Any herd which the Secretary has reason to believe is infected with or has been exposed to pseudorabies shall be quarantined and no livestock may be moved from or to a quarantined herd without written permission of the Secretary. The quarantine will be lifted when tests and examinations, as the Secretary may require, indicate that the herd is not infected. If the Secretary permits swine to be moved from a quarantined herd to a quarantined feedlot, those swine shall be identified individually by a method approved by the Secretary.