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991.
A. Vlassoff Jennifer M. Ayling L.W. McMurtry Shona J. Smith A.J. Watson 《New Zealand veterinary journal》2013,61(6):79-81
Forty-three randomly selected farms located throughout South Island, excluding the Nelson region, were surveyed for anthelmintic usage and for sheep nematodes resistant to anthelmintics. Most farmers had used both benzimidazole and non-benzimidazole broad-spectrum drenches on their properties in previous years. Sheep were being drenched, on average, 5.6 times within their first year of life but much less frequently thereafter. Commercial interests played the dominant role in helping farmers formulate their drenching policies. On each farm 24 numbered ewe replacement lambs, born during the spring of 1980, were sampled for faeces at the beginning of the trial to provide material for egg counts and larval cultures. The lambs were weighed and divided into three groups of eight. One group received thiabendazole (TBZ) at 66 mg/kg, the second levamisole (LEV) at 8 mg/kg while the third remained untreated as controls. All were resampled 4 to 10 days later. On 32 (88%) of the 40 farms where drenching trials were successfully carried out during autumn 1981, the faecal egg count depression (FECD) following treatment with either drench was 100%. On one farm TBZ was less than 100% effective as gauged by FECD. LEV proved to be less than 100% effective on 7 farms. On one farm the FECD was less than 80%, on 2 between 90% and 95% and on 4 between 95% and 99%. 相似文献
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Zhao Lu Ynte H. Schukken Rebecca L. Smith Rebecca M. Mitchell Yrjö T. Gröhn 《Preventive veterinary medicine》2013,108(2-3):148-158
The objective of this study was to investigate the potential impacts of imperfect Mycobacterium avium subsp. paratuberculosis (MAP) vaccines on the dynamics of MAP infection in US dairy herds using a mathematical modeling approach. Vaccine-based control programs have been implemented to reduce the prevalence of MAP infection in some dairy herds; however, MAP vaccines are imperfect. Vaccines can provide partial protection for susceptible calves, reduce the infectiousness of animals shedding MAP, lengthen the latent period of infected animals, slow the progression from low shedding to high shedding in infectious animals, and reduce clinical disease. To quantitatively study the impacts of imperfect MAP vaccines, we developed a deterministic multi-group vaccination model and performed global sensitivity analyses. Our results explain why MAP vaccination might have a beneficial, negligible, or detrimental effect in the reduction of prevalence and show that vaccines that are beneficial to individual animals may not be useful for a herd-level control plan. The study suggests that high efficacy vaccines that are aimed at reducing the susceptibility of the host are the most effective in controlling MAP transmission. This work indicates that MAP vaccination should be integrated into a comprehensive control program that includes test-and-cull intervention and improved calf rearing management. 相似文献
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J.M. Herring M.A. McMichael S.A. Smith 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2013,27(5):1020-1033
Microparticles (MPs), small membrane‐derived vesicles, are derived from many cell types and released into the circulation. Microparticles can express antigens, and contain cell surface proteins, cytoplasmic contents, and nuclear components from their cell of origin that determines their composition, characterization, and transfer of biologic information. Certain prompts for this release include shear stress, complement activation, proapoptotic stimulation, cellular damage, or agonist interaction with cell surface receptors. Release can be physiologic or pathologic and is associated with proinflammatory and procoagulant effects and has been implicated in thrombotic states. Microparticles also contribute to systemic inflammation and cardiovascular, hematologic, and oncologic disease states. The study of MPs in human medicine is rapidly advancing and extends into the physiology of health, the pathophysiology of disease, and the role of MPs in transfusion medicine. In veterinary medicine, published work on MPs has been limited to the area of inherited disorders, blood storage, and leukoreduction (LR). Microparticle research is still in its infancy, and this review should be seen as a snapshot of what is currently known. As research continues important limitations, including variations in preanalytic variables such as collection, storage, or centrifugation, and limitations of quantitation are coming to the forefront. Correlation of quantitation of MPs with assays of activity will hopefully shed light on the true nature of MPs in health and disease. This review will focus on the role of cellular exocytic vesiculation in health, disease, and transfusion medicine. 相似文献
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Martin E. Smith John D. C. Linnell John Odden Jon E. Swenson 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2013,63(4):304-315
The use of aversive conditioning, repellents and deterrents in the management of predator-livestock problems is evaluated based on a comprehensive literature review, contact with leading authorities and visits to areas with similar predation problems. The status of these management tools is reported and their applicability under Scandinavian conditions evaluated. Aversive conditioning usually involves treating baits with an emetic compound (usually lithium chloride), and has shown inconsistent and inconclusive results. Repellents and deterrents include physical, chemical and acoustic stimuli or devices that cause predators to stop an unwanted behaviour or to retreat from an area. Chemical repellents are not particularly effective against coyotes but have been effective for wolverines and bears under some conditions (e.g. with the availability of untreated, alternative prey). Projectile repellents give an immediate, positive result with bears, but their use is limited. Visual and acoustic devices work well, but only for a limited time, as predators quickly habituate to these devices. To summarize, these methods generally show little promise in reducing livestock depredation on a large-scale or long-term basis, especially under the conditions prevailing in Scandinavia. 相似文献