21 CFR § 558.274 - Hygromycin B.
---
identifier: "/us/cfr/t21/s558.274"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "21 CFR § 558.274 - Hygromycin B."
title_number: 21
title_name: "Food and Drugs"
section_number: "558.274"
section_name: "Hygromycin B."
chapter_name: "FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES"
subchapter_number: "E"
subchapter_name: "ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS"
part_number: "558"
part_name: "NEW ANIMAL DRUGS FOR USE IN ANIMAL FEEDS"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "21 U.S.C. 354, 360b, 360ccc, 360ccc-1, 371."
regulatory_source: "40 FR 13959, Mar. 27, 1975, unless otherwise noted."
cfr_part: "558"
---
# 558.274 Hygromycin B.
(a) *Specifications.* Type A medicated articles containing 2.4 or 8 grams hygromycin B per pound (g/lb).
(b) *Sponsor.* See No. 058198 in § 510.600(c) of this chapter for as follows:
(c) *Related tolerances.* See § 556.330 of this chapter.
(d) *Special considerations.* (1) Federal law restricts medicated feed containing this veterinary feed directive (VFD) drug to use by or on the order of a licensed veterinarian. See § 558.6 for additional requirements.
(2) The expiration date of VFDs for hygromycin B medicated feeds must not exceed 6 months from the date of issuance. VFDs for hygromycin B shall not be refilled.
(e) *Conditions of use.* It is used in feed as follows:
(1) *Chickens*—
| Hygromycin B grams/ton | Combination in grams/ton | Indications for use | Limitations | Sponsor |
| --- | --- | --- | --- | --- |
| (i) 8 to 12 | | Chickens: For control of infections of large roundworms (), cecal worms (), and capillary worms () | Use in complete feed. Withdraw 3 days before slaughter | 058198 |
| (ii) [Reserved] | | | | |
(2) *Swine*—
| Hygromycin B grams/ton | Combination in grams/ton | Indications for use | Limitations | Sponsor |
| --- | --- | --- | --- | --- |
| (i) 12 | | Swine: For control of infections of large roundworms (), nodular worms (), and whipworms () | In market hogs, use in complete feed for 8 weeks during the growing period. Withdraw 15 days before slaughter | 058198 |
| (ii) [Reserved] | | | | |
[81 FR 95005, Dec. 27, 2016]