Bluetongue virus seropositivity in sheep flocks in North West Frontier Province, Pakistan     

Saeed Akhtar  Nakiri Djallem  Gul Shad  Olaf Thieme 《Preventive veterinary medicine》1997,29(4):293-298

The objectives of this study were to describe the prevalence and distribution of serum antibodies to Bluetongue virus (BTV) in a sample of 38 sheep flocks in northern areas of the North West Frontier Province of Pakistan and to identify demographic and productivity variables that are associated with BTV seropositivity. Blood samples were taken from a random sample of ewes in each flock in April 1995. The owners of the flocks were interviewed regarding some demographic, husbandry and productivity variables of the flocks on the day of blood sampling. A competitive enzyme-linked immunosorbent assay was conducted to test the serum samples for BTV group-specific antibodies. BTV seropositive reactions were obtained in 184 (48.4%) out of 380 tested sera, and in 89.5% (34/38) of the flocks. In the 34 seropositive flocks, the prevalences ranged from 12.5 to 100% (median = 47). A multivariable logistic analysis was carried out to study the influence of demographic and productivity variables on the BTV serological status of the sheep flocks. Abortion risk in the previous lambing season was mildly associated with the serological status of the flock (adjusted odds ratio = 1.16, P = 0.07). For the seropositive flocks, a linear multiple regression showed that distance travelled by the flock during transhumant movement was significantly associated with percent seropositivity (partial regression coefficient (± SE) = − 0.091 ± 0.045).  相似文献   

Letters to the Editor ◆ Lettres À La Rédaction: Prescribing and selling pharmaceuticals          下载免费PDF全文

Olaf Swarbrick 《The Canadian veterinary journal. La revue veterinaire canadienne》1997,38(1):5

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INFLUENCE OF ORGANIC AND MINERAL FERTILIZATION ON GERMINATION,LEAF NITROGEN,NITRATE ACCUMULATION AND YIELD OF VEGETABLE AMARANTH     

Cecilia M. Onyango  Jeremy Harbinson  Jasper K. Imungi  Solomon S. Shibairo  Olaf van Kooten 《Journal of plant nutrition》2013,36(3):342-365

The influence of manure and diammonium phosphate (DAP) mineral fertilizer on germination, leaf nitrogen content, nitrate accumulation and yield of vegetable amaranth (Amaranthus hypochondriacus) was investigated. Field trials were set up at the University of Nairobi Field Station at the Upper Kabete Campus during the long rains of March–May in 2007 and 2008. Trials were laid out as complete randomized block design with four fertilization treatments: 20, 40, and 60 kg nitrogen (N) ha^?1 supplied by DAP (18:46:0), 40 kg N ha^?1 supplied by cattle manure and an unfertilized control variant. The vegetables were harvested at three maturity stages at 6, 7, and 8 weeks after planting. Results indicated that there were significant differences between treatments in germination percentage, leaf nitrogen content, nitrate accumulation and vegetable yield. Plants that received manure had a higher germination percentage than those that received the same amount of N supplied by the chemical fertilizer DAP. The yields generally increased from week 6 to week 8. The highest yield was recorded in plots receiving 40 kg N ha^?1 from DAP at eight weeks after planting. Plots that were supplied with manure recorded the lowest yield when compared to the fertilizer treated plots at all rates. Leaf nitrogen content increased with increasing rate of N but only when N was supplied by DAP fertilizer. The leaf nitrogen content decreased with increasing age of the plants. The leaf nitrate content increased with increase in DAP application rate. Results indicate that manure application produced quality vegetables in terms of low nitrate levels, but leaf nitrogen and vegetable yields were low. DAP application effected higher yields, but the vegetables had high though acceptable nitrate levels.  相似文献   

Respiratory chlamydial infection based on experimental aerosol challenge of pigs with Chlamydia suis     

Sachse K  Grossmann E  Berndt A  Schütt C  Henning K  Theegarten D  Anhenn O  Reinhold P 《Comparative immunology, microbiology and infectious diseases》2004,27(1):7-23

An experimental study of aerogeneous challenge in pigs was conducted in order to reveal characteristic features of porcine respiratory chlamydiosis. Eight conventionally raised pigs were exposed to a pathogenic strain of Chlamydia (C.) suis, four controls were mock infected. Besides pathological changes, the acute-phase and humoral immune responses, as well as the dissemination and transmission of the challenge strain was monitored in the course of infection. The data from clinical investigations, LPS-binding protein assay, antibody ELISAs, confocal laser scanning and light microscopy, immunohistochemical staining and PCR provided extensive evidence of the pathogenic potential of C. suis for the porcine respiratory system. This model appears suitable for further pathophysiological and immunological investigations of chlamydial respiratory infections and can also be recommended for studies of Chlamydia-associated infections of the human lung.  相似文献   

FISHY FISH? THE ECONOMIC IMPACTS OF ESCAPED FARMED FISH     

Yajie Liu  Jon Olaf Olaussen  Anders Skonhoft 《Aquaculture Economics & Management (Blackwell Science)》2013,17(3):273-302

The escape of cultured fish from a marine aquaculture facility is a type of biological invasion that may lead to a variety of potential ecological and economic effects on native fish. This article develops a general invasive species impact model to capture explicitly both the ecological and economic effects of invasive species, especially escaped farmed fish, on native populations and harvests. First, the possible effects of escaped farmed fish on the growth and stock size of a native fish are examined. Next, a bioeconomic model to analyze changes in yield, benefit distribution, and overall profitability is constructed. Different harvesting scenarios, such as commercial, recreational, and joint commercial and recreational fishing are explored. The model is illustrated by a case study of the interaction between native and farmed Atlantic salmon in Norway. The results suggest that both the harvest and profitability of a native fish stock may decline after an invasion, but the total profits from the harvest of both native and farmed stocks may increase or decrease, depending on the strength of the ecological and economic parameters.  相似文献   

Organic matter composition and the protist and nematode communities around anecic earthworm burrows     

Walter S. Andriuzzi  Phuong-Thi Ngo  Stefan Geisen  Aidan M. Keith  Kenneth Dumack  Thomas Bolger  Michael Bonkowski  Lijbert Brussaard  Jack H. Faber  Abad Chabbi  Cornelia Rumpel  Olaf Schmidt 《Biology and Fertility of Soils》2016,52(1):91-100

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Evaluating the transferability of measurements from simple constructed non weighable gravitation lysimeters to predict the water regime on field scale—a case study          下载免费PDF全文

Denise Bednorz  Nadine Tauchnitz  Olaf Christen  Holger Rupp  Ralph Meissner 《植物养料与土壤学杂志》2016,179(6):809-820

The transfer of lysimeter‐based water balances to field scale is still a challenge, whereby the reliability of measured data from non‐weighable gravitation lysimeters (NWGL) is more questioned than the transferability of data from more modern lysimeter devices. The hypothesis of this study was to predict the water regime of a drained arable field (81 ha) based on measurement results of three neighboring (distance of 20 km northern Altmark region Saxony‐Anhalt, Germany) NWGL (surface area of 1 m², depth of 1.25 m) for three hydrological years (HY) from 11/1/2012 to 10/31/2015. For the first two HY, manually collected monthly outflow rates from the NWGL were comparable to registered (data logger) drain rates of the field. But NWGL outflow was underestimated as compared to field drainage in the third HY. This deficit in the lysimeter water balance was caused by heavy rain events in summer 2014 in combination with wind and interception by the crop canopy (Zea maize). Precipitation did not match the NWGL surface whereas this canopy effect did not play a role at the field site. Thus, further numerical simulations of the soil water flow with the HYDRUS 1D/2D‐software package, which were based only on input data determined at the NWGL (stand precipitation, potential evaporation/ transpiration) without taking into account the canopy effect, described registered outflow of the field adequately for the whole observation period. But determining precipitation matching the NWGL surface, which was not registered due to the missing weighing mechanism, is absolutely required to interpret deviating measured outflow rates.  相似文献   

From a stinking wastewater disposal field toward a recreation area—the story of an unconventional soil remediation in Berlin,Germany     

Gerd Wessolek  Björn Kluge  Steffen Trinks  Michael Facklam  Olaf Zeuschner 《Journal of Soils and Sediments》2018,18(2):481-493

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Yield,yield formation,and blackleg disease of oilseed rape cultivated in high-intensity crop rotations     

Hannes Hegewald  Barbara Koblenz  Monika Wensch-Dorendorf  Olaf Christen 《Archives of Agronomy and Soil Science》2017,63(13):1785-1799

The short-term economic benefit has in recent years prompted farmers to grow oilseed rape (OSR) (Brassica napus L.) and thus the frequency of this crop increased in German crop rotations. Here, we investigate the impact of high-intensity OSR crop rotations on yield, yield formation, and blackleg disease (Leptosphaeria maculans) in a rotation experiment in the Hercynian dry region of Central Germany over two seasons (2014/2015?–?2015/2016). The preceding crop combinations compared were winter wheat (WW) (Triticum aestivum L.)-WW, WW-OSR, OSR-OSR, and an OSR monoculture. Furthermore, the fertilizer treatments 120 kg N ha^?1 and 180 kg N ha^?1 were analyzed.

Higher OSR cropping intensity decreased seed yields, however, with a variation among years and oil yield was highest when OSR was following WW-WW over both years. Minor differences were observed among the yield components, but significantly less pods per m² were developed in a long-term OSR monoculture. The disease assessment clearly showed an increased blackleg incidence and severity when OSR was grown successively.

Results of our study emphasize that high-intensity OSR production will very likely be unsustainable over the long term associated with yield losses and increased infestation levels of blackleg disease.  相似文献   

Spatial analysis of an anthrax outbreak in Saskatchewan, 2006     

Epp T  Argue C  Waldner C  Berke O 《The Canadian veterinary journal. La revue veterinaire canadienne》2010,51(7):743-748

An outbreak of anthrax in Saskatchewan in 2006 affected more than 800 animals at 150 locations. The purpose of this study was to assess the spatial and temporal patterns among the cases to determine if there were any significant trends associated with this outbreak. Case and population data were first analyzed for each individual farm location and then again as aggregate data per rural municipality using spatial and spatiotemporal statistical methods such as Oden's Ipop, Cuzick-Edwards' test, spatial scan test, and other mapping techniques. East central Saskatchewan was identified as a primary high risk area, particularly during July 2006. The results of the study led to the conclusion that within this high-risk region, flooding in spring followed by hot and dry conditions could have been a factor in the development of the outbreak.  相似文献