Effect of five mediterranean shrubs extracts on larval exsheathment of Haemonchus contortus

Mediterranean shrub species cover more than 70% of the total area in Tunisia and in summer when the herbaceous species have wilted, they constitute feeding resource for livestock. The use of tanniniferous shrubs seems to be a good alternative to control gastrointestinal nematodes infections in small ruminants. This study evaluated the in vitro anthelmintic (AH) effect of Ceratonia siliqua (C. siliqua), Periploca angustifolia Labill. (P. angustifolia) and Medicago arborea (M. arborea) against Haemonchus contortus third stage larvae (L3).

The larval exsheathment assay (LEA) was used to determine the proportions (%) of exsheathment of five acetonic extracts at different concentrations (1200, 600, 300, 150 |jg/ml). To confirm the role of tannins in the AH effects of extracts, polyvinyl polypyrolidone (PVPP) was used as deactivating chemical tannins.

The highest % L3 exsheathed was recorded for M. arborea (55.01%) and the lowest value was founded for C. siliqua and P. angustifolia leaves (16.26%). Our results were concentration-dependent (P<0.001). The % of exsheathment increased as the time of incubation increased (P<0.001). P. angustifolia pods recorded the lowest EC50 value (P<0.05). After PVPP addition, all the acetonic extracts showed a restoration of L3 exsheathment values similar to control values (P<0.001).