Iowa Code § 163.36: Identification required.

1. All boars, sows and stags received for sale or shipment to slaughter by a livestock dealer, livestock market operator or stockyard operator shall be identified at the first point of concentration by such dealer or operator by application of a slap tattoo or other identification approved by the department.

2. All boars, sows and stags consigned directly from a farm to a slaughtering establishment shall be identified at the first point of concentration by the consignee.