Shares in US poultry processor Sanderson Farms fell earlier this week after it was discovered that the Food and Drug Administration (FDA) had sent a warning letter to the company regarding its feed mill operations in Gallman, Mississippi.

The letter, addressed to company CEO Joseph F. Sanderson, Jr., said that a January inspection of the company's medicated and non-medicated animal feed operations in Gallman had found "significant deviations" from the current good manufacturing practice for such types of feed.

The letter, dated 7 April, went on to say that the company had failed to investigate and take corrective action for significant discrepancies between actual drug usage and theoretical drug usage, and that although the company had begun to address the FDA's concerns, it had not provided any documents showing that corrections had been made or how the company would prevent such "deviations" reoccurring.

Sanderson Farms said that in January, immediately after receiving the FDA's inspection report, the company responded in writing to the FDA and took corrective and preventive action addressing the issues raised by the FDA.

"On 9 April, Sanderson provided FDA with the requested information and is confident that its Gallman operations comply with all applicable FDA requirements. The company expects no further action by FDA in connection with this matter," the company said.