Nafus A.M.,Oregon State University |
Davies K.W.,Eastern Oregon Agricultural Research Center
Invasive Plant Science and Management | Year: 2014
The spread of medusahead across the western United States has severe implications for a wide range of ecosystem services. Medusahead invasion reduces biodiversity, wildlife habitat and forage production, and often leads to increased fire frequency and restoration costs. Medusahead is problematic in the Intermountain West and California Annual Grasslands. The last review of medusahead ecology and management was completed 20 years ago. Since the last review, there have been scientific advances in medusahead management suggesting a significant need to develop an up-to-date synthesis. Medusahead continues to pose a serious threat to rangeland ecosystems. In this synthesis, we present new information regarding the ecology of medusahead, suggest a framework for managing medusahead based on invasion level, and identify research needs to further improve management of this invasive annual grass. Success of different management practices varies between the Intermountain West and California Annual Grasslands, signifying that the best management practices are those specifically tailored with consideration of climate, soil, plant community characteristics, and management objectives. Prevention and control treatments that are useful in the Intermountain West may not be practical or effective in the California Annual Grasslands and vice-versa. Nomenclature: Medusahead, Taeniatherum caput-medusae (L.) Nevski; ELYCM.
Johnson C.G.,U.S. Department of Agriculture |
Vavra M.,U.S. Department of Agriculture |
Willis M.,Eastern Oregon Agricultural Research Center |
Parks C.G.,U.S. Department of Agriculture
Rangelands | Year: 2013
On the Ground Managers charged with managing landscapes influenced by elk are challenged to establish monitoring protocols that identify when impacts are responsible for declining ecological condition. We assessed the impact of elk herbivory on plant communities on an elk winter range by comparing canopy cover of common species that represented subjectively selected heavy and light elk impacts. Winter elk use has little direct impact on existing bunchgrasses, but winter elk traffic disrupts soils and provides the potential for invasive plant establishment. © 2013 by the Society for Range Management.
Tanaree D.D.,Oregon State University |
Duringer J.M.,OSU |
Bohnert D.W.,Eastern Oregon Agricultural Research Center |
Craig A.M.,11 Veterinary Research Laboratory
World Mycotoxin Journal | Year: 2013
'Fescue toxicosis' is a disease in livestock caused by ingestion of ergot alkaloids produced by the fungal endophyte Neotyphodium coenophialum in tall fescue; it is estimated to cost 1 billion USD in damages per year to the beef industry alone. Clinical signs include decreased reproductive fitness, necrosis of extremities, and reduced average daily gain and milk production. Little is known about the cellular mechanisms that mediate these toxic sequelae. We evaluated the effects of ergovaline-based fescue toxicosis on gene expression via oligonucleotide microarray. Liver biopsies were obtained from steers (n=4) pre- and post-exposure (0 and 29 days) to feed containing 579 ng/g ergovaline. Analyses were performed using both ANOVA with false discovery rate correction and Storey's optimal discovery procedure. Overall, down-regulation of gene expression was observed; heart contraction and cardiac development, apoptosis, cell cycle control, and RNA processing genes represented the bulk of differentially expressed transcripts. 2 CYPs (CYP2E1 and CYP4F6) were amongst the significantly upregulated results. Thus, exposure of cattle to toxic levels of ergovaline caused widespread changes in hepatic gene expression, which can both help explain macroscopic clinical signs observed in ruminant animals, and reinforce previous findings in monogastric models.
Mueller C.J.,Oregon State University |
Mueller C.J.,Eastern Oregon Agricultural Research Center |
Sexson C.,Oregon State University |
Mills R.R.,Oregon State University
Professional Animal Scientist | Year: 2013
Sixty-four (224 ± 33 kg) Angus-cross calves were stratified by BW and sex and then randomly allotted to one of four 35-d preconditioning diets to evaluate the effect of supplemental vitamin E with or without dietary oil on BW gain and carcass characteristics. Diets were based on ad libitum grass hay (6.2% CP) and the following concentrates: corn and soybean meal only (CON), CON plus vitamin E (VITE), VITE plus 1.5% safflower oil (ELA), or VITE plus 1.5% flaxseed oil (ELNA). Vitamin E amounts were targeted for 150 IU/kg of total DMI (supplement plus hay). Following preconditioning, calves were shipped to a commercial feedlot and received a modified-live intranasal vaccine against infectious bovine rhinotracheitis and parainfluenza-3 following arrival to stimulate immune activity. Blood samples were obtained before transit and 30 d posttransit to quantify glucose and antibody titers. Data were evaluated as a randomized complete block design with sex as block using the preplanned contrasts of CON versus VITE, VITE versus oil (mean of ELA and ELNA), and ELA versus ELNA. No differences (P. >. 0.10) were observed for either preconditioning or feedlot ADG or for any carcass traits. Morbidity rates were less than 1% and consistent across treatments. No differences (P. >. 0.10) were observed for infectious bovine rhinotracheitis, parainfluenza-3, or IgM antibody titer concentrations across treatments. Preconditioning diets containing 150 IU of vitamin E/kg of DMI, regardless of oil, showed limited to no change in performance, immune, or carcass characteristics of weaned beef calves. © 2013 American Registry of Professional Animal Scientists.
Davies K.W.,U.S. Department of Agriculture |
Bates J.D.,U.S. Department of Agriculture |
Nafus A.M.,Eastern Oregon Agricultural Research Center
Rangeland Ecology and Management | Year: 2012
A decrease in fire frequency and past grazing practices has led to dense mountain big sagebrush (Artemisia tridentata Nutt. subsp. vaseyana [Rydb.] Beetle) stands with reduced herbaceous understories. To reverse this trend, sagebrush-reducing treatments often are applied with the goal of increasing herbaceous vegetation. Mechanical mowing is a sagebrush-reducing treatment that commonly is applied; however, information detailing vegetation responses to mowing treatments generally are lacking. Specifically, information is needed to determine whether projected increases in perennial grasses and forbs are realized and how exotic annual grasses respond to mowing treatments. To answer these questions, we evaluated vegetation responses to mowing treatments in mountain big sagebrush plant communities at eight sites. Mowing was implemented in the fall of 2007 and vegetation characteristics were measured for 3 yr post-treatment. In the first growing season post-treatment, there were few vegetation differences between the mowed treatment and untreated control (P>0.05), other than sagebrush cover being reduced from 28% to 3% with mowing (P<0.001). By the second growing season post-treatment, perennial grass, annual forb, and total herbaceous vegetation were generally greater in the mowed than control treatment (P<0.05). Total herbaceous vegetation production was increased 1.7-fold and 1.5-fold with mowing in the second and third growing seasons, respectively (P<0.001). However, not all plant functional groups increased with mowing. Perennial forbs and exotic annual grasses did not respond to the mowing treatment (P>0.05). These results suggest that the abundance of sagebrush might not be the factor limiting some herbaceous plant functional groups, or they respond slowly to sagebrush-removing disturbances. However, this study suggests that mowing can be used to increase herbaceous vegetation and decrease sagebrush in some mountain big sagebrush plant communities without promoting exotic annual grass invasion.