[Code of Federal Regulations] [Title 21, Volume 4] [Revised as of April 1, 2001] From the U.S. Government Printing Office via GPO Access [CITE: 21CFR225.158] [Page 143] TITLE 21--FOOD AND DRUGS CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES PART 225--CURRENT GOOD MANUFACTURING PRACTICE FOR MEDICATED FEEDS--Table of Contents Subpart G--Product Quality Assurance Sec. 225.158 Laboratory assays. Where the results of laboratory assays of drug components, including assays by State feed control officials, indicate that the medicated feed is not in accord with the permissible limits specified in this chapter, investigation and corrective action shall be implemented immediately by the firm and such records shall be maintained on the premises for a period of 1 year.