Cost Analysis of Cattle Feedlot Designs

A cost analysis of fixed and non-fixed costs of gain was conducted on 3 cattle feedlot designs. The three facility designs compared were conventional open pens (OPN), open pens with shelter over the feeding area (OS), and a monoslope confinement barn (MON). The OPN design was the least expensive facility to build and operate. However, because of poorer cattle performance (P \u3c 0.05), it was not the most cost effective. The MON design had significantly higher operating costs when compared to the OPN or OS designs, especially for the tractor/spreader (P \u3c 0.05), skid loader (P \u3c 0.10), labor (P \u3c 0.05), and straw (P \u3c 0.05). The operating and fixed costs, combined, made the MON design the most expensive cost of gain design (P \u3c 0.05). The OS design was the most expensive facility to build but with current feed prices and the cattle performance, it was the most cost effective cattle feeding design

SDSU Calf Value Discovery 2011 Summary Report

The Calf Value Discovery Program (CVD) allows cow-calf producers to gain knowledge of the finishing segment of the beef cattle industry and the marketing of fed cattle. Specifically, CVD provides an opportunity for cow-calf producers to learn how their calves perform in a feedlot and their carcass value when sold in a value-based marketing system. Each producer taking part in the program could consign a minimum of 5 steers weighing between 500 and 800 pounds to the CVD program. Animals were finished in a calf-fed program using typical diets and management protocols at VanderWal Yards (Bruce, SD). Carcass and feedlot performance information from calves were returned to producers for use in making future management decisions to improve profitability

Comparing Pfizer GeneSTAR and Igenity PROFILE DNA tests in Crossbred Cattle

Our objective was to compare the performance of Pfizer’s GeneSTAR and Igenity’s PROFILE DNA tests in crossbred beef cattle. Hair follicles were collected from 394 crossbred steers that were part of the South Dakota State University Calf Value Discovery project (n = 145) and calves that were fed at the SDSU Southeast Research Farm (n = 249) in 2011. Hair follicles were sent to Pfizer Animal Genetics and Igenity for testing with their GeneSTAR and PROFILE DNA tests, respectively. Marbling score (100-999 scale), ribeye area, fat thickness, carcass weight, yield grade, quality grade, and % kidney, pelvic, and heart fat was collected post-harvest on all steers. Using this dataset, we first asked whether each DNA test was associated with marbling scores. If the DNA tests were not associated with marbling, then the tests may not be useful for predicting genetic merit for marbling in crossbred cattle. The GeneSTAR and PROFILE DNA tests were associated with marbling scores, but this association was not high. Second, we asked whether GeneSTAR and PROFILE DNA test results were associated with each other. If test results were not correlated, then using both DNA test results together may improve genetic predictions. GeneSTAR and PROFILE tests for tenderness were highly correlated, suggesting that DNA markers for tenderness are similar for both tests. GeneSTAR and PROFILE DNA tests for marbling and feed efficiency were not highly correlated, raising the possibility that both tests could be used jointly to improve genetic predictions for these traits. However, using both GeneSTAR and PROFILE DNA tests jointly did not appreciably improve predictions for marbling score in our dataset. We conclude that, although both GeneSTAR and PROFILE DNA tests were associated with marbling score, the correlation between these tests and marbling was low in our sample of crossbred cattle. Further, using GeneSTAR and PROFILE DNA tests for marbling and feed efficiency may improve genetic predictions for these traits, but we did not find evidence that using both tests jointly improves predictions for marbling

The Influence of Growth Stage on Carcass Compositionand Factors Associated with Marbling Development in Beef Cattle

There are many cellular regulatory factors that ultimately determine the intramuscular fat, or marbling content and quality of beef carcasses. Identifying factors which play a critical role in the development of intramuscular fat throughout the feeding period and determining how cattle feeders can manipulate these factors will be crucial to continue improving beef quality. Ideally, marbling must increase without excess accumulation of adipose in depots that are undesirable and economically detrimental (subcutaneous and visceral). The results of this study are novel as they show not only what cellular factors play a role in marbling development, but also how their expression and presence change as an animal grows in an American‐style production system. The increase in both expression and presence of peroxisome proliferator‐activated receptor γ (PPARγ) at the end of the feeding phase suggest the proliferation and differentiation of additional cells to adipocytes is required in order to increase intramuscular fat content. This does not mean that adipocyte filling (lipogenesis) does not play a key role as well. However marbling content will reach a plateau without the recruitment of additional adipocytes. While it has been previously established that intramuscular adipocytes have a pattern of metabolism unique to other adipocytes, further research into how the metabolism of intramuscular fat differs from other fat depots and how this metabolism changes throughout the feeding phase will enhance the ability to produce high quality carcasses while limiting undesirable carcass fat

Thermalization of an impurity cloud in a Bose-Einstein condensate

We study the thermalization dynamics of an impurity cloud inside a Bose-Einstein condensate at finite temperature, introducing a suitable Boltzmann equation. Some values of the temperature and of the initial impurity energy are considered. We find that, below the Landau critical velocity, the macroscopic population of the initial impurity state reduces its depletion rate. For sufficiently high velocities the opposite effect occurs. For appropriate parameters the collisions cool the condensate. The maximum cooling per impurity atom is obtained with multiple collisions.Comment: 4 pages 6 figure

Exact first-order density matrix for a d-dimensional harmonically confined Fermi gas at finite temperature

We present an exact closed form expression for the {\em finite temperature} first-order density matrix of a harmonically trapped ideal Fermi gas in any dimension. This constitutes a much sought after generalization of the recent results in the literature, where exact expressions have been limited to quantities derived from the {\em diagonal} first-order density matrix. We compare our exact results with the Thomas-Fermi approximation (TFA) and demonstrate numerically that the TFA provides an excellent description of the first-order density matrix in the large-N limit. As an interesting application, we derive a closed form expression for the finite temperature Hartree-Fock exchange energy of a two-dimensional parabolically confined quantum dot. We numerically test this exact result against the 2D TF exchange functional, and comment on the applicability of the local-density approximation (LDA) to the exchange energy of an inhomogeneous 2D Fermi gas.Comment: 12 pages, 3 figures included in the text, RevTeX4. Text before Eq.(25) corrected. Additional equation following Eq.(25) has been adde

Control of an atom laser using feedback

A generalised method of using feedback to control Bose-Einstein condensates is introduced. The condensates are modelled by the Gross-Pitaevskii equation, so only semiclassical fluctations can be suppressed, and back-action from the measurement is ignored. We show that for any available control, a feedback scheme can be found to reduce the energy while the appropriate moment is still dynamic. We demonstrate these schemes by considering a condensate trapped in a harmonic potential that can be modulated in strength and position. The formalism of our feedback scheme also allows the inclusion of certain types of non-linear controls. If the non-linear interaction between the atoms can be controlled via a Feshbach resonance, we show that the feedback process can operate with a much higher efficiency.Comment: 6 pages, 7 figure

Input-output theory for fermions in an atom cavity

We generalize the quantum optical input-output theory developed for optical cavities to ultracold fermionic atoms confined in a trapping potential, which forms an "atom cavity". In order to account for the Pauli exclusion principle, quantum Langevin equations for all cavity modes are derived. The dissipative part of these multi-mode Langevin equations includes a coupling between cavity modes. We also derive a set of boundary conditions for the Fermi field that relate the output fields to the input fields and the field radiated by the cavity. Starting from a constant uniform current of fermions incident on one side of the cavity, we use the boundary conditions to calculate the occupation numbers and current density for the fermions that are reflected and transmitted by the cavity

Theory of output coupling for trapped fermionic atoms

We develop a dynamic theory of output coupling, for fermionic atoms initially confined in a magnetic trap. We consider an exactly soluble one-dimensional model, with a spatially localized delta-type coupling between the atoms in the trap and a continuum of free-particle external modes. Two important special cases are considered for the confinement potential: the infinite box and the harmonic oscillator. We establish that in both cases a bound state of the coupled system appears for any value of the coupling constant, implying that the trap population does not vanish in the infinite-time limit. For weak coupling, the energy spectrum of the outgoing beam exhibits peaks corresponding to the initially occupied energy levels in the trap; the height of these peaks increases with the energy. As the coupling gets stronger, the energy spectrum is displaced towards dressed energies of the fermions in the trap. The corresponding dressed states result from the coupling between the unperturbed fermionic states in the trap, mediated by the coupling between these states and the continuum. In the strong-coupling limit, there is a reinforcement of the lowest-energy dressed mode, which contributes to the energy spectrum of the outgoing beam more strongly than the other modes. This effect is especially pronounced for the one-dimensional box, which indicates that the efficiency of the mode-reinforcement mechanism depends on the steepness of the confinement potential. In this case, a quasi-monochromatic anti-bunched atomic beam is obtained. Results for a bosonic sample are also shown for comparison.Comment: 16 pages, 7 figures, added discussion on time-dependent spectral distribution and corresponding figur

Mode Selectivity and Stability of Continuously Pumped Atom Lasers

A semiclassical, multimode model of a continuously pumped atom laser is presented. For a spatially independent coupling process it is found that the system is unstable below a critical scattering length. As large atomic interactions will increase the phase diffusion of the lasing mode, it is desirable to obtain a stable atom laser with low nonlinearity. It is shown that spatially dependent pumping stabilizes the atom laser to a finite number of modes, and can induce single-mode operation