A randomized trial comparing effects of respiratory disease metaphylaxis with gamithromycin or ceftiofur crystalline free acid on the health, performance, and economic return of auction market-derived stocker calves backgrounded on Missouri pastures

Abstract

The objective was to compare gamithromycin (GAM) and ceftiofur crystalline free acid (CCFA) metaphylaxis for controlling bovine respiratory disease (BRD) impacts in auction market-derived steers. Steers (n=240; initial BW = 537.54 ± 60.61 lb [243.82 ± 27.49 kg]) were randomly allocated to 16 pastures randomized to the 2 treatment groups. Caretakers and data analyst were masked to treatments. Data were analyzed using linear models with means ( ± standard errors of means) reported. Following metaphylaxis, 16 steers (GAM, n=3; CCFA, n=13) required treatment for BRD. Mean BRD morbidity was higher (P=0.03) in the CCFA group (10.83 ± 2.84%) compared to the GAM group (2.50 ± 1.43%). Four steers in each group died or were removed from the 59-day trial due to non-BRD health reasons. Average daily gain in steers finishing the study was greater (P=0.03) in GAM (2.90 ± 0.09 lb [1.32 ± 0.04 kg]) vs CCFA (2.57 ± 0.09 lb [1.17 ± 0.04 kg]) steers. Mean net return per head for steers finishing the study was greater (P≤0.01) for GAM ($22.34 ± 6.75) vs CCFA (-$6.67 ± 6.75). Overall, steers administered GAM metaphylaxis had lower morbidity, increased weight gain, and increased net revenue, compared to those given CCFA.