Federal regulations · Through 2026-08-25 · Newer source version available

21 CFR 558.4: Requirement of a medicated feed mill license.

(a) A feed manufacturing facility must possess a medicated feed mill license in order to manufacture a Type B or Type C medicated feed from a Category II, Type A medicated article.
(b) The manufacture of the following types of feed are exempt from the required license, unless otherwise specified:
(1) Type B or Type C medicated feed using Category I, Type A medicated articles or Category I, Type B or Type C medicated feeds; and
(2) Type B or Type C medicated feed using Category II, Type B or Type C medicated feeds.
(c) The use of Type B and Type C medicated feeds shall also conform to the conditions of use provided for in subpart B of this part.
(d) This paragraph identifies each drug by category, the maximum level of drug in Type B medicated feeds, and the assay limits for the drug in Type A medicated articles and Type B and Type C medicated feeds, as follows:
Category I
Drug Assay limits percent 1 Type A Type B maximum (200x) Assay limits percent 1 Type B/C 2
Amprolium with Ethopabate 94-114 22.75 g/lb (5.0%) 80-120.
Avilamycin 90-110 7.3 g/lb (1.6%) 80-110.
Bacitracin methylenedisalicylate 85-115 25.0 g/lb (5.5%) 70-130.
Bacitracin zinc 84-115 5.0 g/lb (1.1%) 70-130.
Bambermycins 90-110 800 g/ton (0.09%) 80-120/70-130.
Chlortetracycline 85-115 40.0 g/lb (8.8%) 80-115/70-130.
Coumaphos 95-115 6.0 g/lb (1.3%) 80-120.
Decoquinate 90-105 2.72 g/lb (0.6%) 80-120.
Dichlorvos 100-115 33.0 g/lb (7.3%) 90-120/80-130.
Diclazuril 90-110 182 g/t (0.02%) 85-115/70-120.
Efrotomycin 94-113 1.45 g/lb (0.32%) 80-120.
Iodinated casein 85-115 20.0 g/lb (4.4%) 75-125.
Laidlomycin propionate potassium 90-110 1 g/lb (0.22%) 90-115/85-115.
Lasalocid 95-115 40.0 g/lb (8.8%) Type B (cattle and sheep): 80-120; Type C (all): 75-125.
Lincomycin 90-115 20.0 g/lb (4.4%) 80-130.
Lubabegron 87-107 908 g/ton 85-115/80-120.
Melengestrol acetate 90-110 10.0 g/ton (0.0011%) 70-120.
Monensin 85-115 40.0 g/lb (8.8%) Chickens, turkeys, and quail: 75-125; Cattle: 5-10 g/ton 80-120; Cattle: 10-30 g/ton 85-115; Goats: 20 g/ton 85-115; Liq. feed: 80-120.
Narasin 90-110 9.0 g/lb (1.98%) 85-115/75-125.
Nicarbazin (granular) 90-110 9.0 g/lb (1.98%) 85-115/75-125.
Narasin 90-110 9.0 g/lb (1.98%) 85-115/75-125.
Nystatin 85-125 5.0 g/lb (1.1%) 75-125.
Oxytetracycline 90-120 20.0 g/lb (4.4%) 75-125/65-135.
Poloxalene 90-110 54.48 g/lb (12.0%) Liq. feed: 85-115.
Ractopamine 85-105 2.46 g/lb (0.54%) 80-110/75-125.
Salinomycin 90-110 6.0 g/lb (1.3%) 80-120.
Semduramicin (as semduramicin sodium) 90-110 2.27 g/lb (0.50%) 80-110
Semduramicin (as semduramicin sodium biomass) 90-110 2.27 g/lb (0.50%) 80-120
Tylosin 80-120 10.0 g/lb (2.2%) 75-125.
Tylvalosin 90-110 3.86 g/lb 85-115.
Virginiamycin 85-115 10.0 g/lb (2.2%) 70-130.
Zoalene 92-104 11.35 g/lb (2.5%) 85-115.
1 Percent of labeled amount.
2 Values given represent ranges for either Type B or Type C medicated feeds. For those drugs that have two range limits, the first set is for a Type B medicated feed and the second set is for a Type C medicated feed. These values (ranges) have been assigned in order to provide for the possibility of dilution of a Type B medicated feed with lower assay limits to make Type C medicated feed.
Category II
Drug Assay limits percent 1 Type A Type B maximum (100x) Assay limits percent 1 Type B/C 2
Amprolium 94-114 11.35 g/lb (2.5%) 80-120.
Apramycin 88-112 7.5 g/lb (1.65%) 80-120.
Carbadox 90-110 2.5 g/lb (0.55%) 75-125.
Clopidol 94-106 11.4 g/lb (2.5%) 90-115/80-120.
Erythromycin 85-115 4.625 g/lb (1.02%) 75-125.
Famphur 100-110 5.5 g/lb (1.21%) 90-115/80-120.
Fenbendazole 93-113 8.87 g/lb (1.96%) 75-125.
Florfenicol 90-110 9.1 g/lb (2.0%) Swine feed: 85-115 Catfish feed: 80-110. Salmonid feed: 80-110.
Halofuginone hydrobromide 90-115 272.0 g/ton (.03%) 75-125.
Hygromycin B 90-110 1,200 g/ton (0.13%) 75-125.
Ivermectin 95-105 1,180 g/ton (0.13%) 80-110.
Maduramicin ammonium 90-110 545 g/ton (.06%) 80-120.
Morantel tartrate 90-110 66.0 g/lb (14.52%) 85-115.
Neomycin 80-120 20 g/lb (4.4%) 70-125.
Oxytetracycline 80-120 20 g/lb (4.4%) 65-135.
Neomycin sulfate 80-120 100 g/lb (22.0%) 70-125.
Nicarbazin (granular) 90-110 5.675 g/lb (1.25%) 85-115/75-125.
Nicarbazin (powder) 96-104 9.08 g/lb (2.00%) 85-115/80-120.
Novobiocin 85-115 17.5 g/lb (3.85%) 80-120.
Pyrantel tartrate 90-110 36 g/lb (7.9%) 75-125.
Robenidine 95-115 1.5 g/lb (0.33%) 80-120.
Sulfadimethoxine 90-110 Poultry: 5.675 g/lb Fish: 85.1 g/lb 80-115/75-125.
Ormetoprim 90-110 Poultry: 3.405 g/lb Fish: 17.0 g/lb 80-115.
Sulfamerazine 85-115 18.6 g/lb (4.0%) 85-115.
Sulfamethazine 85-115 10.0 g/lb (2.2%) 80-120.
Chlortetracycline 85-115 10.0 g/lb (2.2%) 85-125/70-130.
Sulfamethazine 85-115 10.0 g/lb (2.2%) 80-120.
Tylosin 80-120 10.0 g/lb (2.2%) 75-125.
Sulfaquinoxaline 98-106 11.2 g/lb (2.5%) 85-115.
Tiamulin hydrogen fumarate 90-115 10 g/lb 90-115/70-130.
Tilmicosin 90-110 37.9 g/lb (8.35%) Swine Type B/C feed: 85-115. Cattle Type B feed: 85-115. Cattle Type C feed: 80-110.
Zilpaterol 90-110 680 g/t (0.075%) 80-110/75-115.
1 Percent of labeled amount.
2 Values given represent ranges for either Type B or Type C medicated feeds. For those drugs that have two range limit, the first set is for a Type B medicated feed and the second set is for a Type C medicated feed. These values (ranges) have been assigned in order to provide for the possibility of dilution of a Type B medicated feed with lower assay limits to make a Type C medicated feed.
(e) When drugs from both categories are in combination, the Category II requirements will apply to the combination drug product.

Where this section sits in the code

Title 21—Food and Drugs
CHAPTER I—FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES
SUBCHAPTER E—ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS
PART 558—NEW ANIMAL DRUGS FOR USE IN ANIMAL FEEDS
Subpart A—General Provisions

(a) A feed manufacturing facility must possess a medicated feed mill license in order to manufacture a Type B or Type C medicated feed from a Category II, Type A medicated article.

(b) The manufacture of the following types of feed are exempt from the required license, unless otherwise specified:

(1) Type B or Type C medicated feed using Category I, Type A medicated articles or Category I, Type B or Type C medicated feeds; and

(2) Type B or Type C medicated feed using Category II, Type B or Type C medicated feeds.

(c) The use of Type B and Type C medicated feeds shall also conform to the conditions of use provided for in subpart B of this part.

(d) This paragraph identifies each drug by category, the maximum level of drug in Type B medicated feeds, and the assay limits for the drug in Type A medicated articles and Type B and Type C medicated feeds, as follows:

Category I

Drug Assay limits percent 1 Type A Type B maximum (200x) Assay limits percent 1 Type B/C 2

Amprolium with Ethopabate 94-114 22.75 g/lb (5.0%) 80-120.

Avilamycin 90-110 7.3 g/lb (1.6%) 80-110.

Bacitracin methylenedisalicylate 85-115 25.0 g/lb (5.5%) 70-130.

Bacitracin zinc 84-115 5.0 g/lb (1.1%) 70-130.

Bambermycins 90-110 800 g/ton (0.09%) 80-120/70-130.

Chlortetracycline 85-115 40.0 g/lb (8.8%) 80-115/70-130.

Coumaphos 95-115 6.0 g/lb (1.3%) 80-120.

Decoquinate 90-105 2.72 g/lb (0.6%) 80-120.

Dichlorvos 100-115 33.0 g/lb (7.3%) 90-120/80-130.

Diclazuril 90-110 182 g/t (0.02%) 85-115/70-120.

Efrotomycin 94-113 1.45 g/lb (0.32%) 80-120.

Iodinated casein 85-115 20.0 g/lb (4.4%) 75-125.

Laidlomycin propionate potassium 90-110 1 g/lb (0.22%) 90-115/85-115.

Lasalocid 95-115 40.0 g/lb (8.8%) Type B (cattle and sheep): 80-120; Type C (all): 75-125.

Lincomycin 90-115 20.0 g/lb (4.4%) 80-130.

Lubabegron 87-107 908 g/ton 85-115/80-120.

Melengestrol acetate 90-110 10.0 g/ton (0.0011%) 70-120.

Monensin 85-115 40.0 g/lb (8.8%) Chickens, turkeys, and quail: 75-125; Cattle: 5-10 g/ton 80-120; Cattle: 10-30 g/ton 85-115; Goats: 20 g/ton 85-115; Liq. feed: 80-120.

Narasin 90-110 9.0 g/lb (1.98%) 85-115/75-125.

Nicarbazin (granular) 90-110 9.0 g/lb (1.98%) 85-115/75-125.

Narasin 90-110 9.0 g/lb (1.98%) 85-115/75-125.

Nystatin 85-125 5.0 g/lb (1.1%) 75-125.

Oxytetracycline 90-120 20.0 g/lb (4.4%) 75-125/65-135.

Poloxalene 90-110 54.48 g/lb (12.0%) Liq. feed: 85-115.

Ractopamine 85-105 2.46 g/lb (0.54%) 80-110/75-125.

Salinomycin 90-110 6.0 g/lb (1.3%) 80-120.

Semduramicin (as semduramicin sodium) 90-110 2.27 g/lb (0.50%) 80-110

Semduramicin (as semduramicin sodium biomass) 90-110 2.27 g/lb (0.50%) 80-120

Tylosin 80-120 10.0 g/lb (2.2%) 75-125.

Tylvalosin 90-110 3.86 g/lb 85-115.

Virginiamycin 85-115 10.0 g/lb (2.2%) 70-130.

Zoalene 92-104 11.35 g/lb (2.5%) 85-115.

1 Percent of labeled amount.

2 Values given represent ranges for either Type B or Type C medicated feeds. For those drugs that have two range limits, the first set is for a Type B medicated feed and the second set is for a Type C medicated feed. These values (ranges) have been assigned in order to provide for the possibility of dilution of a Type B medicated feed with lower assay limits to make Type C medicated feed.

Category II

Drug Assay limits percent 1 Type A Type B maximum (100x) Assay limits percent 1 Type B/C 2

Amprolium 94-114 11.35 g/lb (2.5%) 80-120.

Apramycin 88-112 7.5 g/lb (1.65%) 80-120.

Carbadox 90-110 2.5 g/lb (0.55%) 75-125.

Clopidol 94-106 11.4 g/lb (2.5%) 90-115/80-120.

Erythromycin 85-115 4.625 g/lb (1.02%) 75-125.

Famphur 100-110 5.5 g/lb (1.21%) 90-115/80-120.

Fenbendazole 93-113 8.87 g/lb (1.96%) 75-125.

Florfenicol 90-110 9.1 g/lb (2.0%) Swine feed: 85-115 Catfish feed: 80-110. Salmonid feed: 80-110.

Halofuginone hydrobromide 90-115 272.0 g/ton (.03%) 75-125.

Hygromycin B 90-110 1,200 g/ton (0.13%) 75-125.

Ivermectin 95-105 1,180 g/ton (0.13%) 80-110.

Maduramicin ammonium 90-110 545 g/ton (.06%) 80-120.

Morantel tartrate 90-110 66.0 g/lb (14.52%) 85-115.

Neomycin 80-120 20 g/lb (4.4%) 70-125.

Oxytetracycline 80-120 20 g/lb (4.4%) 65-135.

Neomycin sulfate 80-120 100 g/lb (22.0%) 70-125.

Nicarbazin (granular) 90-110 5.675 g/lb (1.25%) 85-115/75-125.

Nicarbazin (powder) 96-104 9.08 g/lb (2.00%) 85-115/80-120.

Novobiocin 85-115 17.5 g/lb (3.85%) 80-120.

Pyrantel tartrate 90-110 36 g/lb (7.9%) 75-125.

Robenidine 95-115 1.5 g/lb (0.33%) 80-120.

Sulfadimethoxine 90-110 Poultry: 5.675 g/lb Fish: 85.1 g/lb 80-115/75-125.

Ormetoprim 90-110 Poultry: 3.405 g/lb Fish: 17.0 g/lb 80-115.

Sulfamerazine 85-115 18.6 g/lb (4.0%) 85-115.

Sulfamethazine 85-115 10.0 g/lb (2.2%) 80-120.

Chlortetracycline 85-115 10.0 g/lb (2.2%) 85-125/70-130.

Sulfamethazine 85-115 10.0 g/lb (2.2%) 80-120.

Tylosin 80-120 10.0 g/lb (2.2%) 75-125.

Sulfaquinoxaline 98-106 11.2 g/lb (2.5%) 85-115.

Tiamulin hydrogen fumarate 90-115 10 g/lb 90-115/70-130.

Tilmicosin 90-110 37.9 g/lb (8.35%) Swine Type B/C feed: 85-115. Cattle Type B feed: 85-115. Cattle Type C feed: 80-110.

Zilpaterol 90-110 680 g/t (0.075%) 80-110/75-115.

1 Percent of labeled amount.

2 Values given represent ranges for either Type B or Type C medicated feeds. For those drugs that have two range limit, the first set is for a Type B medicated feed and the second set is for a Type C medicated feed. These values (ranges) have been assigned in order to provide for the possibility of dilution of a Type B medicated feed with lower assay limits to make a Type C medicated feed.

(e) When drugs from both categories are in combination, the Category II requirements will apply to the combination drug product.

Collected 2026-08-27T02:24:47Z. Source file · JSON

Browse this collection