应用计算机和气象资料预测牧地上捻转血矛线虫（Haemonchus conto…

根据土源性寄生线虫体外发育期间受温度，湿度，季节和宿主地动物影响的原理，采用电子计算机对上述多因子捻转血矛线虫从卵发育到侵袭性幼虫的速度，数量进行分析回归，制定出模拟模型，设计出牧地上该种线虫从卵发育到侵袭性幼虫数量的预测预报公式，将气象资料代入公式计算出的侵袭性幼虫季节消失曲线，与牧地上羊体内成虫数量消长曲线相互对比，初步显示可以采用气象资料通过计算机计算处理预测牧草地上捻转血矛线虫侵袭性幼虫数     

应用计算机和气象资料预测粗纹食道口线虫（Oesophagostomum asperum）数量季节消长的研究

根据土源性寄生线虫体外发育期间受温度、湿度、季节和宿主动物影响的原理，采用电子计算机对上述四因子和食道口线虫从卵发育到侵袭性幼虫速度、数量进行回归分析，制定出模拟模型，设计出了在牧地上该种线虫从卵发育到侵袭性幼虫数量预测预报公式，用该公式和气象资料计算出的侵袭性幼虫季节消长曲线，与牧地上宿主羊体内成虫数量消长曲线相一致，初步显示可以采用气象资料和计算机预测牧地上粗纹食道口线虫侵袭性幼虫量的季节动态，从而为防治措施的制定提供依据。     

应用计算机和气象资料预测粗纹食道口线虫（Oesophagostomunasper…

根据土源性寄生线虫体外发育期间受温度、湿度、季节和宿主动物影响的原理，采用电子计算机对上述四因子和食道口线虫从卵发育到侵袭性幼虫速度、数量进行回归分析，制定出模拟模型，设计了在牧地上该种线虫从卵发育到侵袭性性幼虫数量预测预报公式，用该公式和气象资料计算出的侵袭性幼虫季节消长曲线，与牧地上宿主羊体内成虫数量消和曲线相一致，初步显示可以采用气象资料和计算机预牧地上粗纹食道口线虫侵侵袭性幼虫量的季节动态     

应用计算机和气象资料对草场上马歇尔线虫数量季节消长预测技术的研究

根据土源性寄生线虫体外发育期间受温度、湿度、季节和宿主动物影响的原理,采用电子计算机对上述因子和马歇尔线虫从虫卵发育到侵袭性幼虫的速度、数量进行分析回归,制定出模拟模型,设计出草场上该种线虫从虫卵发育到侵袭性幼虫数量的预测预报公式。将气象资料代入公式计算出侵袭性幼虫季节消长曲线,并与草场上羊体内成虫数量消长曲线相互对比。研究初步显示,可以采用气象资料通过计算机计算处理预测草场上马歇尔线虫侵袭性幼虫数量的季节动态,从而为制订防治措施提供科学依据。     

两种线虫在牧草地上季节动态预测预报模拟模型的应用

两种线虫在牧草地上季节动态预测预报模拟模型的应用孟秀珍，沈杰，曹杰我们曾建立了捻转血矛线虫和粗纹食道口线虫在牧地上季节动态预测预报模拟模型［１，２］，由于宜昌县百里荒草畜示范场羊寄生虫优势虫种仍为这两种［３］，因此我们应用这两个模拟模型对百里荒牧地羊...     

羊消化道4种易混淆线虫虫卵的形态学观察与比较

为了方便临床上鉴定羊消化道常见且易混淆线虫虫卵并丰富相关资料,试验从羊消化道中采集疑似捻转血矛线虫、夏伯特线虫、食道口线虫和奥斯特线虫共4种线虫,采用形态学和分子生物学方法鉴定虫种,将4种线虫于体外短暂培养后得到纯种虫卵,通过观察虫卵不同发育阶段的胚胎形态变化获取每种线虫虫卵形态特征,并对虫卵的长径、宽径和长宽比进行测定。结果表明：经鉴定4种线虫分别为捻转血矛线虫、绵羊夏伯特线虫、粗纹食道口线虫和普通奥斯特线虫。4种线虫虫卵初期胚胎多呈收缩状态且形似桑葚,在外观形态上具有相似性,均为双层卵壳,多数对称,少数不对称。捻转血矛线虫虫卵呈短椭圆形,颜色较浅;绵羊夏伯特线虫虫卵呈椭圆形,颜色较捻转血矛线虫虫卵深;粗纹食道口线虫虫卵呈长椭圆形,颜色较捻转血矛线虫虫卵深,与绵羊夏伯特线虫虫卵相近;普通奥斯特线虫虫卵亦呈长椭圆形,颜色与捻转血矛线虫相近,较绵羊夏伯特线虫和粗纹食道口线虫虫卵浅。虫卵在生理盐水中培养1～6 d后,捻转血矛线虫、绵羊夏伯特线虫和普通奥斯特线虫依次进入蝌蚪期和幼虫期,但仅凭肉眼依然难以区分虫卵种类;绵羊食道口线虫未观察到含蝌蚪或含幼虫的虫卵,仅在桑葚期观察到胚胎收缩成1团及...     

自然条件下奥斯特线虫和细颈线虫外生期发育规律的模拟模型研究

对奥斯特线虫和细颈线虫外生期发育温度和湿度的关系进行回归分析和曲线拟合，初步建立了模拟模型，该模型描述的理论消长曲线与野外观察的实际数据曲线基本一致，研究结果表明，利用计算机和气象资料可以预测牧场上奥斯特线虫和细颈线虫外生期的发育季节动态，从而为制定防治措施提供理论依据。     

羊体的三种线虫在不同温湿度条件下从卵到侵袭性幼虫发育能力的观察

对寄生于羊的捻转血矛线虫、粗纹食道口线虫、环纹奥斯特线虫在不同恒温和恒湿条件下从卵发育到侵袭性幼虫的育成率和所需时间作了观察，温度有４０、３７．５、３５、３０、２５、２０、１５、１０、７．５和５℃等１０个段，相对湿度有１００、９０、８５、８０、７５％等５个相。结果捻转血矛线虫仅在１０～３５℃温度和８０％以上相对湿度条件下能完成发育，１００％相对湿度和２０℃条件下育成率最高；粗纹食道口线虫和环纹奥斯特线虫在７．５～３７．５℃和相对湿度８０％以上能完成发育，也是在１００％湿度和２０℃条件下育成率最高。试验结果可供研究这些寄生虫的地理分布和制定其防治措施时作依据。     

捻转血矛线虫纯净3期幼虫制备方法的改进

从自然感染羊体内获得捻转血矛线虫雌虫后,收集其子宫中的虫卵进行培养,再将纯净的第3期幼虫感染保种山羊,于虫卵排出高峰期大量收集粪便,进行幼虫培养,可获得大量纯净的捻转血矛线虫第3期幼虫。     

捻转血矛线虫HSP60原核表达及特性分析

根据Gen Bank公布的捻转血矛线虫热休克蛋白60(HSP60)基因序列,设计一对特异性引物,以捻转血矛线虫总RNA为模板,通过RTPCR技术扩增出一条约为1 700 bp的DNA片段,将该片段克隆到p MD19-T载体上进行序列分析,结果显示该片段长1 710 bp,编码569个氨基酸。将该基因片段亚克隆到p ET32a(+)载体上,转化大肠杆菌BL21,用IPTG进行诱导表达,SDS-PAGE显示,该基因成功表达,其融合蛋白分子量为80.7 ku,主要分布于菌体上清中。Western blot结果显示该重组蛋白可被人工感染捻转血矛线虫山羊血清所识别。Real-time PCR分析显示,HSP60基因在第三期幼虫和活化第三期幼虫中的相对表达量分别为1.0和0.88。本文探讨捻转血矛线虫HSP60功能奠定了基础。     

湖北省百里荒草畜示范场羊蠕虫病防治研究

根据寄生虫预测预报模拟模型预测羊蠕虫在牧地上季节数量变化而制定防治计划，于１１月下旬每羊投服１０ｍｇ／ｋｇ芬苯哒唑片剂，于第二年４月初每羊投服该药长效控释丸一粒，于６月中旬考核结果，发现羊粪中虫卵量显著减少，羊各项生产指标均有所提高，显示了防治效果良好。     

火烧坪种草养畜示范场羊寄生虫病防治研究

在火烧坪种草养畜示范场羊寄生虫种类调查和主要虫种生态学观察和抗寄生虫药物及适宜制剂试验研究基础上，设计了用高效低毒抗寄生虫药的给药程序，在秋末冬初牧地上寄生虫停止发育初，给每只羊以治疗剂量的广谱抗寄生虫药片剂，以驱除羊体内的寄生虫，第２年春牧地上寄生虫即将开始发育时，再给羊以同样剂量片剂，以驱除冬季又感染上和上次驱虫残存的虫体，同时给每只羊一粒连续释放可达３个半月的长效控释药丸，以避免春夏牧地上寄生虫的感染。经过２年实施，羊体内寄生虫荷量下降９５．２％，牧地也得到了净化，养羊经济效益提高非常显著。     

Dynamics of pasture contamination by gastrointestinal nematodes of cattle under extensive management systems: proposal for strategic control.

An epidemiological study of gastrointestinal nematode parasitism in beef cattle in mountainous areas of Spain was performed. The dynamics of contamination with gastrointestinal nematode larvae of Pyrenean pastures was studied over four years at five areas at different altitudes (900 m to 2100 m), grazed by animals according to traditional systems of beef cattle in mountainous areas. Grass samples were taken every two weeks and larval differentiation was performed. Worm egg counts of grazing animals were assessed in cows, heifers and calves. A consistent seasonal pattern of infective larvae on pasture through the study was observed. In hay meadows, located below 1000 m, infective larvae were found from the end of October until June of the following year. At higher altitudes (1200-2100 m), a bimodal pattern of pasture larvae contamination was observed with increases in late spring (March-June) and in late autumn (September-November). Ostertagia spp., Cooperia spp., Trichostrongylus spp., Oesophagostomum spp., and Nematodirus spp. were found, with Ostertagia spp. being the most frequently found, followed by Cooperia spp. The highest increase of larval contamination in autumn coincided with the grazing of animals in hay meadows. This elevated autumn larval population had a very important epidemiological role because these larvae remained as overwintered larvae until the following grazing season, starting the cycle of contamination of the animals.     

Development,Survival and Availability of Gastrointestinal Nematodes of Sheep and Pastures in a Semi-arid Area of Kajiado District of Kenya

A study was carried out on a ranch in the semi-arid area of Kajiado District in Kenya during the period July 2000 to June 2001 to determine the seasonal patterns of development and survival of gastrointestinal nematodes of sheep on pastures. A series of plots were contaminated with sheep faeces every month and pasture samples were collected weekly for the recovery and identification of larvae. The availability of infective larvae on naturally contaminated pastures was also monitored on the paddocks grazed by sheep and around the night pen and the watering point every month from July 2000 to June 2001. The results from the examination of the pasture samples indicated that rainfall distribution was the major factor governing the development and survival of the pre-parasitic stages. No parasitic larvae were detected from the plots contaminated during the dry months from July to October 2000, but development and translocation of infective larvae on pastures occurred on plots contaminated during the rainy seasons and soon after when relatively high moisture was present in the herbage (November 2000 to June 2001). During this period, peak larval counts occurred between the first and the second week post contamination, then declined to undetectable levels between week 4 and 16 post contamination. The lack of development of infective larvae during the dry season and the relatively rapid decline of their population during the wet season presents an opportunity for the use of pasture spelling as a means of helminth control in the study area. The availability of infective larvae on naturally contaminated pastures, around the night pen and around the watering point also followed the rainfall distribution pattern. Infective larvae were consistently recovered around the watering point throughout the study period. This indicated that the point is an important source of infection for sheep, especially during the dry season when other pastures are non-infective.     

The origin and overwintering survival of the free living stages of cattle parasites in Sweden

During the 1997 Swedish grazing season, faeces were collected every 3 weeks on 7 occasions from young grazing cattle with moderate nematode parasite infections. From this source 12, 400 g dung pats were set up on each sampling occasion on a specially designated area of pasture. Half of these pats were placed on pasture where it was aimed to prevent snow cover during the subsequent winter. During the grazing season, herbage growth was kept at reasonably uniform height by clipping and the dung pats were protected from destruction by animals and birds. At the time of animal turn-out the following year (7th April 1998), it was observed that all dung pats had disappeared. Assessments of the survival of infective larvae, both on pasture and in soil, were made in a circular area encompassing the location of each pat. These sampling procedures were completed within a 3 week period. All faecal deposits yielded infective larvae at turn-out the following year, with proportionally greater numbers developing from nematode eggs deposited in cattle dung during the mid third of the previous grazing season. The surface layer of soil was found to be an important reservoir for infective larvae, with numbers recovered being approximately half those found in the overlying pasture samples. No significant differences were found between the normal pasture and snow excluded pasture in the number of infective larvae recovered from both pasture and soil samples. The epidemiological consequences of these findings are discussed.     

The origin of winter populations of infective larvae of nematode parasites of cattle in a Mediterranean-type climatic environment

An experiment to determine the origin of populations of infective larvae of cattle nematode parasites on pasture during winter was conducted in south-west Western Australia. Six pasture plots were contaminated with worm eggs by grazing worm-infected cattle for periods of a month during summer and autumn. Each plot was contaminated at a different time from the rest. The levels of infective larvae were determined by counting the worm burdens of tracer calves which test-grazed the plots the following winter.Tracer calves which grazed the plots contaminated during summer acquired few worms, whereas those that grazed the plots contaminated during autumn acquired many worms. It was concluded that the hot, dry conditions prevailing during summer and early autumn prevented the development of eggs or survival of larvae in dung pats or free on pasture. In this environment, a programme of worm control which relied on administration of anthelmintic to grazing cattle to prevent autumn contamination of pasture would be most likely to succeed if the first treatment was given in early autumn.     

Development and survival of infective larvae of gastrointestinal nematodes of cattle on pasture in central Kenya

On a series of pasture plots, 2 kg pats of bovine faeces containing known numbers of strongylid (Haemonchus, Cooperia, Oesophagostomum and Trichostrongylus) eggs were deposited at intervals of 4 weeks from July 1995 to June 1996. The plots were sampled every 2 weeks after contamination and infective larvae were identified and counted. Larvae of all the genera developed throughout the year, but the pats exposed during the rainy season yielded more abundant larvae on the herbage. Irrespective of the season of deposition of the pats, larvae were found in larger numbers from 2 to 6 weeks after deposition and generally declined to below detectable levels within 12 to 16 weeks of contamination. The comparatively short survival times noted in this experiment may present opportunities for manipulation of the population dynamics of the gastrointestinal nematodes in the tropical environment of Kenya.     

Development of free-living stages of equine strongyles in faeces on pasture in a tropical environment

The development of the free-living stages and yields of infective third stage strongyle larvae in faeces from a horse with a mixed natural infection deposited on pasture plots were studied over a 2-year period in a coastal area in tropical north Queensland. Two sets of faecal masses (one exposed to, and the other protected from the action of a natural population of dung beetles) were deposited monthly and after 7 days faecal samples were taken for larval recovery and counts. Hatching and development of the free-living stages occurred in faeces on pasture throughout the year. Development was rapid as infective stages were reached within a week of faecal deposition in all months. Yields of infective larvae were affected by the season and the action of dung beetles on the faecal masses. Highest yields were obtained from both beetle-exposed and protected faeces during winter (June to August) and lowest yields were in spring (September to November). High temperatures in spring and summer resulted in low yields of larvae, however, the dry conditions in spring made this season the most unfavourable period. In autumn and winter the temperatures were never low enough to stop or markedly slow down the rate of development, and allowed the development of large numbers of infective larvae. Dung beetle activity was observed throughout the year, and exposed faeces were usually completely dispersed within 24 h of deposition. This resulted in lower yields of infective larvae from these than from protected faeces. Though larval yields were lower, the actual numbers were still substantial so as to cast doubt on the usefulness of these beetles as biological control agents for equine strongylosis in the dry tropics.     

Seasonal development of Cyathostominae larvae on pasture in a northern temperate region of the United Kingdom

A study following the development of Cyathostominae from egg to the infective larval third stage was conducted from April to December 2001 in west central Scotland. Duplicate samples (1 kg) of naturally infected faeces were placed on a 78 cm2 plot each week on a cyathostomin-free pasture. Subsamples of the grass surrounding the faecal plot were collected weekly on four occasions and the number of larvae obtained determined. Few larvae were recovered in the first week of development of individual plots, followed by a rise in the numbers of larvae in second, third and fourth weeks of development of each sample. The climatic conditions were seen to have an effect on the rate of development. Specifically, from multilevel, multivariable linear regression models it was evident that the factors associated with numbers of infective larvae recovered from pasture were the time since the faeces samples were laid down, the average temperature and rainfall during the previous week, as well as the interaction between temperature and rainfall. Conversely, from the model, the number of larvae recovered from pasture was associated with neither the number of eggs within the faeces samples placed on the plots nor with the viability of these eggs.