---
kind: "section"
citation: "21 C.F.R. § 522.2680"
title: "21"
number: "522.2680"
heading: "Zeranol."
url: "https://uscodex.org/cfr/21/522.2680"
---

# §522.2680. Zeranol.

- (a) **Specifications.** Each pellet contains 12, 18, or 20 milligrams (mg) zeranol.
- (b) **Sponsor.** See 000061 in [§ 510.600(c)](/cfr/21/510.600.md?p=c) of this chapter.
- (c) **Related tolerances.** See [§ 556.760](/cfr/21/556.760.md) of this chapter.
- (d) **Conditions of use—**
  - (1) **Beef cattle—**
    - (i) **Amount.** 36 mg zeranol (one implant consisting of 3 pellets, each pellet containing 12 mg zeranol) per implant dose.
    - (ii) **Indications for use.**
      - (A) For increased rate of weight gain and improved feed efficiency in growing beef steers and heifers fed in confinement for slaughter.
      - (B) For increased rate of weight gain in beef calves 2 months of age or older, in growing beef steers and heifers on pasture (stocker, feeder, and slaughter), and in growing beef steers and heifers in a dry lot.
    - (iii) **Limitations.** Implant pellets subcutaneously only. Not approved for repeated implantation (reimplantation) with this or any other cattle ear implant within a single production phase as safety and effectiveness have not been evaluated. Do not use in beef calves less than 2 months of age, dairy calves, and veal calves because effectiveness and safety have not been evaluated. A withdrawal period has not been established for this product in preruminating calves. Do not use in replacement beef heifers after weaning or in bulls, dairy cows, or replacement dairy heifers.
  - (2) **Feedlot lambs—**
    - (i) **Amount.** 12 mg zeranol (one implant consisting of 1 pellet containing 12 mg zeranol) per implant dose.
    - (ii) **Indications for use.** For increased rate of weight gain and improved feed conversion.
    - (iii) **Limitations.** Implant subcutaneously in ear only. Do not use in breeding animals. Do not implant animals within 40 days of slaughter. Safety and effectiveness have not been established in veal calves. A withdrawal period has not been established for this product in preruminating calves. Do not use in calves to be processed for veal.
  - (3) **Steers fed in confinement for slaughter—**
    - (i) **Amount.** 72 mg zeranol (one implant consisting of 6 pellets, each pellet containing 12 mg zeranol) per implant dose.
    - (ii) **Indications for use.** For increased rate of weight gain and improved feed efficiency.
    - (iii) **Limitations.** Implant subcutaneously in ear only. Safety and effectiveness have not been established in veal calves. A withdrawal period has not been established for this product in preruminating calves. Do not use in calves to be processed for veal.
  - (4) **Pasture cattle (slaughter, stocker, feeder steers, and heifers)—**
    - (i) **Amount.** 138 mg zeranol (one implant consisting of 7 pellets, each of 6 pellets containing 20 mg zeranol and a seventh pellet containing 18 mg zeranol) per implant dose.
    - (ii) **Indications for use.** For increased rate of weight gain.
    - (iii) **Limitations.** Implant subcutaneously in ear only. Safety and effectiveness have not been established in veal calves. A withdrawal period has not been established for this product in preruminating calves. Do not use in calves to be processed for veal.

## Notes

### Amendments

[59 FR 19639, Apr. 25, 1994; 60 FR 26360, May 17, 1995, as amended at 62 FR 61625, Nov. 19, 1997; 64 FR 46840, Aug. 27, 1999; 67 FR 6867, Feb. 14, 2002; 70 FR 6764, Feb. 9, 2005; 88 FR 55566, Aug. 16, 2023; 91 FR 5301, Feb. 6, 2026]

### Authority

Authority: 21 U.S.C. 360b.

### Source

Source: 40 FR 13858, Mar. 27, 1975, unless otherwise noted.

### Amendments

[59 FR 19639, Apr. 25, 1994; 60 FR 26360, May 17, 1995, as amended at 62 FR 61625, Nov. 19, 1997; 64 FR 46840, Aug. 27, 1999; 67 FR 6867, Feb. 14, 2002; 70 FR 6764, Feb. 9, 2005; 88 FR 55566, Aug. 16, 2023; 91 FR 5301, Feb. 6, 2026]