Immediately before commencing the test, if it is deemed advisable by the department, an appraisement may be made by the owner and an authorized agent or representative of the department of the market value of the animals as of the day of appraisement, and in case the animals so appraised react to such official tuberculin test the amount of the appraisement as agreed upon prior to tuberculin testing shall be official and shall be accepted by the owner and the department.