Effects of condensed tannins on goats experimentally infected with Haemonchus contortus

Abstract

Although the use of tanniferous plants or condensed tannins as an alternative to anthelmintics to control gastrointestinal nematodes has been largely documented in sheep, studies remain scarce in goats. The objective of this study was therefore to assess the possible impact of condensed tannins in goats infected with adult Haemonchus contortus. Two groups of cull goats were experimentally infected with 10.000 L3 of H. contortus. After 4 weeks, quebracho extracts, representing 5% of the diet DM, were administered for 8 days to one of the two groups. Goats of the second group remained as controls. One week after the end of quebracho administration, the goats were euthanised. Individual egg excretion and pathophysiological parameters were measured weekly during the study. At the end of the study, worm counts were assessed and histological samples from the abomasa were taken to count the numbers of mucosal mast cells, globule leukocytes and eosinophils. The administration of tannins was associated with a significant decrease in egg excretion, which persisted until the end of experiment. This reduction was not associated with any difference in worm number but with a significant decrease in female fecundity. No significant changes in the mucosal density of the three inflammatory cell types were detected between the two groups. These results indicate that the major consequence of tannin consumption in goats is a reduction in worm fecundity and egg output, which does not seem related to significant changes in the local mucosal response.

Medicinal plants for helminth parasite control: facts and fiction

“…In addition, in vivo studies have shown that the administration of quebracho extract, a commercially available extract from Schinopsis spp., reduced faecal egg counts and worm numbers in parasitised sheep (Athanasiadou et al, 2001a;Butter et al, 2001). Similarly, parasitised goats benefited from the inclusion of plant extracts containing high levels of secondary metabolites in their diets (Akhtar and Ahmad, 1992;Paolini et al, 2003a and. In some cases, the antiparasitic efficacy of plant extracts has been similar to that of broad-spectrum anthelmintic drugs; Satrija et al (1994) almost eliminated intestinal nematodes within 7 days of supplementation with papain extract.…”

“…Alkaloids have also demonstrated strong nematocidal activity towards Strongyloides ratti and S. venezuelensis, two rat nematodes used as models for human nematodes (Satou et al, 2002). The nematocidal activity of tannin extracts has been reported as early as the 1960s (Taylor and Murant, 1966), and more recently evidence on the anthelmintic properties of condensed tannins has been supported by a series of in vitro (Dawson et al, 1999;Athanasiadou et al, 2001a;Molan et al, 2003b;Ademola and Idowu, 2006) and in vivo studies (Athanasiadou et al, 2000;Butter et al, 2001;Paolini et al, 2003a and. However, despite their anthelmintic properties, it is not yet clear whether medicinal plants could actually have a role in controlling parasitism in livestock.…”

“…Compound bioavailability and thus efficacy of medicinal plants may also be related to the host species. For example, although the ingestion of condensed tannins did not affect the abomasal worm burden in sheep, it did in goats (Paolini et al, 2003a). It is known that a number of physiological adaptations have taken place in the gastrointestinal tract of goats, in comparison to that of sheep, to counteract the presence of secondary metabolites in the browse material.…”

Anthelmintic effects of condensed tannins on Trichostrongylus colubriformis in experimentally infected sheep

“…Initially, animals from GII presented lower reduction, followed by GIII on the end of treatment period, confirming the potential use of taniniferous plants in the nematodes control. Many experiments correlated the CT uses with decrease of female helminthes fecundity (ATHANASIADOU et al, 2000a(ATHANASIADOU et al, , 2001aMIN;HART, 2003;PAOLINI et al, 2003aPAOLINI et al, , 2003b, standing out its importance in nematode epidemiology Despite the lower epg values from animals treated with CT in this study, the number of total worms presented in the intestines of sheep from different treatments was similar (P > 0.05). However, sheep treated twice with AE, which did not present the lower epg, showed a significantly lower number of nematode female.…”

Trends and challenges in the effective and sustainable control ofHaemonchus contortusinfection in sheep. Review

“…However, besides its limited usefulness, the use of 4 gm of these wire particles in late pregnancy was reported to threaten the life of multiple born offspring (Burke et al, 2005). On the other hand, plant extracts such as condensed tannins, which are secondary tanniferous plant metabolites, have been found to reduce H. contortus faecal egg counts and the number of eggs per female worm in goats (Paolini et al, 2003) and the faecal egg counts, worm number and fecundity of T. colubriformis in sheep (Athanasiadou et al, 2000). Similarly, flower extracts of Calotropis procera have shown excellent anthelmintic activity against H. contortus in sheep (Iqbal et al, 2005).…”