INRAE, Université de Tours, UMR 1282 Infectiologie et Santé Publique, Nouzilly, France.
Université de Tours, EA 7502 Synthèse et Isolement de Molécules Bioactives, Tours, France.
Int J Parasitol Drugs Drug Resist. 2024 Apr;24:100523. doi: 10.1016/j.ijpddr.2024.100523. Epub 2024 Feb 9.
Cyathostomins are the most prevalent parasitic nematodes of grazing horses. They are responsible for colic and diarrhea in their hosts. After several decades of exposure to synthetic anthelmintics, they have evolved to become resistant to most compounds. In addition, the drug-associated environmental side-effects question their use in the field. Alternative control strategies, like bioactive forages, are needed to face these challenges. Among these, chicory (Cichorium intybus, Puna II cultivar (cv.)) is known to convey anthelmintic compounds and may control cyathostomins in grazing horses. To challenge this hypothesis, we measured fecal egg counts and the rate of larval development in 20 naturally infected young saddle horses (2-year-old) grazing either (i) a pasture sown with chicory (n = 10) or (ii) a mesophile grassland (n = 10) at the same stocking rate (2.4 livestock unit (LU)/ha). The grazing period lasted 45 days to prevent horse reinfection. Horses in the chicory group mostly grazed chicory (89% of the bites), while those of the control group grazed mainly grasses (73%). Cyathostomins egg excretion decreased in both groups throughout the experiment. Accounting for this trajectory, the fecal egg count reduction (FECR) measured in individuals grazing chicory relative to control individuals increased from 72.9% at day 16 to 85.5% at the end of the study. In addition, larval development in feces from horses grazed on chicory was reduced by more than 60% from d31 compared to control individuals. Using a metabarcoding approach, we also evidenced a significant decrease in cyathostomin species abundance in horses grazing chicory. Chicory extract enriched in sesquiterpenes lactones was tested on two cyathostomins isolates. The estimated IC was high (1 and 3.4 mg/ml) and varied according to the pyrantel sensitivity status of the worm isolate. We conclude that the grazing of chicory (cv. Puna II) by horses is a promising strategy for reducing cyathostomin egg excretion and larval development that may contribute to lower the reliance on synthetic anthelmintics. The underpinning modes of action remain to be explored further.
马胃线虫是放牧马最常见的寄生线虫。它们会导致宿主出现腹痛和腹泻。在接触合成驱虫药几十年后，它们已经进化到对大多数化合物产生耐药性。此外，药物相关的环境副作用也引发了对其在该领域应用的质疑。需要采用替代控制策略，如生物活性饲料，来应对这些挑战。其中，菊苣（Cichorium intybus，Puna II 品种（cv.））已知具有驱虫化合物，并可能控制放牧马中的马胃线虫。为了验证这一假设，我们测量了 20 匹自然感染的年轻鞍马（2 岁）的粪便卵计数和幼虫发育率，这些马分别在（i）种植菊苣的牧场（n=10）或（ii）同样放牧密度（2.4 个牲畜单位（LU）/公顷）的温带草地（n=10）放牧 45 天以防止马再次感染。菊苣组的马主要采食菊苣（89%的啃咬），而对照组的马主要采食草（73%）。两组的马胃线虫卵排泄在整个实验过程中都有所减少。考虑到这一轨迹，与对照组个体相比，在菊苣组放牧的个体的粪便卵计数减少（FECR）从第 16 天的 72.9%增加到研究结束时的 85.5%。此外，与对照组个体相比，在菊苣组放牧的马的粪便中的幼虫发育减少了 60%以上。使用代谢组学方法，我们还证明了在采食菊苣的马中，马胃线虫的物种丰度显著下降。用富含倍半萜内酯的菊苣提取物对两种马胃线虫分离株进行了测试。估计的 IC 值很高（1 和 3.4mg/ml），并根据蠕虫分离株对吡喹酮的敏感性而变化。我们得出结论，马采食菊苣（cv. Puna II）是减少马胃线虫卵排泄和幼虫发育的一种很有前途的策略，这可能有助于降低对合成驱虫药的依赖。其潜在的作用机制仍有待进一步探索。
