Efficacy of ivermectin against gastrointestinal nematodes in cattle in South Africa

The efficacy of ivermectin administered at 200 micrograms/kg was evaluated against induced infestations of 5 gastrointestinal nematode species in cattle. Results were analysed by the modified non-parametric method and a "A" class (more than 80% effective in more than 80% of the treated animals) was achieved with an oral drench and subcutaneous injection against the third and fourth larval and adult stages of Bunostomum phlebotomum, Cooperia spp. (C. pectinata and C. punctata), Haemonchus placei, Oesophagostomum radiatum and Ostertagia ostertagi. Ivermectin was 77,5-100% effective against naturally acquired infestations of Trichuris spp.