746 resultados para COMMUNAL NESTING


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The purpose of this study was to investigate whether sheep grazing communal alpine pastures with cattle can transmit Border disease virus (BDV) to cattle. A total of 1170 sheep and 923 cattle were tested for BDV using RT-PCR (sheep) and for pestivirus antibodies using an ELISA (cattle), respectively, before being moved to one of 4 pastures (A, B, C and D). Eight sheep from pasture C were viraemic. 396 of 923 cattle examined before the pasture season were seronegative. The latter were re-examined after the pasture season and 99 were seropositive or indeterminate. Antibody specificity was determined in 25 of these using a serum neutralization test (SNT). BDV infection was confirmed in 10 cattle and was considered likely in 8 others. BVDV infection was confirmed in 4 cattle and considered likely in 3 after pasturing. The study has shown that the transmission of BDV from sheep to cattle is possible on communal alpine pastures.

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Abstract Staphylococcus aureus is a major mastitis-causing pathogen. Various genotypes have been recently identified in Switzerland but Staph. aureus genotype B (GTB) was the only genotype associated with high within-herd prevalence. The risk of introducing this Staph. aureus genotype into a herd may be increased by frequent animal movements. This may also be the case when cows from different herds of origin are commingled and share their milking equipment for a limited period of time. The aim of the present study was to determine the prevalence of Staph. aureus GTB in seasonally communal dairy herds before and after a summer period when dairy farming is characterized by mixing cows from different herds of origin in 1 communal operation. In addition, the environment was investigated to identify potential Staph. aureus GTB reservoirs relevant for transmission of the disease. A total of 829 cows from 110 herds of origin in 9 communal operations were included in the study. Composite milk samples were collected from all cows during the first or second milking after arrival at the communal operation and again shortly before the end of the season. Swab samples from the environment, involved personnel, and herding dogs present were collected before the cows arrived. At the end of the season, sampling of personnel was repeated. All samples were analyzed for the presence of Staph. aureus GTB using an established quantitative PCR. At the beginning of the season, Staph. aureus GTB-positive cows were identified in 7 out of 9 communal operations and the within-communal operation prevalence ranged from 2.2 to 38.9%. At the second sampling, all communal operations were Staph. aureus GTB positive, showing within-communal operation prevalence from 1 to 72.1%. The between-herd of origin prevalence increased from 27.3 to 56.6% and the cow-level prevalence increased from 11.2% at the beginning of the season to 29.6% at the end of the season. On 3 different communal operations, Staph. aureus GTB-positive swabs from seasonally employed personnel were identified at the end of the season. The results indicate that Staph. aureus GTB can easily spread in communal operations when cows from different herds of origin are mixed during the summer season. Effective management measures need to be designed to prevent the spread of Staph. aureus GTB in seasonally communal herds. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved. KEYWORDS: Staphylococcus aureus; biosecurity; communal herd; epidemiology

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arranged by Miriam Blaustein

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Au travers de stratégies appropriées, les ménages, appelés ici Unités de Production et de Consommation (UPC), cherchent à faire face à différents évènements et à améliorer leur situation économique et sociale tout en tenant compte des conditions écologiques. Au travers de l’Assemblée Générale Communale (AGC), les UPC peuvent créer des conditions cadres locales plus ou moins favorables aux stratégies qu’ils poursuivent. Par le développement d’une stratégie d’investissement communale mise en œuvre par l’AGC et une bonne coordination entre les UPC, les joueurs peuvent optimiser leurs investissements au niveau des ménages. Vainqueur est l’UPC qui à la fin du jeu dispose du plus grand patrimoine.

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Simulating surface wind over complex terrain is a challenge in regional climate modelling. Therefore, this study aims at identifying a set-up of the Weather Research and Forecasting Model (WRF) model that minimises system- atic errors of surface winds in hindcast simulations. Major factors of the model configuration are tested to find a suitable set-up: the horizontal resolution, the planetary boundary layer (PBL) parameterisation scheme and the way the WRF is nested to the driving data set. Hence, a number of sensitivity simulations at a spatial resolution of 2 km are carried out and compared to observations. Given the importance of wind storms, the analysis is based on case studies of 24 historical wind storms that caused great economic damage in Switzerland. Each of these events is downscaled using eight different model set-ups, but sharing the same driving data set. The results show that the lack of representation of the unresolved topography leads to a general overestimation of wind speed in WRF. However, this bias can be substantially reduced by using a PBL scheme that explicitly considers the effects of non-resolved topography, which also improves the spatial structure of wind speed over Switzerland. The wind direction, although generally well reproduced, is not very sensitive to the PBL scheme. Further sensitivity tests include four types of nesting methods: nesting only at the boundaries of the outermost domain, analysis nudging, spectral nudging, and the so-called re-forecast method, where the simulation is frequently restarted. These simulations show that restricting the freedom of the model to develop large-scale disturbances slightly increases the temporal agreement with the observations, at the same time that it further reduces the overestimation of wind speed, especially for maximum wind peaks. The model performance is also evaluated in the outermost domains, where the resolution is coarser. The results demonstrate the important role of horizontal resolution, where the step from 6 to 2 km significantly improves model performance. In summary, the combination of a grid size of 2 km, the non-local PBL scheme modified to explicitly account for non-resolved orography, as well as analysis or spectral nudging, is a superior combination when dynamical downscaling is aimed at reproducing real wind fields.

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When the Shakers established communal farms in the Ohio Valley, they encountered a new agricultural environment that was substantially different from the familiar soils, climates, and markets of New England and the Hudson Valley. The ways in which their response to these new conditions differed by region has not been well documented. We examine patterns of specialization among the Shakers using the manuscript schedules of the federal Agricultural Censuses from 1850 through 1880. For each Shaker unit, we also recorded a random sample of five farms in the same township (or all available farms if there were fewer than five). The sample of neighboring farms included 75 in 1850, 70 in the next two census years, and 66 in 1880. A Herfindahl-type index suggested that, although the level of specialization was less among the Shakers than their neighbors, trends in specialization by the Shakers and their neighbors were remarkably similar when considered by region. Both Eastern and Western Shakers were more heavily committed to dairy and produce than were their neighbors, while Western Shakers produced more grains than did Eastern Shakers, a pattern imitated in nearby family farms. Livestock and related production was far more important to the Eastern Shakers than to the Western Shakers, again similar to patterns in the census returns from other farms. We conclude that, despite the obvious scale and organizational differences, Shaker production decisions were based on the same comparative advantages that determined production decisions of family farms.

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In our late twentieth century experience, survival of an economy seems critically dependent on well established rights to private property and a return to labor that rewards greater effort. But that need not be so. History provides examples of micro-socialist economies that internally, at least, allow for little private property for participants and a constant return to labor that is independent of effort. Some such economies may even be termed 'successful,' if success is taken to mean survival over several generations. If these communities survived without conditions that are generally thought to be necessary for success, a question worth asking is how this occurred, for we can then shed some light on what really is necessary for economic survival. Addressing this issue emphasizes the critical role of time, for even if the microsocialist economies that we study here eventually became the merest shadow of their former selves, the fact that they did flourish for so long makes them a valuable counterexample, and hence, a phenomenon in need of explanation. We consider here the dairy industry of the Shakers, which was characterized by intensive efforts to increase productivity, in part through the use of market signals, but efforts that were also limited by the ideological goals of the community. The Shakers were (and are, but since it is the historical Shakers that concern this paper, the past tense will be used) a Christian communal group. Some of their distinctive beliefs included the existence of a male and female Godhead, from which followed sexual equality, and active communication between Believers (a Shaker term for members of the sect) and denizens of the spirit world. Practices of the Society (their official name is the United Society of Believers in Christ's Second Appearing, the second appearing being in the body of their foundress, an illiterate Englishwoman named Ann Lee) included pacifism, celibacy, confession of sins to elders, and joint or communal ownership of the Society's assets. Each Shaker received the same return for his or her labor: room, board, clothing, and the experience of divine proximity in a community of like minded Believers (Stein 1992).

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Isolated Shaker communal farms stressed self-sufficiency as an ideal but carefully chose which goods to buy and sell in external markets and which to produce and consume themselves. We use records of hog slaughter weights to investigate the extent to which the Shakers incorporated market-based price information in determining production levels of a consumption good which they did not sell in external markets: pork. Granger causality tests indicate that Shaker pork production decisions were influenced as hypothesized, strongly by corn prices and weakly by pork prices. We infer that attention to opportunity costs of goods that they produced and consumed themselves was a likely factor aiding the longevity of Shaker communal societies.

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Resource pulses are common in various ecosystems and often have large impacts on ecosystem functioning. Many animals hoard food during resource pulses, yet how this behaviour affects pulse diffusion through trophic levels is poorly known because of a lack of individual-based studies. Our objective was to examine how the hoarding behaviour of arctic foxes (Alopex lagopus) preying on a seasonal pulsed resource (goose eggs) was affected by annual and seasonal changes in resource availability. We monitored foraging behaviour of foxes in a greater snow goose (Chen caerulescens atlanticus) colony during 8 nesting seasons that covered 2 lemming cycles. The number of goose eggs taken and cached per hour by foxes declined 6-fold from laying to hatching, while the proportion of eggs cached remained constant. In contrast, the proportion of eggs cached by foxes fluctuated in response to the annual lemming cycle independently of the seasonal pulse of goose eggs. Foxes cached the majority of eggs taken (> 90%) when lemming abundance was high or moderate but only 40% during the low phase of the cycle. This likely occurred because foxes consumed a greater proportion of goose eggs to fulfill their energy requirement at low lemming abundance. Our study clearly illustrates a behavioural mechanism that extends the energetic benefits of a resource pulse. The hoarding behaviour of the main predator enhances the allochthonous nutrients input brought by migrating birds from the south into the arctic terrestrial ecosystem. This could increase average predator density and promote indirect interactions among prey.