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Growth promotion can impede carcass quality

Growth implants are commonly used in the cattle industry with little regard to how they influence marbling, says Gary Fike, feedlot specialist for Certified Angus Beef LLC (CAB).

"For every dollar invested in an implant, the return could be more than $6 in increased weight and efficiency in today's marketplace," he says. "Most producers can't afford to leave that kind of money on the table, but if the implants aren't used properly, they could cost significant dollars in lost grid premiums."

Implants shift nutrient use to lean muscle, rather than marbling or intramuscular fat, which decreases quality grades. Since 1995, packers have paid more than $200 million in grid premiums for cattle meeting the Certified Angus Beef® (CAB®) brand specifications. Those who want these bonuses must pay attention to management decisions that affect the end meat product.

"The degree to which implants suppress marbling can be minimized," Fike says, "if used judiciously and in harmony with nutrition, timing and age of the cattle."

He analyzed the CAB database that tracks cattle fed in nearly 70 partner feedlots across the country. The Feedlot-Licensing Program (FLP) information shows that both the number and potency of the implants used affect quality grade.

Fike asks, "Why not try to reap the economic benefits of the implant on growth and performance and couple that with quality premiums?"

Looking at 12,000 rows of detailed carcass records from the 2005 data set, he divided cattle into four CAB acceptance rate groups: 0% to 9.9%, 10% to 19.9%, 20% to 29.9%, and more than 30% CAB. Feeders submit the number of times cattle were implanted and the brand name of the implant used. Cattle in the more-than-30%-CAB group were implanted 0.91 times — significantly fewer times than all other acceptance rate groups. The average on all 2005 cattle was 1.3 times, and non-implanted cattle achieved 37% CAB acceptance.

Chris Reinhardt, Extension feedlot specialist at Kansas State University, ranked implant potency by active ingredient. "Potency scores" ranged from 1 for "low" to 5 for "very high." Averages were figured for each lot of cattle. The mean implant potency score for the top CAB group was 1.88, significantly lower than for the other three groups. "The lower CAB-acceptance groups had been implanted with much more aggressive products," Fike says. "The acceptance rates were most affected when average potency score exceeded 3."

Overall implant values were assigned to lots by multiplying average potency by the number of times implanted. The results mirrored the implant potency scores.

"This doesn’t tell the entire story," he says. "Whether the timing of the implant matches nutrition level can make or break quality grade."

An implant containing both trenbolone acetate (TBA) and estrogen can be beneficial to performance and not affect quality grade significantly, Fike says. That’s if it is given at the right time with a nutrition program that matches the dose.

On the other hand, aggressive use of high-dose implants used early in life — immediately pre- or post-weaning — can "wreck" marbling, he explains. That's especially true if the diet is high in roughage and low in energy.

"If a producer holds off on implanting them until the cattle are on high-energy feed, the depression of marbling will be much less," Fike says.

South Dakota State University research found that delayed implanting results in a 15% increase in the number of cattle reaching Premium Choice or higher, with virtually no change in the effectiveness of the implant. A research paper by ruminant nutritionist Robbi Pritchard can be found at
For more information on the CAB study, read Fike's summary, "Traits of Cattle That Hit the Quality Target," at