Cow-calf Corner: What implants can I use for cattle on my operation? Stocker and grower cattle 

Paul Beck, Oklahoma State University, Extension State Beef Cattle Nutrition Specialist

The last couple of weeks 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. 

(From: https://www.fda.gov/animal-veterinary/product-safety-information/fda-provides-list-currently-approved-and-currently-marketed-implants-available-beef-cattle-target )

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 stocker or grower phase of production.
2. Compudose and Encore are only labeled for use in steers during the stocker and grower phase.
3. Ralgro is the only implant approved for the “Drylot” phase of production.
   • 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. 
4. Synovex-S and Synovex-H are not approved as pasture implants.
5. Until the finishing phase of production both Compudose and Encore are only approved in steers.
6. 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.

It appears there will be a lot of research focused on the label claims for finishing cattle, since that segment will be the most impacted. Therefore, there is not likely going to be any new implant products for cattle in the pre-finishing stages of production.