Norwegian Centre for Organic Agriculture, Gunnarsveg 6, 6630, Tingvoll, Norway.
Department of Animal Health and Food Safety, Norwegian Veterinary Institute, Ås, Norway.
Acta Vet Scand. 2022 Apr 23;64(1):10. doi: 10.1186/s13028-022-00629-y.
Eimeria spp. are widespread apicomplexan parasites known to cause coccidiosis in livestock, resulting in reduced animal welfare and productivity, particularly in sheep. The treatment options are limited, and there is an emerging development of resistance against registered pharmaceuticals. Spruce bark is rich in plant secondary metabolites (PSM), such as condensed tannins, which are bioactive compounds previously shown to have antiparasitic activity. Here, we examined the anticoccidial properties of bark extract of Norway spruce (Picea abies) against a field isolate of ovine Eimeria spp. by treating Eimeria-infected pre-ruminant lambs with water-extracted bark daily for 12 days. We hypothesised that the bark extract would reduce the faecal oocyst excretion and, consequently, the severity of diarrhoea.
Oral administration of spruce bark extract significantly reduced the excretion of Eimeria oocysts in milk-fed lambs post treatment till the end of the trial 22 days post infection. This difference in oocyst excretion between the treated and the untreated infected animals increased with time. Compared to the untreated and the sham-infected control group, the group treated with bark extract had softer faeces and reduced milk intake during the treatment period. After discontinuing the treatment, the treated animals got a more solid and formed faeces compared to that of the untreated control group, and the milk intake increased to the level of the sham-infected, untreated control group. The bark extract treated animals had a lower body weight and a lower mean daily body weight gain throughout the whole duration of the experiment.
Bark extract from Norway spruce showed marked anticoccidial properties by reducing the faecal oocyst count and associated diarrhoea in young lambs. Simultaneously we experienced detrimental effects of the treatment, displayed as reduced feed intake and daily body weight gain. Therefore, we suggest conducting similar studies with lower bark extract dosage to explore the possibilities of a better trade-off to reduce the negative impact while maintaining the antiparasitic effect.
艾美耳球虫是广泛存在的顶复门寄生虫，已知会导致家畜的球虫病，从而降低动物福利和生产力，特别是在绵羊中。治疗选择有限，而且针对已注册的药物出现了耐药性的发展。云杉树皮富含植物次生代谢物（PSM），如缩合单宁，这些物质是具有抗寄生虫活性的生物活性化合物。在这里，我们通过每天用提取自云杉树皮的水对感染艾美耳球虫的未反刍羔羊进行 12 天的治疗，研究了挪威云杉（Picea abies）树皮提取物对绵羊艾美耳球虫田间分离株的抗球虫特性。我们假设树皮提取物会减少粪便卵囊排泄，从而减轻腹泻的严重程度。
口服云杉树皮提取物显著减少了牛奶喂养的羔羊在治疗后直至感染后 22 天试验结束时的艾美耳球虫卵囊排泄。与未处理的感染动物相比，处理组和未处理的感染动物之间卵囊排泄的差异随着时间的推移而增加。与未处理和假感染对照组相比，在治疗期间，用树皮提取物处理的组的粪便变软，牛奶摄入量减少。停止治疗后，与未处理的对照组相比，处理组的动物的粪便变得更结实和成形，牛奶摄入量增加到假感染、未处理的对照组的水平。在整个实验过程中，处理组动物的体重和平均日体重增加均低于未处理的对照组。
挪威云杉树皮提取物通过减少幼羊粪便卵囊计数和相关腹泻，表现出明显的抗球虫特性。同时，我们也经历了治疗的不利影响，表现为饲料摄入量和日体重增加减少。因此，我们建议进行类似的研究，使用较低剂量的树皮提取物，以探索在保持抗寄生虫作用的同时减少负面影响的可能性。
