Contacts: Dan Loy, Extension feedlot nutrition specialist, 515-294-1058
Wendy Miller, Iowa Beef Center, 515-294-9124

The Mystery of Feeder Implant Strategy: What To Do and When

AMES, Iowa – Today, at least 22 brand name growth implants are available for feedlot cattle. That works out to nearly 500 possible implant combinations in a reimplant program and more than 10,000 possible combinations if three implants are given to long-fed cattle.

Whew. And that’s only one decision a beef feedlot operator might face daily.

"Developing a good implant strategy can improve daily gains by up to 20 percent, improve efficiency up to 15 percent and potentially reduce production costs by at least 10 percent," said Dan Loy, Iowa State University Extension feedlot nutrition specialist and with the Iowa Beef Center. "I don’t think there’s any one technology that is more important in cattle feeding as it relates to profitability."

Complicating the decision is the rapidly changing implant market with even more choices being made available as well as the foreign fervor against growth hormone usage. Loy pointed out that producers can make their choices somewhat easier by categorizing available implants and honing their implanting techniques, as well as carefully assessing what markets they plan to sell into.

"Producers can sort implants by active ingredient and relative potency," Loy explained. "Implants within a category should give somewhat similar responses and a producer’s final decision should also be based on price, convenience, availability and general preference."  (See a grouped list of implants)

Developing a Strategy

"When developing an implant strategy, producers should keep in mind that the most important implant in terms of improving performance and reducing cost is the last implant used prior to marketing," Loy said. "Therefore, producers need to carefully consider slaughter date as well as growth and efficiency."

Terminal Implants. Using a combination implant as a terminal implant 80 to 140 days prior to slaughter is the most common implant strategy currently recommended. However, recent evidence suggests the ideal time to terminal implant may be 80 to 90 days prior rather than 100 to 120 days as commonly recommended, Loy said.

"Remember that cattle given combination implants not only grow faster and more efficiently, but must be fed an additional 50 to 150 lbs. heavier to reach the same endpoint – that may require an additional 10 to 20 days on feed," Loy said. "With this in mind, estimate a slaughter date and count back 80 to 100 days. This should give an accurate date for administering the terminal implant."

Until recently, the choice of terminal implant was affected by animal sex. Now, both strong combination implants are cleared for both steers and heifers. When the additive MGA is fed, natural estrogen production in heifers is increased, therefore, implanting with an androgen implant produces nearly the same response as a combination implant, Loy said. This is particularly true with older, heavier heifers.

Early Implants. Once the timing of the terminal implant is determined, producers can calculate the number days between first implant and terminal implant. This time span will help narrow the choice of early implant. If the number of days on the early implant exceeds 140, then producers will have to either administer two implants to cover the period or use one of the silicone rubber, long-acting estrogen implants that are effective for 180 to 300-plus days.

Implants used during this phase are mostly medium-potency estrogen or estrogen-like implants, Loy said, and implants from this group should give similar responses if the time period is 70 to 100 days. For periods less than 60 to 80 days, a low potency estrogen or estrogen-like implant is often chosen. "Some recent limited data suggests that using a low-potency implant as the first implant may have less negative carcass effects," Loy said.

There are many other considerations producers should realize when developing an implant plan. "These recommendations reflect the current thinking relative to the best ‘tradeoff’ between optimum performance and carcass quality," Loy emphasized. "More aggressive implant programs that involve high potency combination implants given early and reimplanted yield maximum performance and lowest cost of gain, but increase the risk of lower quality grades at the packing plant."

Therefore, specific marketing systems should be examined while choosing the best implant strategy. Markets that demand lean beef with more retail product are best met by a more aggressive implanting strategy. High quality markets demand either less aggressive implant strategies or longer feeding periods and heavier weights. "Moderate dosage combination implants just recently released for use in feedlots appear to offer improved carcass quality without giving up large performance response when used as a terminal implant," Loy said.

Often overlooked in implant strategies is technique. Surveys by major implant companies show problems with abscesses, crushed and/or missing implants with nearly 15 percent of implants administered. "Proper use of disinfectants, use of sharp needles and taking the proper time to ensure quality implanting are all very important," Loy said. "Implants coupled with antibiotics can help reduce infections, but shouldn’t be substituted for good technique."

Improper implant use and lack of management adjustments to certain implant programs can reduce quality grade and increase the likelihood of undesired side effects.

For more information about implant strategies and for a grouped list of implants, see the Iowa Beef Center's implant page.

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