Wis. Admin. Code Department of Agriculture, Trade and Consumer Protection ATCP 60.19
If a drug residue test is performed on a bulk load of milk collected from several dairy farms, the test must be completed within 72 hours after the milk hauler collects milk from the first farm. Confirmation of positive drug residue screening tests, if required under s. ATCP 60.22(1) (b) 3., must be completed within the same 72-hour period.