Synthetic Hormones in Animal Husbandry

Introduction: There are three synthetic hormones approved by the U.S. Food and Drug Administration (U.S. FDA) for growth promotion in cattle and sheep raised for meat production: the estrogenic compound zeranol, the anabolic steroid trenbolone acetate (TBA), and the progestin melengestrol acetate (MGA). The FDA approves and regulates the use of hormone implants, establishing tolerance levels (maximal allowable residue concentrations) and minimum withdrawal times for these hormones to prevent animal food products from exceeding tolerance concentrations. Hormonally active substances have been banned for use in food-producing animals in the European Community since 1988, and this ban applies to use in the production of meat imported to Europe.