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61.
Sinclair M Bührmann G Gummow B 《Journal of the South African Veterinary Association》2006,77(4):191-196
African Horsesickness (AHS) is a controlled disease in South Africa. The country is divided into an infected area and a control area. An outbreak of AHS in the control area can result in a ban of exports for at least 2 years. A retrospective epidemiological study was carried out on data collected during the 2004 AHS outbreak in the surveillance zone of the AHS control area in the Western Cape Province. The objective of this study was to describe the 2004 outbreak and compare it with the 1999 AHS outbreak in the same area. As part of the investigation, a questionnaire survey was conducted in the 30 km radius surrounding the index case. Spatial, temporal and population patterns for the outbreak are described. The investigation found that the outbreak occurred before any significant rainfall and that the main AHS vector (Culicoides imicola) was present in abundance during the outbreak. Furthermore, 63% of cases occurred at temperatures < or = 15 degrees C, the Eerste River Valley was a high risk area, only 17% of owners used vector protection as a control measure and 70% of horses in the outbreak area were protected by means of vaccination at the start of the outbreak. The study revealed that the current AHS control measures do not function optimally because of the high percentage of vaccinated horses in the surveillance zone, which results in insufficient sentinel animals and the consequent failure of the early warning system. Alternative options for control that allow continued export are discussed in the paper. 相似文献
62.
OBJECTIVE: To determine the cardiovascular effects of dopamine and dobutamine infusions during nor-movolemia, hypovolemia (HV) through blood loss of 10 mL/kg (HV(10)), further loss to 25 mL/kg (HV(25)), and volume replacement (VR) in isoflurane-anesthetized dogs. ANIMALS: 7 healthy young dogs. PROCEDURES: Dogs were anesthetized with isoflurane 2 times (3 weeks apart). Cardiovascular measurements were obtained for each volume state. The cardiac index (CI) determined by the lithium dilution technique was compared with CI assessed by the arterial pulse contour technique. At each volume state, random treatment with dobutamine or dopamine was assessed (CI by the arterial pulse contour technique). Ten-minute treatments with 3 and 6 microg of dobutamine/kg/min or 7 and 14 microg of dopamine/kg/min (low and high doses, respectively) were administered sequentially. Differences from baseline were determined for volume, drug, and dose effects. RESULTS: Significant proportional changes in blood pressure (BP), stroke index (SI), and CI were evident with changes in volume state. Systemic vascular resistance (SVR) decreased after VR. Dobutamine induced little change in BP; increased heart rate (HR), SI, and CI; and decreased SVR (high dose). Dopamine increased BP and SI, did not change CI, and increased SVR (high dose). The arterial pulse contour technique underestimated changes in CI associated with volume changes. CONCLUSIONS AND CLINICAL RELEVANCE: Isoflurane eliminates clinically obvious compensatory increases in HR during HV. Dopamine is suitable for temporary management of blood loss in isoflurane-anesthetized dogs. Dobutamine increased CI without an associated improvement in BP. The arterial pulse contour monitor should be recalibrated when volume status changes. 相似文献
63.
喀斯特地区烟田土壤有效态微量元素的空间变异特征——以贵州省毕节地区为例 总被引:1,自引:0,他引:1
以典型的喀斯特地区——贵州省毕节地区为研究区域,采用地统计学和地理信息系统(GIS)相结合的方法,对烟田土壤中有效态微量元素Cu、Zn、Fe、Mn、B和Mo含量的空间变异特征进行研究。结果表明,烟田土壤中各微量元素的变异系数在45.75%~82.45%,均属于中等变异。半方差函数分析表明,烟田土壤微量元素中Cu、Zn、Fe的最适模型是线性模型,而Mn、B和Mo的最适模型为指数模型;各微量元素的块基比〔C0/(C0+C)〕均在25%~75%,表现为中等空间相关性,其空间变异受结构性因素(土壤母质、地形地貌、气候)和随机性因素(施肥、耕作措施、工业污染等)的共同影响。烟田土壤微量元素的空间分布表明,除有效铁含量分布呈现连续空间分布特点外,其他几种微量元素的空间分布并未呈现明显的分布规律。 相似文献
64.
有机氮部分替代无机氮对香料烟产量、产值及品质的影响 总被引:2,自引:0,他引:2
为了提高香料烟的产量、产值和品质,采用田间小区试验研究了有机氮部分替代无机氮(取代比例分别为0、25%、50%)对香料烟产值及品质的影响。结果表明,有机氮取代部分无机氮对烤烟的产量、产值、上等烟比例和化学成分协调程度及矿质营养元素含量有很大的影响。其中,产量、产值和上等烟比例以有机氮取代50%无机氮处理最高,分别达到2 212.00kg/hm2、53 362.00元/hm2和70.22%。有机氮部分取代无机氮对香料烟叶片中化学成分、矿质元素的影响比较复杂,不同部位叶片以及不同化学成分的响应不同,但总体表现为有机氮取代无机氮改善了烤烟化学成分的协调程度,促进了有益矿质元素的积累。总之,对浙江省绍兴香料烟烟区来说,在施氮水平为105kg/hm2情况下,有机氮取代50%的无机氮时香料烟的经济产量、产值和烟叶品质较好。 相似文献
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69.
A.N. Sinclair M.V.Sc. F.R.C.V.S. M.A.C.V.Sc. 《New Zealand veterinary journal》2013,61(7):149-152
Abstract Extract Fleece derangement, characterized by matted chewed wool in a region accessible to the sheep's mouth — i.e., behind a line approximately from elbow to hip, — indicates a typical behavioural response by sensitive sheep infested with Psorergates ovis. The condition was recorded by Bekker (1928) long before the mite was found (Carter, 1941; Womersley 1941). Fleece derangement is seen easily at flock inspection and so is used as anindication of P. ovis infestation in a flock, though Baker (1968) showed that a greater proportion of sheep in which heavy skin scurf was present, with or without fleece derangement, may be infested. Inspecting individual sheep closely for scurf is slow, while examining skin scrapings limits the number of sheep that can be inspected to less than about twenty per day, so the ready convenience of observing fleece derangement favours its use. 相似文献
70.
Nematode parasites have been a major factor limiting sheep production in New Zealand for more than 100 years. Twenty-nine species of nematodes were unintentionally introduced with sheep into New Zealand, but it is principally species of Haemonchus, Ostertagia, Trichostrongylus, Nematodirus and Cooperia that are associated with production losses and clinical disease. The seasonal dynamics of nematode infection are the consequence of complex inter-relationships between the sheep, their husbandry and the prevailing climate. The patterns of pasture contamination by nematode eggs and then larvae, and the subsequent levels of infection in ewes and lambs are broadly similar throughout New Zealand. Numbers of infective larvae on pasture build up over summer to a peak in autumn/early winter with, in some years, a spring peak derived from the parturient rise in faecal nematode egg counts (FEC), expressed in eggs per gram of faeces (epg), in lactating ewes. The immune capability of lambs is initially low but increases with the magnitude and duration of exposure to infection. Once significant immunity has developed (usually by 10–12 months of age), sheep are capable of markedly restricting parasite infection, except during times of disease, malnutrition or stress. For the effective control of nematode parasites, farmers have come to rely almost exclusively on broad-spectrum anthelmintics. However, issues relating to resistance, residues and eco-toxicity increasingly threaten the sustainability of chemotherapy. In order to maintain present levels of parasite control and productivity in the long term, farmers need to integrate management practices aimed at minimising animal exposure to parasites with reduced reliance on anthelmintics. 相似文献