463 research outputs found
The effect of different levels of spring grass supply and stocking rate on the performance and intake of cows in early lactation
End of project reportGrazed herbage can supply nutrients to dairy cows at a lower cost than alternative feeds (Shalloo et al., 2004). Therefore, the objective of pasture-based systems must be to maximize the proportion of grazed grass in the diet of the dairy cow (Dillon et al., 2005). The extension of the grazing season into the early spring period can be facilitated by ceasing grazing of pastures earlier in autumn which allows grass to accumulate, thereby ensuring an adequate herbage supply in early spring when animal demand exceeds grass growth/supply (OâDonovan, 2000). Grazing pastures in early spring has previously been shown to increase herbage utilization and condition swards for subsequent grazing rotations (OâDonovan et al., 2004; Kennedy et al., 2006)
An investigation into the effects of different starts to the grazing season on sward structure and sward dynamics and dairy cow performance during the grazing season.
End of Project ReportSummary and Implications
â˘Cows outdoors from mid February to early April offered an 80:20 grazed grass concentrate diet produced similar milk yield with higher protein yield and content compared to cows offered a 40:60 grass silage concentrate diet.
â˘The improvement in animal performance is attributed to a higher energy, protein and total DM intake.
â˘In the carryover period when both groups were grazing fulltime, the cows with early turnout had higher milk protein concentrations and higher grass DM intakes (1kg DM/cow/day)
â˘An early grazed sward had a similar grass growth potential as a late grazed sward.
â˘Herbage from early grazed swards have higher grass digestibility (OMD and UFL) value than late grazed swards
â˘A lower daily herbage allowance can be tolerated with early grazed swards to achieve similar milk production performance as from late grazed swards. Up to 5-6 kg grass DM of late grazed swards will achieve the same level of milk production from early grazed swards.
â˘With late turnout allocating high daily herbage allowance with large pre -grazing herbage mass is wasteful and compounds the effects of poor grass utilisation and undergrazing.
â˘Early grazing is recommended when conditions allow even on heavy soil types.
â˘From mid April onwards the optimum-stocking rate on early grazed swards is between 4.0 - 4.5 cows/ha. At this stocking rate a balance is found between feeding the cow adequately at pasture and achieving the correct post - grazing residuals.
â˘Grass dry matter intake was significantly higher for the early grazed medium stocked cows in both studies, which clearly shows that the improvements in sward quality with early grazed swards can be converted to higher dairy cow performance.
â˘Cows grazing the early grazed sward at a medium stocking rate had higher milk production performance which persisted in subsequent grazing rotations. This was due to the higher quality herbage available with the lower herbage mass swards.
â˘When modelled to the whole farm system the reduced feed cost and higher performance achieved with early grazing, resulted in each extra day at grass increasing cow profitability by âŹ2.70 cow/da
Cultivar Influences Milk Production of Grazing Dairy Cows
Perennial ryegrass is considered one of the most important forage grass species used in temperate ruminant animal production systems. Maximizing milk production from grazed grass is a major objective of pastoral-based dairy systems. While DM yield is an important trait, it fails to define the ultimate value of a grass cultivar, which is its potential to improve animal performance from a pasture sward (Reed 1994). The majority of cultivar evaluation trials are conducted under cutting, so therefore inferior cultivars from an animal production perspective may not be identified until commercialisation when animals graze a pasture sward. Reed (1978) reported that ryegrass pastures of similar digestibility can have different animal production responses depending on the season. Without exposure to animal production trials, practical differences between cultivars under field conditions may not be detected.
The objective of the current study was to evaluate the effect of four perennial ryegrass cultivars with different sward characteristics on milk yield, milk composition and dry matter intake (DMI) of lactating dairy cows during the spring and mid-season period
Illicit Trafficking Radiation Assessment Program (ITRAP+10) Test campaign summary report
The Illicit Trafficking Radiation Assessment Program (ITRAP+10) is a program initiated by the European Union and the United States to evaluate the performance of available commercial radiation detection equipment against consensus standards. Through ITRAP+10, the international partners worked to ensure that testing standards are clearly defined, comprehensive and realistic in order to provide decision makers and private sector stakeholders with reliable detection system performance information as well as possible methods to enhance equipment performance. To ensure the review of commercial equipment would be relevant to the global commons, the European Commission Directorate General for Home Affairs (EC-HOME), the Joint Research Centre (EC-JRC), the U.S. Department of Homeland Security Domestic Nuclear Detection Office (US-DHS DNDO), the U.S. Department of Energy (US-DOE), and the International Atomic Energy Agency (IAEA) agreed to collaborate on the conduct of the ITRAP+10 test campaign and share in the design of the tests, their execution, and the analysis of the data.
This summary report aims at making the results of the ITRAP+10 test campaign available to the international community. It includes an overview of the ITRAP+10 test program, a summary of test results across the nine classes of instruments (tested by US-DHS DNDO and by EC-JRC) with scientific and technical data, and information about the manufacturers of the instruments tested. Moreover, it also takes into account the discussion of the standards used for testing and the feedback provided to the standards community to help with the standards' revisions.JRC.A.7-Euratom Coordinatio
The Arduous Journey to Black-Hole Formation in Potential Gamma-Ray Burst Progenitors
We present a quantitative study on the properties at death of fast-rotating
massive stars evolved at low-metallicity, objects that are proposed as likely
progenitors of long-duration gamma-ray bursts (LGRBs). We perform 1D+rotation
stellar-collapse simulations on the progenitor models of Woosley & Heger (2006)
and critically assess their potential for the formation of a black hole and a
Keplerian disk (namely a collapsar) or a proto-magnetar. We note that
theoretical uncertainties in the treatment of magnetic fields and the
approximate handling of rotation compromises the accuracy of stellar-evolution
models. We find that only the fastest rotating progenitors achieve sufficient
compactness for black-hole formation while the bulk of models possess a core
density structure typical of garden-variety core-collapse supernova (SN)
progenitors evolved without rotation and at solar metallicity. Of the models
that do have sufficient compactness for black-hole formation, most of them also
retain a large amount of angular momentum in the core, making them prone to a
magneto-rotational explosion, therefore preferentially leaving behind a
proto-magnetar. A large progenitor angular-momentum budget is often the sole
criterion invoked in the community today to assess the suitability for
producing a collapsar. This simplification ignores equally important
considerations such as the core compactness, which conditions black-hole
formation, the core angular momentum, which may foster a magneto-rotational
explosion preventing black-hole formation, or the metallicity and the residual
envelope mass which must be compatible with inferences from observed LGRB/SNe.
Our study suggests that black-hole formation is non trivial, that there is room
for accommodating both collapsars and proto-magnetars as LGRB progenitors,
although proto-magnetars seem much more easily produced by current
stellar-evolutionary models.Comment: 10 emulateapj pages, 3 figures, 1 table, matches published versio
Shock-heating of stellar envelopes: A possible common mechanism at the origin of explosions and eruptions in massive stars
Observations of transient phenomena in the Universe reveal a spectrum of
mass-ejection properties associated with massive stars, covering from Type
II/Ib/Ic core-collapse supernovae (SNe) to giant eruptions of Luminous Blue
Variables (LBV) and optical transients. Here, we hypothesize that a fraction of
these phenomena may have an explosive origin, the distinguishing ingredient
being the ratio of the prompt energy release E_dep to the envelope binding
energy E_binding. Using one-dimensional one-group radiation hydrodynamics and a
set of 10-25Msun, massive-star models, we explore the dynamical response of a
stellar envelope subject to a strong, sudden, and deeply-rooted energy release.
Following energy deposition, a shock systematically forms, crosses the
progenitor envelope on a day timescale, and breaks-out with a signal of
hour-to-days duration and a 10^5-10^11 Lsun luminosity. For E_dep > E_binding,
full envelope ejection results with a SN-like bolometric luminosity and kinetic
energy, modulations being commensurate to the energy deposited and echoing the
diversity of Type II-Plateau SNe. For E_dep ~ E_binding, partial envelope
ejection results with a small expansion speed, and a more modest but year-long
luminosity plateau, reminiscent of LBV eruptions or so-called SN impostors. For
E_dep < E_binding, we obtain a "puffed-up" star, secularly relaxing back to
thermal equilibrium. In parallel with gravitational collapse and Type II SNe,
we argue that the thermonuclear combustion of merely a few 0.01Msun of C/O
could power a wide range of explosions/eruptions in loosely-bound massive
stars, as those in the 8-12Msun range, or in more massive ones owing to their
proximity to the Eddington limit and/or critical rotation.Comment: 20 pages, 16 figures, 2 tables; accepted to MNRA
Recent developments in German corporate governance.
This paper provides an overview of the German corporate governance system. We review the governance role of large shareholders, creditors, the product market and the supervisory board. We also discuss the importance of mergers and acquisitions, the market in block trades, and the lack of a hostile takeover market. Given that Germany is often referred to as a bank-based economy, we pay particular attention to the role of the universal banks (Hausbanken). We show that the German system is characterised by a market for partial corporate control, large shareholders and bank/creditor monitoring, a two-tier (management and supervisory) board with co-determination between shareholders and employees on the supervisory board, a disciplinary product-market, and corporate governance regulation largely based on EU directives but with deep roots in the German codes and legal doctrine. Another important feature of the German system is its corporate governance efficiency criterion which is focused on the maximisation of stakeholder value rather than shareholder value. However, the German corporate governance system has experienced many important changes over the last decade. First, the relationship between ownership or control concentration and profitability has changed over time. Second, the pay-for-performance relation is influenced by large shareholder control: in firms with controlling blockholders and when a universal bank is simultaneously an equity- and debtholder, the pay-for-performance relation is lower than in widely-held firms or blockholder-controlled firms. Third, since 1995 several major regulatory initiatives (including voluntary codes) have increased transparency and accountability
Deficiency and Also Transgenic Overexpression of Timp-3 Both Lead to Compromised Bone Mass and Architecture In Vivo
Tissue inhibitor of metalloproteinases-3 (TIMP-3) regulates extracellular matrix via its inhibition of matrix metalloproteinases and membrane-bound sheddases. Timp-3 is expressed at multiple sites of extensive tissue remodelling. This extends to bone where its role, however, remains largely unresolved. In this study, we have used Micro-CT to assess bone mass and architecture, histological and histochemical evaluation to characterise the skeletal phenotype of Timp-3 KO mice and have complemented this by also examining similar indices in mice harbouring a Timp-3 transgene driven via a Col-2a-driven promoter to specifically target overexpression to chondrocytes. Our data show that Timp-3 deficiency compromises tibial bone mass and structure in both cortical and trabecular compartments, with corresponding increases in osteoclasts. Transgenic overexpression also generates defects in tibial structure predominantly in the cortical bone along the entire shaft without significant increases in osteoclasts. These alterations in cortical mass significantly compromise predicted tibial load-bearing resistance to torsion in both genotypes. Neither Timp-3 KO nor transgenic mouse growth plates are significantly affected. The impact of Timp-3 deficiency and of transgenic overexpression extends to produce modification in craniofacial bones of both endochondral and intramembranous origins. These data indicate that the levels of Timp-3 are crucial in the attainment of functionally-appropriate bone mass and architecture and that this arises from chondrogenic and osteogenic lineages
Mechanism of succinate efflux upon reperfusion of the ischaemic heart.
AIMS: Succinate accumulates several-fold in the ischaemic heart and is then rapidly oxidized upon reperfusion, contributing to reactive oxygen species production by mitochondria. In addition, a significant amount of the accumulated succinate is released from the heart into the circulation at reperfusion, potentially activating the G-protein-coupled succinate receptor (SUCNR1). However, the factors that determine the proportion of succinate oxidation or release, and the mechanism of this release, are not known. METHODS AND RESULTS: To address these questions, we assessed the fate of accumulated succinate upon reperfusion of anoxic cardiomyocytes, and of the ischaemic heart both ex vivo and in vivo. The release of accumulated succinate was selective and was enhanced by acidification of the intracellular milieu. Furthermore, pharmacological inhibition, or haploinsufficiency of the monocarboxylate transporter 1 (MCT1) significantly decreased succinate efflux from the reperfused heart. CONCLUSION: Succinate release upon reperfusion of the ischaemic heart is mediated by MCT1 and is facilitated by the acidification of the myocardium during ischaemia. These findings will allow the signalling interaction between succinate released from reperfused ischaemic myocardium and SUCNR1 to be explored
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