include formulation of government and industry policies, and later application of some range management principles, without an understanding of the evolutionary and landscape history of the northern Chihuahuan Desert. In addition, as causes of mesquite expansion were determined, primary factors leading to mesquite{\textquoteright}s eventual dominance did not receive adequate attention, most likely because they did not fit within dominant scientific paradigms, or social-political realities of the time. Future work needs to focus on better understanding evolutionary and landscape legacies of this region; including factors that created and maintained the original desert grasslands prior to desert scrub conditions. Using this understanding we must create appropriate theory that will guide future human-ecological interactions and assessment of ecological trajectories. This knowledge must affect policy and eventual management. We must relax the need for ecosystems to adapt to human behaviors and consider how human behaviors can best adapt to the ecosystems on which they depend.}, keywords = {Chihuahuan Desert}, author = {E.L. Fredrickson and Jeffrey E. Herrick and H. Raul Peinetti and Andrea S. Laliberte} } @article {50329, title = {Volatile compounds on the leaf surface of intact and regrowth tarbush (Flourensia cernua DC) canopies}, journal = {Journal of Chemical Ecology}, volume = {33}, year = {2007}, month = {September 25, 20}, pages = {1867-1875}, abstract = {

Shrub expansion into desert grasslands is a serious problem resulting in loss of forage and rangeland productivity. Flourensia cernua DC (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 compounds such as terpenes often change with plant age and phenology. Our objective was to examine the effect of altering the vegetative state of tarbush on volatile chemicals. 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 analyzed by gas chromatography-mass spectroscopy 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 = 0.062) than that of regrowth (3642 vs. 4684 {\`\i}g/g DM). Nine compounds in the discriminant analysis ({\'a}-muurolene, iso-borneol, unknown$\#$6, p-cymen-8-ol, unknown$\#$7, sabinene, {\^a}-caryophyllene, {\"a}-cadinene, and {\'a}-copaene) explained 95\% of the variation between canopy and regrowth samples. Lower cumulative concentration of volatile compounds in canopy than regrowth samples suggests repsrouts may be less vulnerable to herbivory than intact tarbush.

}, keywords = {Flourensia cernua, plant secondary metabolites, regrowth, tarbush, terpenes}, doi = {10.1007/s10886-007-9360-8 }, url = {/files/bibliography/07-029.pdf}, author = {E.L. Fredrickson and Richard E. Estell and M.D. Remmenga} } @article {50442, title = {Mesquite recruitment in the Chihuahuan Desert: historic and prehistoric patterns with long-term impacts}, journal = {Journal of Arid Environments}, volume = {65}, number = {2}, year = {2006}, month = {April 1, 2006}, pages = {285-295}, abstract = {Mesquite (Prosopis glandulosa) has increased in dominance over large areas of the Chihuahuan Desert, chiefly at the expense of once expansive desert grasslands. Excessive grazing and seed dissemination by livestock are often cited as the cause of this transition. We propose an alternate hypothesis that expansion of mesquite is not simply due to cause and effect relationships during recent history; rather, mesquite expansion is a result of a series of cause and effect relationships that transpired over a much longer timeframe (centuries). We assert that mesquite expansion may have ultimately occurred in the absence of widespread livestock grazing during the last 130 years because of removal of barriers to mesquite expansion created by Pleistocene megafauna and indigenous peoples. We explore factors that attenuate or intensify mesquite expansion and examine how a series of fine=scale, but temporally seminal, events can propagate across multiple scales. Furthermore, we examine the relevance of this hypothesis for present day remediation of shrub-dominated grasslands and conclude that knowledge of historic and prehistoric events and processes are essential to effectively manage landscapes. http://www.sciencedirect.com/science?_ob=MImg\&_imagekey=B6WH9-4HSY4WS-3-5\&_cdi=6845\&_user=1496926\&_orig=browse\&_coverDate=04\%2F30\%2F2006\&_sk=999349997\&view=c\&wchp=dGLbVtz-zSkWW\&md5=a516e16003fd57a18d1e636650b3d2eb\&ie=/sdarticle.pdf}, keywords = {historic legacy, invasive species, landscape history, prosopis glandulosa, seed dispersal}, url = {/files/bibliography/06-001.pdf}, author = {E.L. Fredrickson and Richard E. Estell and Andrea S. Laliberte and D.M. Anderson} } @conference {50549, title = {Collaborative animal science research: impacts of agriculture and trade policies on cross-border rangeland research and management}, booktitle = {Society for Range Management, 58th Annual Meeting and Trade Show}, year = {2005}, month = {February 5, 2005}, pages = {Paper No. 115}, address = {Fort Worth, TX}, abstract = {In sharing a common boundary, Mexico and the United States also shares common landscapes and an agricultural economy that is inextricably linked. Due to the high degree of connectedness between these countries, factors that affect one country also affect the other, either directly or indirectly. Current problems in the border region include extended drought, land degradation, and depletion of essential resources such as water. These problems are exacerbated by ensconced political and social systems resistant to change. The implications of these events are profound, and often referred to as being near catastrophic. Collaborative research between Mexican and US researchers offers numerous benefits by combining human and material resources to solve common problems. Despite these benefits, language, social customs, and political policies can create barriers to collaborative efforts that reduce the effectiveness and the overall number of collaborative efforts. When anticipated and appropriately planned for, these barriers can effectively be dealt with. We discuss these potential barriers and how to address them by relating our experiences with collaborative Mexican-US projects on the conservation and use of northern Mexican criollo beef cattle breeds in semiarid and arid environments.}, keywords = {agriculture and trade policies, animal science research, cross-border, management, rangeland, research}, author = {E.L. Fredrickson and G. Bezanilla} } @conference {50552, title = {Criollo Cattle: An Examination of the Past with an Eye to the Future}, booktitle = {American Society of Animal Science, New Mexico Branch American Association of Laboratory Animal Scientists}, year = {2005}, month = {August 5, 2005}, address = {New Mexico State University, Las Cruces, NM}, abstract = {During his second voyage in 1492, Columbus introduced the first cattle to the New World. Since their introduction from Andalusia, these cattle have undergone 500 year sof co-evolution with the lanscapes of North and South America. Focusing on arid regions of Chihuahua, Sonora, and Baja California, we are undertaking a series of studies to better understand the arid land adaptations of "criollo" cattle and their potential effects on vegetation change. While the oldest breed in the United States, these cattle may again prove useful in shaping the future of the North American beef cattle industry.}, keywords = {1492, Andalusia, cattle, Columbus}, author = {E.L. Fredrickson and Richard E. Estell} } @conference {50550, title = {Drought as a Dynamic Process: Recovering from Long Term Rangeland Impacts of Drought}, booktitle = {2005 3rd Annual Drought Summit: "The Drought: It Ain{\textquoteright}t OVer {\textquoteright}Til It{\textquoteright}s Over, and It Ain{\textquoteright}t Over!", USDA Natural Resources Conservation Service}, year = {2005}, month = {October 6, 2005}, pages = {pp. 20}, publisher = {University of New Mexico Continuing Education Center}, organization = {University of New Mexico Continuing Education Center}, address = {Albuquerque, NM}, abstract = {Central tenets of living with drought rangelands are complex, often unpredictable lanscapes, in which drought is a constant feature. The effects of drought are dependent on prior conditions that are largely the result of the continual interplay of humans and their environment. By investing in human capital, and the large social context, we can better manage this interplay to meet a diversity of needs. It is knowledge, and the creation of knowledge, through monitoring and scientific investigation, that allows land management professionals to better adapt and innovate to ever chaning conditions. Likewise, the greater society provides the ethic and the needed flexibility for the land manager to operate within. Without first adressing this often ignored framework, use of other management tools are likely to be costly, have short-lived benefits, and uninteded consequences.}, keywords = {drought management, long term, rangeland}, author = {E.L. Fredrickson} } @conference {50652, title = {Management effects on livestock use of landscapes: Protein supplementation}, booktitle = {89th Annual Meeting, Ecological Society of America}, year = {2004}, month = {August 1, 2004}, pages = {Abstract p. 166}, address = {Portland, OR}, abstract = {Over half of the Earth{\textquoteright}s land surface is grazed by livestock. The effects of livestock grazing on terrestrial ecosystems range from detrimental to beneficial depending on ecosystem attributes and livestock management. Understanding the ecological implications of livestock management decisions is central to successful human interactions with complex environments. For example, supplementing heifers with a 32\% protein supplement concentrated heifer movements in areas near water and supplementation points. Prior to supplementation, animal movements were dispersed throughout the pasture. While concentrated movements are at times desirable, they can also trigger undesirable ecosystem trajectories. As part of a larger goal to better understand the ecological impacts of livestock grazing, we designed a study to examine the effects of protein supplementation, a common management practice, on livestock use of landscapes. Thirty-six multiparous, lactating, Angus x Hereford cows were randomly assigned to one of three treatments: (1) control (CON), no supplementation, (2) supplementation each day at 0700 (AM) with 0.75 kg of a 32\% crude protein pellet, or (3) supplementation at 1300 (PM) each day with the same supplement. Fifteen days prior to the study, animals were allowed to become familiar with experimental procedures and the 2,425 ha study pasture described as Chihuahuan Desert grassland ecotype. Animals from each treatment were fitted with Lotek GPS collars and rotated into the study pasture for a period of 5 days for three rotations. Animal position was acquired every 5 minutes. Mean distance from water differed (P < .0001) across treatments (2.55, 2.09, and 1.53 km for CON, PM, and AM, respectively). Distance traveled per day also differed (P < .0001) across treatments (7.17, 7.20, and 7.96 km/day for CON, PM, and AM, respectively). The area encompassing daily activities (Jennrich-Turner estimate of home range) also differed (P < .0001; 4.3, 2.8, and 3.9 square km/day for CON, PM, and AM, respectively). Protein supplementation and timing of supplementation affect the spatial use of desert grasslands and is likely to have important ecological implications. Furthermore, research examining livestock impacts must do so with an understanding of the effects of management on livestock behavior.}, keywords = {ecological impacts, ecosystems, livestock, livestock behavior, livestock management, protein supplementation}, author = {E.L. Fredrickson and J. Koppa and Richard E. Estell and D.M. Anderson and Kris Havstad} } @conference {50653, title = {Mesquite recruitment: historic patterns with long-term impacts}, booktitle = {Sixth Symposium on the Natural Resources of the Chihuahuan Desert Region}, year = {2004}, month = {October 15, 2004}, pages = {24}, address = {Alpine, TX}, abstract = {Mesquite (Prosopis glandulosa Torrey) has increased in dominance over large areas of the Chihuahuan Desert, chiefly at the expense of once expansive desert grasslands. Excessive grazing and seed dissemination by livestock are often attributed as the cause of this transition. We propose an alternate hypothesis that expansion of mesquite is not due to simple cause and effect relationships, but rather a network of cause and effect relationships. We assert that mesquite expansion may have occurred even in the absence of the widespread livestock grazing occurring during the last 130 years. We then look at factors that attenuate or intensify mesquite expansion and how a series of small-scale but temporally seminal events propagate across multiple scales. Lastly, we examine how acceptance of this hypothesis, or its parts, might be useful in enhancing 21st century efforts focused on remediation of desert grasslands.}, keywords = {Chihuahuan Desert, excessive grazing, long-term impacts, mesquite, patterns, seed dissemination, small-scale events}, author = {E.L. Fredrickson and Laurie Abbott and D.M. Anderson and Richard E. Estell} } @proceedings {50864, title = {Complexity, desertification and livestock production: Dancing with the winds of change}, year = {2002}, month = {September 19-21,}, pages = {1-4}, address = {Chihuahua, Mexico}, abstract = {During the last 150 years the Jornada Experimental Range has undergone a transition from desert grasslands to desert scrubland vegetation. This transition is characteristic of desertification, a process occurring in arid and semiarid regions worldwide. While livestock grazing is commonly isolated as the sole driver of desertification in the northern Chihuahuan Desert, it appears that actual causes are complex and difficult to untangle. Principal factors thought to cause current desertified conditions are shifts in seasonal precipitation with winter precipitation favoring shrubs and summer rainfall favoring grasses. Increasing CO2 may have a fertilization effect that favors C3 shrubs over C4 grasses. Human effects on mammalian predator-prey dynamics may have caused alterations in small herbivore populations that normally dampen oscillations in plant demographics. Whether current trends in desertification are due to human or non-human forces is, at present, indeterminable. What is certain is that we live in an environment that is complex, chaotic, and at times catastrophic. Our world is dynamic, constantly evolving, and rarely at equilibrium. Future success will result because of a society{\textquestiondown}s ability to adapt and innovate in response to change, and to do so within an ethical framework that creates potential benefit to current and future societies.}, author = {E.L. Fredrickson and Amy L. Gonzalez} } @proceedings {50865, title = {Desertification: Weaving together the complexities of time and place}, year = {2002}, month = {September 17-20,}, pages = {18-26}, address = {Durango, Mexico}, abstract = {Desertification is an active process in the Chihuahuan Desert that is typified by a vegetation transition from desert grasslands to desert scrub. Throughout much of geological time, deserts have waxed and waned without human intervention. Currently, it is difficult to segregate human and nonhuman causes. One obvious cause of this transition is a dynamic interaction between plant species with and without specific adaptations to large animal herbivory. An examination of vegetation change with time reveals that deserts are complex, chaotic, and often catastrophic. New models are being developed to deal with the resulting uncertainty. These models include complex adaptive systems and adaptive management. These models are discussed and applied to conditions prevalent in the Chihuahuan Desert.}, url = {/files/bibliography/02-023.pdf}, author = {E.L. Fredrickson and Amy L. Gonzalez} } @conference {50863, title = {Mowing versus fire on expansion of black-tailed prairie dogs reintroduced into Chihuahuan Desert grasslands}, booktitle = {87th Annual Meeting, Ecological Society of America}, year = {2002}, month = {August 4-9, 2002}, pages = {352}, address = {Tucson, AZ}, abstract = {Black-tailed prairie dogs (Cynomys ludovicianus) populations have declined more than 98\% due to eradication programs, habitat loss, and introduced pathogens. Active conservation measures for this species, including reintroduction, are under way in a number of areas. Because of their effects on landscape pattern and ecosystem process, they may act as a keystone species in desert grassland communities. As part of a larger study of reciprocal effects of landscape and ecosystem factors on establlishment and growth of prairie dog colonies, we investigated the effects of fire and mowing in promoting colony numerical growth and areal expansion. Three prairie dog colonies were established in the northern Chihuahuan Desert in 1998-1999 ranging in size from 1.27 to 8 ha. Adjacent to each colony we established six 50m x 50m experimental plots randomly assigned to burn or mow treatments. The response variable was number of new burrows appearing in each experimental plot. No significant differences were detected in the number of new burrows in burned vs. mowed plots, suggesting that either fire or mowing can be used interchangeably as management tools in the reintroduction of prairie dogs.}, author = {E.L. Fredrickson and C.A. Anderson and P. L. Ford and J. Truett and G. Roemer} } @article {50987, title = {Pen confinement of yearling ewes with cows or heifers for 14 days to produce bonded sheep}, journal = {Small Ruminant Research}, volume = {40}, year = {2001}, month = {June 1, 2001}, pages = {291-297}, abstract = {

Mixed species stocking uses forage resources more efficiently when compared to single species stocking, especially in pastures having complex assemblages of forage species. When mixed species (sheep and cattle) remain consistently as a cohesive group (flerd), predation risks are lessened and fencing and herding costs are reduced. To maintain a cohesive egroup, a 30-day bonding period is recommended in which young sheep and bovine pairs are penned together. This research tested if pen confinement can be reduced from 30 to 14 days, reducing feed, labor and overhead costs. Sixteen mature cows (7 to 8 years of age) and 16 9-month-old heifers were randomly paired with 1 of 32 yearling ewe lambs. Eight cow/ewe (PC) and eight heifer/ewe (PH) pairs were maintained individually in 2mx6m pens for 14 days. The other eight-cow/ewe (NC) and heifer/ewe (NH) pairs were separated by species with each species maintained on separate pastures for 14-day period. After 14 days, pairs were released in observation paddocks and separation distances between treatment pairs were measured during a 30-minute open field test. Separation distance did not differ (P=0.973) between the PC and PH treatments; however, separation distance for NC vs NH, NC versus PC, and NH vs PH all differed. Mean separation distance (meters) and standard errors were 40+/-3.9, 3+/-0.3, 76+/-5.3, and 4+/-1.4 for CH, PH, CC and PC treatments, respectively. Previously penned animals spent more time grazing and less time walking than nonpenned animals. Cow age was not found important in establishing a bond. These data suggest that an interspecific bond using pen confinement can be formed within 14 days, representing 53\% savings in time and associated costs when compared to confinement lasting 30 days.

}, keywords = {beef cattle, bonded sheep, bonding, cows, heifers, Mixed species stocking, Multispecies stocking, pen confinement, sheep, yearling ewes}, doi = {10.1016/S0921-4488(01)00183-3}, url = {/files/bibliography/01-022.pdf}, author = {E.L. Fredrickson and D.M. Anderson and Richard E. Estell and Kris Havstad and Shupe, W. Larry and M.D. Remmenga} } @article {51071, title = {The effect of feeding ewe lambs a 15\% tarbush (Flourensia cernua DC) pellet pre- and post-weaning on the subsequent diet selection of tarbush}, journal = {Journal of Arid Environments}, volume = {44}, number = {1}, year = {2000}, month = {January 1, 2000}, pages = {123-131}, abstract = {

The shrub Flourensia cernua (tarbush) has rapidly increased in dominance within Chihuahuan Desert grasslands, and is comparable to alfalfa in nutrient density. Increasing tarbush in livestock diets may improve diet quality, while decreasing tarbush dominance. We determined dietary preference for tarbush by sheep and the effect of previous exposure on preference. Thirty-eight ewe lambs received either tarbush or alfalfa in sorghum-based pellet 120 days postparturition; after which, dietary preference was assessed. Previous exposure averted lambs from tarbush consumption. Lambs without previous exposure maintained greater intakes initially, but declined with time. This decline corresponds with onset of tarbush toxicosis.

}, keywords = {ewe lambs, Flourensia cernua, post-weaning, pre-weaning, tarbush}, doi = {10.1006/jare.1999.0571}, url = {/files/bibliography/00-003.pdf}, author = {E.L. Fredrickson and Richard E. Estell and Kris Havstad and Shupe, W. Larry and L. W. Murray} } @conference {51146, title = {Role of herebivorous and granivorous fauna in the maintenance of mesquite coppice dune systems}, booktitle = {5th Symposium on Resources of the Chihuahuan Desert Region: U.S. and Mexico}, year = {1999}, month = {October 7-8, 199}, pages = {17-18}, address = {Alpine, TX}, abstract = {Part of the ongoing desertification process within the Chihuahuan Desert involves replacement of former grasslands by shrubs. At the U.S. Department of Agriculture, Agricultural Research Service, Jornada Experimental Range, vast areas of Black Grama, Bouteloua eriopoda, grasslands were replaced by mesquite, Prosopis glandulosa glandulosa, which hsubsequently facilitates the formation of coppice dunes or mounds of sand around established shrubs. Three studies were designed to assess the effects of two broad guilds of fauna herbivores (foliage eaters) and granivores (seed eaters) in maintaining coppice dune states. We also consider in greater detail species-specific roles played by a group of desert rodents known to have keystone effects on Chihuahuan Desert plant communities. These studies indicate the small mammals studied both maintain and probably augment coppice dune systems.}, author = {E.L. Fredrickson and Longland, W.S. and P.W. Hyder and Hu, D. and Richard E. Estell} } @conference {51215, title = {Concentrations and distributions of nordihydroguaiaretic acid, total phenolics and condensed tannins in creosotebush (Larrea tridentata)}, booktitle = {Annual Meeting, Society for Range Management}, volume = {51}, year = {1998}, month = {1998}, pages = {29}, abstract = {Creosotebush contains a variety of secondary metabolites that have important ecological roles. Some, such as nordihydroguaiaretic acid (NDGA), have been proposed to have allelopathic effects that may contribute to the rapid expansion of creosotebush. Studies suggest phenolic compounds in roots affect root longevity, soil microbial processes and may have allelopathic properties. While NDGA concentrations in the above ground fraction has been extensively studied, other phenolic compounds throughout the plant, including the roots, have received little attention. Five creosotebush plants were collected and divided into 9 tissue categories. These categories were then analyzed for concentrations of NDGA, total phenolics and condensed tannins. NDGA was confined to "green" tissues such as leaves, flowers and stem tips. Total phenolics were found in all tissues with leaves, green stems and roots containing the highest concentrations. Condensed tannins were found in relatively low concentrations throughout all tissues except for seeds, which had levels roughly 17 times the mean concentration found in the rest of the plant. Future studies will look at the role of phenolics in modifying the plants immediate environment including allelopathic effects on sympatric plant species.}, author = {E.L. Fredrickson and P.W. Hyder and M.R. Tellez and Richard E. Estell} } @article {51216, title = {Perspectives on desertification: Southwestern United States}, journal = {Journal of Arid Environments}, volume = {39}, year = {1998}, month = {1998}, pages = {191-207}, abstract = {

Several climatic changes occurred in the northern Chihuahuan Desert and other parts of the southwest United States during the last 12,000 years leading to a markedly warmer and drier climate.\  Vegetation changed in response to this climatic shift. Generally, this transition was from coniferous woodland to grasslands and eventually to the present day desert scrub.\  Pre-Columbian inhabitants of this region adapted by changing from hunter-gatherer to primarily agrarian economics.\  European immigrations into the southwest U.S. beginning in the mid 1500s greatly affected this region.\  The greatest impact occurred after the U.S. Civil war in the 1860s.\  Before that time land use tended to be localized near small agricultural areas, mines, and military installations.\  The post-war range livestock industry expanded dramatically, especially during the 1880s {\textendash} a period of general abuse of arid lands in the region.\  Recognition of this abuse and the deteriorating productivity of the land led to greater government involvement, including establishment of experimental stations and eventually management of the public domain by governmental agencies.\  Fire suppression, mismanaged grazing, changing climatic conditions, loss of soil and increasing atmospheric CO2 concentrations, mainly due to the burning of fossil fuels, are among the probable causes of continued desertification trends\ \  Urban and rural populations, presently technologically isolated from their environment, need to better understand the dynamic nature of their environment.\  A greater degree of co-operation among diverse entities will be crucial.

}, keywords = {Chihuahuan Desert, desertification, Sonoran Desert, south-west United States}, doi = {10.1006/jare.1998.0390}, url = {/files/bibliography/613.pdf}, author = {E.L. Fredrickson and Kris Havstad and Richard E. Estell and P.W. Hyder} } @article {51276, title = {Effects of ruminant digestion on germination of Lehmann lovegrass seed}, journal = {Journal of Range Management}, volume = {50}, number = {1}, year = {1997}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {January 1, 1997}, pages = {20-26}, abstract = {

Lehmann lovegrass (Eragrostis lehmanniana Nees) seed (germination 96\%, dormant 0\%) was used in 4 experiments to study the potential of sheep as a dispersal agent. Five, 4-year-old, ruminally cannulated wethers were used to examine effects of ruminant digestion on seed recovery and germination. All wethers were ruminally evacuated, and rumens were cleansed and reinoculated with strained ruminal fluid. After a 21-day adaptation to pelleted alfalfa, 4 experiments were conducted. Experiment 1 was designed to test viability of Lehmann lovegrass seeds exposed to ruminal and postruminal digestion. Lehmann lovegrass seed (10 g) was dosed intra-ruminally via ruminal fistula, and total fecal collections made. Of the viable seed ruminally dosed, 37\% germinated within 21 days after recovery. Also, 98 to 100\% of the seed that germinated was recovered within 72 hours of dosing. Experiment 2 was designed to test the influence of ruminal microbial digestion on seed degradation and viability, using in sacco nylon bag techniques. In sacco dry matter disappearance increased linearly from 5.5\% at 3 hours of incubation to 16 \% at 120 hours. Germination of seed was not greatly affected until after 72 hours of ruminal incubation. Experiment 3 was designed to examine the effect of mastication on viability of Lehmann lovegrass seeds. Seeds were mixed with seed-free Lehmann lovegrass straw in a proportion of 1 to 10 (seed to straw) and 10 g fed to each wether. Boli were recovered manually via ruminal fistula. Thirty five percent of the seed fed entered the rumen without damage due to mastication. Experiment 4 compared in vitro techniques and in sacco techniques used to estimate the effect of digestion on seed viability. In vitro incubation techniques yielded similar results as in sacco techniques. We conclude that ruminants are potential disseminating agents of Lehmann lovegrass seed.

}, keywords = {Eragrostis lehmanniana, in vitro digestibility, introduced species, mastication, rumen fermentation, seed dispersal, Seed germination, seeds, selective grazing, sheep, sheep dung}, doi = {10.2307/4002700 }, url = {/files/bibliography/582.pdf}, author = {E.L. Fredrickson and Richard E. Estell and Kris Havstad and Ksiksi, T. and VanTol, J. and M.D. Remmenga} } @conference {51277, title = {Perspectives on desertification: Southwestern United States}, booktitle = {International Symposium Workshop, Combating Desertification: Connecting Science with Community Action}, year = {1997}, month = {1997}, pages = {10}, abstract = {Several climatic changes occurred in the northern Chihuahuan Desert and other parts of the southwest United States during the last 12,000 years, leading to a markedly warmer and drier climate. Vegetation also changed in response to the climatic shift. Generally this transition was from coniferous woodland to grasslands and eventually to the present day desert scrub. Pre-Columbian people occupying this region adapted by changing from hunter-gatherer to largely agrarian economies. During this time the level of cooperation among people apparently increased as shown by the formation of pueblos (cities) and greater trade among diverse regions. This increase in cooperation probably resulted as a response to increasing aridity and more frequent droughts. Recent European immigration into the southwest U.S. beginning in the mid 1500s greatly affected this region. The greatest impact occurred after the U.S. Civil War in the 1860s. Before the 1860s land use tended to be localized around small agricultural areas, mines, and military installations. After the war, however, the range livestock industry expanded dramatically, especially in the 1880s. During this time grazing land was viewed as limitless, but as H.L. Bentley stated in 1898, "... grasses were entirely consumed; their roots were trampled into the dust.. ." This period represents a time of general abuse of arid lands in the region. Recognition of the abuse and the deteriorating productivity of the land led to greater government involvement, including establishing experimental stations and eventually managing of the public domain by governmental agencies. Despite improved land management, desertification processes continue. Continued livestock grazing, changing climatic conditions, soil loss, and increasing atmospheric CO2 concentrations (mainly due to the burning of fossil fuels) are among the probable causes of current desertification trends. Urban and rural populations, now technologically isolated from their environment, need to better understand the dynamic nature of their environment and adapt to these conditions to lessen the human influ-snce on the desertification process. A greater degree of cooperation among diverse entities will be crucial.}, author = {E.L. Fredrickson and Kris Havstad and Richard E. Estell and P.W. Hyder} } @article {51330, title = {Low-cost seeding practices for restoring desert environments (New Mexico)}, journal = {Restoration and Management Notes}, volume = {14}, year = {1996}, month = {1996}, pages = {72-73}, abstract = {

Over the past 120 years, the grasslands of the northern Chihuahuan desert have been converted to shrublands dominate by species such as mesquite (Prosopis spp.). Unfortunately, attemptsto restore these grasslands have often been unsuccessful despite substantial expenditures of money, labor, and fossil fuels. At the Jornada Experimental Range, we have recently begun to test low-input restoration technologies in an attempt to remedy this situation. One aspect of this program focuses on the use of both water and animals to deposit viable seeds into favorable micro-sites.

}, url = {/files/bibliography/480.pdf}, author = {E.L. Fredrickson and J.R. Barrow and Jeffrey E. Herrick and Kris Havstad and Longland, B.} } @conference {51331, title = {Working together to restore desert rangelands}, booktitle = {International Conference, Society for Ecological Restoration}, year = {1996}, month = {June 17-22, 1996}, pages = {54}, address = {New Brunswick, NJ}, abstract = {We have formed a partnership with local ranchers, environmental groups and government agencies to develop restoration technologies for desertified arid lands. The USDA Agricultural Research Service, Jornada Experimental Range, is a 78,266-hectare desert laboratory located in the northern Chihuahuan Desert. During the last 100 years, much of this area has undergone a transition from desert grasslands to desertified shrublands, a trend that is occurring in most of the world{\textquoteright}s arid lands. In addition to research examining basic ecosystem function, we have set aside 8,259 hectares to be managed by ranchers working with local environmental organizations. Presently, this group is using knowledge of desert ecosystems to create low-cost, restoration technologies for arid lands. Current projects are designed to promote natural restoration processes and include: (1) targeted application or organic waste to enhance soil stability and productivity, (2) placement of watering points that provide a seed source while attracting seed-dispersing wildlife, (3) creation of predator habitat to reduce herbivore pressure during vegetation establishment.}, author = {E.L. Fredrickson and Jeffrey E. Herrick and Kris Havstad and J. A. Winder} } @article {51388, title = {Potential toxicity and feed value of onions for sheep}, journal = {Livestock Production Science}, volume = {42}, year = {1995}, note = {Reprinted with permission from Elsevier, Copyright {\textcopyright} 1995. (http://www.sciencedirect.com/science/journal/03016226)}, month = {1995}, pages = {45-54}, abstract = {

The feeding, ruminal effects and potential toxicity of cull onions bulbs (Allium cepa) was compared to whole sorghum grain for growing wethers. In Expt. 1, 56 Polypay X Rambouillet wethers (avg. initial BW of 32.7 {\textpm} 0.88 kg) were assigned randomly to one of four dietary treatments (dry matter basis): (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\% was pelleted alfalfa (19\% CP). All wethers were group fed (seven wethers per pen; two replicates per treatment) for 6 weeks. Weight gain during the trial did not differ (P\> 0.05) among treatments. Packed cell volume tended to be less (P = 0.057) for the 33\% and 50\% onion groups during weeks 1 and 2, and was less (P\< 0.0001) for the same groups during week 3 (34, 33, 29 and 29\% for CON, 17, 33 and 50\%, respectively). Serum lactate dehydrogenase was increased (P\< 0.05) at weeks 3 and 6 in sheep on the 33\% and 50\% onion treatments. During Expt. 2, 15 ruminally cannulated wethers were individually fed diets similar to those Expt. 1, except onions were fed to replace sorghum grain to provide 0, 25 and 50\% of the dietary DM as onions. Ruminal fluid (P\> 0.05) and particulate passage (P\> 0.05) were not altered by feeding onions. Water intake by drinking decreased (P\< 0.0001) as percentage of onions in the diet increased, whereas total water intake (drinking and fed) increased (P\< 0.0001). Effects of onions on volatile fatty acid concentrations and ruminal pH were minimal (P\< 0.05), whereas ruminal ammonia-N concentration was greater (P\< 0.05) in wethers fed onions. We conclude that under conditions similar to those in our study, onions can be fed safely to sheep with weight gains comparable to those from whole sorghum grain.

}, keywords = {Allium cepa, digestion, sheep}, doi = {10.1016/0301-6226(94)00066-G}, url = {/files/bibliography/442.pdf}, author = {E.L. Fredrickson and Richard E. Estell and Kris Havstad and Shupe, W. Larry and L. W. Murray} } @article {51443, title = {Effects of chronic ingestion of tarbush (Flourensia cernua) on ewe lambs}, journal = {Veterinary and Human Toxicology}, volume = {36}, number = {5}, year = {1994}, month = {1994}, pages = {409-415}, abstract = {

Efforts to increase livestock utilization of tarbush are being coupled with studies to examine tarbush toxicity. Thirty-eight (19/treatment) ewe lambs were assigned at birth to receive either tarbush or alfalfa (15\%, dry matter basis) in a sorghum-based growing ration. Lambs were pen-fed this diet 60 d pre-weaning and 60 d post-weaning. No differences existed between treatments in feed consumption. In the tarbush group, 1 lamb died of unknown causes at 90 d of age, while 3 lambs died between 115 and 120 d of age. There were no deaths in the alfalfa group. Shortly before death, lambs fed tarbush appeared lethargic, disoriented and anorectic. At 122 d of age, 5 lambs were randomly selected from each group. Feces and jugular blood samples were obtained from each lamb before being euthanized and necropsied the following day. All fecal samples were negative for occult blood. Serum gamma glutamyl-transpeptidase (P\  \<\  0.001) and aspartate aminotransferase (P\  \<\  0.001) activities and platelet counts (P\  \<\  0.05) were elevated in lambs fed tarbush, while serum calcium concentrations tended (P\  \<\  0.10) to be greater. Histologic examination revealed diffuse liver apoptosis in lambs fed tarbush. These data indicate tarbush leaves cause liver damage when fed for extended periods of time.

}, keywords = {chronic ingestion, ewe lambs, Flourensia cernua, tarbush}, url = {/files/bibliography/421.pdf}, author = {E.L. Fredrickson and Thilsted, J.P. and Richard E. Estell and Kris Havstad} } @conference {51482, title = {Animal and shrub interactions: Developing a tarbush model}, booktitle = {8th Wildland Shrub and Arid Land Restoration Symposium}, year = {1993}, month = {1993}, pages = {Abstract 7}, address = {Las Vegas, NV}, abstract = {Large areas of the Chihuahuan Desert are undergoing a transition from semiarid grassland to desert scrub. The role of mammalian herbivores in mediating this transition has been suggested but has not been adequately described. A better understanding of plant-animal interactions may assist in developing animal-based technologies to increase shrub use while mediating vegetational change. Tarbush (Flourensia cernua), an aromatic shrub rapidly invading productive range sites, was used as a model to examine the influence of leaf surface compounds on the use of tarbush by domestic sheep. Additional studies also were designed to examine the digestive and physiological consequences of ingestion of tarbush leaves. Results from these studies indicate: (1) dietary preference is influenced by either epicuticular waxes or a component of the wax, (2) intraspecific variation of epicuticular chemistry varies both temporally and spatially, (3) nutrient concentrations are similar to alfalfa, (4) ruminal fermentation patterns are altered by inclusion of tarbush in grass diets, and (5) toxicosis can result from chronic consumption of tarbush leaves. Interpretation of these data suggest controlled use of tarbush by sheep is possible, but use of sheep to mediate desired vegetational change may be limited.}, author = {E.L. Fredrickson and Richard E. Estell and Kris Havstad} } @conference {51480, title = {Effect of chronic ingestion of tarbush (Flourensia cernua) on the serum chemistry, occult blood and histopathology of ewe lambs}, booktitle = {Annual Meeting, Society for Range Management}, year = {1993}, month = {1993}, pages = {130}, abstract = {

Current efforts to increase livestock utilization of tarbush have been coupled with studies to examine potential tarbush toxicity. To examine the effects of long term ingestion of tarbush by lambs, 38 (19/treatment) ewe lambs were assigned at birth to receive either tarbush or alfalfa (15\%, dry matter basis) in a sorghum-based pelleted creep feed. Lambs were pen-fed this diet 60 days pre-weaning and 60 days post-weaning. No differences existed between treatments in feed consumption. One Iamb died of unknown causes at 90 days of age, while three lambs died between US and 120 days of age. There were no deaths in the alfalfa group. Prior to death lambs appeared lethargic, disoriented and anorectic. At 122 days of age, five Iambs from each treatment were randomly selected from the remaining lambs. Fcces and jugular serum samples were obtained from these animals before necropsy the following day. All fecal samples were negative for occult blood. Serum creatine kinase (P \< .05), gamma glutamyl-transfcrase (P \< .01), aspartate aminotransfcrase (P \< .01), lactate dehydrogenase(P \< .01) and total cholesterol (P \< 0.5) concentrations were elevated in lambs fed tarbush, while conjugated bilirubin concentrations and platelet counts tended (P \< 0.1) to be elevated. Histologic examinations revealed myopathic lesions and diffuse apoptotic liver necrosis in lambs fed tarbush. Interestingly, four out of five lambs fed alfalfa had renal and urinary calculi, while calculi were not found in lambs fed tarbush. These data indicate tarbush will cause muscle and liver damage, with possible secondary cholcstasis when fed for extended periods of time.

}, keywords = {chronic ingestion, ewe lambs, histopathology, occult blood, serum chemistry}, author = {E.L. Fredrickson and Thilsted, J.P. and Richard E. Estell and Shupe, W. Larry} } @article {51483, title = {Effects of four cereal grains on intake and ruminal digestion of harvested forage by beef steers}, journal = {Animal Feed Science and Technology}, volume = {40}, number = {2-3}, year = {1993}, note = {Reprinted with permission from Elsevier, Copyright {\textcopyright} 1989. (http://www.sciencedirect.com/science/journal/03778401)}, month = {January 1, 1993}, pages = {93-107}, abstract = {

Effects of grain supplements on intake and digestion of roughage diets have been studied extensively, but studies comparing these effects among different grains are limited. Our experiment compared the effects of four cereal grains on roughage intake and ruminal digestion. Five separately penned ruminally cannulated beef steers (average body weight (BW) 194 kg) were used in a 5 {\texttimes} 5 Latin square design; treatments included prairie hay, or prairie hay plus supplemental barley, corn, sorghum or wheat. Each grain was dry rolled and fed to provide 0.25\% BW as starch to a basal diet of prairie hay (in vitro organic matter digestibility, 56 g 100 g-1; crude protein, 10.8 g 100 g-1 of organic matter). Urea was added to grains to ensure that supplements were isonitrogenous. Grain supplementation did not affect (P\> 0.10) hay organic matter intake, although digestible organic matter intake was increased (P\< 0.10) by supplementation. Ruminal pH was not affected (P\> 0.10) by grain supplementation. Ruminal ammonia-nitrogen was increased (P\< 0.10) by grain supplements containing urea (barley, corn, and sorghum). Ruminal fluid volume and dilution rate was not affected (P\> 0.10) by grain supplementation, nor were particulate passage rate, ruminal or intestinal retention time, or gastrointestinal dry matter fill. Total tract mean retention time was decreased (P\< 0.10) by barley, corn and wheat supplementation, but unaffected (P\> 0.10) by sorghum. A treatment {\texttimes} sampling time interaction (P\< 0.05) was detected for proportions of ruminal acetate and propionate. Acetate was decreased (P\< 0.01) by barley and increased (P\< 0.01) by sorghum. 4 h after supplementation. At 8 h after supplementation, wheat decreased (P\< 0.10) acetate proportions, while sorghum increased acetate proportions (P\< 0.01). Propionate proportions were not affected (P\> 0.10) by treatments. Wheat supplementation increased (P\< 0.01) ruminal butyrate at 2 and 12 h after supplementation, but sorghum decreased butyrate proportions at 2, 8 and 12 h after supplementation. Barley increased (P\< 0.10) total volatile fatty acid (VFA) concentrations at 4 h after supplementation, but VFA concentrations were not affected by other grains. Grain supplementation increased (P\< 0.10) in sacco organic matter disappearance of prairie hay at 48 h of incubation. We conclude that grain supplementation, to provide 0.25\% of BW as starch, did not affect hay intake adversely, and slightly increased in sacco digestion of hay organic matter. More readily fermentable grains (barley and wheat) affected ruminal VFA proportions and concentrations.

}, doi = {10.1016/0377-8401(93)90149-E}, url = {/files/bibliography/402.pdf}, author = {E.L. Fredrickson and Galyean, M.L. and Cheema, A.U. and Beaty, R. and Byrum, G.} } @article {51479, title = {Influence of ruminally dispensed monensin and forage maturity on intake and digestion}, journal = {Journal of Range Management}, volume = {46}, number = {3}, year = {1993}, note = {Permission to post articles granted by the Society for Range Management; www.rangelands.org.}, month = {1993}, pages = {214-220}, abstract = {

Eight ruminally cannulated crossbred steers (average weight 336 kg) grazing native blue grama (Bouteloua gracilis\  [H.B.K.]) rangeland were used in a repeated measures design to evaluate effects of monensin ruminal delivery devices (MRDD) and forage phenology on ruminal digestion.\  Three periods were assessed: mid-August (Aug.), early October (Oct.), and mid-November (Nov.).\  One MRDD was placed in the reticulum of 4 steers via the ruminal cannula 21 days before each period.\  Intake was estimated using total fecal collections.\  Diet samples were collected using 3 esophogeally fistulated steers. Ruminal fill was measured by ruminal evacuation; rate and extent of in situ ruminal neutral detergent fiber disappearance were estimated before ruminal evacuations.\  Ruminal passage rates, retention time, and apparent total tract organic matter digestibility were estimated using indigestible neutral detergent fiber.\  In vitro organic matter disappearance of esophageal masticate did not differ (P\>.05) in Aug. and Oct. (average of 53.7\%), but declined (P\<.05) in Nov. (48.7\%), whereas organic matter digestibility was greater (P\<.10) in Aug. (62.3\%) than in either Oct. (55.2\%) or Nov. (53.9\%).\  Release of monensin from the bolus (68 mg day-1) was less than expected (100 mg day-1).\  Intake, organic matter digestibility, ruminal passage rates, retention time, pH, and ammonia were not affected (P\>.10) by MRDD.\  In situ neutral detergent fiber disappearance at 96 hours was decreased (P\<.10) by MRDD (68 vs 65\% for control and MRDD, respectively).\  As the grazing season progressed, intake declined (P\<.10), whereas ruminal fill and retention time increased (P\<.05), and passage rate of indigestible neutral detergent fiber decreased (P\<.05). At 48 hours in situ neutral detergent fiber was greatest (P\<.05) in Aug. and least (P\<.05) in Nov.

}, keywords = {beef, cattle, digestion, forage quality, rangeland}, url = {/files/bibliography/401.pdf}, author = {E.L. Fredrickson and Galyean, M.L. and Branine, M.E. and Sowell, B.F.} } @conference {51481, title = {Use of domestic animals as biological control agents of desert shrubs: Problems and promise}, booktitle = {4th Symposium on the Chihuahuan Desert Region: US and Mexico}, year = {1993}, month = {1993}, pages = {11}, abstract = {Inseparable anthropogenic and nonanthropogenic factors have altered the dynamics and form of the Chihuahuan Desert. This alteration is characterized by replacement of desert grasslands with shrub species. When this change is viewed as deleterious, few remedial technologies are available either because of economics or potential ecological constraints. In conjunction with skillful management, domestic animals may provide an accessible bioremediation tool that provides additional nutritional and economic benefits. Attempts to use domestic animals to facilitate vegetational change have been successful; however, failures often occur because of animal rejection of target plants. Aspects of animal preference, plant palatability, and plant toxicity are causes of this rejection that may be biochemically mediated. Focusing on carbon-based phytochemicals within tarbush (Flourensia cernua), we have documented substantial temporal and spatial variability in plant phytochemistry while identifying compounds suspected to influence plant palatability. Furthermore, we have observed considerable variation in animal preference for tarbush within and among animal species. Although chemo- and electromagnetic receptors are generally considered to affect animal preference, we provide evidence that preference is also affected by visceral afferents which signify hepatic toxicosis. Examining plant-animal interactions from a biochemical perspective will enhance our understanding of vegetation change and development of potential restorative technologies.}, keywords = {biological control agents, desert shrubs, domestic animals}, author = {E.L. Fredrickson and Richard E. Estell and Kris Havstad} } @article {51521, title = {Feeding cull onions: The {\textquoteright}ins{\textquoteright} and {\textquoteright}outs{\textquoteright}}, journal = {Sheep Magazine}, year = {1992}, month = {October 1, 1992}, pages = {17,32}, abstract = {

The most costly aspect of any sheep operation is the cost associated with feed. Because of this, a resourceful operator is always looking for ways to cut feed costs as a means of increasing profits. One potential source of low cost, good quality, feed is cull onions.

}, url = {/files/bibliography/383.pdf}, author = {E.L. Fredrickson} } @article {51522, title = {Feeding cull onions to sheep}, journal = {Ranch Magazine}, year = {1992}, month = {October 1, 1992}, pages = {44}, abstract = {Several years ago during a visit to the Las Cruces city landfill, we saw a small mountain of cull onions with several pickups parked around it. People were climbing over the pile looking for the best onions to load in their pickups to either eat or sell. While watching the people sort through the onions we wondered if we could use onions as a livestock feed. Sometime later we searched various journals to learn what is currently known about feeding cull onions to livestock. To our surprise, there was very little information. Most all the articles available only described a condition termed "oxlion poisoning," a condition where sulfur compounds in onions cause red blood cells to loose their ability to carry oxygen and eventually the red blood cells die. Despite these reports in the literature, we knew of a few sheep producers who were feeding cull onions. It became obvious to us that research designed to determine the amount of onions that could safely be fed to sheep might be useful to sheep producers and onion growers alike. Onions are potentially an inexpensive feed. Also, cull onions reentering the market place negatively affect market demand for onions and onion prices. With aid from the New Mexico Dry Onion Commission, we completed two studies using sheep.}, keywords = {cull onions, inexpensive feed, livestock feed, oxlion poisoning, sheep}, url = {/files/bibliography/384.pdf}, author = {E.L. Fredrickson and Shupe, W. Larry} } @proceedings {51563, title = {Effects of monensin supplementation on grazing beef cattle}, volume = {70 (12)}, year = {1991}, month = {1991}, pages = {6-7}, author = {E.L. Fredrickson and Galyean, M.L.} }