After cattle, in quarantine on account of tuberculosis, under sections 267.010 to 267.460, have been duly appraised, said condemned cattle may, at the discretion of the state veterinarian, be shipped by their owner, under the supervision of the state veterinarian, by legal permit, to any slaughtering plant which is provided with state or federal meat inspection service, to be slaughtered and disposed of under the rules of meat inspection. Before shipment, however, each animal shall be branded, tagged or marked in such way as to make its identity certain. Such animals must be kept separate from all healthy animals and be sold as tuberculous^* cattle for immediate slaughter.