Comparison of Reimplantation Strategies Using Synovex Choice and Synovex Plus with Revalor-XS in Feedlot Steers1

A feedlot experiment (160 d) was conducted using 1,231 yearling crossbred steers (380 kg) to evaluate reimplant programs using Synovex Choice and Synovex Plus compared with a one-dose program using Revalor-XS. Reimplanted cattle received respiratory viral revaccination and external parasite control at reprocessing. Cattle receiving Revalor-XS were not removed from their pens at reprocessing. Treatments (6 replications) were 1) Synovex Choice on d 0 and Synovex Choice on d 79 (Ch + Ch), 2) Synovex Choice on d 0 and Synovex Plus on d 70 (Ch + P), and 3) Revalor-XS on d 0 (Rev-XS). There was a tendency (P < 0.07) for final BW, total BW gain, and ADG to be greater for cattle implanted with Ch + P compared with Ch + Ch or Rev-XS. The G:F was improved by 3.8% (P = 0.01) for steers receiving Ch + P compared with those receiving Ch + Ch or Rev-XS. Cost of BW gain was 4.0% lower (P = 0.01) for cattle implanted with Ch + P than for those implanted with Rev-XS or Ch + Ch. Hot carcass weight tended (P = 0.07) to be 6 to 7 kg more for cattle receiving Ch + P than for those receiving Ch + Ch or Rev-XS. Dressing percentage was not different (P = 0.72) among treatments and averaged 64.54%. Carcasses grading USDA Prime + Choice tended (P = 0.08) to be greater for cattle implanted with Ch + Ch than for those implanted with Ch + P or Rev-XS. Average USDA YG was not different (P = 0.88) among treatments. An average improvement in cost of BW gain of $17.62/steer was realized for Ch + P compared with the other 2 treatments.