Controlling risks of pathogen transmission by flies on organic pig farms - A review

Fly prevention and control on animal production units is necessary to prevent the transmission of pathogens that could affect animal and human health and the maintenance of good hygiene. Organic farmers are often hesitant to apply insecticides for this purpose because of their farming philosophy. Organic production systems are relatively open as pigs generally have access to the outdoors. Here, we investigate the need for fly control and analyse various possibilities that organic farmers have to reduce the number of flies on their farms. We conclude that although biological control looks promising, more research should be done concerning its side effects. Currently, optimal monitoring and prevention seem to offer the best solution

Prevention and treatment of parasitic infections in organic pigs

Organic and free range pigs are potentially exposed to a wider range of parasites and zoonotic challenges. The livestock Subproject QLIF addresses 4 strategies to combat these challenges, and the present paper describes the initial results. Rodent control is the first strategy, and a survey concludes that Salmonella and Campylobacter infections were encountered in house mice and Norway rats, but not in other species. T. gondii antibodies could be detected in 6.4% of the blood samples taken from 235 wild small mammals. To reduce the presence of rodents around farms, the use of live-traps may be a good alternative for the use of rodenticides on organic farms. A second strategy is aimed at directing pig dunging behaviour in such a way that contact with (infected) faeces is minimised. The study showed that a rooting area resulted in a cleaner outdoor are and an extra outdoor drinker led to a cleaner area around the drinker, but to a dirtier indoor area. However, no difference in Ascaris suum infection were found. The nutritional strategy tested showed that pure inulin appeared the most effective as Oesophagostomum dentatum presence was reduced by 91%. Finally, as part of Strategy 4, a mixture of dried Thymus vulgaris, Melissa officinalis and Echinacea purpurea in a dosage of 5% in the diet showed to be preventive against a mild round-worm infection. The same mixture, however, was not effective in a lower dosage (3% in the diet) against a serious round-worm infection. Work is continuing to develop the above strategies further

Triterpenic Acids Present in Hawthorn Lower Plasma Cholesterol by Inhibiting Intestinal ACAT Activity in Hamsters

Hawthorn (Crataegus pinnatifida) is an edible fruit used in traditional Chinese medicine to lower plasma lipids. This study explored lipid-lowering compounds and underlying mechanisms of action of hawthorn. Hawthorn powder extracts inhibited acylCoA:cholesterol acyltransferase (ACAT) activity in Caco-2 cells. The inhibitory activity was positively associated with triterpenic acid (i.e., oleanolic acid (OA) and ursolic acid (UA)) contents in the extracts. Cholesterol lowering effects of hawthorn and its potential additive effect in combination with plant sterol esters (PSE) were further studied in hamsters. Animals were fed a semi-synthetic diet containing 0.08% (w/w) cholesterol (control) or the same diet supplemented with (i) 0.37% hawthorn dichloromethane extract, (ii) 0.24% PSE, (iii) hawthorn dichloromethane extract (0.37%) plus PSE (0.24%) or (iv) OA/UA mixture (0.01%) for 4 weeks. Compared to the control diet, hawthorn, PSE, hawthorn plus PSE and OA/UA significantly lowered plasma non-HDL (VLDL + LDL) cholesterol concentrations by 8%, 9%, 21% and 6% and decreased hepatic cholesterol ester content by 9%, 23%, 46% and 22%, respectively. The cholesterol lowering effects of these ingredients were conversely associated with their capacities in increasing fecal neutral sterol excretion. In conclusion, OA and UA are responsible for the cholesterol lowering effect of hawthorn by inhibiting intestinal ACAT activity. In addition, hawthorn and particularly its bioactive compounds (OA and UA) enhanced the cholesterol lowering effect of plant sterols

Phase Transitions in Granular Packings

We describe the contact network of granular packings by a frustrated lattice gas that contains steric frustration as essential ingredient. Two transitions are identified, a spin glass transition at the onset of Reynolds dilatancy and at lower densities a percolation transition. We describe the correlation functions that give rise to the singularities and propose some dynamical experiments

Stress-strain behavior and geometrical properties of packings of elongated particles

We present a numerical analysis of the effect of particle elongation on the quasistatic behavior of sheared granular media by means of the Contact Dynamics method. The particle shapes are rounded-cap rectangles characterized by their elongation. The macroscopic and microstructural properties of several packings subjected to biaxial compression are analyzed as a function of particle elongation. We find that the shear strength is an increasing linear function of elongation. Performing an additive decomposition of the stress tensor based on a harmonic approximation of the angular dependence of branch vectors, contact normals and forces, we show that the increasing mobilization of friction force and the associated anisotropy are key effects of particle elongation. These effects are correlated with partial nematic ordering of the particles which tend to be oriented perpendicular to the major principal stress direction and form side-to-side contacts. However, the force transmission is found to be mainly guided by cap-to-side contacts, which represent the largest fraction of contacts for the most elongated particles. Another interesting finding is that, in contrast to shear strength, the solid fraction first increases with particle elongation, but declines as the particles become more elongated. It is also remarkable that the coordination number does not follow this trend so that the packings of more elongated particles are looser but more strongly connected.Comment: Submited to Physical Review

Failure of a geotextile-reinforced embankment using the material point method (MPM)

In a wide spectrum of geotechnical applications, materials undergo large deformations and/or large displacements. On modeling these problems with a Lagrangian finite element method, the mesh can become too distorted and re-meshing is essential. In the past decades, considerable efforts have been made to adopt what is called meshfree methods to mitigate the problems related to mesh distortion. One of these methods is the Material Point Method (MPM) that represents the continuum field as Lagrangian material points (particles), which can move through the fixed background of an Eulerian mesh. In this paper, the tensile membrane is modeled using the coupled FEM-MPM approach which adopts two-dimensional triangular elements for the membrane discretisation which is free to move through a three-dimensional mesh of non-structured tetrahedral elements. Apart from the membrane, the soil is treated with the classical procedure of MPM. To show the potential of the method and the presented membrane scheme, a failure of an embankment with and without geotextile has been presented in this paper. The analyses of failure mechanism and the embankment stability using undrained conditions were investigated to determine the critical embankment height and the corresponding geotextile forces. For the sake of comparison, Plaxis 2D with large deformation formulation is considered as a reference solution

Beyond deficiency:Potential benefits of increased intakesof vitamin K for bone and vascular health

Vitamin K is wellknown for its role in the synthesisof a number of blood coagulationfactors.During recent years vitaminK-dependent proteins werediscovered to be of vital importancefor bone and vascular health.Recommendations for dietary vitaminK intake have been made onthe basis of the hepatic requirementsfor the synthesis of bloodcoagulation factors.Accumulatingevidence suggests that the requirementsfor other functions thanblood coagulation may be higher.This paper is the result of a closedworkshop (Paris,November 2002)in which a number of Europeanvitamin K experts reviewed theavailable data and formulated theirstandpoint with respect to recommendeddietary vitamin K intakeand the use of vitamin K-containingsupplements