The Commissioner of Agriculture may make regulations to establish and maintain brucellosis class free areas in conformity with the uniform methods and rules established by the Animal and Plant Health Inspection Service, Veterinary Services, of the United States Department of Agriculture. Such regulations shall establish standards and procedures for the quarantine, testing, vaccination and identification of cattle, control of shipment of cattle into such areas, branding and disposal of reactors and disinfection of premises, for the control and eradication of brucellosis. The Brucella ring test shall be an official part of the state-federal cooperative brucellosis program, and the commissioner may exercise discretion in establishing intervals between herd tests with the Brucella ring test, based on the best interests of the eradication program. Brucella ring test antigens used in conducting such tests and test procedures employed shall be only those jointly approved by the cooperating agencies, the Department of Agriculture and the Animal and Plant Health Inspection Service, Veterinary Services, of the United States Department of Agriculture. Certified status of herds may be retained by annual retesting, request for which shall be made in writing to the commissioner, the expense of such tests to be borne by the state. Infected herds shall be quarantined. In such case the entire herd shall be confined to the premises and movement of all cattle shall be prohibited until the herd has passed at least three negative herd retests as required by the uniform methods and rules established by the Animal and Plant Health Inspection Service, Veterinary Services, of the United States Department of Agriculture following removal of reactors; except that cattle consigned for immediate slaughter under permit may be moved from the quarantined premises to the point where slaughter is to be effected if accompanied by such permit. Any person purchasing such animals shall exercise all reasonable diligence in determining that a valid permit is received by him to move such animals from the premises directly to a point where immediate slaughter will be conducted and that such permit shall accompany such animals to slaughter.