Abstract
This study determined the most effective of three doses per plant extract on L3 nematode larvae. Seven plant species: Crinum macowanii, Gunnera perpensa, Nicotiana tabacum, Sarcostema viminale, Vernonia amygdalina, Zingiber officinale and Zizyphus mucronata, had alkaloids and tannins as bioactive principle. Oven-dried leaf samples (40 g; 20 g; 10 g) of each species were extracted in 70% ethanol, and concentrated to 100 ml; constituting 4×, 2× and 1× crude extract concentration. Rectal faecal materials were collected from 10 Merino sheep and 25 Nguni goats, pooled within species and hand-mixed. Dung samples (5 g) were weighed and cultured for 12 days at 27°C. On day 13, four plates were watered, and others (4) treated with 70% ethanol to correct solvent effect on mortality. The trial had 2 (animal species) × 7 (plant species) × 3 (extract concentrations) factorial design. In each run, three plates were treated with each crude extract concentrations. L3 larvae were isolated on day 14, larval counts done, and mortality became indices of dosed anthelmintic efficacy. The study was re-run three times. Animal species (p = 0.0107) and concentration (p = 0.0005) affected efficacy; a change in crude extract concentration resulted to efficacy of 71.2 ± 2.62%, 88.0 ± 1.88% and 97.9 ± 0.91% for goats and 93.8 ± 2.62%, 96.0 ± 1.88% and 98.0 ± 0.91% for sheep. Interaction of crude extract concentration and animal species affected efficacy (p = 0.0127). Condensed tannin and alkaloid content was high, but within close range. Differences in specific anthelmintic activity exist among plants possessing the two principle(s); suggesting that combined activity of any two species extract may have enhanced activity.
Highlights
Widespread emergence of resistant strains of livestock nematode parasites globally (Jackson & Coop, 2000; Kaplan, 2004), resulting from the exclusive/extensive use of chemical anthelmintic therapy (Geerts & Gryseels, 2000; Makkar, Francis, & Becker, 2007; Vercruysse, Charlier, Dorny, & Claerebout, 2006; Waller, 2006), serves as an urgent call for alternative modes of application and more sustainable methods of control (Waller, 2006)
Anthelmintic efficacy of the same plant species crude extract possessing condensed tannins and alkaloids (Table 1) at the same concentration was different for both goats and sheep (Figures 1 and 2), suggesting that animal species related traits might have affected efficacy as concentration increased (Hoste, Jackson, Athanasiadou, Thamsborg, & Hoskin, 2006; Paolini et al, 2003)
This is consistent with the suggestion that specific requirements of animal species be considered in order to maintain or enhance anthelmintic efficacy of relevant plant species because of inherent disparities (Vercruysse et al, 2001)
Summary
Widespread emergence of resistant strains of livestock nematode parasites globally (Jackson & Coop, 2000; Kaplan, 2004), resulting from the exclusive/extensive use of chemical anthelmintic therapy (Geerts & Gryseels, 2000; Makkar, Francis, & Becker, 2007; Vercruysse, Charlier, Dorny, & Claerebout, 2006; Waller, 2006), serves as an urgent call for alternative modes of application and more sustainable methods of control (Waller, 2006). Common occurring animal nematode parasites such as Haemonchus contortus (blood worm), Trichostrongylus colubriformis and Ostertagia circumcinta cause anaemia, depress; feed intake, body-weight gain (Agrawal & Banerjee, 2007; Ploeger & Kloosterman, 1993) and, milk and wool production at subclinical levels (Makkar et al, 2007). At clinical level, they are highly pathogenic (especially H. contortus) and capable of causing acute diseases and/or mortality (Allonby & Urquhart, 1975). Plant species exhibiting anthelmintic activity constitute a very important option and alternative to chemical anthelmintic use
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