Strategies to Optimize Confinement Fed Beef Cattle in the Northern Plains

The goal of this dissertation was to understand the strategies needed to optimize performance of confinement fed beef cattle in the Northern Plains. This was accomplished through three objectives: 1) evaluate health, growth performance, and antibody titers in previously vaccinated, newly weaned calves administered a respiratory and clostridia vaccine upon arrival compared to no vaccination; 2) determine the influence of manger space restriction on program-fed feedlot heifers during the growing phase; and 3) to evaluate growth performance and carcass traits following transit of feedlot heifers sourced and finished in different regions of the United States. For objective 1, single-sourced, newly weaned steers [n = 70; initial body weight (BW) = 254±5.9 kg] were blocked by BW in a randomized complete block design (RCBD) of VAC (vaccinated for respiratory and clostridial diseases upon arrival) or NOVAC (not vaccinated upon arrival). Timing of vaccine administration did not appreciably influence 42-d growth performance and vaccinated calves had increased antibody titer response. For objective 2, Charolais × Angus heifers (initial BW = 329±22.1 kg) were used in a 109-d backgrounding study. Heifers were blocked by BW in a RCBD into one of two treatments: 20.3 cm (8IN) or 40.6 cm (16IN) of linear bunk space/heifer. Restricting manger space allocation from 40.6 cm to 20.3 cm did not negatively influence gain efficiency or the efficiency of energy utilization in heifers program fed a concentrate-based diet to gain 1.36 kg daily. For objective 3, yearling heifers (n = 190; initial BW 483 and 425 kg for SD and TX sourced, respectively) were used in a 2×2 factorial arrangement of origin state (SD vs TX) and finishing state (SD vs TX). Heifers transported to higher ambient temperatures had improved yield grades, but had reduced dry matter intake, quality grades and limited growth recovery. Heifers transported to lower ambient temperatures recovered growth and had improved quality grades at the same level of rib fat but had reduced yield grades. Collectively, these results indicate the management of cattle influences growth performance and that there are multiple ways to manipulate performance based on management decisions in each beef cattle sector

On the effective bare work function of bcc thermionic electrode materials

An equation is derived for the effective work function of a polycrystalline metal with a fiber texture. This equation contains two parameters: the temperature and the maximal tilt angle, i.e. the maximal deviation from the fiber axis. A linear relationship is assumed between the work function of a uniform lattice plane and the angle of a low index plane with respect to the uniform lattice plane. The proportionality constant D in the [100] zone is evaluated from experimental data for tungsten: D=0.035 * (eV/degree). It is expected that D has the same value in other bcc metals. For a given maximal tilt angle, a higher temperature results in a higher effective work function. A reasonable agreement is found for the calculated effective work functions of tungsten with 110 fiber textures of various sharpness and the experimentally determined work functions from the literature. Furthermore, the effective work function of texture-free polycrystalline tungsten is calculated. The agreement with the experimentally determined value reported in the literature is excellent

A thermionic energy converter with an electrolytically etched tungsten emitter

The bare work functions of etched and unetched plasma-sprayed tungsten were found to be 4.8 and 4.5 eV, respectively. The electron emission of plasma-sprayed tungsten, both etched and unetched, was measured over a wide range of temperatures in a cesium atmosphere. Work functions were derived from the saturation current densities. In the ignited mode, current-voltage (I-V) characteristics were measured. The influence of the emitter, collector, and cesium reservoir temperatures on the I-V characteristics was investigated. Barrier indexes of 2.06 and 2.30 eV were found for etched and unetched tungsten emitters, respectively. At an emitter temperature of 1400¿°C, in the case of an unetched tungsten emitter a power density of 1.5 W/cm2 was found, while for an etched tungsten emitter it was 4.5 W/cm2. This increased power density could be attributed to a lower collector work function. The lower cesiated collector work function resulted from the evaporation of oxygen, as WO3, from the etched tungsten emitter

WF6-CVD tungsten film as an emitter for a thermionic energy converter I. Production, texture and morphology of WF6-CVD tungsten films

The as-deposited WF6-CVD tungsten film consists of columnar grains about 3 µm in diameter and about 30 µm in length. The film has a 100 fiber texture with a clear tendency to the formation of a pseudo-mono-crystal. The overwhelming part of the grains have their 100 axes within 27° of the surface normal. The as-deposited film surface consists of {111} crystal planes. Two hours annealing at 2273 K resulted in grain growth leading to a grain diameter of more than 70 µm. Inspection of etch pits revealed that 62% of the surface area consists of grains which have their 100 axis within 16° of the surface normal

Beetle eater beheerst de aspergekever bij de oogst van groene asperges in 2010

In Canada is een grote stofzuiger die voor of achter een tractor bevestigd kan worden “Beetle Eater” genaamd, gebruikt ter bestrijding van de coloradokever in aardappelen. Biologische telers hebben zo’n apparaat gekocht om hem in te zetten ter bestrijding van de wortelvlieg in peen. De resultaten vielen tegen en het apparaat is na twee jaar experimenteren niet meer gebruikt. In 2010 is de machine getest in groene asperges tegen de aspergekever op een gangbaar bedrijf in Noord - Brabant. Omdat groene asperges bij gunstige weersomstandigheden dagelijks geoogst worden, is het lastig om tegen dit insect gewasbeschermingsmiddelen in te zetten vanwege de veiligheidstermijn. Door de Beetle eater 1 of 2 keer (direct na elkaar) in te zetten worden de aspergekevers met 50 of 74% gereduceerd. De asperge oogsters merkten meteen wanneer de machine was ingezet omdat het aantal eitjes op de aspergestengels duidelijk afnam. Door de Beetle eater regelmatig in te zetten bleven het aantal afgezette eitjes op de stengels beperkt en zijn het gehele seizoen geen groene asperges bij deze teler afgekeurd en geen asperges daardoor aangemerkt als kwaliteit II. Een aandachtspunt is wel dat na iedere behandeling aspergestengels afbreken. Dit komt enerzijds omdat de rijafstand niet correspondeerde met de zuigmonden van de Beetle eater (scheelde 5 cm) en anderzijds omdat bij oudere percelen de aspergestengels verder uit het hart van de rug kunnen groeien. Door de zuigmond aan te passen (verbreden en iets te vergroten) is de verwachting dat het afbreken van de stengels beperkt wordt

A thermionic energy converter with a molybdenum-alumina cermet emitter

A study is made of the properties of cermets as electrode materials for thermionic energy converters. For thermodynamic reasons it is expected that all cermets composed of pure Mo and refractory oxides have the same bare work function. From data on the work function of Mo in an oxygen atmosphere this bare work function is estimated to be F=4.9 eV (at T=1400¿°C). Experimentally, the bare work function of Al2O3-Mo cermets was found to be F=4.5 eV, independent of the relative amounts of Al2O3 and Mo. The cesiated work function of the Al2O3-Mo cermets was found to be 0.15 eV lower than the cesiated work function of pure Mo. The bare work function of Mo3Al was found to be F=4.0 eV. The cesiated work function of Mo3Al at collector temperature conditions was 0.3 eV lower than the cesiated work function of pure Mo. The electrical power density of a diode with an Al2O3-Mo cermet emitter was 0.4 W/cm2 at 1300¿°C. The barrier index at this temperature was 2.36 V. The high barrier index is attributed to a high plasma voltage drop Vd=0.91 V

Resonances in rotationally inelastic scattering of OH(X2ΠX^2\Pi) with helium and neon

We present detailed calculations on resonances in rotationally and spin-orbit inelastic scattering of OH (X\,^2\Pi, j=3/2, F_1, f) radicals with He and Ne atoms. We calculate new \emph{ab initio} potential energy surfaces for OH-He, and the cross sections derived from these surfaces compare favorably with the recent crossed beam scattering experiment of Kirste \emph{et al.} [Phys. Rev. A \textbf{82}, 042717 (2010)]. We identify both shape and Feshbach resonances in the integral and differential state-to-state scattering cross sections, and we discuss the prospects for experimentally observing scattering resonances using Stark decelerated beams of OH radicals.Comment: 14 pages, 15 Figure

Effects of Low-stress Weaning on Calf Growth Performance and Carcass Characteristics

The objective of this study was to compare the influence of two low-stress weaning methods with conventional weaning on post-weaning performance and carcass characteristics of beef steers