Paul Beck, Oklahoma State University, Extension State Beef Cattle Nutrition Specialist
Last week we discussed the new rules put forth by the U. S. Food and Drug Administration regarding reimplanting of growth promoting implants. In brief, reimplanting within a production phase is now (as of July 1, 2023) off-label unless the label specifically states it is approved for reimplanting.
The FDA provided a list of currently approved and marketed implants available.
Beef Calves
| Implant Name | Approved use | Approved for Reimplant in this class |
| Component E-C(progesterone and estradiol benzoate implants) | For increased rate of weight gain in beef calves 45 days of age or older and weighing up to 400 pounds | No |
| Component E-C w/ Tylan‡(progesterone and estradiol benzoate and tylosin tartrate implants) | For increased rate of weight gain in beef calves 45 days of age or older and weighing up to 400 pounds | No |
| Compudose(estradiol extended-release implants) | For increased rate of weight gain for up to 200 days in beef steer calves 2 months of age and older | No |
| Encore(estradiol extended-release implants) | For increased rate of weight gain for up to 400 days in beef steer calves 2 months of age and older | No |
| Ralgro(zeranol implants) | For increased rate of weight gain in beef calves 2 months of age or older | No |
| Synovex C(progesterone and estradiol benzoate implants) | For increased rate of weight gain in beef calves 45 days of age and older and weighing up to 400 lbs | No |
Growing Beef Cattle on Pasture (Stocker, Feeder, and Slaughter)
| Implant Name | Approved use | Approved for Reimplant in this class |
| Component TE-G (trenbolone acetate and estradiol implants) | For increased rate of weight gain in growing beef steers and heifers on pasture (stocker, feeder, and slaughter) | No |
| Component TE-G w/ Tylan‡ (trenbolone acetate and estradiol and tylosin tartrate implants) | For increased rate of weight gain in growing beef steers and heifers on pasture (stocker, feeder, and slaughter) | No |
| Compudose (estradiol extended-release implants) | For increased rate of weight gain for up to 200 days in growing beef steers on pasture (stocker, feeder, and slaughter) | No |
| Encore (estradiol extended-release implants) | For increased rate of weight gain for up to 400 days in growing beef steers on pasture (stocker, feeder, and slaughter) | No |
| Ralgro (zeranol implants) | For increased rate of weight gain in growing beef steers and heifers on pasture (stocker, feeder, and slaughter) | No |
| Revalor-G (trenbolone acetate and estradiol implants) | For increased rate of weight gain in growing beef steers and heifers on pasture (stocker, feeder, and slaughter) | No |
| Synovex ONE Grower (trenbolone acetate and estradiol benzoate extended-release implants) | For increased rate of weight gain for up to 200 days in growing beef steers and heifers on pasture (stocker, feeder, and slaughter) |
Growing Beef Cattle in a Dry Lot
| Implant Name | Approved use | Approved for Reimplant in this class |
| Ralgro (zeranol implants) | For increased rate of weight gain in growing beef steers and heifers in a dry lot | No |
In summary:
1) There are no implants available with reimplant claims on the label for used during the preweaning phase of production.
2) Prewean implants are only labeled for either 45 or 60 days of age and older.
3) Compudose and Encore are only labeled for use in steers during the preweaning phase.
4) Ralgro is the only implant approved for the “Drylot” phase of production.
a. Ralgro is approved for the preweaning “Beef Calves”; “Growing Beef Cattle on Pasture” and “Growing Beef Cattle Fed in Confinement for Slaughter” stages as well, but has no reimplant label claims.
2) Synovex-S and Synovex-H are not approved as pasture implants.
3) Until the finishing phase of production both Compudose and Encore are only approved in steers.
4) All Component brand implants containing Tylan (Elanco Animal Health products) will now have to be approved and scripted by a veterinarian due to the VMD ruling.
5) The only implants labeled for reimplanting during finishing are Synovex brand implants.