Medicated Feed

Medicated Feed Mill Inspections

If a feed manufacturer adds antibiotics or other drugs to any of the feeds it produces, whether for the treatment or prevention of disease, or as an aid in promoting animal growth or feed efficiency, the Michigan Department of Agriculture and Rural Development (MDARD) periodically conducts a special type of inspection at their facility. The purpose of this inspection is to determine if the firm is in compliance with federal current good manufacturing practice regulations (CGMPs) for manufacturers of medicated feeds. These inspections are usually conducted under the authority of the Michigan Commercial Feed Law.

Certain types of medicated feeds can only be manufactured by a firm that holds a federal Feed Mill License (FML). See the section, "Classification of Drugs Used in Animal Feeds," below, for details. The CGMP requirements for these firms are more stringent than those applied to firms that do not use these types of drugs. MDARD usually inspects FML-licensed firms annually to determine compliance with these stricter requirements.

Federal laws require FML-licensed firms to undergo routine inspection by the U.S. Food and Drug Administration every 2 years, and more frequently if critical deviations from the requirements have been observed. MDARD usually conducts these biennial inspections for the FDA. They are performed under contract, using FDA-trained and commissioned inspectors. When MDARD conducts an inspection under the authority of the FDA, federal credentials and a federal Notice of Inspection are presented to management at the start of the inspection.

MDARD has prepared a guidance for medicated feed manufacturers who are not required to have a Federal Feed Mill License.  This guidance provides self-inspection tips to help management comply with the regulations and avoid costly mistakes that can lead to product adulteration and increased risks to animal and/or public health.  The Food and Drug Administration also provides its own useful industry guidance for these regulations.

Classification of Drugs Used in Animal Feeds

Under federal rules, all animal drugs approved for use in animal feeds are classified as either Category I or Category II drugs.

  • Category I - those drugs for which no withdrawal period is required at the lowest continuous feeding level for any approved animal. A federal Feed Mill License (FML) is not required by a company that uses Category I drugs.
  • Category II - those drugs that either require a withdrawal period at the lowest continuous feeding level in at least one animal for which the drug is approved, or are regulated on a "zero residue" basis because of a carcinogenic concern. A federal FML is required to manufacture medicated feeds using Type A Category II drugs, or any legal combination of Category II drugs and Category I drugs.

Three medicated product types, Type A articles and Type B or C medicated feeds, are defined as follows:

  • Type A- a product that consists of one or more new animal drugs of standardized potency, intended solely for use in manufacturing another Type A article or in the manufacturing of either a Type B or a Type C medicated feed.
  • Type B- a medicated feed that contains a Type A medicated article or another Type B medicated feed plus a substantial quantity of nutrients (not less than 25% of the total weight) and is intended solely for use in the manufacturing of another Type B medicated feed or a Type C medicated feed. Before being fed to animals, it has to be substantially diluted with one or more nutrients to produce a Type C medicated feed. The maximum permitted concentration of a drug in a Type B medicated feed is 100 times the highest continuous use level for Category II drugs. The "highest continuous use level" is the highest dosage at which a drug is approved for continuous use (14 days or more) or, if not approved for continuous use, the highest level used for disease prevention or control.
  • Type C- a medicated feed containing a new animal drug and is intended to be offered as a complete feed for the animal, or may be top-dressed or offered free-choice in conjunction with other animal feed to supplement the animal's total daily ration. A Type C medicated feed is produced by substantially diluting a Type A medicated article, a Type B or another Type C medicated feed.

Monensin Use in Dairy Cows

The Food and Drug Administration approved the drug monensin for increased milk production efficiency in dairy cows in total mixed ration systems in October 2004, and in component feeding systems (including top dress) in December 2005. For answers to some of the most Frequently Asked Questions concerning these uses, click on this link.