94 research outputs found

    Effects of Varying Levels of Silage Inclusion and Brown Midrib Corn Silage on Finishing Performance of Steers

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    A 2 × 3 factorial finishing study evaluated traditional or brown midrib corn silage fed at three inclusions in finishing diets. Silage inclusion was 15%, 45%, or 75% inclusion (DM basis) for 70 days followed by 15% inclusion for the remainder of the finishing phase. Cattle were ultrasounded twice to calculate backfat deposition rate for a target backfat of 0.55 inches, as cattle were fed longer if silage inclusion was 45 or 75/15%. Cattle fed 45% or 75/15% silage inclusion had greater final body weight (BW) and days on feed, but higher feed:gain (F:G) than cattle fed 15% silage. Daily gain was greatest for cattle fed 15% silage, but not different between cattle fed 45% and 75/15% treatments. Cattle fed 45% and 75/15% silage had greater final hot carcass weight (HCW) and longissimus muscle (LM) area than 15% but fed for 28 additional days. Dry matter intake was greater for cattle fed brown midrib (bm3) silage but gain or F:G were not affected. Backgrounding cattle on a low energy diet followed by a high energy diet resulted in similar growth performance and carcass endpoint as cattle fed a consistent inclusion of silage throughout the entirety of the feeding period. Feeding cattle 45% or 75/15% silage resulted in larger carcass weights and more days on feed (DOF) than cattle fed 15% silage for the finishing period. This resulted in greater returns for cattle fed 45% and 75/15% silage diet as compared to cattle fed a high energy 15% silage diet throughout the feeding period

    Corn Oil Supplementation on Performance and Methane Production in Finishing Steers

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    A finishing trial was conducted to evaluate the effects of corn oil on animal performance, carcass characteristics, and methane production in finishing cattle. Corn oil was supplemented at 3% of the diet (dry matterbasis) and led to a decrease in intake, a numerical improvement in average daily gain, and improved feed efficiency compared to the control cattle. Dry matter intake while in the methane barn was not decreased between treatments, although it was numerically similar to what was observed outside of the methane barn. Corn oil did not affect any carcass parameters. Methane production (g/d) was reduced with the inclusion of corn oil compared to the control. Methane (g/lb of gain) was also reduced with the inclusion of corn oil compared to the control. A numerical reduction of methane (g/lb of intake) was observed when corn oil was included in the diet. Corn oil appears to be a viable option for both improving performance as well as decreasing methane production in beef cattle finishing diets

    Evaluation of Reimplant Window with Revalor-200 ® on Steer Performance and Carcass Characteristics

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    A feedlot study utilizing 800 crossbred steers (initial BW = 727 ± 55 lb) compared 5 different terminal implant (Revalor-200) times (160, 120, 100, 80, or 40 d prior to harvest) for steers fed 180 days on performance and carcass characteristics. All steers were implanted with Revalor-IS as an initial implant at trial initiation. Carcass-adjusted final BW, ADG, and F:G responded quadratically, with cattle implanted 80 to 120 d prior to harvest being the greatest. However, there was less than a 2% difference in performance between 120 and 80 days on terminal implant. Hot carcass weight responded quadratically, with no difference in fat thickness, rib eye area, marbling score, or calculated yield grade. When solved for the first derivative, all variables were maximized at 87 to 104 days on terminal implant when steers are fed for 180-d

    Confined Cow-Calf Production System and Post-Weaning Management Impact on Calf Production

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    Calf performance was measured in a 3-yr study with a 2 × 2 factorial treatment design: 1) cow-calf production system (dry lot feeding or grazing corn residue) and 2) directly finishing calves or growing prior to finishing. Calves wintered on cornstalks were lighter at weaning than calves wintered in the dry-lot. However, following the finishing period, there were no effects of pre-weaning production system on final body weight or hot carcass weight. Calves directly adapted to a finishing diet had greater gain and improved efficiency compared to calves fed a grower diet prior to finishing. However, calves that were grown first produced 51 lb greater hot carcass weight. Directly finishing calves resulted in greater net profit as the extra hot carcass weight did not offset the cost of the additional 49 days in the feedlot. Wintering cows with calves on cornstalks instead of in a dry-lot resulted in lighter calves, but calves compensated in the feedlot

    Impact of Corn Silage Inclusion on Finishing Cattle Performance

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    Cattle fed high grain diets with little to no roughage are typically at greater risk for acidosis and reduced dry matter intake and average daily gain. An individual feeding study was conducted to compare different inclusions of corn silage used as a roughage source on finishing performance and liver abscess rate. Treatments consisted of 3 inclusions of corn silage at 0, 7.5 and 15% of the diet DM and a control treatment with 7.5% alfalfa. There were no differences for live animal performance or carcass characteristics. There were also no differences in liver abscess incidence. Feeding corn silage at 15% gave similar performance responses compared to 7.5% alfalfa. These data suggest that roughage is not required in a finishing diet when feeding individual animals

    T Cell Responses to Human Endogenous Retroviruses in HIV-1 Infection

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    Human endogenous retroviruses (HERVs) are remnants of ancient infectious agents that have integrated into the human genome. Under normal circumstances, HERVs are functionally defective or controlled by host factors. In HIV-1-infected individuals, intracellular defense mechanisms are compromised. We hypothesized that HIV-1 infection would remove or alter controls on HERV activity. Expression of HERV could potentially stimulate a T cell response to HERV antigens, and in regions of HIV-1/HERV similarity, these T cells could be cross-reactive. We determined that the levels of HERV production in HIV-1-positive individuals exceed those of HIV-1-negative controls. To investigate the impact of HERV activity on specific immunity, we examined T cell responses to HERV peptides in 29 HIV-1-positive and 13 HIV-1-negative study participants. We report T cell responses to peptides derived from regions of HERV detected by ELISPOT analysis in the HIV-1-positive study participants. We show an inverse correlation between anti-HERV T cell responses and HIV-1 plasma viral load. In HIV-1-positive individuals, we demonstrate that HERV-specific T cells are capable of killing cells presenting their cognate peptide. These data indicate that HIV-1 infection leads to HERV expression and stimulation of a HERV-specific CD8+ T cell response. HERV-specific CD8+ T cells have characteristics consistent with an important role in the response to HIV-1 infection: a phenotype similar to that of T cells responding to an effectively controlled virus (cytomegalovirus), an inverse correlation with HIV-1 plasma viral load, and the ability to lyse cells presenting their target peptide. These characteristics suggest that elicitation of anti-HERV-specific immune responses is a novel approach to immunotherapeutic vaccination. As endogenous retroviral sequences are fixed in the human genome, they provide a stable target, and HERV-specific T cells could recognize a cell infected by any HIV-1 viral variant. HERV-specific immunity is an important new avenue for investigation in HIV-1 pathogenesis and vaccine design

    Design and development of a field-deployable single-molecule detector (SMD) for the analysis of molecular markers

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    Single-molecule detection (SMD) has demonstrated some attractive benefits for many types of biomolecular analyses including enhanced processing speed by eliminating processing steps, elimination of ensemble averaging and single-molecule sensitivity. However, it's wide spread use has been hampered by the complex instrumentation required for its implementation when using fluorescence as the readout modality. We report herein a simple and compact fluorescence single-molecule instrument that is straightforward to operate and consisted of fiber optics directly coupled to a microfluidic device. The integrated fiber optics served as waveguides to deliver the laser excitation light to the sample and collecting the resulting emission, simplifying the optical requirements associated with traditional SMD instruments by eliminating the need for optical alignment and simplification of the optical train. Additionally, the use of a vertical cavity surface emitting laser and a single photon avalanche diode serving as the excitation source and photon transducer, respectively, as well as a field programmable gate array (FPGA) integrated into the processing electronics assisted in reducing the instrument footprint. This small footprint SMD platform was tested using fluorescent microspheres and single AlexaFluor 660 molecules to determine the optimal operating parameters and system performance. As a demonstration of the utility of this instrument for biomolecular analyses, molecular beacons (MBs) were designed to probe bacterial cells for the gene encoding Gram-positive species. The ability to monitor biomarkers using this simple and portable instrument will have a number of important applications, such as strain-specific detection of pathogenic bacteria or the molecular diagnosis of diseases requiring rapid turn-around-times directly at the point-of-use.close5
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