#### § 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](/on/2024-09-17/title-21/part-558/subpart-B).

(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 percent1 Type A | Type B maximum (200x) | Assay limits percent1 Type B/C2 |
| --- | --- | --- | --- |
| 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 percent1 Type A | Type B maximum (100x) | Assay limits percent1 Type B/C2 |
| --- | --- | --- | --- |
| 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.

[[51 FR 7392](https://www.federalregister.gov/citation/51-FR-7392), Mar. 3, 1986]

###### Editorial Note

#### Editorial Note:

For Federal Register citations affecting [§ 558.4](/on/2024-09-17/title-21/section-558.4), see the List of CFR Sections Affected, which appears in the Finding Aids section of the printed volume and at *[www.govinfo.gov](http://www.govinfo.gov).*