Newly born mammals depend on milk as their sole source of food, and when milk is not available, milk replacers can provide the nutrients and fluid necessary for the newborn to grow and thrive. Because no single feed ingredient can entirely replace milk, milk replacers are mixtures of feed ingredients that collectively mimic milk in taste and in nutritional properties. Some milk replacers are formulated to contain one or more animal drugs, which are specifically approved for such use by FDA and published in Title 21, Code of Federal Regulations, Part 558 (21 CFR 558).  The following drugs and uses are approved in medicated milk replacers for calves:

Adding a drug to a milk replacer makes the milk replacer a medicated feed. Medicated feeds (including medicated milk replacers) must be handled and used according to their approved labeling, because the extra-label use of a medicated feed is prohibited by the Animal Medicinal Drug Use Clarification Act of 1994 (AMDUCA) and 21 CFR 530.11. Such prohibited uses are also a potential public health risk. For example, when medicated milk replacers are not reconstituted with water (as directed), but instead, reconstituted with waste milk, which may contain drug residues from treated dairy cattle, the drug residues could pose harm to the calves and affect the safety of products derived from the treated calves.

Medicated milk replacers are manufactured like other dry medicated feeds. An approved Type A medicated article (the drug – e.g., lasalocid), or an approved Type B medicated feed (the drug mixed with the feed – e.g., lasalocid mixed with dry milk replacer), is diluted to an approved drug level, leading to a Type C medicated feed (i.e., medicated milk replacer). The resulting dry Type C medicated milk replacer may be stored until needed for feeding, at which point it is reconstituted with warm water and fed immediately. Typically, the dry medicated milk replacer may be stored for up to three months after the date of manufacture, unless labeled with a different expiration date. Expired medicated milk replacers should not be used because they may degrade in potency and safety after their expiration date.

Neither Type A medicated articles nor Type B medicated feeds should be reconstituted and fed to calves. Only Type C medicated feeds may be reconstituted and fed. 

A dry Type C medicated milk replacer may only be reconstituted with warm water. This means a medicated milk replacer fed to calves, or other young mammals, may not be reconstituted with milk, including waste milk. 

FDA is aware that some medicated milk replacers are manufactured and labeled for use with drug levels much higher than the approved levels, and for reconstituting with milk.  This is against the law and may pose a public health risk. It is a violation of the Federal Food, Drug and Cosmetic Act (FD&C Act) to label a Type C medicated feed with directions for use that are contrary to the drug’s approval. Both FDA and State feed officials have the authority to take enforcement action. FDA has created this page to educate stakeholders and clarify its expectations for compliance with regulations and conditions of drug approval. Should manufacturers, animal producers, or veterinarians have questions or concerns about medicated milk replacers, please contact MedicatedFeedsTeamMail@fda.hhs.gov for assistance.

If you have concerns that any animal food product may be the cause of an animal illness or death, or is defective in some way, you should report it to the manufacturer and the FDA.  You can report livestock food complaints electronically through the Safety Reporting Portal, or you can call your state’s FDA Consumer Complaint Coordinators.

Additional Resources

• The Center for Veterinary Medicine Safe Food Facts: Storing, Handling and Using Animal Milk Replacer Products
• Extra-Label Use of FDA Approved Drugs in Animals
• The Ins and Outs of Extra-Label Drug Use in Animals: A Resource for Veterinarians
• Medicated Feeds
• Veterinary Feed Directive (VFD)