University of Saskatchewan, Saskatoon, SK, Canada.
University of Calgary, Calgary, AB, Canada.
Parasit Vectors. 2022 Jan 6;15(1):17. doi: 10.1186/s13071-021-05137-y.
The species composition of cattle gastrointestinal nematode (GIN) communities can vary greatly between regions. Despite this, there is remarkably little large-scale surveillance data for cattle GIN species which is due, at least in part, to a lack of scalable diagnostic tools. This lack of regional GIN species-level data represents a major knowledge gap for evidence-based parasite management and assessing the status and impact of factors such as climate change and anthelmintic drug resistance.
This paper presents a large-scale survey of GIN in beef herds across western Canada using ITS-2 rDNA nemabiome metabarcoding. Individual fecal samples were collected from 6 to 20 randomly selected heifers (n = 1665) from each of 85 herds between September 2016 and February 2017 and 10-25 first season calves (n = 824) from each of 42 herds between November 2016 and February 2017.
Gastrointestinal nematode communities in heifers and calves were similar in Alberta and Saskatchewan, with Ostertagia ostertagi and Cooperia oncophora being the predominant GIN species in all herds consistent with previous studies. However, in Manitoba, Cooperia punctata was the predominant species overall and the most abundant GIN species in calves from 4/8 beef herds.
This study revealed a marked regional heterogeneity of GIN species in grazing beef herds in western Canada. The predominance of C. punctata in Manitoba is unexpected, as although this parasite is often the predominant cattle GIN species in more southerly latitudes, it is generally only a minor component of cattle GIN communities in northern temperate regions. We hypothesize that the unexpected predominance of C. punctata at such a northerly latitude represents a range expansion, likely associated with changes in climate, anthelmintic use, management, and/or animal movement. Whatever the cause, these results are of practical concern since C. punctata is more pathogenic than C. oncophora, the Cooperia species that typically predominates in cooler temperate regions. Finally, this study illustrates the value of ITS-2 rDNA nemabiome metabarcoding as a surveillance tool for ruminant GIN parasites.
牛胃肠道线虫（GIN）群落的物种组成在不同地区可能有很大差异。尽管如此，关于牛 GIN 物种的大规模监测数据却非常少，这至少部分是由于缺乏可扩展的诊断工具。这种缺乏区域 GIN 物种水平数据的情况代表了一个主要的知识空白，对于基于证据的寄生虫管理以及评估气候变化和驱虫药物耐药性等因素的现状和影响至关重要。
本研究使用 ITS-2 rDNA 宏条形码技术对加拿大西部的肉牛群进行了大规模的 GIN 调查。2016 年 9 月至 2017 年 2 月期间，从 85 个牛群中每个牛群随机选择 6 至 20 头后备牛（n=1665）采集个体粪便样本，2016 年 11 月至 2017 年 2 月期间从 42 个牛群中每个牛群采集 10-25 头初产牛（n=824）。
后备牛和初产牛的胃肠道线虫群落在艾伯塔省和萨斯喀彻温省相似，所有牛群中优势 GIN 物种均为 O. ostertagi 和 C. oncophora，这与先前的研究一致。然而，在马尼托巴省，C. punctata 是总体上的主要物种，也是 8 个肉牛群中 4 个牛群的初产牛中最丰富的 GIN 物种。
本研究揭示了加拿大西部放牧肉牛群中 GIN 物种的明显区域异质性。马尼托巴省 C. punctata 的优势地位出乎意料，因为尽管这种寄生虫通常是更南部纬度地区牛 GIN 物种的主要组成部分，但它通常只是北部温带地区牛胃肠道线虫群落的次要组成部分。我们假设，C. punctata 在如此北的纬度地区的优势地位代表了一种范围的扩大，可能与气候变化、驱虫药物使用、管理和/或动物运动有关。无论原因是什么，这些结果都具有实际意义，因为 C. punctata 比通常在较凉爽的温带地区占优势的 C. oncophora 更具致病性。最后，本研究说明了 ITS-2 rDNA 宏条形码作为反刍动物 GIN 寄生虫监测工具的价值。
