PSVIII-4 Live growth performance of Jersey steers using an aggressive implant strategy

Abstract This experiment was designed to study the effect of days on feed and an aggressive implant strategy on Jersey steer growth performance. Steers (n = 30; start of trial body weight (BW) 183 ± 43 kg) were randomly assigned to one of two treatments; negative control (CON) or implanted with Revalor 200 every 70 d (REV; d 0, d 70, d 140, d 210, d 280, d 350) for a total of 6 implants. Steers were weighed every 35 d and daily feed delivery was recorded daily. Data for dry matter intake (DMI) and gain to feed ratio (G:F) were analyzed via a mixed model; the fixed effects were day and treatment. Live growth BW and average daily gain (ADG) used day as the repeated measure and animal as the subject in a repeated measures analysis. Change in BW increased linearly (P < 0.01); treatments differed in BW from d 280 through d 350 (P < 0.01). Average daily gain decreased (P < 0.01) linearly and differed (P < 0.01) at d 70, d 140, d 280, and d 350, but not (P ≥ 0.10) at d 210 or d 420. Dry matter intake was greater (P < 0.05) for REV steers (7.6 kg/d) than CON (6.8 kg/d). Gain to feed ratio did not differ (P ≥ 0.78) between CON steers (0.13 kg/kg dry matter (DM)) and REV (0.14 kg/kg DM) steers, yet G:F differed (P < 0.01) amongst periods (d 70 = 0.21 kg/kg, d 140 = 0.16 kg/kg, d 210 = 0.15 kg/kg, d 280 = 0.13 kg/kg, d 350 = 0.08 kg/kg, d 420 = 0.08 kg/kg). Aggressively implanting Jersey steers improved growth performance by 9.6%, 13.2%, 11.3%, and 7.7% for BW, ADG, DMI, and G:F, respectively.