Wis. Stat. § 126.49: Milk contractors; records and reports.

(1) Required records. A milk contractor shall keep accurate records and accounts of milk receipts, payments for milk received, and amounts owed to milk producers. The department may, by rule, specify records that a milk contractor must keep.

(2) Required reports. The department may, by rule, require a milk contractor to file with the department periodic reports of information needed for the administration of this chapter.

(3) Records retention; inspection. A milk contractor shall retain records required under sub. (1) for at least 6 years after the records are created. A milk contractor shall make the records available to the department for inspection and copying upon request.