Summary and Implications
One hundred sixty one steers were finished in a total confinement deep-bedded system at the Armstrong Research Farm, Lewis, IA during 2008. The three treatment groups were implanted with Synovex-Choice 112, 82 and 56 days prior to harvest. The implant resulted in an immediate and significant improvement in average daily gain. In the weigh period immediately after receiving the implant average daily gains increased from .72 to 1.35 lb/day compared to treatment groups or group that had not yet received their implant. The overall average daily gain of steers implanted 112 days (3.76 lb/day) and 82 days (3.70 lb/day) prior to harvest was significantly more than steers implanted 56 days (3.44 lb/day) prior to harvest. The 112 day implant group produced significantly heavier carcasses than the 56 day implant group While the 82 day implant group average carcass weight was intermediate and not significantly different from the other treatment groups. There was no significant difference in carcass fat cover, however, steers implanted 112 and 82 days had significantly larger ribeyes than steers implanted 56 days prior to harvest. Numerically the 53% low Choice or better was lower for the steers implanted 56 days prior to harvest compared to 60% low Choice or better for the other two treatments. The increase in carcass weights resulted in incremental, nonsignificant increases in carcass value.
Iowa State University
Busby, W. Darrell; Maxwell, Dallas L.; and Strohbehn, Daryl R.
"Effect of Implant Timing on Feedlot Gain and Carcass Traits,"
Animal Industry Report:
AS 655, ASL R2424.
Available at: http://lib.dr.iastate.edu/ans_air/vol655/iss1/47