When the director of the State Livestock-Poultry Health Commission shall deem it advisable to test all cattle in any specified county within the State, in accordance with the provisions of this article or upon receipt of a petition containing at least seventy-five per cent or more of the livestock owners holding ninety-five per cent or more of the cattle in the county, the test of all cattle in such county shall become compulsory and the cattle owners or persons in charge, upon notification from the livestock and poultry health department or one of the department’s inspectors, shall assemble or have assembled such animals at the times and places designated by an inspector of the livestock and poultry health department or the Animal Disease Eradication Division, United States Department of Agriculture, and give such assistance as may be necessary for the proper testing of the cattle. Inspectors engaged in the area testing of cattle for brucellosis shall have due authority to enter premises. No cattle, except for immediate slaughter, shall be brought into the county in which area work is being or has been conducted, unless accompanied by a proper test chart and health certificate issued by an approved accredited veterinarian, showing that the cattle have passed a proper test for brucellosis.