Administration of spruce bark (Picea abies) extracts in young lambs exhibits anticoccidial effects but reduces milk intake and body weight gain

Berit Marie Blomstrand*, Heidi Larsen Enemark, Havard Steinshamn, Inga Marie Aasen, Juni Rosann Engelien Johanssen, Spiridoula Athanasiadou, Stig Milan Thamsborg, Kristin Marie Sørheim

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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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.

Original languageEnglish
Article number10
JournalActa Veterinaria Scandinavica
Issue number1
Early online date23 Apr 2022
Publication statusFirst published - 23 Apr 2022


  • spruce bark
  • Lambs
  • Milk feeding
  • Weight gain
  • anticoccidial
  • Eimeria
  • Feces/parasitology
  • Veterinary Drugs/pharmacology
  • Plant Bark
  • Sheep Diseases/drug therapy
  • Antiparasitic Agents/therapeutic use
  • Diarrhea/drug therapy
  • Animals
  • Abies
  • Chickens
  • Sheep
  • Coccidiostats/pharmacology
  • Coccidiosis/drug therapy
  • Plant Extracts/pharmacology
  • Weight Gain
  • Poultry Diseases
  • Oocysts
  • Picea
  • Milk
  • Coccidia
  • Coccidiocide
  • Industrial by-products


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