Effect of Synovex Choice Implant on Performance and Carcass Traits of Steer Calves

  • W. Darrell Busby (Iowa State University)
  • Daniel D. Loy (Iowa State University)
  • Dallas L. Maxwell (Iowa State University)


A study was conducted at the Iowa State University Armstrong Research Farm to evaluate two intermediate dosage, combination implant systems. Two of four pens were implanted with Synovex Choice on day one and reimplanted on day 86 in the feedlot (Choice/Choice). The remaining two pens were implanted with Synovex-S on day one and reimplanted with Revalor-IS on day 86 (Syn/Rev). Steers were stepped up to a .60 Mcal/lb of DM finishing diet, and harvested in one of two groups based on real-time ultrasound evaluation. Total days on on feed were 166 for the Choice/Choice cattle and 164 days on feed for the Syn/Rev cattle. All cattle performed very well averaging 3.74 lb per day gain on less than 6 lb. of dry matter per lb. of gain. Carcass quality was high for both treatments, averaging nearly 90% USDA Choice. There were no differences between the implant treatments in feedlot performance or carcass measurements, other than percent rib fat. Cattle implanted with Syn/Rev had a slightly higher percent rib fat than the Choice/Choice cattle. This is consistent with a trend towards more carcass fatness for the Syn/Rev cattle in this study. Overall, it was determined that the two implant treatments yield similar performance and carcass effects in high quality steer calves.

Keywords: ASL R1889

How to Cite:

Busby, W. D., Loy, D. D. & Maxwell, D. L., (2004) “Effect of Synovex Choice Implant on Performance and Carcass Traits of Steer Calves”, Iowa State University Animal Industry Report 1(1). doi:

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Published on
01 Jan 2004
Peer Reviewed