Comparison of fresh and ensiled white and red clover added to ryegrass on energy and protein utilization of lactating cows

Two respiratory chamber experiments were conducted with dairy cows to compare metabolizable energy and protein utilization when feeding white or red clover with ryegrass. In experiment 1, fresh ryegrass was mixed with fresh white (WF) or red clover (RF) (60/40, on dry matter (DM) basis). Experiment 2 involved similar mixed diets in ensiled form (WS and RS, respectively), and two ryegrass silage diets, without (GS) or with supplementary maize gluten (GS+). Barley was supplemented according to requirements for milk production. Voluntary forage DM intake remained unaffected in experiment 1 and was higher (P<0·01) in experiment 2 for WS than for GS and GS+(128 v. 98 and 106 g/kg M0·75). Within experiments, no treatment effects occurred for apparent nutrient digestibilities, milk yield, and composition. Protein utilization (milk-N/N-intake) was numerically lower on all clover-based diets (0·24 to 0·25) versus GS (0·29). With added maize gluten (GS+), protein utilization decreased to 0·23, indicating that ryegrass silage (plus barley) alone provided sufficient metabolizable protein. Consequently, higher (P<0·01) urinary energy losses occurred in GS+ compared with GS, despite similar metabolizable energy intakes, and a trend for the highest plasma urea levels was found for GS+ cows (7·59 mmol/l; P<0·1). Overall, this study illustrates that the white and red clovers investigated were equivalent in energy and protein supply, also in comparison to the ryegrass. It remains open whether these forage legumes, when supplemented to a moderate-protein ryegrass, would have contributed to metabolizable protein supply or would have merely increased metabolic nitrogen loa

First-principles investigation of spin polarized conductance in atomic carbon wire

We analyze spin-dependent energetics and conductance for one dimensional (1D) atomic carbon wires consisting of terminal magnetic (Co) and interior nonmagnetic (C) atoms sandwiched between gold electrodes, obtained employing first-principles gradient corrected density functional theory and Landauer's formalism for conductance. Wires containing an even number of interior carbon atoms are found to be acetylenic with sigma-pi bonding patterns, while cumulene structures are seen in wires containing odd number of interior carbon atoms, as a result of strong pi-conjugation. Ground states of carbon wires containing up to 13 C atoms are found to have anti-parallel spin configurations of the two terminal Co atoms, while the 14 C wire has a parallel Co spin configuration in the ground state. The stability of the anti-ferromagnetic state in the wires is ascribed to a super-exchange effect. For the cumulenic wires this effect is constant for all wire lengths. For the acetylenic wires, the super-exchange effect diminishes as the wire length increases, going to zero for the atomic wire containing 14 carbon atoms. Conductance calculations at the zero bias limit show spin-valve behavior, with the parallel Co spin configuration state giving higher conductance than the corresponding anti-parallel state, and a non-monotonic variation of conductance with the length of the wires for both spin configurations.Comment: revtex, 6 pages, 5 figure

Effect of Red and White Clover Added to a Rye Grass-Based Diet on Intake, Fibre Digestion and Methane Release of Dairy Cows

Forage legumes like white and red clover are widely grown in association with grass, with the intention to improve the quality of grass-based diets. However little is known about the effect of either white or red clover added to a grass-based diet on methane release, and existing studies are not conclusive. The objective of this study, applying the respiratory chamber technique, was to determine the effect of red and white clover added to a rye grass-based diet on intake, fibre digestion and methane release of dairy cows

The key role of topography in altering North Atlantic atmospheric circulation during the last glacial period

The Last Glacial Maximum (LGM; 21 000 yr before present) was a period of low atmospheric greenhouse gas concentrations, when vast ice sheets covered large parts of North America and Europe. Paleoclimate reconstructions and modeling studies suggest that the atmospheric circulation was substantially altered compared to today, both in terms of its mean state and its variability. Here we present a suite of coupled model simulations designed to investigate both the separate and combined influences of the main LGM boundary condition changes (greenhouse gases, ice sheet topography and ice sheet albedo) on the mean state and variability of the atmospheric circulation as represented by sea level pressure (SLP) and 200-hPa zonal wind in the North Atlantic sector. We find that ice sheet topography accounts for most of the simulated changes during the LGM. Greenhouse gases and ice sheet albedo affect the SLP gradient in the North Atlantic, but the overall placement of high and low pressure centers is controlled by topography. Additional analysis shows that North Atlantic sea surface temperatures and sea ice edge position do not substantially influence the pattern of the climatological-mean SLP field, SLP variability or the position of the North Atlantic jet in the LGM

Effect of the tropical tannin-rich shrub legumes Calliandra calothyrsus and Flemingia macrophylla on methane emission and nitrogen and energy balance in growing lambs

The objective of this study was to test whether the use of tannin-rich shrub legume forage is advantageous for methane mitigation and metabolic protein supply at unchanged energy supply when supplemented in combination with tannin-free legumes to sheep. In a 6 × 6 Latin-square design, foliage of two tannin-rich shrub legume species (Calliandra calothyrsus and Flemingia macrophylla) were used to replace either 1/3 or 2/3, respectively, of a herbaceous high-quality legume (Vigna unguiculata) in a diet composed of the tropical grass Brachiaria brizantha and Vigna in a ratio of 0.55 : 0.45. A Brachiaria-only diet served as the negative control. Each experimental period lasted for 28 days, with week 3 serving for balance measurement and data collection inclusive of a 2-day stay of the sheep in open-circuit respiration chambers for measurement of gaseous exchange. While Vigna supplementation improved protein and energy utilisation, the response to the partial replacement with tannin-rich legumes was less clear. The apparent total tract digestibilities of organic matter, NDF and ADF were reduced when the tannin-rich plants partially replaced Vigna, and the dose-response relationships were mainly linear. The tannin-rich plants caused the expected redistribution of more faecal N in relation to urinary N. While Flemingia addition still led to a net body N retention, even when fed at the higher proportion, adding higher amounts of Calliandra resulted in body protein mobilisation in the growing lambs. With respect to energy, supplementation of Vigna alone improved utilisation, while this effect was absent when a tannin-rich plant was added. The inclusion of the tannin-rich plants reduced methane emission per day and per unit of feed and energy intake by up to 24% relative to the Vigna-only-supplemented diet, but this seems to have been mostly the result of a reduced organic matter and fibre digestion. In conclusion, Calliandra seems less apt as protein supplement for ruminants while Flemingia could partially replace a high-quality legume in tropical livestock systems. However, methane mitigation would be small due to associated reductions in N and energy retentio

Characterization of fecal nitrogen forms produced by a sheep fed with 15N labeled ryegrass

Little is known about nitrogen (N) forms in ruminant feces, although this information is important to understand N dynamics in agro-ecosystems. We fed 15N labeled ryegrass hay to a sheep and collected 15N labeled feces. Nitrogen forms in the feces were characterized by chemical extractions, solid-state cross polarization 15N nuclear magnetic resonance spectroscopy (SS CP/MAS 15N NMR) and Curie-point pyrolysis-gas chromatography/mass spectrometry (Cp Py-GC/MS). A 4months incubation experiment was conducted to assess N release from the feces. Half of the fecal N could be ascribed to bacterial and endogenous debris and a third to undigested dietary N. About a tenth of the fecal N was mineralized during the incubation experiment. The 15N abundance of nitrate released during the incubation remained constant and close to the 15N abundance of the total feces N. The NMR analysis of the feces showed that most of the N was present in proteins, while some was present as heterocyclic N, amino acids and ammonium. The Cp Py-GC/MS analysis confirmed the presence of proteins, amino acids and heterocyclic N in the feces. Comparing these results to those obtained from the 15N labeled hay suggests that some N compounds present in the plant were not digested by the animal, and that the animal excreted de novo synthesized N compounds. The low content in ammonium and amino acids, the low rate of N release from these feces during the incubation and the relatively high fecal protein content, particularly the hard to mineralize undigested and microbially bound forms, can explain the low transfer of N from these feces to crops observed in a previous wor

Modified triangular posterior osteosynthesis of unstable sacrum fracture

We report preliminary results for unstable sacral fractures treated with a modified posterior triangular osteosynthesis. Seven patients were admitted to our trauma center with an unstable sacral fracture. The average age was 31years (22-41). There were four vertical shear lesions of the pelvis and three transverse fracture of the upper sacrum. The vertical shear injuries were initially treated with an anterior external fixator inserted at the time of admission. Definitive surgery was performed at a mean time of 9days after trauma. The operation consisted in a posterior fixation combining a vertebropelvic distraction osteosynthesis with pedicle screws and a rod system, whereby the transverse fixation was obtained using a 6mm rod as a cross-link between the two main rods. Late displacement of the posterior pelvis or fracture was measured on X-ray films according to the criteria of Henderson. The patients were followed-up for a minimum time of 12months. Four patients who presented with a pre-operative perineal neurological impairment made a complete recovery. No iatrogenic nerve injury was reported. One case of deep infection was managed successfully with surgical debridement and local antibiotics. All patients complained of symptoms related to the prominence of the iliac screws. The metalwork was removed in all cases after healing of the fracture, at a mean time of 4.3months after surgery. No loss of reduction of fracture was seen at final radiological follow-up. The preliminary results are promising. The fixation is sufficiently stable to allow an immediate progressive weight-bearing, and safe nursing care in polytrauma cases. The only problem seems to be related to prominent heads of the distal screw

Awe and Wonder in Scientific Practice: Implications for the Relationship Between Science and Religion

This paper examines the role of awe and wonder in scientific practice. Drawing on evidence from psychological research and the writings of scientists and science communicators, I argue that awe and wonder play a crucial role in scientific discovery. They focus our attention on the natural world, encourage open-mindedness, diminish the self (particularly feelings of self-importance), help to accord value to the objects that are being studied, and provide a mode of understanding in the absence of full knowledge. I will flesh out implications of the role of awe and wonder in scientific discovery for debates on the relationship between science and religion. Abraham Heschel argued that awe and wonder are religious emotions because they reduce our feelings of self-importance, and thereby help to cultivate the proper reverent attitude towards God. Yet metaphysical naturalists such as Richard Dawkins insist that awe and wonder need not lead to any theistic commitments for scientists. The awe some scientists experience can be regarded as a form of non-theistic spirituality, which is neither a reductive naturalism nor theism. I will attempt to resolve the tension between these views by identifying some common ground

The compositional and evolutionary logic of metabolism

Metabolism displays striking and robust regularities in the forms of modularity and hierarchy, whose composition may be compactly described. This renders metabolic architecture comprehensible as a system, and suggests the order in which layers of that system emerged. Metabolism also serves as the foundation in other hierarchies, at least up to cellular integration including bioenergetics and molecular replication, and trophic ecology. The recapitulation of patterns first seen in metabolism, in these higher levels, suggests metabolism as a source of causation or constraint on many forms of organization in the biosphere. We identify as modules widely reused subsets of chemicals, reactions, or functions, each with a conserved internal structure. At the small molecule substrate level, module boundaries are generally associated with the most complex reaction mechanisms and the most conserved enzymes. Cofactors form a structurally and functionally distinctive control layer over the small-molecule substrate. Complex cofactors are often used at module boundaries of the substrate level, while simpler ones participate in widely used reactions. Cofactor functions thus act as "keys" that incorporate classes of organic reactions within biochemistry. The same modules that organize the compositional diversity of metabolism are argued to have governed long-term evolution. Early evolution of core metabolism, especially carbon-fixation, appears to have required few innovations among a small number of conserved modules, to produce adaptations to simple biogeochemical changes of environment. We demonstrate these features of metabolism at several levels of hierarchy, beginning with the small-molecule substrate and network architecture, continuing with cofactors and key conserved reactions, and culminating in the aggregation of multiple diverse physical and biochemical processes in cells.Comment: 56 pages, 28 figure