Relative cost-effectiveness of treatment of feedlot calves with ivermectinversus treatment with a combination of fenbendazole, permethrin, and fenthion

Objective-To compare growth performance, animal health characteristics, and carcass characteristics of feedlot calves treated with ivermectin topicall y with that of feedlot calves treated with a combination of fenbendazole or ally and permethrin and fenthion topicaily. Design-Clinical trial. Animals-14,184 British crossbred steer calves (mean weight, 286 kg [630 lb] ) in 30 pens at a commercial feedlot in Nebraska. Procedure-On arrival at the feedlot, calves were randomly assigned to be tr eated with ivermectin topically or with a combination of fenbendazole orall y and permethrin and fenthion topically (control). At the time of assignmen t to treatment groups, fecal samples were collected from 5% of the calves. Growth performance, carcass characteristics, and health information were re corded. Results-Geometric mean fecal egg counts at the time of arrival at the feedl ot were not significantly different between groups. Final weight, weight ga in, average daily gain, and the dry matter intake-to-gain ratio were signif icantly improved for calves in the ivermectin group. The percentage of carc asses classified as quality grade choice was higher for the ivermectin grou p than the control group; however, the percentage of carcasses classified a s yield grade 1 and the dressing percentage were higher for the control gro up than for the ivermectin group. Conclusions and Clinical Relevance-Results suggest that topical administrat ion of ivermectin to feedlot carves is relatively more cost-effective than administration of a combination of fenbendazole orally and permethrin and f enthion topically.