| Summary: | 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.
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