The Cattle Business -- Implant Update

Livestock Update, May 1997

Bill McKinnon, Animal and Poultry Sciences, Virginia Tech

Cattle growth promotant implants continue to be an effective tool for cattlemen seeking to lower the cost per pound of production. In general, implants are going to improve the rate of gain on growing cattle by roughly 8% to 15%. Implants have offered one of the best economic returns per dollar invested of any management practice. Within the realm of cattle implants there have been several changes and new implants introduced within the last year to eighteen months.

The Hoechst-Roussel company has released a product targeted toward stocker cattle referred to as Revalor G. This product is essentially a third of a dose of the Revalor S product used in feedlot steers.

There has been a proliferation in the number of implant products aimed a finishing cattle. Four of these products utilize varying combinations of trembolone acetate and estradiol benzoate. These implants include Revalor S, Revalor H, Component TE-S, and Synovex Plus. These newer implants with the estradiol addition minimize the problem of carcass quality grade depression experienced with the trembolone acetate only product.

Another change in the implant market has been the VetLife company's acquisition of the marketing rights for Compudose. This company also now markets the products formally known as Implus S, Implus H, and Implus C under the names of Component E-S, Component E-H, and Component E-C, respectively (See Table 1).

The cow/calf operator has commonly asked about the issue of implanting heifer calves and its potential impact upon future reproductive performance. Three implants are labeled for use on suckling heifer calves which might be kept as replacements. The data suggests that if Ralgro, Component E-C, or Synovex are used in heifer calves over six weeks of age and before weaning there is no significant impact upon future reproductive performance.

A Kansas State University study published in 1994 showed a tendency for lower first service conception rates for heifers implanted at approximately three months of age. After a 45 day breeding period there was no difference in conception rates. There were some reports of implanting heifers improving pelvic area. This study confirmed larger pelvic areas on implanted heifers at the yearling stage, but the differences disappeared at the precalving measurement (the more critical time for pelvic area).

A summary of nine separate trials involving the use of Synovex C in heifer calves at two to three months of age calculated a 2.6% reduction in pregnancy rate during the first breeding season. None of the trials observed a positive or negative effect of implanting on pregnancy rate that was statistically significant.

A recent study by Kansas State University utilizing 548 heifer calves on ranches in Kansas and Nebraska found no negative effects on reproduction from appropriate Component E-C implant use on heifer calves. In each trial heifers were allotted to three treatment groups: no implant (Control), one implant at 45 to 120 days of age (Early IMP), or one implant at 200 days of age (Wean-IMP). Table 2 illustrates that there was no significant differences between treatments as measured by first service conception rate, overall pregnancy rate or calving rate.

Table 2. Conception and Calving Rate for Control, Early-IMP, and Wean-MP Heifers

Treatment	First Service Conception Rate %	Overall Pregnancy Rate %	Calving Rate %
Control	55.6	84.5	78.3
Early-IMP	56.2	85.6	81.0
Wean-IMP	52.1	84.6	80.7

The bulk of the information suggests that if implants are going to be used on heifer calves that might be kept for replacements, they should be implanted only once between six weeks of age and weaning.

Ralgro is the only implant with a label for use in calves under 45 days of age. For operations in a terminal program, keeping no replacement heifers, implanting each calf at birth with Ralgro and then again later during the suckling period with Ralgro or another product would tend to make economic sense. If keeping heifer calves for replacements, Ralgro should not be used in heifers under six weeks of age.

Sometimes we hear the concerns from the uninformed that cattlemen are "pumping their cattle full of hormones." Hormones are present in almost all foods whether of animal or plant origin. Hormones are naturally occurring chemicals that are essential to life. There is no "hormone free" beef or any other meat for that matter. Table 3 illustrates that beef is a relatively low source of estrogen (the hormone level most commonly impacted by implant use). The increase in the level of estrogen in beef from an implanted steer is biologically insignificant. Groups such as the World Health Organization and the United Nations Food and Agricultural Organization have concluded that the proper use of growth promotant implants is safe.

Table 3. Various Foods as a Source of Estrogen

Food source	Serving (ounces)	Estrogen (nanograms)
Steer beef, implanted	3	1.85
Steer beef, non-implanted	3	1.01
Hen's egg (one egg)	2	1,750.00
Cabbage	3	2,016.00
Peas	3	336.00
Milk	8	35.48

(Source: Inter-American Institute for Cooperation on Agriculture, Report on Use of Hormonal Substances in Animals, December, 1986)

Table 4. Daily Human Estrogen Production (nanograms)

Female child, before puberty	31,000
Male child, before puberty	6,000
Non-pregnant female, adult	45,000
Pregnant female, third trimester	37,800,000
Adult male	48,000

(Source: Expert Committee on Additives, Food and Agriculture Organization, June, 1987)

With the insignificant cost of implants of $1 to $2 per head and the return with moderately growing cattle of 20 to 25 pounds, it is a little surprising that all cattle producers are not using implants. The proper use of implants is an important method in which the overall efficiency of the beef industry can be improved.

CATTLE GROWTH IMPLANTS
Suckling Calves
Implant *	Company	Ingredient	Steer Restrictions	Heifer Restrictions**
Component E-C	VetLife	100 mg Progesterone + 10 mg Estradiol benzoate	> 45 days old < 400 lbs Veal calves - No	> 45 days old < 400 lbs Veal calves - No
Compudose	VetLife	24 mg Estradiol benzoate	> 45 days old	No
Ralgro	Mallinckrodt	36 mg Zeranol	OK any age	OK any age, but if replacements, >1 mo but preweaning
Synovex C	Fort Dodge	100 mg Progesterone + 10 mg Estradiol benzoate	> 45 days old < 400 lbs Veal calves - No	> 45 days old < 400 lbs Veal calves - No
** Heifer calves intended as possible replacements should receive no more than one implant
Growing Cattle (Stockers & Backgrounders)
Component E-H	VetLife	200 mg Testosterone propionate + 20 mg Estradiol benzoate	Steers - No	400 lbs + Replacements -No
Component E-S	VetLife	200 mg Progesterone + 20 mg Estradiol benzoate	400 lbs +	Heifers - No
Compudose	VetLife	24 mg Estradiol benzoate	> 45 days old	Feedlot heifers only
Ralgro	Mallinckrodt	36 mg Zeranol	OK	OK Replacements - No
Revalor G	Hoechst-Roussel	40 mg Trenbolone acetate + 8 mg Estradiol benzoate	OK	OK Replacements - No
Synovex H	Fort Dodge	200 mg Testosterone propionate + 20 mg Estradiol benzoate	Steers - No	400 lbs + Replacements - No
Synovex S	Fort Dodge	200 mg Progesterone + 20 mg Estradiol benzoate	400 lbs +	Heifers - No
Feedlot Finishing Cattle
Component E-H	VetLife	200 mg Testosterone propionate + 20 mg Estradiol benzoate	Steers - No	400 lbs +
Component E-S	VetLife	200 mg Progesterone + 20 mg Estradiol benzoate	400 lbs +	Heifers - No
Component TE-S	VetLife	120 mg Trenbolone Acetate + 24 mg Estradiol benzoate	Feedlot only	Heifers - No
Compudose	VetLife	24 mg Estradiol benzoate	OK any age	Feedlot heifers only
Finaplix s	Hoechst-Roussel	140 mg Trenbolone Acetate	Feedlot only	Heifers - No
Finaplix h	Hoechst-Roussel	200 mg Trenbolone Acetate	Steers - No	Feedlot heifers only
Ralgro	Mallinckrodt	36 mg Zeranol	OK	OK
Ralgro Magnum	Mallinckrodt	72 mg Zeranol	600 lbs +	Heifers - No
Revalor H	Hoechst-Roussel	140 mg Trenbolone Acetate + 14 mg Estradiol benzoate	Steers - No	OK
Revalor S	Hoechst-Roussel	120 mg Trenbolone Acetate + 24 mg Estradiol benzoate	Feedlot only	Heifers - No
Synovex Plus	Fort Dodge	200 mg Trenbolone Acetate + 28 mg Estradiol benzoate	Feedlot only	Heifers - No
Synovex H	Fort Dodge	200 mg Testosterone propionate + 20 mg Estradiol benzoate	Steers - No	400 lbs +
Synovex S	Fort Dodge	200 mg Progesterone + 20 mg Estradiol benzoate	400 lbs +	Heifers - No
* All are given as subcutaneous (SQ) ear implantation ^ Effective times are approximates

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