By Jerad Jaborek
As of July 1, 2023, label claims on cattle steroid implant products were updated by their respective manufacturing companies to meet a request from the FDA to provide clarification on reimplanting use within a production phase. There are currently 25 approved implants for use in beef production in the U.S.
Three main types of hormones are used in cattle ear implants: androgens, estrogens and progestins. Estrogens consist either of the naturally occurring estradiol-17β, a synthetic version called estradiol benzoate or an estrogen-like compound called zeranol. Estrogens can be used either alone or in combination with the naturally occurring progestin, progesterone, or a synthetic version of testosterone, trenbolone acetate. Implants vary in potency and are commonly classified as low-, medium- or high-potency implants depending on their active ingredients and the concentration of their active ingredients (Table 1). Less potent implants usually contain an estrogenic hormone only or an estrogenic hormone with progesterone. Implants with medium potency usually contain an estrogenic hormone with a lesser concentration of an androgenic hormone, while higher potency implants contain an estrogenic hormone in combination with a greater concentration of trenbolone acetate.
Source : msu.edu