Participation in this program of grading and inspection of livestock shall be completely voluntary on the part of all persons so affected by the provisions of this article. Any person, in his discretion, may elect not to have his livestock graded and inspected as provided herein and nothing herein shall give the Department authority to compel any person to have his livestock so graded and inspected. A person may elect to include any or all classes of cattle and swine, or either of them, under the provisions of this article.