Comparison of growth-promoting implant regimens from calfhood to finishing in beef steers: finishing phase

The objective of this study was to compare growthpromoting implant regimens and their effect on growth performance and carcass traits. Crossbred beef steers (n = 106; body weight = 96 ± 3.9 kg; age = 74 ± 2.0 d) were blocked by parity of dam (≤ 2 or > 2 parities), and stratified by birth weight, calf age, calf sire, cow body weight and body condition score then were assigned randomly to 1 of 4 treatments: 1) administered Ralgro at branding (D 0), Ralgro at weaning (D 156), and Revalor XS at feedlot processing (D 325; RALG), 2) administered Component E-C at branding, Component TE-G at weaning, and Revalor XS at feedlot processing (COMP), 3) no growth-promoting implant at branding, administered Revalor-G at weaning, and Revalor XS at feedlot processing (N-REV), or 4) no growth-promoting implants administered during any phase of production (CTRL). Quantitative data were analyzed using PROC MIXED, whereas qualitative data were analyzed using the PROC GLIMMIX of SAS. At the end of the stocker phase (d 323), RALG (330 kg), COMP (324 kg), and N-REV (318 kg) were heavier (P = 0.02) compared to CTRL (297 kg). Calves implanted at branding, weaning, and feedlot entry (RALG and COMP) were ≥ 87 kg heavier than CTRL and 17 kg heavier compared to calves implanted only at weaning and feedlot entry (N-REV). Overall ADG during the feedlot phase were greater (P < 0.01) for RALG (2.17), COMP (2.17), and N-REV (2.09) compared to CTRL (1.76 kg). Hot carcass weights were greater (P < 0.01) in implanted steers compared to CTRL; however, quality grade was not affected (P = 0.79) by growth-promoting implant regimen. Implanting steers at branding or weaning may not negatively affect feedlot growth performance or carcass traits.