Eine Erhebung zur Parasitenkontrolle auf biologisch wirtschaftenden Schaf- und Ziegenbetrieben in der Schweiz

To determine the current control measures for strointestinal nematodes (GIN) on Swiss organic small ruminant farms, a phone questionnaire was developed and conducted. The survey also aimed to assess the understanding and implementation of possible alternative GIN control options. In total, 52 meat sheep and 58 dairy goat farm questionnaires were completed, and it was found that in general, farmers were aware of the potential benefit of an adequate grazing management to reduce GIN infection. However, practical realisation was often limiting. On average it was stated that adult meat sheep and dairy goats were drenched 1.5 and 1.3 times per animal and year, respectively, whilst lambs and kids were treated 1.6 and 1.3 times per animal and year, respectively. Sixteen percent of the interviewed organic goat farmers and 10% of the organic meat sheep farmers stated that they have confirmed anthelmintic resistance on their properties

Sainfoin – New Data on Anthelmintic Effects and Production in Sheep and Goats

Gastrointestinal nematodes (GIN) are one of the most important problems affecting health and therefore performance and welfare in small ruminant husbandry. The control of these parasites in the past strongly relied on the repeated use of anthelmintic drugs. This has led to nematode populations which are resistant to most of the currently available anthelmintics. Furthermore customer’s demands for organic and residue free animal products are increasing. The aforementioned problems have given a strong impetus for the development of new non-chemical strategies to control GIN. Previous research has pointed out the anthelmintic potential of sainfoin (Onobrychis viciifolia) and other tanniferous (CT) feed sources in goats and lambs infected with GIN. A recent Swiss experiment focussed on the use of sainfoin and field bean (Vicia faba, cv. Scirocco) as single CT sources as well as in combination for additional synergic effects, to reduce periparturient GIN egg rise of ewes in late gestation and early lactation. Another experiment with Alpine goats concentrated on the influence of sainfoin on milk performance and cheese quality. The results of these experiments will be presented and discussed in connection with previous knowledge on (i) anthelmintic effects of sainfoin and (ii) the influence of sainfoin administration on performance

Genetic parameters for nematode resistance in dairy sheep

Resistance of gastrointestinal nematodes (GIN) in sheep to anthelmintics is rapidly increasing. The results of several studies indicate that selection for increased nematode resistance in sheep is possible, and the trait of interest is faecal egg count (FEC). Phenotyping of FEC is rather timeconsuming and often costly, auxiliary traits that are more effective and easier would be greatly appreciated. The extent of Haemonchus contortus infestation is often measured by the coloration of the conjunctiva and the so-called FAMACHA© test. In our study, we aimed to test whether FAMACHA© could also be used as auxiliary trait for FEC. Additionally we aimed to provide genetic parameters for FEC, milk yield and packed cell volume (PCV). We phenotyped 1150 naturally infected Lacaune ewes on 15 commercial Swiss farms. Phenotypic correlation between FEC and FAMACHA© as well as FAMACHA© and PCV resulted in 0.25 (SE 0.03) and -0.35 (SE 0.08), respectively. Subsequent genetic analysis was carried out with a multi-trait animal model in order to estimate the genetic parameters of the traits mentioned above. We found moderate heritabilities of FEC, FAMACHA©, PCV and milk yield in the range of 0.30 to 0.36 (SE 0.08 for all traits). The particular focus was on the genetic correlation of FEC and FAMACHA© and was estimated to be 0.03 (SE 0.22). The distribution of the FAMACHA© score indicated a medium to high worm infestation, but FEC was relatively low compared to other studies. Eventually the infection pressure was not high enough to yield a good genetic correlation of FEC and FAMACHA©. In general, it can be concluded that the heritability for FEC is very appealing and that a selection program could be based on them. FAMACHA© as an auxiliary trait could not be confirmed in this study. Either further studies need to be designed differently to better explore the relationship between FAMACHA© and FEC or other possible auxiliary traits need to be sought of and developed

Absence of seasonal patterns in MBT-CBT indices in mid-latitude soils

The degree of methylation and cyclization of bacteria-derived branched glycerol dialkyl glycerol tetraether (GDGT) membrane lipids in soils depends on temperature and soil pH. Expressed in the methylation index of branched tetraethers (MBT) and cyclization ratio of branched tetraethers (CBT), these relationships are used to reconstruct past annual mean air temperature (MAT) based on the distribution of branched GDGTs in ancient sediments; the MBT-CBT proxy. Although it was shown that the best correlation of this proxy is with annual MAT, it remains unknown whether a seasonal bias in temperature reconstructions could occur, such as towards a seasonal period of optimal growth’ of the, as yet, unidentified soil bacteria which produce branched GDGTs. To investigate this possibility, soils were sampled from eight different plots in the USA (Minnesota and Ohio), The Netherlands (Texel) and the UK (Devon) in time series over 1 year and analyzed for their branched GDGT content. Further analyses of the branched GDGTs present as core lipids (CLs; the presumed fossil pool) and intact polar lipids (IPLs; the presumed extant pool) were undertaken for two of the investigated soil plots. The amount of IPL-derived branched GDGTs is low relative to the branched GDGT CLs, i.e. only 6–9% of the total branched GDGT pool.In all soils, no clear change was apparent in the distribution of branched GDGT lipids (either core or IPL-derived) with seasonal temperature change; the MBT–CBT temperature proxy gave similar temperature estimates year-round, which generally matched the mean annual soil temperature. In addition to a lack of coherent changes in relative distributions, concentrations of the branched GDGTs did not show clear changes over the seasons. For IPL-derived GDGTs these results suggest that their turnover time in soils is in the order of 1 year or more. Thus, our study does not provide evidence for seasonal effects on the distribution of branched GDGTs in soils, at least at mid-latitudes, and therefore, no direct evidence for a bias of MBT–CBT reconstructed temperatures towards a certain season of optimal growth of the source bacteria. If, however, there is a slight seasonal preference of branched GDGT production, which can easily be obscured by natural variability due to the heterogeneity of soils, then a seasonal bias may potentially still develop over time due to the long turnover time of branched GDGTs

Engineering quantum dots for electrical control of the fine structure splitting

We have studied the variation in fine-structure splitting (FSS) under application of vertical electric field in a range of quantum dots grown by different methods. In each sample we confirm that this energy splitting changes linearly over the field range we can access. We conclude that this linear tuning is a general feature of self-assembled quantum dots, observed under different growth conditions, emission wavelengths and in different material systems. Statistical measurements of characteristic parameters such as emission energy, Stark shift and FSS tuning are presented which may provide a guide for future attempts to increase the yield of quantum dots that can be tuned to a minimal value of FSS with vertical electric field

Calibrating the Mixing Length Parameter for a Red Giant Envelope

Two-dimensional hydrodynamical simulations were made to calibrate the mixing length parameter for modeling red giant's convective envelope. As was briefly reported in Asida & Tuchman (97), a comparison of simulations starting with models integrated with different values of the mixing length parameter, has been made. In this paper more results are presented, including tests of the spatial resolution and Large Eddy Simulation terms used by the numerical code. The consistent value of the mixing length parameter was found to be 1.4, for a red giant of mass 1.2 solar-mass, core mass of 0.96 solar-mass, luminosity of 200 solar-luminosities, and metallicity Z=0.001.Comment: 18 pages, 1 table, 13 figures. Accepted for publication in Ap.

Hydrothermal inputs drive dynamic shifts in microbial communities in Lake Magadi, Kenya Rift Valley

The Methane Index (MI) is an organic geochemical index that uses isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs) as a proxy for methane cycling. Here, we report results from core spanning > 700 ka in Lake Magadi, Kenya, which shows abrupt shifts between high and low MI values in the core. These shifts coincide with interbedded tuffaceous silt. Where tuffaceous silts are present, MI “switches off” (MI < 0.2); in contrast, where these silts are absent in the core, the MI increases (MI > 0.5). Bulk organic matter is enriched in 13C in Magadi during “MI-off” periods, with values of ~ −18 ‰ in the upper part of the core and −22 to −25 ‰ in the lower portion. Evidence from n-alkanes and fatty acid methyl esters (FAMEs) support previous interpretations of an arid environment with a shallower lake where Thermoproteotal (formerly Crenarchaeota) archaea thrive in a hot spring rich environment over Euryarchaeota. Sediments deposited when the MI switches “on” showed δ13COM values as low as −89.4 ‰, but most were within the range of −28 to −30 ‰, which is consistent with contributions from methanogens rather than methanotrophs. Thus, the likely source of these high MI values in Lake Magadi is methanogenic archaea. Our results show that hydrothermal inputs of bicarbonate-rich waters into Lake Magadi cause a shift in the dominant archaeal communities, alternating between two stable states

The energy budget in Rayleigh-Benard convection

It is shown using three series of Rayleigh number simulations of varying aspect ratio AR and Prandtl number Pr that the normalized dissipation at the wall, while significantly greater than 1, approaches a constant dependent upon AR and Pr. It is also found that the peak velocity, not the mean square velocity, obeys the experimental scaling of Ra^{0.5}. The scaling of the mean square velocity is closer to Ra^{0.46}, which is shown to be consistent with experimental measurements and the numerical results for the scaling of Nu and the temperature if there are strong correlations between the velocity and temperature.Comment: 5 pages, 3 figures, new version 13 Mar, 200

Entropy production and Lyapunov instability at the onset of turbulent convection

Computer simulations of a compressible fluid, convecting heat in two dimensions, suggest that, within a range of Rayleigh numbers, two distinctly different, but stable, time-dependent flow morphologies are possible. The simpler of the flows has two characteristic frequencies: the rotation frequency of the convecting rolls, and the vertical oscillation frequency of the rolls. Observables, such as the heat flux, have a simple-periodic (harmonic) time dependence. The more complex flow has at least one additional characteristic frequency -- the horizontal frequency of the cold, downward- and the warm, upward-flowing plumes. Observables of this latter flow have a broadband frequency distribution. The two flow morphologies, at the same Rayleigh number, have different rates of entropy production and different Lyapunov exponents. The simpler "harmonic" flow transports more heat (produces entropy at a greater rate), whereas the more complex "chaotic" flow has a larger maximum Lyapunov exponent (corresponding to a larger rate of phase-space information loss). A linear combination of these two rates is invariant for the two flow morphologies over the entire range of Rayleigh numbers for which the flows coexist, suggesting a relation between the two rates near the onset of convective turbulence.Comment: 5 pages, 4 figure