Anthelmintic resistance in the Netherlands, an overview and possible correlations

Abstract

Anthelmintic resistance is becoming a serious problem in the Netherlands. To see how big the problem is this research was performed. 37 commercial farms and large private herds participated. On these farms we performed fecal egg count reduction tests with six different products (Bovex 2.265%, Cydectin 1%, Zolvix, Oramec, Endec 8.75% and Flukiver 5%). We performed these FECRT on ewes just after or close to lambing so results were more clear due to the periparturient egg rise. In addition to the FECRT larval cultures were performed to be able to see if there was a difference between resistances in Haemonchus contortus and Teladorsagia/Trichostrongylus against the different products. Resistances in Haemonchus varied between 94% resistant populations (Oramec) and 0% resistant populations (Endex), in our Teladorsagia/Trichostrongylus group resistance was between 93% of populations tested (Flukiver) and 0% of populations tested (Zolvix). In addition we investigated if there are any correlations in resistance between the different helminth populations, no significant (p<0.05) results were found.