Implants
The proper development of an implant strategy can improve daily gains up to 20%, improve efficiency up to 15% and reduce cost of production at least 10%. Improper implant use and lack of management adjustments with certain implant programs may reduce quality grade, and increase undesirable side effects. Perhaps no technology is more important in cattle feeding as it relates to profitability. Complicating the decision is the rapidly changing implant market with more choices and more potential implant strategies to choose from. Proper implant administration can improve the response to implanting. Surveys by the major implant companies have shown problems with abscesses, crushed or missing implants, etc. with as many as 15% of implants administered. Proper use of disinfectants, using sharp needles, and taking the proper time to ensure quality implanting are important. Recent availability of implants with antibiotics to prevent infection and abscesses can reduce infection, but should not substitute for proper technique.

Implants available
Currently at least 22 brand names of implants are available for feedlot cattle. This means there are nearly 500 possible implant combinations in a reimplant program, and over 10,000 possible combinations if three implants are given to long fed cattle. One helpful approach to developing an implant system is to categorize the currently available implants by active ingredient and relative potency. The following is one example of this approach. Implants within a category should give somewhat similar responses and the decision should be based on price, convenience, availability, and general preference.

Ingredients Brands
Medium Potency Estrogen or Estrogen-like implants:

EB20/PROG200 (estradiol benzoate, 20 mg; Progesterone, 200 mg) Synovex-S, Component E-S

EB20/TEST200 (estradiol benzoate, 20 mg; Testosterone, 200 mg) Synovex-H, Component E-H

E 25.7 (estradiol, 25.7 mg) Compudose

E 43.9 (estradiol, 43.9 mg) Encore

Z72 (zeranol, 72 mg) Magnum

Lower potency Estrogen or Estrogen-like implants:

Z36 (zeranol, 36 mg) Ralgro

EB10/PROG100 (estradiol benzoate, 10 mg; Progesterone, 100 mg) Synovex-C, Component E-C

Androgen implants:

TBA 140 (trenbolone acetate, 140 mg) Finaplix-S, Component T-S

TBA 200 (trenbolone acetate, 200 mg) Finaplix-H, Component T-H

Combination (higher potency) implants:

E24/TBA120 (estradiol, 24mg; trenbolone acetate, 120 mg) Revalor-S, Component TE-S

E14/TBA140 (estradiol 14mg, trenbolone acetate, 140 mg) Revalor-H

E28/TBA200 (estradiol benzoate, 28mg; trenbolone acetate, 200 mg) Synovex Plus

E20/TBA200 (estradiol 20 mg; trenbolone acetate, 200 mg) Revalor-200

Lower potency combination implants:

E8/TBA40 (estradiol, 8 mg; trenbolone acetate, 40 mg) Revalor-G

E16/TBA80 (estradiol 16 mg; trenbolone acetate, 80 mg) Revalor-IS

E8/TBA80 (estradiol, 8 mg; trenbolone acetate, 80 mg) Revalor-IH

Developing a strategy
Step 1 – Terminal Implants. When developing an implant strategy, keep in mind that the most important implant in terms of improving performance and reducing cost is the last implant used prior to marketing. The most common implant strategy currently recommended is to use a combination implant as a terminal implant the last 80 to 140 (100-120 is ideal) days prior to slaughter. Keep in mind that cattle given combination implants not only grow faster and more efficiently, but must be fed an additional 50 to 150 pounds heavier to reach the same endpoint. This may require and additional 10-20 days on feed. With this in mind, estimate a slaughter date and count back 100 to 120 days. This should give you the date for administering the terminal implant. Until recently, the choice of implant for a terminal implant is affected by the sex of the animal. Now both the E24 TBA120 implants and E28 TBA200 are cleared for both steers and heifers. When the feed additive MGA is fed, natural estrogen production of heifers is increased, so implanting with and androgen implant (TBA200) produces nearly the same response as a combination implant. This is particularly true with older, heavier heifers.

Step 2 – Early implants. Once the timing of the terminal implant is determined, determine the number of days from arrival or first implant until the terminal implant date. This number of days will help narrow down the implant choice for early implant(s). If the number of days on the early implant exceeds 140, then either two implants are needed to cover this period or a longer acting implant (E25.7, 180-200 days or E43.9, 300 days+) is required. Implants used during this phase are most commonly medium potency estrogen or estrogen like implants. Implants from this group should give similar responses if the period is 70-100 days. For periods less than 60-80 days a low potency estrogen or estrogen-like implant is often the implant of choice. Some recent limited data suggests that using a low potency implant as the first implant may have less negative carcass effects.

Other considerations – These recommendations reflect the current thinking relative to the best tradeoff between optimum performance and carcass quality. More aggressive implant programs (high potency combination implants given early and reimplanted) yield maximum performance and lowest cost of gain, but increase the risk of lowered quality grade. Therefore, the marketing system should be a consideration in choosing the best implant strategy. Markets that demand leaner beef and more retail product are best met by a more aggressive implant 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 the feedlot appear to offer improved carcass quality without giving up a large performance response when used as the terminal implant.

What if I sell my calves before harvest weight? – Calfhood implants can add 20-40 pounds (3-5%) to weaning weights. Stocker cattle that are gaining over 1.5 lb. per day will increase weight gain 8-18 percent or 15-40 lb. during the grazing season. Cattle that have been implanted as calves or stockers may have a slightly lower response to feedlot implants than those that have not been implanted. Keep this thumb rule in mind: The most important implant you give is the last one before you sell the cattle. In the feedlot that is the terminal implant. If you background calves, the implant used the last 80-120 days will give you the most return per dollar invested.