21 CFR § 225.158 - Laboratory assays.

---
identifier: "/us/cfr/t21/s225.158"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "21 CFR § 225.158 - Laboratory assays."
title_number: 21
title_name: "Food and Drugs"
section_number: "225.158"
section_name: "Laboratory assays."
chapter_name: "FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES"
subchapter_number: "C"
subchapter_name: "DRUGS: GENERAL"
part_number: "225"
part_name: "CURRENT GOOD MANUFACTURING PRACTICE FOR MEDICATED FEEDS"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "21 U.S.C. 351, 352, 360b, 371, 374."
regulatory_source: "41 FR 52618, Nov. 30, 1976, unless otherwise noted."
cfr_part: "225"
---


# 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.