PSIX-31 - The effect of days on feed and trenbolone acetate + estradiol-17β implants on the dimensional measurements of serially harvested steer carcasses

Charolais x Angus steers (n = 80) were serially harvested to evaluate the effect of days on feed and exogenous growth promotion on dimensional measurements of chilled carcasses. Steers were randomly distributed to treatment and harvest day in a 2 x 10 factorial design. Steers were paired by genetic similarity and randomly assigned one of two treatments; implanted with Revalor-XS (REV) on d 0 and d 190 or non-implanted control (CON). Four pairs were randomly assigned to market endpoints of 0, 42, 84, 126, 168, 210, 252, 294, 336, or 378 DOF. Forty-eight h after harvest, a digital image was obtained of the lateral aspect of the right side of each carcass in front of a grid containing 390 contrasting black and green squares (100 cm² each). Images were individually calibrated to a common standard and digitally measured for 2-dimensional surface area and maximal carcass length and width. Maximal length was measured from the caudal tip of the hindshank to cranial edge of the foreshank and maximal width was measured from the dorsal edge of the crest to the ventral edge of the foreshank. Carcass dimensional measurements were analyzed using mixed models; fixed effects were implant treatment and DOF with d 0 BW as a covariate. No TRT x DOF interaction was observed (P ≥ 0.13) for any dependent variable. Steers administered REV yielded 516 cm² greater (P < 0.01) surface area than CON; moreover surface area increased 21.0 cm² /day. No TRT effect (P = 0.57) was observed for maximal length, however maximal width was 3.9 cm greater (P < 0.01) for REV steers. Steer carcasses increased 0.16 cm/day in length and 0.07 cm/day in width. These data illustrate growth in carcass size following exogenous growth promotant administration and finishing steers for various lengths of time.