Thesis (Ph. D.)--University of Wisconsin--Madison, 1949. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 53-55).

Thesis (M.A.)--Utah State University, 2008. / Title from title screen (viewed Dec. 15, 2008). Department: History Includes bibliographical references. Archival copy available in print.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 86-93). Also available on the World Wide Web.

Three experiments were conducted to determine the effects of source (experiment 1), frequency, and level (experiments 2 and 3) of energy supplementation on performance, forage utilization and intake, productivity, rumen fermentation, and nutrient digestibility of growing beef cattle fed stockpiled forage. In experiment 1 (EXP1) and experiment 2 (EXP2), 45 cross bred yearling steers were managed on stockpiled crested wheatgrass pasture over 70 days during summer/fall of 2011 and 2012. Steers were stratified by IBW (EXP1 = 334±1.2 kg; EXP2 = 358±1.8 kg) and allocated randomly to 1 of 9 crested wheatgrass pastures (5 steers/pasture). Each pasture was randomly assigned to 1 of 3 replicated (n = 3) treatments. In EXP1, two isonitrogenous and isocaloric by-product feed pellets that differed in starch and degradable fiber content were used in one of three supplementation strategies: 1) no supplement (CON), or supplemented at 0.6 % of BW with 2) low starch/high fibre (LS/HF) pellet (40.3% starch; 29.5% NDF DM basis) pellet, or 3) high starch/low fibre (HS/LF; 48.6% starch; 22.8% NDF DM basis) pellet. In EXP2 a by-product feed pellet was formulated to provide ruminal and post-ruminal energy (30.3 % NDF; 32.0 % starch; 7.2 % fat) supplementation strategies included: 1) daily (DLY) supplementation at 0.6 % of BW, 2) low-alternate (LA) supplementation at 0.9 % of BW, and 3) high-alternate (HA) supplementation at 1.2 % of BW. There was no effect (P > 0.05) of treatment on forage utilization in either experiment. In EXP 1, final BW and ADG were not different (P > 0.05) between LS/HF (435 kg; 1.4 kg d-1) and HS/LF (439 kg; 1.5 kg d-1). However, supplemented cattle had higher (P < 0.05) final BW and ADG than CON cattle (402 kg; 1.0 kg d-1). Supplementation increased production costs by 450 %. In EXP 2, no difference (P > 0.05) was observed for final BW and ADG among DLY (435 kg; 1.1 kg d-1), LA (424 kg; 0.9 kg d-1), and HA (428 kg; 1.0 kg d-1). Production costs were reduced by 23 % with alternate supplementation and LA had 19 % less production costs than HA. In experiment three (EXP 3), four ruminally cannulated beef heifers were individually fed a stockpiled grass hay and offered the same pelleted supplement as in EXP2. Treatments consisted of 4 supplementation strategies: 1) no supplement (CON), 2) daily (DLY) supplementation at 0.6% BW, 3) low-alternate (LA) supplementation at 0.9 % of BW, and 4) high-alternate (HA) supplementation at 1.2 % of BW. Forage intake, rumen fermentation parameters, and apparent total tract digestibility were measured. Three data sets were analyzed: 1) overall (average of all collection days), 2) day of supplementation (DS) and 3) non-supplementation day (NSD) for alternating treatments. Overall, hay DMI (kg d-1) was lower (P = 0.04) for DLY (7.1) vs. CON (8.1), but no different (P ≥ 0.11) for DLY vs. LA (6.9), or vs. HA (6.4). On DS, hay DMI (kg d-1) of DLY (7.3) differed (P < 0.05) vs. HA (6.0), but was not different (P = 0.16) vs. LA (6.4). On NSD, hay DMI (kg d-1) of DLY (7.0) was not different (P ≥ 0.48) to those of LA (7.3) and HA (6.9). Overall, total VFA concentration (mM) was lower (P < 0.01) for CON (69.2) vs. DLY (77.1); but not different (P ≥ 0.45) for DLY vs. LA (75.8) or HA (75.1). Rumen NH3 (mg/dL) was lower (P < 0.01) for CON (3.4) and higher (P < 0.01) for LA (5.8) vs. DLY (4.6), but not different (P = 0.37) for DLY vs. HA (4.3). Overall, ruminal pH was lower (P ≤ 0.04) for DLY (6.65) vs. CON (6.75) and HA (6.72), but similar (P = 0.18) for DLY vs. LA (6.70). On DS, ruminal pH was lower (P = 0.04) for HA (6.59) vs. DLY (6.64), but higher (P < 0.01) on NSD for HA (6.85) vs. DLY (6.67). Apparent DM, OM and GE digestibility coefficients were lower (P ≤ 0.03) for CON and LA vs. DLY, but no difference (P ≥ 0.36) for DLY vs. HA. These results indicate that beef steers grazing stockpiled crested wheatgrass were limited in energy intake and that supplementation of metabolizable energy improved animal performance regardless of the source of energy. Reducing the frequency of energy supplementation and level offered on alternate days do not affect animal performance and reduces the production costs of the system. Negative effects of alternate day supplementation on forage intake and rumen fermentation are reduced when a lower level is offered relative to simply doubling the daily amount of supplement.

No description available.

Agropyron scribneri Vasey (spreading wheatgrass) is endemic to the Rocky Mountains of the Intermountain West. Each distinct population is widely separeated by valley and desert floors. It is morphologically similar to the hybrid between Agropyron trachycaulum (Link) Malte and Sitanion hystrix between Agropyron trachycaulum (Link) Malte and Sitanion hystrix (Nutt.) J. G. Smith as well as the hybrid, A. trachycaulum x A. scribneri. It appears that A. scribneri may have originated de novo from hybidization products of A. trachycaulum and S. hystrix. Agropyron scribneri appears to be morphologically similar to the population of S. hysterix with which it is associated. There is some fertility in the A. trachycaulum x S. hysterix hybrids, and back-crossing onto both A. trachucaulum and S. hysterix is common. Sterile backcross derivatives, (A. trachycaulum x S. hysterix) x S. hysterix, were found which possess characters similar to A. scribneri and which phenotypically resemble A. scribneri. These are considered to be stabilized hybrid segregants which indicate that the incipient formation of A. scribneri is in progress.

Thesis (M. Sc.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on Jan. 22, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Ecology, Department of Biological Sciences, University of Alberta. Includes bibliographical references.

Cheatgrass is an invasive weed that has come to dominate large areas of the western United States. Once an ecosystem has been converted to a cheatgrass monoculture, it is extremely difficult to restore native vegetation. Cheatgrass negatively impacts wildlife and increases wildfire frequency and intensity. Understanding how cheatgrass so effectively invades western ecosystems is essential to turning the tide of invasion. One possible key to cheatgrass’ success is alteration of soil nutrient cycling. The goal of this study is to explore how nitrogen (N) may accumulate in cheatgrass soils via redistribution of N within soil N pools. To accomplish this we investigated soil N cycling in soils underneath cheatgrass and crested wheatgrass. We used a 15N isotope tracer to determine the contribution of root exudates to soil N pools. During the 1-week 15N tracer experiment, cheatgrass roots exuded more than twice as much N (0.11 mg N kg-1 soil d-1) as crested wheatgrass roots (0.05 mg N kg-1 soil d-1). We propose that exudation of high N content root exudates leads to the changes in soil N pool size and transformation rates commonly observed in soils under cheatgrass. This research uses a simple and relatively inexpensive isotope tracer to shed light on mechanisms by which invasive plants may alter soil processes. By understanding these mechanisms we may be able to develop strategies for better managing cheatgrass invasion.

The free-roaming ruminant requires energy for the demands of vii grazing, traveling and thermoregulation that are not required by its confined counterpart. Literature estimates of these additional costs range from 10 to 170 percent above maintenance. The uncertain magnitude of this increased demand and the factors that contribute to it impede the ability of the rangeland ruminant nutritionist to establish guidelines for the energy requirements of the free-roaming herbivore. This study was designed to estimate the energy expenditure of yearling Angus heifers while grazing a declining supply of available crested wheatgrass forage (Agropyron cristatum) on rangeland in west-central Utah. Free-ranging energy expenditure was estimated twice for four heifers during each of five ten-day periods during June, July August and early September, 1979. These estimates were obtained using the carbon dioxide entry rate technique. In addition, total fecal output, dietary crude protein and dietary in vitro organic matter digestibility were estimated for animals grazing the 20- hectare crested wheatgrass pasture. From these data, daily forage intake was calculated. The level of available forage during each period was estimated using the ocular weight-estimate technique applied on forty 1 m2 circular plots. Energy expenditure was estimated as 161 (with a confidence interval of ±43) kcal·kg body weight-.75.d-1 (n=10), and was independent of the decline in available forage from 880 to 284 kg dry matter·hectare-1 that occurred over the course of the grazing season. Daily intake was 54.5 grams (organic matter basis) per unit body weight.75 for the 305 kg heifers. Daily intake was independent of the supply of available forage. During early July, 1980, crested wheatgrass was harvested as hay and fed to 260 kg yearling Angus heifers in metabolism stalls in a thermoneutral and constantly illuminated laboratory. Daily feeding levels were set at 54.5 grams (organic matter basis) per unit body weight.75. Energy expenditure under these conditions was estimated as 111 (±12) kcal·kg body weight-.75·day-1 , 6 kcal per unit body weight.75 greater than the mean estimate of the fasting metabolism rate. The latter estimate was obtained following a 48-hour fast. These estimates of maintenance and fasting metabolism were combined to provide a mean estimate of 110 (±10) kcal·kg body weight-.75·day-1 (n=14). Of the 45 percent (51 kcal·kg body weight-.75·day-1) increase in the estimated energy expenditures by heifers under free-roaming conditions, 50 percent was attributed to the energetic cost of grazing. A daily average 9.2 hours were spent in this activity. The energetic cost of grazing was assumed as 0.82 kcal·kg body weight-1·hour-1 spent grazing. Daily travel was estimated as 3.9 km at an assumed energetic cost of 0.58 kcal·kg body weight-1·km-1. This accounted for a 20 percent estimated increase in energy expenditure. Average daily temperatures were generally between 12°C and 30°C and thermoregulatory demands were not considered as a substantial energetic expense. The remaining 30 percent (12 kcal) of the additional increment due to free-roaming conditions could not be explained.

Complementary greenhouse and field studies investigated the effects of ambient environmental conditions on cattle dungpat moisture, temperature, nutrient concentration, and crust formation dynamics, which in turn influence seed germination and seedling establishment in dungpats. 'Hycrest' crested wheatgrass [Agropyron desertorum (Fisch. ex Link) X A. cristatum (L.) Gaert.] was used as a representative revegetation species. After collecting feces from Holstein steers that had been fed crested wheatgrass seeds, uniform dungpats were prepared and placed on two soil types (loam and coarse sand) in containers under three watering treatments (field capacity, 1/2 field capacity, and no water) in the greenhouse. Dungpat and underlying soil microenvironmental factors, and germination and seedling development, were monitored for 14 weeks. Moisture and temperature were favorable for germination during the first 4 weeks, but increasing crust thickness prevented most of the developing seedlings from emerging from dungpats. Seedling emergence, development, and survival were greatest at the peripheral region of dungpats on the loam soil at moisture contents of 1/2 field capacity or higher. Uniform dungpats containing passed seeds and unpassed seeds were placed on a silt loam soil in the field in the spring (late April 1993) under natural and above-normal precipitation regimes and in the fall (late October 1993) under natural precipitation. Unpassed seeds were also broadcast and drill-seeded into soil seedbeds at the same times. Microenvironmental factors and germination and plant establishment were monitored for 49 weeks in the spring experiment and 17 weeks in the fall experiment. For dungpat treatments, seedling emergence and survival were greater for unpassed than passed seeds in both precipitation regimes; however, sufficient numbers of seedlings established from passed seeds, and these plants had greater biomass and similar or greater seed production than plants from unpassed seeds. Slight changes in nutrients in dungpats and underlying soil indicated that partial decomposition and mineralization of dungpats had occurred by the end of the spring experiment. Both studies indicate that dungpat microenvironmental factors are greatly influenced by ambient moisture, temperature, and insolation, and by the nature of the underlying soil. These studies support the claim that plants established in dungpats could serve as nuclei of seed production for surrounding areas.