Comparative effects of therapeutic programs on bovine respiratory disease, performance, carcass, and profitability of high-risk feedlot heifers

ABSTRACT Two therapeutic programs were compared in heifers at high risk for bovine respiratory disease (BRD) during a 208-d feeding period. Program 1 [metaphylactic tulathromycin followed by as-needed use of ceftiofur crystalline free acid, after a 14-d postmetaphylactic interval (PMI; treatment moratorium); T01] was compared with program 2 [metaphylactic tilmicosin phosphate followed by as-needed use of enrofloxacin, after a 3-d PMI (treatment moratorium); T02]. Auction-sourced heifers (n = 1,236; initial BW = 258 ± 2.1 kg) were randomized to treatment [T01, n = 620; T02, n = 616; 8 pens/treatment] and processed. Rates of BRD (10.3 vs. 26.0%; P = 0.0001), BRD re-treatment (1.6 vs. 6.3%; P = 0.0001), and G:F [0.27 vs. 0.24, deads in (P = 0.004); 0.28 vs. 0.27, deads out (P = 0.099)] were improved during the initial 70 d for T01 versus T02 heifers, respectively, but not during d 71 to 208. Medicine costs ($2.56 vs. $7.90/heifer; P