Implanting beef calvesand stocker cattle

F.T. McCollum IIIExtension Beef Cattle Specialist

The Texas A&M University System

Implants for calvesand stocker cattle

Table 1 lists implants available for use insuckling calves and pasture cattle. The ac-tive compounds in calf implants are zeranol,estradiol benzoate-progesterone, or estradiol17-beta. Stocker cattle implants contain thesame active compounds, plus a combinationof estradiol and trenbolone acetate. Somestocker cattle implants are designated for usein heifers or steers; they generally are de-noted by an “H” or “S” in the implant name.These implants have no withdrawal timebefore sale or slaughter.

Implant administrationTo administer implants, designate one

person to implant while processing or work-ing cattle. To avoid infections and reducedimplant performance, make sure the ear sur-face, the implant applicator needle and thehands of the person implanting the cattle areclean. Some companies distribute disinfec-tant trays along with the implant applicator.Use these trays at chuteside as a place torest the implant applicator when not in useand to clean the applicator needle. Beforeadministering the implant, use a spongesoaked in disinfectant to remove manure andother foreign material from the ear surface.You can also use the sponge to clean the ap-plicator needle.

Protect implant cartridges and belts fromdust and other contaminants during storageand at chuteside. Some implants must be re-frigerated during storage.

Place the implant under the skin on thebackside of the middle third of the ear (Fig-ure 1). Implanting at any other location vio-lates federal law.

Applicators vary for different implants. Be-come familiar with the mechanical opera-tion of the applicator to ensure proper im-plant placement, and avoid crushing, bunch-ing or wasting implant pellets. The needleon the implant applicator must be sharp andfree of spurs to avoid unnecessary traumato the ear and implant site.

Figure 1. Proper implant placement on thebackside of the ear.

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Of all the management practices available to cow/calf and stocker cattle produc-

ers, implanting suckling calves and stocker cattle offers one of the highest ben-

efit-to-cost ratios. Many implants are available, but selection of an implant is

less critical than the decision on whether to implant or not.

Table 1. Guidelines for currently approved implants for suckling beef calves and stocker cattle.

Implant Estimatedtrade Marketing payoutname company Active ingredient(s) Target animal period

Implus-C®or UpJohn Co. 100 mg progesterone Suckling beef calves up to 400 lbs.; 100 - 140 daysCalf-oid® 10 mg estradiol benzoate not for use in calves less than 45 days

old or calves intended for reproduction

Component-C® VetLife, Inc. 100 mg progesterone Steer and heifer calves up to 400 lbs.; 100 - 140 days10 mg estradiol benzoate not for use in calves less than 45 days

old or bull calves intended for reproduction

Synovex-C® Ft. Dodge Animal 100 mg progesterone Steer and heifer calves up to 400 lbs.; 100 - 140 daysHealth 10 mg estradiol benzoate not for use in calves less than 45 days

old or bull calves intended for reproduction

Ralgro® Schering-Plough 36 mg zeranol Steer and heifer calves; weaned steers 70 - 100 daysAnimal Health and heifers; not for use in calves less

than 30 days old or bull calves intendedfor reproduction

Compudose® VetLife, Inc. 25.7 mg estradiol Suckling steers; weaned steers and heifers; 170 - 200 daysnot for replacement heifers

Encore® VetLife, Inc. 43.9 mg estradiol Suckling steers; weaned steers and heifers; 400 daysnot for replacement heifers

Component-H® VetLife, Inc. 200 mg testosterone Heifers over 400 lbs.; 100 - 140 days20 mg estradiol benzoate not for replacement heifers

Component-S® Vetife, Inc. 200 mg progesterone Steers over 400 lbs. 100 - 140 days20 mg estradiol benzoate

Implus-H® UpJohn Co. 200 mg testosterone Heifers over 400 lbs.; 100 - 140 days20 mg estradiol benzoate not for replacement heifers

Implus-S® UpJohn Co. 200 mg progesterone Steers over 400 lbs. 100 - 140 days20 mg estradiol benzoate

Synovex-H® Ft. Dodge Animal 200 mg testosterone Heifers over 400 lbs.; 100 - 140 daysHealth 20 mg estradiol benzoate not for replacement heifers

Synovex-S® Ft. Dodge Animal 200 mg progesterone Steers over 400 lbs. 100 - 140 daysHealth 20 mg estradiol benzoate

Revalor-G® Hoechst-Roussel 8 mg estradiol Weaned steers and heifers; 100 - 140 daysAgri-Vet Co. 40 mg trenbolone acetate not for replacement heifers

After placing the implant in the ear,palpate the site to ensure that the im-plant was properly placed. Apply pres-sure on the area punctured by theneedle to help the wound close and pre-vent dirt and other foreign materialsfrom entering the implant site.

Cattle performanceSuckling calves: Implanting suck-

ling calves once with zeranol or estra-diol-progesterone type implants will in-crease daily weight gains an average of0.10 pound per day for steer calves and0.12 pound per day for heifer calves(Selk, 1997). Implus-C® (Calf-oid®), Com-ponent-C®, Compudose®, Encore®,

Ralgro®, and Synovex-C® are labeled forsuckling steers and heifers. Component-S®, Component-H®, Implus-S®, Implus-H®, Synovex-S®, and Synovex-H® canalso be used in sucking calves but arerecommended for calves weighing over400 pounds. Table 1 lists specific infor-mation and restrictions.

Potential replacement heifers:Concerns about reproductive perfor-mance have limited the use of growthimplants in heifer calves that are po-tential herd placements. Currently,Synovex-C®, Component-C® and Ralgro®

are the only implants labeled for use inreplacement heifer calves (see Table 1).Use is restricted to heifers older than

Table 2. Estrogenic activity of several com-mon foods (adapted from Preston, 1997).

Estrogenic activityFood (nanograms/lb.

of food)

Soybean oil 908,000

Cabbage 10,896

Wheat germ 1,816

Peas 1,816

Eggs 15,890

Ice cream 2,724

Milk 59

Beef from a pregnant cow 636

Beef from implanted cattle 10

Beef from non-implanted cattle 7

30 days for Ralgro® and 45 days forSynovex-C® and Component-C®.

Implanting heifers at or near birthcan reduce future reproductive perfor-mance. However, research has shownthat one implant administered between2 months of age and weaning has littleeffect on subsequent reproductive per-formance. The impacts on future repro-ductive performance are less predict-able and can be severe in some caseswhen implants are administered afterweaning. The probability and severityof reduced reproductive performanceincreases when heifers are implantedmore than once between birth and pu-berty. Heifer calves that have been im-planted have a larger pelvic area at 1year of age. However, by calving timeat 2 years of age, these differences aresmall and calving ease is not improved.

If replacement heifers are identifiedat a young age, do not implant them, asit provides no benefits; implants do notimprove age at puberty nor calving ease.However, if replacement heifers cannotbe identified at an early age, implant-ing all the heifer calves once between 2months of age and weaning does notsignificantly affect reproduction inheifer calves eventually selected for re-placements. The remaining heifercalves will be heavier at weaning.

Potential herd bulls: No implantsare labeled for use in bull calves in-tended for future use as herd sires. Im-plants can suppress testicular develop-ment and reduce libido and semen qual-ity.

Stocker cattle: A single implant willincrease weight gain 8 to 18 percent, or15 to 40 pounds, during the grazing sea-son (Kuhl, 1997). If the grazing seasonis more than 100 to 120 days and theplane of nutrition is adequate, reim-planting or using an implant with alonger release period stimulates addi-tional weight gain. All the implantslisted in Table 1 can be used in stockercattle. Implus-C® (Calf-oid®), Compo-nent-C®, and Synovex-C® are recom-mended for calves weighing less than400 pounds and can be used with light-weight stocker cattle.

Reimplanting cattle: Reimplanting,or administering a second implant at

some interval after the first implant,improves performance if the plane ofnutrition is adequate. An implant re-leases (or “pays out”) compound for 70to 400 days depending on the implant(Table 1).

Although the implant releases activecompound over an extended period, atsome point the quantity of active ingre-dient released declines to a level thatdoes not stimulate performance ad-equately. Therefore, the recommendedreimplanting interval for each implantis shorter than the estimated payout.

As a rule of thumb, the window toreimplant cattle is about 30 days lessthan the estimated payout. So, if animplant has a 100- to 140-day payout,then administer another implant be-tween 70 and 100 days if you want tomaintain circulating levels of the activecompounds.

Food safety concernsThe Food and Drug Administration

requires no withdrawal period beforeslaughter of implanted cattle. Beef fromimplanted cattle has a very low level ofestrogen activity compared to othercommon foods. Table 2 lists the estro-genic activity of several common foods.Likewise, the potential amount of es-trogen consumed in beef from im-planted cattle is extremely low com-pared to that produced daily by the

human body. If a person consumed 1pound of beef per day from implantedcattle, the potential estrogen intakewould be about 10 nanograms. In com-parison, the daily estrogen productionby the human body is about 100,000nanograms for adult men, about5,000,000 nanograms for non-pregnantwomen, and about 40,000 nanogramsfor a prepuberal child.

References

Kuhl, Gerry L. 1997. Stocker cattle re-sponses to implants. pp. 51-62. In:Symposium: Impact of implants on

performance and carcass value ofbeef cattle. Oklahoma AgriculturalExperiment Station P-957.

Preston, R.L. 1997. Rationale for thesafety of implants. pp. 199-203. In:Symposium: Impact of implants onperformance and carcass value ofbeef cattle. Oklahoma AgriculturalExperiment Station P-957.

Selk, Glenn. 1997. Implants for suck-ling steer and heifer calves and po-tential replacement heifers. pp. 40-50. In: Symposium: Impact of im-plants on performance and carcassvalue of beef cattle. Oklahoma Agri-cultural Experiment Station P-957.

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