The Effect of Delaying Initial Feedlot Implant on Body Weight, Average Daily Gain, and Carcass Characteristics of Calf-Fed Steers1

Two experiments were conducted to determine the effect of delaying initial feedlot implant on BW, ADG, and carcass characteristics. At receiving, steers were assigned to 1 of 2 treatments: 1) implant at feedlot entry (NORM) or 2) implant 30 d after feedlot entry (DELAY). In Exp. 1, steers (n = 200) were not implanted until feedlot entry; however, in Exp. 2 steers (n = 209) were implanted at approximately 50 d of age. In Exp. 1, there was a tendency (P = 0.11) for BW at d 30 to be heavier (10 kg) for NORM compared with DELAY; however, all other BW measures were similar (P = 0.29). In Exp. 2, BW measures were also similar (P = 0.82) for NORM and DELAY. In both experiments, carcass weight, fat thickness, LM area, and YG were similar (P = 0.51). Additionally, in both experiments marbling scores (P = 0.58) and the percentage of carcasses grading USDA Choice and greater were similar (P = 0.54) when comparing NORM and DELAY. In these studies, delaying initial feedlot implant had no effect on BW, ADG, or carcass measures including YG and QG.