Epidemiology and Control of Gastrointestinal Nematodes of Cattle in Northern Climates
Epidemiology and Control of Gastrointestinal Nematodes of Cattle in Northern Climates
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DOI：
10.1016/j.cvfa.2019.11.008
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发表时间：
2020-03-01
影响因子：
4.1
通讯作者：
McKenzie, John B.
中科院分区：
文献类型：
--
作者：
Hildreth, Michael B.;McKenzie, John B.
由于放牧季节较短和冬季严酷，在加拿大和美国北方感染牛的胃肠道线虫数量普遍低于南方各州。在北方气候条件下，胃肠道线虫在放牧季节使牛体重增加减少约0.05-0.15 kg/天。在春季使用持久性驱虫药以恢复其中一些损失;然而，驱虫药耐药性水平的增加正在降低这种控制策略的有效性。这一点对于诸如Haemonchus placer的物种尤其如此，其分布正在扩展到北方各州，尽管其幼虫无法在牧场越冬。
Gastrointestinal nematodes populations infecting cattle throughout Canada and northern United States are generally lower than in southern states because of shorter grazing seasons and harsh winters. In northern climates, gastrointestinal nematodes diminish cattle weight gains by roughly 0.05-0.15 kg/day during the grazing season. Persistent anthelmintics have been used during the spring to recover some of these losses; however, increasing levels of anthelmintic resistance are decreasing the effectiveness of this control strategy. This is particularly true for species such as Haemonchus placer whose distribution is expanding into northern states even though its larvae are not able to overwinter in pastures.