WARNING LETTER

Ridley USA Inc. MARCS-CMS 720800 — April 03, 2026

Delivery Method:: VIA EMAIL NO HARD COPY TO FOLLOW
Product:: Animal & Veterinary

Recipient:: Recipient Name

Darrell K. Meyer; Recipient Title

Plant Manager; Ridley USA Inc.; 2420 Old Highway 218 South
Iowa City, IA 52246-5818
United States; darrell.meyer@alltech.com

Issuing Office:: Center for Veterinary Medicine; United States

WARNING LETTER
CMS # 720800

April 3, 2026

Dear Mr. Meyer,

The U.S. Food and Drug Administration (FDA) conducted an inspection of your licensed medicated feed manufacturing facility located at 2420 Old Highway 218 South, Iowa City, Iowa, from September 2 through September 17, 2025. The inspection was conducted in response to a Reportable Food Registry (RFR) report you filed on August 28, 2025, after you discovered you manufactured a medicated feed for cattle that contained an undeclared new animal drug, monensin, instead of the intended Veterinary Feed Directive (VFD) drug, (b)(4). The drug mix-up resulted in at least 16 cattle deaths. In response, you initiated a voluntary Class I recall on August 26, 2025, for (b)(4), lot (b)(4). We received and evaluated your written responses to the amended Form FDA 483, Inspectional Observations (FDA 483), dated October 16, and November 6, 2025. In these responses, you stated additional documentation would be provided when your corrections are complete. As of the date of this letter, you have provided limited documentation, and therefore we are unable to fully assess your voluntary corrections.

During the inspection, the FDA investigator found evidence of significant violations of the Current Good Manufacturing Practice, Hazard Analysis, and Risk-Based Preventive Controls for Food for Animals requirements found in Title 21, Code of Federal Regulations, Part 507 (21 CFR Part 507) which causes your products to be adulterated because they were prepared, packed, or held under insanitary conditions whereby they may have become contaminated with filth, or whereby they may have been rendered injurious to health.¹ In addition, failure of the owner, operator, or agent in charge of a covered facility to comply with the preventive controls provisions of 21 CFR Part 507 is prohibited.²

Additionally, the investigator found evidence of significant violations of FDA’s Current Good Manufacturing Practice for Medicated Feeds requirements, 21 CFR Part 225. Failure of your medicated feed mill to comply with these requirements causes your medicated feed to be adulterated.³

The inspection revealed evidence you manufactured and distributed (b)(4) that contained unintended monensin. This Type B medicated cattle feed containing a Type A medicated article of monensin is unsafe because the new animal drug it contains was not used in conformance with the drug approval.⁴ As a result, the medicated feed is adulterated.⁵

The doing of any act to a food or drug after shipment of the food or drug and/or its components in interstate commerce and while the food or drug is held for sale (whether or not the first sale) that results in the food or drug being adulterated or misbranded is prohibited.⁶

You may find the Federal Food, Drug, and Cosmetic Act (FD&C Act) and its implementing regulations through links on FDA’s website at www.fda.gov.

At the close of the inspection, you were issued an amended FDA 483. As stated above, we received your written responses, dated October 16, and November 6, 2025, to the amended FDA 483. We address your proposed corrective actions below in relation to each of the noted violations.

Hazard Analysis and Risk-Based Preventive Controls Requirements

Your animal food facility is subject to the hazard analysis and risk-based preventive controls requirements found in 21 CFR Part 507, Subparts A, C, D, E, and F. During the inspection of your facility, the FDA investigator observed evidence of significant violations of these requirements, which included the following:

1. You failed to sufficiently assess the probability that a hazard will occur in the absence of preventive controls, as required by 21 CFR 507.33(c)(1).

Specifically, your hazard analysis identified “incorrect ingredient added due to operator error” at the “(b)(4)” step as a known or reasonably foreseeable hazard. In your hazard analysis you determined that a preventive control was not required due to your prerequisite programs. Your hazard analysis states that (b)(4).” On August 12, 2025, an employee added (b)(4) bags of (b)(4) (monensin) instead of the formulated (b)(4) bags of (b)(4) while manufacturing (b)(4), lot (b)(4). This lot of medicated feed was distributed and fed to cattle. On August 28, 2025, you filed an RFR report that identified (b)(4) contained undeclared monensin and no (b)(4). You attributed the use of this product to cattle deaths in your RFR report. Your prerequisite programs did not reduce the probability of drug contamination occurring in the absence of a preventive control due to incorrect medicated articles being added in your medicated feeds at the “(b)(4)” step.

Evaluation of your response:
In your supplemental written response dated November 6, 2025, you provided an updated Corrective Action Report, CAR No. 902, and Animal Food Safety Plan Development and Maintenance standard operating procedure (SOP), 500-SOP-RID. The Corrective Action Record documents review of your food safety plan, in accordance with your SOP, which includes “(b)(4)” as justification you reduced the probability of the “incorrect ingredient added due to operator error” hazard from occurring. However, you did not present an updated hazard analysis or sufficient records to demonstrate implementation of your prerequisite programs will reduce the probability of occurrence of the hazard. Therefore, we are unable to fully evaluate your corrections at this time.

Current Good Manufacturing Practice (CGMP) for Medicated Feed Requirements

Your animal food facility is subject to the medicated feed CGMP regulations for licensed medicated animal feed manufacturers found in 21 CFR 225.10-225.115. During the inspection of your facility, the FDA investigator noted evidence of significant violations of these requirements, which included the following:

2. You failed to properly identify, handle, and control drugs in the mixing areas to maintain their integrity and identity, as required by 21 CFR 225.42(b)(4).

Specifically, you manufactured (b)(4) pounds of (b)(4), lot (b)(4) that contained a Type A medicated article, monensin, instead of the VFD drug, (b)(4), required by the formula. Upon staging ingredients for the production batch, an employee staged (b)(4) of (b)(4) (monensin) instead of the (b)(4) required by the formula. A (b)(4) operator added the staged monensin without reviewing the drug labeling and comparing the drug labeling to your Lot Usage Records or batch production records to ensure proper formulation.

Furthermore, on August 12, 2025, you did not document the actual use of medicated articles while manufacturing (b)(4) of (b)(4), lot (b)(4), as required by 21 CFR 225.42(b)(6). The (b)(4) operator completed the Lot Usage Records incorrectly to indicate (b)(4), lot (b)(4), was used to manufacture the medicated feed when (b)(4), lot (b)(4), was used instead. Therefore, your (b)(4) inventory Lot Usage Records were not maintained adequately to include the drug used, quantity of drug used, and production batch of medicated feed in which the drug was used.

Evaluation of your response
In your supplemental written response dated November 6, 2025, you provided the updated 030-SOP-RID version 2, “Drug and Critical Premix Handling,” with training records documenting review and assessment of the updated procedure. Your updated procedure permits (b)(4). You also provided example Lot Usage Records - (b)(4), and (b)(4) in your response dated November 6, 2025, to demonstrate implementation of the procedure.

Additionally, in your written response dated October 16, 2025, you explained your expanded use of (b)(4) area. You also provided examples documenting the barcode systems with photographs identified as the “(b)(4)” for manufacturing (b)(4), “(b)(4) (Monensin)” for a bag of (b)(4) with barcode, and “(b)(4)” with barcode for an apparent bag of (b)(4).

However, you did not provide supporting records in your written responses, such as corresponding batch production records and Lot Usage Records, to demonstrate if products were correctly formulated. Therefore, we are unable to fully evaluate your corrections.

3. You did not perform a daily comparison between the actual and theoretical amounts of the drugs used, as required by 21 CFR 225.42(b)(7).

Specifically, you did not reconcile your actual and theoretical drug use in your Lot Usage Record between August 12 and August 26, 2025. For example:

The Lot Usage Record for (b)(4), lot (b)(4), documented the drug was used in (b)(4) on August 12, 2025. However, based on the RFR you filed on August 28, 2025, you determined the (b)(4), lot (b)(4), was not added to this feed. You did not conduct a (b)(4) comparison of the actual amount of (b)(4), lot (b)(4), used with the theoretical usage and only performed a theoretical use reconciliation at the end of the production day on August 12, 2025. An actual inventory of (b)(4), lot (b)(4), was not conducted until August 26, 2025, which revealed your inventory was not accurate.
You conducted only a theoretical use reconciliation for VFD feeds containing (b)(4), lot (b)(4), on August 22, 2025.
The Lot Usage Record for (b)(4), lot (b)(4), did not document that you conducted any reconciliations of this lot of (b)(4) on August 12 and August 13, 2025, even though the drug was used in the manufacturing of medicated feed products.
You manufactured medicated feed products containing (b)(4), lot (b)(4), without any reconciliations of theoretical and actual amounts between August 19 and August 21, 2025.

You use Type A medicated articles to manufacture Type B medicated feeds. The (b)(4) comparison between theoretical and actual drug use requirement in 21 CFR 225.42(b)(7) assists in ensuring proper drug use. If you had been following these requirements and comparing the theoretical inventory against the actual inventory, you may have found the quantity discrepancy earlier and identified that the incorrect ingredient had been added. This would have enabled you to hold or recall the (b)(4) medicated feed more promptly.

Evaluation of your response:
In your written response dated October 16, 2025, you stated that (b)(4) will be performed for (b)(4). We note your updated 030-SOP-RID, “Drug and Critical Premix Handling,” does not describe steps for corporate verification. You also provided example Lot Usage Records - one each for (b)(4)%, and (b)(4) in your written response dated November 6, 2025. The Lot Usage Records showed (b)(4) reconciliation was documented by employees. However, you provided only one occurrence of corporate review for each drug. We are unable to determine the consistent implementation of your corrections at this time.

Conclusion

This letter is not intended to be an all-inclusive statement of violations that may exist at your facility or in connection with your products. You are responsible for investigating and determining the causes of any violations and for preventing their recurrence or the occurrence of other violations. It is your responsibility to ensure that you comply with all requirements of federal law and FDA regulations.

This letter notifies you of our concerns and provides you an opportunity to address them. You should take prompt action to correct any violations. Failure to adequately address this matter may lead to regulatory action, or where appropriate, legal action.

FDA has the following comments regarding the inspection of your facility.

1. (b)(4) is regulated as a VFD drug and (b)(4) is intended to be a VFD feed.⁷ As a distributor (who manufactures VFD feed), you are responsible for the judicious use of the drug and medicated feed to ensure all finished products conform to the written VFD within the veterinarian-client-patient relationship.

2. Your hazard analysis identified (b)(4) toxicity as a hazard requiring a process preventive control. You implemented 015-USFO-SOP, “Product Scheduling Requirements – Non-Medication,” which requires (b)(4). You told the FDA investigator that you intended to validate the preventive control and stated in your October 16 and November 6, 2025, written responses that process validation will be provided to FDA once it is complete. We have not received your validation study for this facility as of the date of this letter. We remind you of the requirements for validation of process preventive controls found within 21 CFR Part 507.⁸

For more information about FDA’s current thinking on the requirements of 21 CFR Parts 507, 225, and 558, see:
• For Industry | FDA (https://www.fda.gov/animal-veterinary/resources-you/industry)

Within fifteen (15) working days of receipt of this letter, please notify this office in writing of the specific steps that you have taken to correct any violations. Include an explanation of each step being taken to prevent the recurrence of violations, as well as copies of related documentation. If you cannot complete corrective actions within fifteen (15) working days, state the reason for the delay and the time within which you will complete the correction. If you believe that your products are not in violation of the FD&C Act and FDA regulations, include your reasoning and any supporting information for our consideration within fifteen (15) working days.

The FDA, Center for Veterinary Medicine, Office of Surveillance and Compliance is encouraging electronic submission of any response you choose to submit to this letter. We encourage you to submit files up to 100 megabytes in a single email, and to divide files greater than 100 megabytes so they may be submitted as smaller files in separate emails. If you submit electronic correspondence, please ensure that your facility’s name, the CMS number at the top of this letter, and the inspection location are included in your correspondence. We intend to issue an electronic acknowledgement upon receipt of your email.

Please direct your electronic correspondence to Compliance Officer Andrew Howard at Andrew.Howard@fda.hhs.gov. If you have questions regarding this letter, please contact Compliance Officer Andrew Howard by telephone at (410) 779-5125, or by the email above.

/S/

Isaac K. Carney
Director of Food Compliance, Office of Surveillance and Compliance
Center for Veterinary Medicine
U.S. Food and Drug Administration

Cc:
Wyatt L. Garriott, Quality Food Safety Regional Manager
Ridley USA Inc.
wyatt.garriott@alltech.com

Alan Keller, Feed & Fertilizer Chief
Iowa Department of Agriculture & Land Stewardship
1305 East Walnut Street
Des Moines, Iowa 50319
alan.keller@iowaagriculture.gov
______________

1 See Section 402(a)(4) of the Federal Food, Drug, and Cosmetic Act (FD&C Act) [21 U.S.C. § 342(a)(4)] and 21 CFR 507.1(a)(1)(ii).

2 See Section 301(uu) of the FD&C Act [21 U.S.C. § 342(uu)].

3 See Section 501(a)(2)(B) of the Federal Food, Drug, and Cosmetic Act (FD&C Act) [21 U.S.C. § 351(a)(2)(B] and 21 CFR 225.1(b)(1).

4 See Section 512(a)(2)(A) of the FD&C Act [21 U.S.C. § 360b(a)(2)(A)].

5 See Section 501(a)(6) of the FD&C Act [21 U.S.C. § 351(a)(6)].

6 See Section 301(k) of the FD&C Act [21 U.S.C. § 331(k)].

7 See 21 CFR 558.6 and 21 CFR 558.128.

8 See 21 CFR Part 507.47.