Efficacy of tilmicosin and tildipirosin for on-arrival treatment of bovine respiratory disease in fall-placed feedlot calves in western Canada

Abstract

A trial was conducted in a commercial finishing feedlot in southern Alberta, Canada using fall-placed steer calves to evaluate the comparative efficacy of metaphylactic treatment with tilmicosin or tildipirosin for control of bovine respiratory disease (BRD). First-pull treatment rates for BRD were significantly lower (P<0.01) in calves administered tildipirosin than those administered tilmicosin on arrival. There were no significant differences in BRD relapse rates, overall mortality, or BRD and histophilosis mortality. While calves treated with tildipirosin on feedlot entry had higher average daily gain (P=0.006) and lower dry-matter conversion (P=0.007) at 56 days-on-feed than those treated with tilmicosin, these performance differences were no longer significant (P>0.05) at 146 days-on-feed. Using current drug prices and based on differences in initial BRD treatment rates, tilmicosin had a net economic advantage of $6.85 CAN/head to those treated with tildipirosin on arrival.