Whole-body fatness is a good predictor of phenotypic feed and liveweight efficiency in adult Merino ewes fed a poor-quality diet

Weight loss due to poor nutrition in adult ewes over summer-autumn is economically expensive due to immediate costs such as feed and labour but also due to ongoing costs to reproductive success and ewe health. We predicted that adult Merino ewes with a higher proportion of fat would be more efficient, both through lower intake and reduced weight loss. Four-year-old Merino ewes (n ≤ 64) were held in single pens and fed a chaff-based diet either ad libitum, with the aim of achieving liveweight maintenance, or a restricted amount to achieve liveweight loss of 100 g/day. Liveweight change and feed intake were measured, and residual liveweight change and residual feed intake were used to indicate efficiency. There was a difference of 2 MJ of metabolisable energy per day between the most efficient and least efficient ewes for residual feed intake, and a difference of 90 g per day between the most efficient and least efficient ewes for residual liveweight change. There was a significant association between blood plasma concentrations of leptin and both liveweight and feed efficiency, so that ewes with high concentrations of leptin had a lower daily intake, and/or lost less weight than did those with low concentrations of leptin. Managing adult Merino ewes to maximise fat-tissue accretion during spring via genetics and/or nutritional management could be a useful strategy to reduce feed requirements during summer-autumn because the ewes will be more efficient and have larger fat reserves to lose before achieving a lower critical limit

MeV Emission from Pulsar Wind Nebulae: Understanding Extreme Particle Acceleration in Highly Relativistic Outflows

The Earth is constantly bombarded from outer space by energetic particles. Where and how these "cosmic rays" are produced is poorly understood, with various particle types and energies likely originating from different sources. Particularly mysterious is the source of high-energy e+/- produced in our Galaxy, especially those responsible for both the high fraction of e+ in the GeV cosmic ray lepton spectrum and the e+/- and observed excess of microwaves and gamma-rays detected towards the Galactic center and bulge. While these particles could be evidence for exotic forms of dark matter, they might also be produced by "normal" astrophysical sources such as pulsars the strongly magnetized, rapidly rotating neutron stars whose rotational energy powers an ultra-relativistic outflow (commonly referred to as a "pulsar wind") whose interaction with the surrounding medium creates a pulsar wind nebula .While the detection of TeV emission from numerous PWNe strongly suggest they contain e+/- with PeV or higher energies, how and to what energies these particles are produced is unknown, let alone their dependence on the properties of the pulsar, pulsar wind, and surrounding medium. A major reason for this uncertainty is the lack of information concerning their MeV properties, since the synchrotron emission from the highest energy e+/- peaks in this waveband. Only by combining the MeV spectrum of PWNe measured by proposed missions with that obtained at lower (primarily radio and X-ray) and higher (TeV) photon energies by current and hopefully future facilities is it possible to measure the full spectrum of e+/- in these sources. The resultant insights into the underlying acceleration mechanism would significantly impact many areas of astrophysics from indirect searches for dark matter to the origin of cosmic rays to the physics of relativistic outflows observed from active galactic nuclei, gamma-ray bursts, and some gravitational wave events

High growth breeding values increase weight change in adult ewes

Ewes that lose less weight under restricted nutrition are potentially more profitable as less supplementary feeding is required or stocking rate can be increased. Heavier strains of Merino sheep have been shown to lose less weight when grazed on dry, poor pasture. Given that sire estimated breeding values (EBVs) for weight positively correlate with mature size, we hypothesise that adult ewes from sires with high EBVs for weight will have reduced annual fluctuation in weight. Spline functions were fitted to liveweight data for ewes from 8 Information Nucleus sites to determine annual weight change (max-mm-max) for each ewe. The 2 to 4 year olds were born between 2007 and 2009 and there were 5,242 records for 2,783 animals. Weights were corrected for conceptus and greasy fleece. Weight gain and loss were analysed using linear mixed effects models with fixed effects for site, breed, year, age, lamb birth type and rear type, and sire of the ewe was included as a random term. Sire EBVs for muscle, fat and growth and, ewe average annual liveweight (frame size) were included simultaneously as covariates. Ewes from sires with low EBVs for growth had no significant change in weight gain across a range of frame size (40-70 kg). In contrast ewes from high growth sires demonstrated similar weight gain at frame sizes of 40 kg, but increased in weight gain by 2.4 kg across the range of frame size. Contrary to our hypothesis, it was sires with less genetic potential for growth that produced progeny with reduced changes in liveweight. In both cases the magnitude of weight gain represented a diminishing proportion of frame size as it increased indicating phenotypically larger animals are more resilient to weight change. Ewes from high growth sires may require more careful management to minimise weight change, particularly when maintained at phenotypically higher weights

Environmental and genetic factors influence the liveweight of adult Merino and Border Leicester × Merino ewes across multiple sites and years

Variation in liveweight change in the ewe flock during periods of poor nutrition can affect farm profitability through the effects of liveweight loss on potential stocking rate, management interventions including supplementary feeding, and ewe and lamb survival and productivity. There is variation between individual animals in their ability to manage periods of poor nutrition, but the links between liveweight change and breeding values in the adult ewe flock have not been quantified. We analysed 5216 liveweight profiles for 2772 ewes managed over 3 years at eight sites across Australia, to define the relative effects of environment, reproductive performance and breeding values on liveweight change. The range in liveweight loss varied from 1.3 kg to 21.6 kg, and for liveweight gain from 0.4 kg to 28.1 kg. Site and year had the largest influence on liveweight change, which demonstrates that seasonal conditions and management were the most important factors influencing liveweight change. Liveweight loss was influenced by previous and current reproductive performance but these effects were small in comparison to the effects of site and year. There were mixed associations with sire breeding values for growth, fat and muscle depending on site. An increase in sire breeding values for fat by 1 mm was associated with a reduction in liveweight loss by up to 1.3 kg regardless of ewe breed, and this was more evident at sites where ewes lost a greater proportion of their liveweight. While management had the greatest effect on liveweight change, there appears to be scope to use breeding values to select sheep that will lose less weight during periods of poor nutrition in some environments

A thermophile under pressure: Transcriptional analysis of the response of Caldicellulosiruptor saccharolyticus to different H2 partial pressures

Increased hydrogen (H2) levels are known to inhibit H2 formation in Caldicellulosiruptor saccharolyticus. To investigate this organism's strategy for dealing with elevated H2 levels the effect of the hydrogen partial pressure (PH2) on fermentation performance was studied by growing cultures under high and low PH2 in a glucose limited chemostat setup. Transcriptome analysis revealed the upregulation of genes involved in the disposal of reducing equivalents under high PH2, like lactate dehydrogenase and alcohol dehydrogenase as well as the NADH-dependent and ferredoxin-dependent hydrogenases. These findings are in line with the observed shift in fermentation profiles from acetate production to the production of acetate, lactate and ethanol under high PH2. Moreover, differential transcription was observed for genes involved in carbon metabolism, fatty acid biosynthesis and several transport systems. In addition, presented transcription data provide evidence for the involvement of the redox sensing Rex protein in gene regulation under high PH2 cultivation condition