Comparative analysis of the anthelmintic efficacy of European heather extracts on Teladorsagia circumcincta and Trichostrongylus colubriformis egg hatching and larval motility.

BACKGROUND: Gastrointestinal nematode (GIN) control is traditionally achieved with the use of anthelmintic drugs, however due to regulations in organic farming and the rise in anthelmintic resistance, alternatives are sought after. A promising alternative is the use of bioactive plant feeding due to the presence of plant secondary metabolites (PSMs) such as proanthocyanidins (PAs). This study focussed on the perennial shrub heather (Ericaceae family), a plant rich in PAs, highly abundant across Europe and with previously demonstrated anthelmintic potential. METHODS: In vitro assays were used to investigate heather's anthelmintic efficacy against egg hatching and larval motility. Heather samples were collected from five European countries across two seasons, and extracts were tested against two GIN species: Teladorsagia circumcincta and Trichostrongylus colubriformis. Polyphenol group-specific ultraperformance liquid chromatography-tandem mass spectrometry analysis was performed to identify relevant polyphenol subgroups present, including the PA concentration and size and ratio of the subunits. Partial least squares analysis was performed to associate efficacy with variation in PSM composition. RESULTS: Heather extracts reduced egg hatching of both GIN species in a dose-dependent manner by up to 100%, while three extracts at the highest concentration (10 mg/ml) reduced larval motility to levels that were not significantly different from dead larvae controls. PAs, particularly the procyanidin type, and flavonol derivatives were associated with anthelmintic activity, and the particular subgroup of polyphenols associated with the efficacy was dependent on the GIN species and life stage. CONCLUSIONS: Our results provide in vitro evidence that heather, a widely available plant often managed as a weed in grazing systems, has anthelmintic properties attributed to various groups of PSMs and could contribute to sustainable GIN control in ruminant production systems across Europe.

Heather (Calluna vulgaris) supplementation does not reduce trapping ability of Duddingtonia flagrans in faeces of Haemonchus contortus infected lambs.

Infection with gastro-intestinal nematodes (GIN) seriously impairs productivity and health of grazing animals. Due to the considerable rise in anthelmintic resistance and the increasing popularity of organic farming, alternative control strategies will replace or complement traditional anthelmintics. The efficacy of two potential alternatives (i) feeding the tanniferous forage heather (Calluna vulgaris) and (ii) the nematophagous fungus Duddingtonia flagrans (isolate FiBL-DF-P14), was tested in a feeding experiment with lambs artificially infected with Haemonchus contortus. Animals received hay supplemented with heather or with a late cut hay (ecohay) as a control feed ad libitum for three weeks. Two doses (1 × 105 and 5 × 104 chlsp/kg LW) of D. flagrans chlamydospores (chlsp) were administered to animals of each roughage treatment and H. contortus larval recovery from faecal cultures was compared with an untreated control (6 animals per D. flagrans-heather combination). Protein, crude fiber and energy contents of ecohay and heather were similar but heather contained approximately twice more fat, four times more lignin and ten times more of all condensed tannin fractions. Heather contained 17.3 mg Proanthocyanidin per g dry matter (DM) while contents of ecohay were 1.7 mg/g DM. Daily average feed intake across both treatments was 1.5 kg DM/animal/day, of which heather/ecohay intake accounted for 0.17/0.19 kg. Overall, there was no significant effect of heather on faecal egg counts (FEC). There was a tendency for a significant interaction between feed supplement and time and a significantly (p = 0.030) lower FEC of nominally 1799 EPG in the heather treatment at the end of the heather feeding period compared with the ecohay treatment. Lambs in this study consumed less heather than grazing sheep in other studies, even though condensed tannin contents were comparably low. Heather supplementation did not affect larval recovery in faecal cultures and trapping ability of D. flagrans. As compared with the untreated control, both doses of D. flagrans reduced larval recovery by 96.2 % and 95.5 %, respectively (p < 0.001), with no significant difference between the doses. The isolate FiBL-DF-P14 was at least as effective as isolates tested in other studies and achieved over 95 % reduction at a low dosage of 5 × 104 chlsp/kg LW. In conclusion, our results confirm the potential of and indicate no negative interactions between both alternative GIN control methods.