The control group presented mean egg counts fluctuating between 140 and 500 epg. The 6 treated groups showed a significant reduction of the epg until day 42 p.t. In the groups treated with Moxidectin, Abamectin and Doramectin there was a significant reduction up until days 63 and 77 p.t. Anthelminthic resistance were found for all products, excepting Doramectin at day 21 p.t. Persistence of effectiveness until 14, 28 and 35 days were found for the products with Ivermectin, 42 days for Moxidectin and Abamectin and 49 days for Doramectin. Until day 63 p.t., all treated animals weighed 15.1 kg more than the control animals (p < 0.05). It was concluded that the products showed differences in their effectiveness and persistence.