Department of disease control, Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Scotland EH26 0PZ, UK.
Department of disease control, Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Scotland EH26 0PZ, UK.
Animal. 2021 Apr;15(4):100176. doi: 10.1016/j.animal.2021.100176. Epub 2021 Feb 23.
Given the economic impact of gastrointestinal nematode infection on livestock farming worldwide, and increasing anthelmintic resistance, it is imperative to develop practical, efficient and sustainable control strategies. Targeted selective treatment (TST), whereby anthelmintic treatments are administered to animals individually, based on selection criteria such as weight gain, has been shown to successfully maintain animal productivity whilst reducing the selection pressure for anthelmintic resistance and the economic cost of treatment in experimental and commercial settings. Despite the benefits of the TST approach, the equipment and time required to monitor animals individually make this strategy unsuitable for some farming enterprises. The sentinel group approach aims to maintain the benefits observed using TST whilst reducing these requirements. The study involved two experiments, each following a group of 80 lambs through their first grazing season. Anthelmintic treatment of the whole group was determined by monitoring the weight gain of identified sentinel lambs within it every 2 weeks: when 40% of the sentinel lambs failed to reach their weight gain targets, the whole group was treated. The sentinel lambs consisted of 45% of the group (n = 36) in experiment one and 20% (n = 16) in experiment two. A control group of 20 lambs was co-grazed with the main group during both experiments; in experiment one, the sentinel approach was compared with a TST approach, in which control lambs were treated on an individual basis in response to weight gain. In experiment two, the sentinel approach was compared with conventional prophylaxis, where all lambs in the control group were treated at strategic time points throughout the season (= strategic prophylactic treatment). The sentinel lambs were found to be representative of overall group performance regardless of the proportion of sentinels within the group: they recorded similar growth rates and reached weight gain targets simultaneously at each time point and overall. Live-weight gain was also similar between sentinel and control animals in both experiments. The findings of the current study suggest that monitoring sentinel lambs comprising 20% of a group of grazing lambs is sufficient to determine the need for anthelmintic treatment within the whole group, and that this approach maintains production in line with conventional or TST treatment regimes.
鉴于胃肠道线虫感染对全球畜牧业的经济影响，以及驱虫药耐药性的不断增加，制定切实可行、高效和可持续的控制策略势在必行。靶向选择性治疗（TST）根据体重增加等选择标准，对动物个体进行驱虫治疗，已被证明可成功维持动物生产力，同时降低驱虫药耐药性的选择压力，并降低实验和商业环境中治疗的经济成本。尽管 TST 方法有其优势，但监测个体动物所需的设备和时间使得这种策略不适合某些养殖企业。哨群方法旨在在降低这些要求的同时保持 TST 观察到的益处。这项研究涉及两项实验，每项实验都跟踪一组 80 只羔羊度过它们的第一个放牧季节。通过每两周监测其中识别出的哨羊的体重增加来确定整个群体的驱虫治疗：当 40%的哨羊未能达到体重增加目标时，整个群体都接受治疗。哨羊由每组的 45%（n=36）组成，在实验一中，由 20%（n=16）组成。在两项实验中，都有 20 只羔羊与主要群体共同放牧作为对照组；在实验一中，哨群方法与 TST 方法进行了比较，后者根据体重增加对个体控制羊进行治疗。在实验二中，哨群方法与常规预防法进行了比较，后者在整个季节的战略时间点对对照组的所有羔羊进行治疗（= 战略预防性治疗）。无论哨羊在群体中的比例如何，哨羊都代表了群体的整体表现：它们在每个时间点的生长速度相似，并同时达到体重增加目标。在两项实验中，哨羊和对照动物的活体重增加也相似。本研究的结果表明，监测占放牧羔羊群体 20%的哨羊足以确定整个群体中驱虫治疗的需求，并且这种方法可保持与常规或 TST 治疗方案一致的生产力。
