Comparative efficacy of tilmicosin versus tulathromycin as a metaphylactic antimicrobial in feedlot calves at moderate risk for respiratory disease.

The purpose of this study was to compare the efficacy and cost-effectiveness of tilmicosin (MIC) versus tulathromycin (DRAX) as a metaphylactic antimicrobial in feedlot calves at moderate risk for bovine respiratory disease (BRD). Calves that received DRAX had significantly (P < or = .05) lower initial BRD treatment rates compared with calves that received MIC. However, there were no significant differences in the BRD relapse rate, railer rate, total mortality rate, BRD mortality rate, average daily gain, and dry matter conversion between the two groups. The economic advantage of the MIC group was Can$8.29/animal. Based on these results, while DRAX was more efficacious in reducing initial treatments for BRD in feedlot calves at moderate risk for disease, MIC was more cost-effective. The lower initial BRD treatment costs in the DRAX group did not offset the higher metaphylactic cost of DRAX.