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Virginia Cooperative Extension -
 Knowledge for the CommonWealth

Beef Management

Livestock Update, June 2008

Dr. Mark Wahlberg, Extension Livestock Specialist, VA Tech

Implanting Calves Still Pays Dividends

Growth-promoting implants are a well-established technology in the beef business.  For more than 30 years some of these products have been available to improve growth and feed efficiency in cattle.  A great deal of the more recent product development has been with implants designed for use in feedlot steers and heifers.  However, there are a few implant products that are approved for use and will effectively work in calves prior to the time of weaning.

The use of all of the implant products is monitored by the Food and Drug Administration (FDA).  Based on the research, FDA has determined that when used as instructed, implants have no withdrawal period. 

Implants produce an increase in muscle growth, at the expense of fat deposition, in cattle of all ages.  This growth effect is variable, and is affected by age and sex of calf, the calf's genetic potential for growth, level of nutrition, and overall health and vigor of the calf.  But in general, one implant administered preweaning generates from 10 to 25 pounds of extra pounds at weaning. 

The implants approved for use in preweaning calves contain lower doses of the growth-enhancing substances.  In addition, the substances used for preweaning calves are less potent than those designed for use in feedlot cattle.  In table 1 are shown the implants approved for preweaning calves.

Table 1. Implants approved for use in preweaning calves



Active Ingredient

Days of Payout



36 mg Zeranol*



Fort Dodge

10 mg Estradiol
100 mg Progesterone


Component E-C


10 mg Estradiol
100 mg Progesterone




24 mg Estradiol


*Zeranol has approximately 30-33% the estrogenic effect of Estradiol.

The mid-summer time period (July) is a good time to do various management practices to winter and spring-born calves.  Applying a dewormer to calves at this time is often advantageous.  Administration of the first round of vaccines is a good start towards immunizing calves leading up to weaning.  At this same time, an implant can be applied to the calves.

Advantages of pre-weaning implants - The big advantage is more pounds at weaning.  The cost-benefit payback is quite high.  Most implants cost from $1.00 to $1.50 per dose.  They typically will generate 10 to 25 extra pounds at weaning.  With higher levels of nutrition, such as with creep feeding or creep grazing, the improvement in gain will likewise be higher.  Put a value on those pounds of calf and it is readily apparent that implanting calves is one of the highest-paying management practices that can be done.

Disadvantages of pre-weaning implants - Nothing is 100% positive.  A few factors to consider about pre-weaning implanting include:

Negative effects on reproduction.  Replacement heifers may have reduced reproductive performance if implanted improperly.  They need to be at least 45 days old, and implanted only one time.  Bulls kept for breeding should never be implanted.  The safe approach with heifers is to not implant unless you are certain those heifers will not be kept for breeding.

Reduced Quality Grade - Quality grade comes from more marbling.  Fat within the lean is marbling.  Implants reduce fat deposition.  Thus, implants reduce Quality Grade.  However, the lower-dose implants used for preweaning calves have less of a fat-reducing effect.  A much greater reduction in quality comes from inappropriate use of the high-potency implants in feedlot cattle.  To reduce the quality grade effect, use just one implant prior to weaning.

Implant Strategy - Producers must evaluate their specific production and marketing situation regarding many management practices.  This is certainly true regarding the use of implants.  The producer who will benefit most from the use of preweaning implants is the one who sells calves at or shortly after weaning.  If the producer offers creep feed or creep grazing, which enhances the nutritional status of the calf, the implant effect will be even higher.  The producer selling at weaning will have the additional pounds of calf to run through the marketplace.

Producers who retain ownership, especially through the feedlot, will benefit less from preweaning implants.  This is because their payday is delayed until the cattle are finished.  The extra pounds at weaning will not be converted into cash right away.  Particularly if the cattle are to be sold on a Quality-oriented pricing grid, a producer may choose to not implant preweaning due to the risk of a quality grade reduction.

Summary - Implanting preweaning calves with one of the implants approved for that use is one of the highest-paying management practices available for beef producers.  The extra pounds of calf at weaning come at a very low cost.  While there are negative effects associated with implants, when just one implant is administered to calves prior to the time of weaning, these effects can be minimized.


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