Effects and economic implications of metaphylactic treatment of feeder cattle with two different dosages of tilmicosin on the incidence of bovine respiratory disease (BRD)
A Summary of Two Studies
Keywords:bovine, feedlot, BRD, metaphylaxis, tilmicosin, economic, aetiology, antibiotics, beef cattle, drug therapy, economic analysis, liveweight gain, morbidity, mortality, potency, respiratory diseases, returns
Two studies were conducted to evaluate the efficacy of tilmicosin for metaphylactic treatment of bovine respiratory disease (BRD), and subsequent effects on calf performance, in newly received, high-risk feedlot cattle. Calves in each study were randomly assigned to one of three treatment groups: negative control; 4.55 mg/lb body weight (BW) (10 mg/kg BW) tilmicosin (TIL10); or 9.1 mg/lb BW (20 mg/kg BW) tilmicosin (TIL20). In Study I, calves receiving tilmicosin had lower BRD morbidity (P<0.01) and mortality rates (P=0.02) compared to controls. Furthermore, BRD morbidity was lower (P≤0.05) in the TIL20 (16.8%) compared to the TIL10 (24.3%) group. Average daily gain was improved (P<0.01) in both tilmicosin metaphylaxis treatment groups compared to controls when deads and removals were not included in the final calculations (2.9 lb and 3.0 lb vs 2.8 lb or 1.32 kg and 1.36 kg vs 1.27 kg), as well as when deads and removals were included in the evaluation (2.7 lb and 2.8 lb vs 2.4 lb or 1.23 kg and 1.27 kg vs 1.09 kg, respectively). Calves treated metaphylactically with tilmicosin had greater economic return per pen (P<0.01) than did controls. In Study II, calves in both TIL10 and TIL20 treatment groups had lower (P≤0.05) morbidity compared to controls (68.5, 49.9, and 44.0% for control, TIL10, and TIL20, respectively). No significant differences in performance were observed between treatment groups.