Thesis (Ph. D.)--Oregon State University, 1997. / Typescript (photocopy). Includes bibliographical references (leaves 219-230). Also available online.

Project (M.B.A.) - Simon Fraser University, 2004. / Theses (Faculty of Business Administration) / Simon Fraser University. MBA-GAWM Program. Senior supervisor: Dr. Robert R. Grauer.

This project was divided into two studies. The first investigated the pharmacokinetics of imipramine hydrochloride (IMI) in bulls. IMI was administered intravenously to three bulls (600-705.5 kg) at a dose of 2mg/kg body weight (BW). Intravenous plasma concentrations of IMI over time were determined by fluorescence polarization immunoassay (FPIA). IMI plasma concentration versus time profile was best described by a two compartmental open model with first-order rate constants. IMI distributed rapidly, (t½<font face="symbol">a</font>) at 7.2 ± 4.2 min, exhibited a very large apparent steady state volume of distribution (Vdss) of 4.2 ± 0.9 <font face="symbol">l</font>/kg BW, had a very short terminal elimination half-life (t½<font face="symbol">b</font>) of 140 ± 15 min and showed a rapid total body clearance (C<font face="symbol">l</font>) of 22.7 ± 7 m<font face="symbol">l</font>/min/kg. Both IMI and the pharmacologically active metabolite, desipramine was negligible in serum at 24 hours. All three bulls treated with IMI showed pronounced central nervous system signs immediately post injection. Signs of generalised weakness and ataxia were evident. All CNS signs dissipated 15-20 minutes post injection and should therefore not influence the treatment interval. An interval of at least 23 hours between repeat treatments of IMI, representing a period of at least 10 half-lives, is recommended. The dose of 2 mg/kg BW used in this study was similar to that routinely used in stallions without fatal side effects. One of the three bulls exhibited spontaneous emission and ejaculation with this dose. The second study investigated the effects of IMI on ampullar strips of bulls in organ baths. Vasa deferentia were collected from 16 freshly slaughtered post-puberal bulls of various breeds. Longitudinal ampullar strips were prepared and placed into 20 ml modified Krebs bicarbonate solution, aerated with a mixture of 02 (95 %) and CO2 (5 %) in water-jacketed organ baths. The effect on the smooth muscle tissue of noradrenaline (NA) alone, NA in combination with IMI and IMI alone was evaluated. NA alone consistently produced dose-dependant smooth muscle tissue contractions. IMI doses equivalent to <1 mg/kg BW (body weight equivalent; bwe) had NA potentiating effects. Doses of <0.1 mg/kg bwe were consistently potentiating while doses of >0.1 mg to <1 mg/kg bwe partially blocked NA stimulating effects. Amplitude of rhythmic contractions increased while contraction frequency decreased at this level. This study supports the adrenergic potentiating effects of IMI at doses of 0.05-0.2 mg/kg bwe with higher doses having paradoxical effects. Doses of IMI < 2 mg/kg bwe completely blocked NA effects. Tissue response to NA, after IMI blockade, started to recover 146-186 minutes after application of IMI at <2 mg/kg bwe. In the absence of NA, IMI had no effect on smooth muscle activity. The time to an IMI effect on NA initiated smooth muscle activity was 8 minutes. On the basis of the results of this in vitro study, we propose that IMI can be used to enhance semen collection by means of electro-stimulation in domestic bulls and immobilised wildlife species such as buffalo, provided that the correct dose is used. / Dissertation (MMedVet (Gyn))--University of Pretoria, 2005. / Production Animal Studies / unrestricted

No description available.

One of the most impactful challenges beef cow-calf producers face is the need to optimize reproductive efficiency. The ability of a veterinarian to identify potential sources of reproductive inefficiency is a valuable service they can offer. The breeding soundness evaluation (BSE) is one tool veterinarians use to identify subfertile bulls prior to use. This body of research shows that producers who have a defined breeding season have higher odds of hiring a veterinarian to perform BSEs, and that as breeding season length decreases, the probability of a management strategy that uses BSEs being profitable increases. Furthermore, not all veterinarians use the same standards for BSEs, which may decrease its utility. Lastly, if a positive test result indicates a subfertile bull, the BSE has a higher specificity than sensitivity, a low positive predictive value at typical pre-test probabilities, and a negative predictive value that is not much more informative than prevalence.

Quantifying spatial and temporal patterns of rapid channelized erosion, on human time scales, is critical to understanding its processes and their consequences. This investigation utilized field observations, repeat terrestrial laser scanning (TLS), and Structure-from-Motion photogrammetry (SfM) to document the size and retreat rates of a knickpoint, defined as a localized near-vertical reach of a fluvial channel, and its contribution to erosion, in an urbanizing landscape with a loess substrate. The Bull Mountain area, in Washington County, southwest of Portland, Oregon, is an ideal study area, offering a measurable knickpoint that translates the response of the rapid erosion throughout this transient system. Previous urbanization there has increased peak flows in streams, potentially initiating rapid channel incision and associated slope instability and sediment pollution, affecting real property and infrastructure. Despite the documented increase in discharge, upstream migration rates of the knickpoint, as well as the overall channel erosion rate, were unknown. Sequential point cloud analysis quantified topographic changes in the landscape, in three dimensions, throughout time. The measured minimum knickpoint migration rates ranged from - 0.23 m/yr to - 2.45 m/yr with an average of - 1.52 m/yr and minimum of total volume eroded of 6.49 m3. The negative sign indicates the upstream direction. An extreme erosion event caused - 12.5 m of erosion in ~ 4.5 months. The interval including the extreme erosion event was recorded separately using traditional measurement techniques and resulted in an average retreat rate of - 4.31 m/yr. Analysis of patterns of erosion revealed four primary modes: exfoliation, large soil block failure, undercutting at the knickpoint base, and upper bank failure. Results from soil analyses indicate a layer of high bulk density (1.85 g/cm3) loess at the base of the upper channel may restrict the channelized incision for that reach and control the height and geometry of the knickpoint face, leading to a parallel mode of retreat. From the observed erosion rates a substrate specific average value of erodibility, or K value, of 0.01 m0.2 yr-1, was determined. As erosion forces the retreat of these knickpoints upstream, the effects of increasing urban runoff are felt throughout the watershed. The work presented here provides insight on the physical controls driving erosion and can serve as a prologue for future mitigation.

Bull Run Watershed was set aside in late the 1800s as the water supply source for the City of Portland. Other than two dams being constructed, Reservoir #1 (1929) and Reservoir #2 (1962), development of the land had been minimal as public access was restricted. In the early 1960s, land management changed with increased road building and timber removal raising concerns about increased sediment discharge into the reservoirs. The objective of this study is to evaluate how much and how fast the sediment has accumulated in Reservoir #1, and to determine if the rate of sediment accumulation has changed over time. Three methods are utilized: 1) differencing map comparing pre- and postimpoundment sediment conditions, 2) analysis of tree-stumps on reservoir floor, and 3) gravity coring of reservoir sediment. Combining these methods, sediment volume is estimated between 254,000-422,000 cubic meters (332,000-552,000 cubic yards) and the rate of accumulation between 11.5-19.1 tonnes/km2/yr, reflecting a relatively low sediment yield rate. Two anomalous event-layers were identified in gravity cores collected. These are interpreted to be the 1964 flood and the 1972 North Fork Slide. Using these two events, sediment yield rate was divided into different historical segments: 15.33 (1930-1965); 43.62 (1965-1972); and 17.00 tonnes/km2/yr (1972-1993). The increase from 1965-1972 is attributed to either residual affects from the 1964 flood and/or changes in land management activities during this time. The source of the reservoir sediment is primarily from upper tributaries, with 20 percent being attributed to the anomalous events. Smaller amounts of sediment come from the reservoir side walls as lake levels raise and lower. Suspension and turbidity conditions in the reservoir are affected by the dynamics of the drainage system including seasonal fluctuations. Turbidity remains high at the upper reaches of the reservoir before settling out closer to the dam. Some sediment possibly leaves the reservoir over the spill-way or when water is removed for power production.

Bull trout are a species of fish native to the coldwater mountain streams of Alberta. Because this species is of special conservation concern and displays finely dissected population structure, it is well suited as a model species to test the utility of versatile conservation genetics tools. One such tool, a genetic clustering method, was used to discern the hierarchical population structure of bull trout in the core of their range in South-West Alberta. The method also revealed patterns of gene flow by way of assignment tests. Populations defined by this method were then used as reference populations for mixed-migrant assignment tests, revealing that clustering method-defined populations may be more suitable for such tests rather than traditional approaches that define reference populations by sampling location. Combined with spatial data a posteriori, assignment tests had additional utility of discerning spatial scale of movement for juvenile and adult salmonids. This technique provided further evidence that assignment tests may be powerful indirect tools for evaluating migration, and that longrange inter-stream dispersal in juvenile salmonid fish may be more common than previously assumed. / xi, 174 leaves : ill. ; 29 cm. --

The conservation of freshwater resources is fundamental in supporting modern society and preserving natural habitats and ecosystems. Deterioration of water quality in urban landscapes and loss of municipal water to leaky water distribution infrastructure are two substantial challenges to water-resource sustainability. I examine the geochemistry of streamwater, municipal water, wastewater, soil, and bedrock from the Bull Creek watershed, a rapidly urbanizing watershed in Austin, Texas, to achieve a better understanding of the processes of geochemical evolution as anthropogenically-sourced water recharges natural systems. Urbanization patterns in the Bull Creek watershed have created a contiguous expanse of urban development that covers roughly two thirds of the watershed, whereas the remaining third is rural, enabling direct comparison between urban and rural streamwater from a single watershed. Results indicate that Na, Cl, K, and SO₄ in urban springs and tributaries are elevated more than two-fold in comparison with rural springs and tributaries. A comparison of Sr concentration and Sr isotopic composition for spring and tributary samples indicates that municipal water and wastewater provide a substantial contribution to the urbanized stream branches of Bull Creek. This water is reactive in the subsurface after it leaks from the municipal system, evolving via a pathway of water-rock interaction with limestone. / text

Este trabalho foi conduzido para avaliar o efeito da condição sexual sobre o desempenho, concentração de testosterona, características de carcaça e qualidade da carne de bovinos Nelore confinados. Cinquenta e oito machos bovinos (430 ± 36 kg; 24 meses de idade), foram divididos em três grupos em um delineamento inteiramente casualizado. Foi realizado, em 15 animais, o procedimento de castração cirúrgica (CC), aos 12 meses de idade, enquanto que 21 animais receberam duas doses da vacina de imunocastração (IC), dentro de um intervalo de 30 dias, e 22 animais permaneceram não-castrados (NC). Os animais foram alocados em baias individuais e alimentados com uma dieta contendo 70% concentrado e 30% volumoso durante noventa dias precedidos por um período de adaptação de vinte e um dias. Foi avaliado o desempenho e características de carcaça a cada 28 dias. Os animais foram abatidos e foi avaliada a qualidade da carne. Animais NC apresentaram maior ganho de peso, eficiência alimentar, peso de carcaça quente e rendimento de carcaça comparado com animais CC e IC (P&lt;0.05). Animais castrados apresentaram maiores valores de cor L*, a*, b* e perda por cocção que animais NC (P&lt;0.05). A imunocastração diminuiu o desempenho dos animais, comparado com animais CC ou NC. Porém, é uma alternativa à castração cirúrgica pois possui as mesmas características de carcaça e qualidade da carne. A imunocastração melhora a cor da carne e diminui a frequência de carnes DFD comparado com animais NC. / This study was carried out to evaluate the effect of the sexual condition on performance, testosterone concentration, carcass traits and meat quality of feedlot Nellore cattle. Fifty-eight males (430 ± 36 kg BW; 24 mo old) were divided into three groups in a randomized complete design. Surgical castration (SC) procedure was performed in 15 animals at 12 months old, whereas 21 animals received two doses of immunocastration vaccine (IM), within an interval of 30 days. In addition, 22 animals remained intact (NC). The animals were allotted in individual pens and daily fed a diet containing 70% concentrate and 30% roughage during ninety days preceded by an adaptation period of twenty one days. Performance and carcass characteristics were evaluated every 28 days. The animals were slaughtered and the meat quality was evaluated. The NC animals showed greater average daily gain, feed efficiency, hot carcass weight and carcass yield compared with SC animals and IM (P &lt;0.05). Castrated animals had higher color values L *, a *, b * and cooking loss that NC animals (P &lt;0.05). Immunocastration decreased performance when compared to SC or NC animals. However, it is an alternative tool to surgical castration because it has the same carcass characteristics and meat quality. Immunocastration improves the color of the meat and reduces the frequency of DFD meat compared to NC animals.