tannins and Trichostrongyloidiasis

We investigated direct anthelmintic effects associated with the feeding of fresh tanniferous forages against established populations of Haemonchus contortus and Cooperia curticei in lambs. Twenty-four parasite naive lambs were inoculated with a single dose of infective larvae of these two parasites 27 days prior to the start of the feeding experiment. Lambs were individually fed with either chicory (Cichorium intybus), birdsfoot trefoil (Lotus corniculatus), sainfoin (Onobrychis viciifolia) or a ryegrass/lucerne mixture (control) for 17 days. Animals where then united to one flock and subjected to control feeding for another 11 days to test the sustainability of potentially lowered egg excretion generated by tanniferous forage feeding. When compared to the control, administration of all tanniferous forages was associated with significant reductions of total daily faecal egg output specific to H. contortus (chicory: 89%; birdsfoot trefoil: 63%; sainfoin: 63%; all tests P<0.05) and a tendency of reduced H. contortus worm burden (chicory: 15%; birdsfoot trefoil: 49% and sainfoin: 35% reduction). Irrespective of the condensed tannin (CT) containing fodder, no anthelmintic effects were found against C. curticei. Cessation of CT-feeding followed by non-CT control feeding did not result in a re-emergence of faecal egg counts based on faecal dry matter (FECDM) in any group, suggesting that egg output reductions are sustainable. The moderate to high concentrations of CTs in birdsfoot trefoil (15.2 g CTs kg(-1) dry matter (DM)) and sainfoin (26.1 g CTs kg(-1) DM) were compatible with the hypothesis that the antiparasitic effect of these forages is caused by their content of CTs. For chicory (3 g CTs kg(-1) DM), however, other secondary metabolites need to be considered. Overall, birdsfoot trefoil and in particular sainfoin seem promising candidates in contributing to an integrated control strategy against H. contortus not only by mitigating parasite related health disturbances of the host but also by a sustained reduction of pasture contamination.

Topics: Animal Feed; Animals; Anthelmintics; Body Weight; Cichorium intybus; Diet; Dose-Response Relationship, Drug; Fabaceae; Feces; Feeding Behavior; Parasite Egg Count; Sheep; Sheep Diseases; Tannins; Trichostrongyloidea; Trichostrongyloidiasis

Most studies on the effects of tanniferous plants on nematodes have examined forages but have neglected the woody plants. Therefore, in vitro effects of extracts from 3 woody plants (Rubus fructicosus, Quercus robur, Corylus avellana) have been tested on trichostrongyles and compared to sainfoin, a legume forage. Because some in vivo results indicated that the effects of tannins differed depending on the parasitic species and/or stages, the effects were measured on 3rd-stage larvae (L3) and adult worms of Teladorsagia circumcincta, Haemonchlus contortus and Trichostrongylus colubriformis. The effects of plant extracts varied according to the plant sources, the parasite species and stages. For the woody plants, significant inhibitory effects were obtained on both stages of abomasal species. Results for T. colubriformis were more variable. Effects of sainfoin extracts were significant on T. colubriformis and H. contortus L3, and on abomasal adult worms. In order to assess the implications of tannins, polyethylene glycol (PEG), an inhibitor of tannins, was added to hazel tree, oak and sainfoin extracts. Without PEG, significant inhibitory effects on L3 and adult worms were confirmed. After addition of PEG, the larval migration and motility of adult worms were restored in most cases. These results confirm variations in effects depending on factors related to plants or parasites and suggest that tannins are partly responsible for the effects.

Topics: Animals; Biological Assay; Corylus; Fabaceae; Goat Diseases; Goats; Phytotherapy; Plant Leaves; Polyethylene Glycols; Quercus; Tannins; Trichostrongyloidea; Trichostrongyloidiasis

Contrasting herbage diets were fed to lambs to evaluate their effect on subsequent development of Trichostrongylus colubriformis larvae in faeces and on pasture. The diets had either no condensed tannin (CT), lucerne (Medicago sativa cv. Otaio), white clover (Trifolium repens cv. Tahora), or had moderate to high concentrations of CT, sulla (Hedysarum coronarium cv. Grassland Aokau), Lotus corniculatus (cv. Grasslands Goldie), L. pedunculatus (cv. Grassland Maku), Dorycnium pentophyllum, and Dorycnium rectum. Trials were carried out in summer (warm) and in autumn (cool and moist). In summer, egg viability was evaluated in vitro with egg hatch and larval development assays. In both seasons faeces were placed on pasture to compare recovery of eggs and larvae from faeces and larvae from herbage on the high and low fertility farmlets on the AgResearch Ballantrae Hill Country Research Station. D. rectum and D. pentophyllum diets decreased (P<0.01) egg hatching and larval development in laboratory assays relative to other diets. In summer, the number of larvae recovered from faeces placed on pasture was far greater (P<0.001) if the lambs had been fed lucerne than any other diet, whereas recovery was always lowest from faeces of sheep fed D. rectum and D. pentophyllum. Although dietary differences were lower in autumn than in summer, larval recoveries were lower (P<0.05) from faeces of lambs fed D. rectum and L. corniculatus than from white clover, lucerne and sulla diets. This study indicates that the diet of the host can have a significant impact on egg hatching and the subsequent development of T. colubriformis larvae in the laboratory and in the field. In particular, D. rectum consistently reduced T. colubriformis development. Effects measured in vitro generally under-estimated effects measured under field conditions.

Topics: Animal Feed; Animals; Feces; Male; Parasite Egg Count; Seasons; Sheep; Sheep Diseases; Tannins; Trichostrongyloidiasis; Trichostrongylus

Thirty yearling F1 Anglo-Nubian x Mubende goats, averaging 21 +/- 0.45 kg, kept on free-range feeding in the Ankole range land, Uganda, were screened for health and nutritional status, effectively treated against helminth parasites, mated, and randomly divided into two equal groups during a 3-month preparatory phase. During the 6 months that followed, the goats in one group received a daily oral dose (50 g/goat) of poly(ethylene glycol) (PEG), while the other group acted as the control (no PEG). The goats were monitored for faecal nematode egg counts and body weight gains, along with the quality of their diet, nematode contamination of the pasture, and the prevailing climatic factors in the area. Goats treated with PEG had significantly (p < 0.05) higher faecal helminth egg loads. The mean nematode eggs per gram of faeces (epg) of the PEG group (290 epg) was more than double that of the control group (129 epg). All the PEG-treated goats exhibited moderate to severe infections at the end of the experiment. The gain in body weight during gestation was lower (p < 0.05) in the PEG group (70.4 g per goat per day) than in the control group (91.8 g per goat per day). The PEG group lost 2.3 g per goat per day in the fifth month. PEG deactivates condensed tannins, and it was concluded that condensed tannins play a significant role in reducing the negative effects of gastrointestinal helminth burdens in the natural free-range feeding system of the Ankole range land in Uganda. Selective feeding on such range lands might expose goats to optimal concentrations of dietary condensed tannins with resultant beneficial effects.

Topics: Administration, Oral; Administration, Topical; Animal Feed; Animals; Feces; Female; Goat Diseases; Goats; Haemonchiasis; Haemonchus; Helminthiasis, Animal; Helminths; Parasite Egg Count; Polyethylene Glycols; Pregnancy; Pregnancy Complications, Parasitic; Prevalence; Random Allocation; Seasons; Strongyloides; Strongyloidiasis; Tannins; Trichostrongyloidiasis; Trichostrongylus; Uganda