In vitro anthelmintic efficacy of Australian plant extracts against gastrointestinal nematode parasites of cattle and goats

Abstract

Infection of ruminant livestock by gastrointestinal nematodes (GIN) is a worldwide problem and the use of synthetic chemical to treat GIN is creating problems for animal welfare, disease resistance and food quality. The study of the anthelmintic properties of plants rich in secondary metabolites (PSM) is a line of investigation that can provide ecologically-sound methods for the treatment of parasites. The purpose of this study was to test in vitro the possible direct anthelmintic effects of 24 Australian plant extracts, rich in PSM, upon the migration of infective larvae (L3) Haemonchus placei, Cooperia punctata and H. contortus, Trichostrongylus colubriformis (goats) in order to identify plants that can then be tested in vivo. Plant extracts were diluted in a range of 5, 15 and 30 mg/ml concentrations and their effects on L3 motility were evaluated using a larval migration inhibition (LMI) assay. The effect of plant extracts on parasite migration was analyzed by ANOVA as a factorial design with two factors: plant species and concentration. Multiple comparisons of least means were made to detect subset with the best combination extract-concentration within each concentration evaluated. When all combination extract-concentration where compared, a subset with the best larval migration inhibition percentage was detected for each parasite specie. In general, plant extracts reduced the larval migration of H.placei,C. punctata. Allocasuarina torulosa, Neolitsea dealbata, Acacia holosericea, Acacia salicina, Callitris endlicheri and Casuarina cunninghamiana were the most effective plants against these parasites.