Comparison of tulathromycin, tildipirosin, and tilmicosin for control of bovine respiratory disease in steers purchased from auction markets and fed in a Texas feedlot

Abstract

Crossbred steers (n=l,370) purchased from auction markets in Texas were received into a commercial feedlot near Hereford, Texas. Steers were recently weaned and considered at high risk of developing bovine respiratory disease (BRO). Upon arrival, steers were randomly assigned (within arrival blocks) to 1 of 3 treatment groups that received: 1) tilmicosin (TLM; 4.5 mg/lb (10.0 mg/kg)), 2) tildipirosin (TLD; 1.82 mg/lb ( 4.0 mg/kg)), or 3) tulathromycin (TUL; 1.14 mg/lb (2.5 mg/kg)). Steers were penned by treatment into 36 pens with 12 pens per treatment. Data were analyzed with linear mixed models for a randomized complete block design. Steers administered TUL had significantly lower BRO morbidity than both TLD and TLM (P< 0.01) treatments, and TLD had lower BRO morbidity than TLM (P < 0.05). Cattle receiving TUL also had a lower percentage of chronic illness than both TLD and TLM treatments (P < 0.05). Steers in the TUL treatment group had lower BRO and overall mortality at closeout than TLD (P < 0.05), but the TLM-treated steers did not differ from the other groups. Deads-in average daily gain was 0.55 lb (0.25 kg) greater in TUL-treated steers than steers administered TLM, and 0.56 lb (0.25 kg) greater than steers receiving TLD (P < 0.05). Cattle receiving TUL had 1.33 lb (0.6 kg) lower deads-in feed-to-gain ratio at closeout than those receiving TLM, and 1.51 lb (0.68 kg) lower than those receiving TLD (P < 0.05). During the first 30 days-onfeed, TUL-treated steers had greater daily dry-matter intake compared with TLD-treated steers (P < 0.01), but no other differences among treatment groups. By closeout, there were no differences in cumulative mean dry-matter intake between treatment groups. Overall, TUL treatment on arrival resulted in improved health and performance as compared to TLM and TLD treatments.