| Abstract: | Based on faecal larval counts, respiratory rates and live-weight gains, the anthelmintics levamisole and fenbendazole were equally efficacious against primary infection with Dictyocaulus viviparus in calves. Calves that were treated with levamisole or fenbendazole resisted the live-weight depressing impact of reinfection. Treatment somewhat impaired resistance to establishment of the secondary challenge as determined at necropsy. However, compared with previously uninfected controls, the treated animals harboured significantly fewer D viviparus, showing that they still strongly resisted reinfecting worms becoming established. The animal responses measured did not demonstrate any difference between levamisole and fenbendazole in relation to efficacy or to effect on resistance. |
