349 Empty body composition and retained energy of Jersey steers using an aggressive implant strategy

Abstract This experiment was designed to quantify the empty body composition of Jersey steers administered an aggressive implant strategy. Jersey steers {n = 30; initial body weight (BW) 183 ± 43 kg} were randomly assigned to one of two implant strategies: negative control (CON), or implanted with Revalor 200 (200 mg trenbalone acetate / 20 mg estradiol 17-β; (REV) every 70 d (d 0, d 70, d 140, d 210, d 280, d 350) during a 420 d feeding period. Steers were harvested on d 421; 6 CON and 6 REV steers were randomly selected for collection of blood, hide, ground viscera, bone, and ground lean and fat to determine empty body composition. Proximate analysis was completed for each sample to determine total body percentages of moisture, crude protein, fat, and ash. Data were analyzed via independent t-test. Percentage empty body moisture (46.48% CON vs 49.69% REV) and empty body protein (15.32% CON vs 17.58% REV) were greater (P < 0.01) in REV cattle. In contrast empty body fat (33.51% CON vs 26.93% REV) was greater (P < 0.01) for CON cattle. Empty body ash did not differ (P > 0.10; 4.69% CON vs 5.80% REV) between treatments. Negative control steers contained a total empty body protein to total empty body fat ratio of 0.44:1 compared to 0.62:1 for REV steers. These data suggest that an aggressive implant strategy alters composition of gain during the finishing of Jersey steers toward increased protein and decreased fat.