The cattle industrys understanding of implant management and its influences on production and carcass traits has increased dramatically in recent years. For example, we now know that various growth-promoting compounds have varying effects on carcass quality, and zeranol is the compound of choice for initial implant use. In the feedyard study reported here, several issues are addressed. The conclusion is that the most appropriate implant strategy is zeranol (Ralgro® implants) on Day 1 followed by trenbolone acetate plus estradiol (Revalor®-S) on Day 70.
This study was conducted at the Agri Research Center, Inc., Canyon, Texas, under the supervision of David Bechtol, DVM. Three hundred fifty steers of moderate frame size and weighing 556 pounds were randomly assigned to one of seven treatment groups, shown in Table 1. Each group consisted of 50 calves. Individual body weights for all steers were determined initially and after 70, 100 and 155 days on feed.
Harvest processing was done by a major commercial packer, which provided individual animal data on hot carcass weight (HCW) and USDA Quality and Yield Grades. Measurements of ribeye area, ribfat depth and KPH fat, and assessment of marbling and maturity were performed by Cattlemans Carcass Data Service, under the supervision of Ted Montgomery, Ph.D.
The results were consistent with expectations based on previous research with these growth promotants.
*Per 100 head. $6/cwt HCW as average Choice/Select spread.
$3/cwt HCW as Certified Angus Beef (CAB) premium.
This study concludes that Ralgro/Revalor-S was the most appropriate implant strategy when considering production and carcass variables. For cattle on feed 200-220 days, Ralgro Magnum implants can be used as an initial implant for 100 to 110 days and as a terminal implant for the remaining 100 to 110 days, with slaughter at 1,200 to 1,250 pounds.
For full details of this study, contact your Merck Animal Health representative or call Livestock Technical Service at 1-800-211-3573.