Growth implant strategy outlined at animal science meetings

by Miranda Reiman

February 2009

Maximizing quality and efficiency calls for different implanting strategies on steers versus heifers.

A Certified Angus Beef LLC (CAB) seven-year study characterized the effect of trenbolone acetate (TBA) growth implants on both sexes. Gary Fike, beef cattle specialist for CAB, presented the results at the recent Southern Section meetings of the American Society of Animal Science in Atlanta, Ga.

“We analyzed the data gathered through our cooperating feedyards and were able to compare Angus-influenced lots implanted at least once with TBA to those that were not,” Fike said.

A second analysis compared cattle that received the highest, 200-mg dose, of TBA against all other protocols, including other lower-dose TBA implants. In all, the study represented 655 lots of steers and 217 lots of heifers.

“For steers, all TBA implants improved average daily gain and feed efficiency, at the expense of much lower quality grade,” Fike said.

TBA reduced Certified Angus Beef ^® (CAB^®) brand acceptance by nearly 10 points, from 30.2% to 20.6% in the steers. However in heifers there was no quality grade, brand acceptance rate, or hot carcass weight (HCW) difference. The heifers responded to the implants in gain and efficiency, but with no advantage for the higher dose.

The steers in the high-dosage TBA group had a 35 pound (lb.) gain in HCW, compared to their counterparts that received lower doses of TBA. “If you’re feeding for a grid, it makes sense to look hard at your use of TBA in steers,” Fike said. “Depending on the market and the premiums, you may be able to recoup that lost weight, and then some, if you limit the TBA implant in favor of quality.”

Heifers, however, can be given TBA in moderation without sacrificing grid performance.

“The highest dose of TBA did not appear to improve growth traits over other implants in this analysis,” Fike said. “So sticking with the lower levels of the hormone looks like a way to get the best combination of feedlot and carcass traits.”

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