Effect of Three Initial Implant Programs with a Common Terminal Revalor®-200 on Feedlot Performance and Carcass Traits of Weaned Steers

A commercial feedlot study compared three implant strategies: Revalor®-IS (d 1), Revalor®-IS (d 1) and Revalor®-200 (d 67), or Revalor®-XS (d 1) for effects on performance and carcass traits. Each initial implant strategy was followed by a terminal Revalor®-200 implant on d 133. Calf-fed steers (n = 1,350 initial BW = 283; SD = 10 kg) sourced in Nebraska, Iowa, Utah, South Dakota, Idaho, and California were used in a randomized block design trial. Steers were assigned to pens by sorting every two steers into one of three pens before processing. Pens were assigned randomly to one of three treatments (six pens/treatment). Mean days on feed across blocks was 215 d. The finishing diet was identical across treatments and any diet changes that occurred across time were the same for all cattle. Live performance was calculated from pen BW shrunk 4% and carcass-adjusted performance was based on HCW divided by a common dressing percentage of 64.25%. Data were analyzed using the Glimmix procedure of SAS and pen served as the experimental unit. There were no differences (P = 0.19) in DMI due to treatment. Using carcass-adjusted performance, no differences in final BW or ADG were observed (P ≥ 0.38). Therefore, G:F (P = 0.55) also was unaffected by implant strategy. Similar results were observed when evaluating performance using final live BW. There were no differences in HCW (P = 0.59), dressing percent (P = 0.93), or in USDA quality grade (P = 0.90) and USDA yield grade (P = 0.23) distributions among implant treatments. When evaluating interim performance, there were no differences in ADG (P = 0.49) or G:F (P = 0.87) from d 1 to 67 as expected due to implant payout. From d 67 to 133, cattle implanted initially with Revalor®-IS and given Revalor®-200 on d 67 had significantly greater ADG (P < 0.01) and G:F (P = 0.02) compared to the other two treatments. Gain (P = 0.11) and G:F (P = 0.21) for d 133 to 215 was not significantly different but numerically greater for the Revalor®-IS treatment suggesting some compensation. Implant strategy resulted in no overall differences, but the changes in ADG and G:F during different periods within the finishing period relate to different implant payout. Steers implanted with Revalor®-IS, Revalor®-IS/200, or Revalor®-XS followed by a common terminal implant had similar overall performance suggesting more aggressive initial implant strategies have minimal impact on performance.