Sinclair Rona, Melville Lynsey, Sargison Fiona, Kenyon Fiona, Nussey Dan, Watt Kathryn, Sargison Neil
University of Edinburgh, Institute of Evolutionary Biology, United Kingdom.
The Moredun Research Institute, United Kingdom.
Vet Parasitol. 2016 Aug 30;227:1-7. doi: 10.1016/j.vetpar.2016.07.020. Epub 2016 Jul 18.
Molecular methods based on ITS2 sequence analysis were used to identify strongylid parasites and describe their diversity in a management intervention and anthelmintic drug treatment-free sheep flock. Fourteen different nematode parasite species were identified in the flock and the results showed a greater level of nematode species diversity than is normally reported in managed farmed flocks, with the presence of parasites such as Bunostomum trigonocephalum, Ostertagia leptospicularis, Spiculopteragia houdemeri and Trichostrongylus retortaeformis that are considered to be absent or rare in sheep kept in comparable localities. The implied prevalences of Haemonchus contortus in lambs, and of Trichostrongylus axei in lambs, ewes and rams, were higher than those in farmed sheep kept in similar regions, while those of Teladorsagia circumcincta and Trichostrongylus vitrinus were lower. Comparison of the patterns of nematode parasite infection between the summer and autumn sampling periods showed differences from the scenarios that are commonplace in comparable managed flocks; with T. vitrinus burdens of the lambs being higher in the summer than in the winter, and Oesophagostomum venulosum being the predominant nematode species in the adult sheep during the summer, while more-or-less absent from these groups during the winter. Rams played an important role in the epidemiology of certain parasitic nematode species. The relatively non-pathogenic O. venulosum was the only parasitic nematode species to predominate in any group during the study. This preliminary characterisation of the nematode parasite burdens of sheep extensively grazed on diverse unimproved pastures will aid in the understanding of the parasitological consequences of intensive grazing management and of the manner in which modern agriculture upsets the equilibrium between parasites and their hosts. These factors must be accounted for when defining the concept of sustainable parasite control and informing sustainability with reference to commercially efficient sheep farming.
基于ITS2序列分析的分子方法被用于鉴定圆线虫寄生虫，并描述其在一个管理干预且未进行驱虫药物治疗的羊群中的多样性。在该羊群中鉴定出了14种不同的线虫寄生虫物种，结果显示线虫物种多样性水平高于通常在管理养殖羊群中报道的水平，存在诸如三角头仰口线虫、细颈奥斯特线虫、胡氏细颈线虫和捻转血矛线虫等寄生虫，而在当地类似饲养条件下的绵羊中，这些寄生虫被认为不存在或很罕见。羔羊体内捻转血矛线虫以及羔羊、母羊和公羊体内斧形毛圆线虫的隐含流行率高于类似地区养殖绵羊中的流行率，而环形泰勒虫和玻璃样毛圆线虫的隐含流行率则较低。夏季和秋季采样期线虫寄生虫感染模式的比较显示，与类似管理羊群中常见的情况有所不同；羔羊体内玻璃样毛圆线虫的感染量夏季高于冬季，而夏季成年绵羊中主要的线虫物种是微小食道口线虫，冬季这些群体中则基本不存在。公羊在某些寄生线虫物种的流行病学中发挥了重要作用。相对无害的微小食道口线虫是研究期间唯一在任何群体中占主导地位的寄生线虫物种。对在多样化未改良牧场上广泛放牧的绵羊的线虫寄生虫感染情况进行的初步特征描述，将有助于理解集约化放牧管理的寄生虫学后果，以及现代农业扰乱寄生虫与其宿主之间平衡的方式。在定义可持续寄生虫控制概念并为商业高效养羊的可持续性提供参考时，必须考虑这些因素。
