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牧地上捻转血矛线虫（Haemonchus contortus）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多因子和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印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长曲线，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地上捻转血矛线虫侵袭性幼虫数量的季节动态，从而为防治措施的制订提供依据。     

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。     

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。     

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。     

山羊寄生虫病用药方法

山羊在整个生长过程中不断受到各种寄生虫的侵袭。寄生线虫一般在5月出现第一个高峰，7—9月出现第二个高峰；吸虫和绦虫多在春、夏、秋三季感染流行，且幼虫在羊体内发育期较长；螨虫多发生于冬春季；每年11月至次年3月外界环境中蠕虫卵不能发育到侵袭性阶段，也不能越冬。根据寄生虫这些消长规律和流行病学特点，我们必须有针对性重点选择药物进行预防和治疗。     

丝状网尾线虫在羔羊体内发育形态观察

用人工孵育的丝状网尾线虫侵袭性幼虫,按每只羊500条经口感染6月龄无虫羔羊13只。以3只无虫羔羊同群饲养作为对照。试验组羊于感染后不同天数分别宰杀剖检,以水浴法同收幼虫。并定期俭查粪便幼虫。观察结果:侵袭性幼虫感染羔羊后,17—113小时陆续通过小肠、血液、脾、肝脏、肠系膜淋巴结完成第三次蜕鞘进入肺脏;第7天发育到可辨认性别的第四期后期幼虫,7—10天在肺脏、小支气管内进行第四次蜕鞘发育为第五期前期幼虫。35—108天以上发育到成虫。还描述了三,四、五期幼虫的形态,并列出了感染后32—105天内宿主粪便排出第一期幼虫的变化曲线。     

绵羊寄生线虫在体内及牧场上各发育阶段的季节动态研究

对亚热带草地模式区──湖北长阳火烧坪草畜示范场绵羊寄生线虫的优势种捻转血矛线虫、环纹奥斯特线虫和粗纹食道口线虫进行了成虫寄生量、羊粪中虫卵排出量和寄生虫体外发育育成率的逐月观察，结合气象资料──气温、相对湿度、蒸发量和雨量的观察记录，得出了这些优势种各发育阶段在绵羊体内及牧地上的季节动态以及与气温、湿度变化的关系。３种线虫在牧地上的体外育成率和在羊体内的寄生量都有２个峰，育成率于４月出现第１个峰，随之在５月成虫出现第１个峰，育成率于６或７月分别出现第２个更高的峰，成虫也于７～９月出现第２个更高的峰。说明成虫峰随体外发育育成峰而来，粪中虫卵的峰值则往往跟随成虫峰而出现。体外育成率的高低又明显受气温及温度影响，平均湿度低于１２℃时无峰出现，低于５℃时育成率为零，湿度在７９％以下时育成率很低。本文还讨论了防制建议。     

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.     

The population dynamics of nematode parasites of sheep in northern England.

An investigation into the population dynamics of sheep nematodes was carried out between April 1970 and September 1971. Faecal egg counts were made from both ewes and lambs at weeks intervals while grass samples were taken fortnightly throughout the summer and monthly during the winter. From these results absolute numbers of nematode eggs and infective larvae were estimated and these figures used as a basis for determining the level of mortality occurring during development from egg to infective larva. The figures were also used to assess the relative importance of the ewe 'spring rise' and the egg output of the lambs in June while grazing contaminated pasture. These calculations suggest that larval mortality was very high and that it may vary considerably from year to year depending upon the climatic conditions prevailing. There was also an indication that the ewe 'spring rise' was the major source of the wave of infection which occurs in the lambs in late August and September.     

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.     

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.     

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.     

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.