PSI-23 The effect of days on feed and trenbolone acetate + estradiol-17β implantation on biometric measurements of Charolais × Angus steers across serial harvest endpoints

Abstract

Abstract A serial harvest study evaluated days on feed (DOF) and trenbolone acetate + estradiol-17β administration on biometric measurements across various harvest endpoints. Charolais x Angus steers [n = 80; start of trial body weight (BW) (271 ± 99 kg)] were randomly allocated to implant treatment and harvest date in a 2 x 10 factorial design. Steers were paired to minimize variation in genetic group, initial BW, frame score (FS), and adjusted final BW. Within each pair, a steer was randomly allocated to one of two treatments; implanted with Revalor-XS (REV) on d 0 and d 190 or non-implanted control (CON). Eight steers comprised of 4 pairs were randomly assigned to 1 of 10 harvest dates at d 0, 42, 84, 126, 168, 210, 252, 294, 336, and 378 DOF. At each harvest date, all steers were measured for hip height, rump length, hip width, shoulder height, 2/3 body length (BL), body depth, body width, and FS. Variables were analyzed as repeated measures via the MIXED procedure of SAS to test the fixed effects of DOF and treatment (TRT). No TRT x DOF interaction was exhibited (P ≥ 0.30) for any variable. Body width was 1.17 cm greater (P < 0.01) in REV steers and BL tended (P = 0.06) to be greater in CON steers. Hip height, rump length, hip width, shoulder height, two-thirds BL, body depth, and body width increased (P < 0.01) 1.9, 1.2, 2.2, 2.4, 4.1, 2.6, and 1.3 cm for each 42 d period, respectively. These data indicate biometric measurements were impacted by both growth enhancement technology and duration of finishing.