Gastrointestinal parasitism is a significant obstacle in the breeding of sheep and goats (Pessoa et al., 2002).
Parasitism, especially by helminth species, impairs health by causing lack of appetite, diarrhea, anemia and, in severe cases, death (Athanasiadou and Kyriazakis, 2004). Synthetic anthelmintics have been used throughout the world for decades to minimize the losses caused by helminth infection.
However, anthelmintic resistance in nematodes has become a major practical problem in many countries(Varady and Corba, 1999). Parasite resistance increases