An animal health commissioner shall be appointed by the secretary of agriculture and shall serve as the executive officer of the Kansas department of agriculture division of animal health. The person so appointed shall have been actively engaged in one of the major phases of the livestock industry for a period of not less than five years immediately preceding such person’s appointment. Before entering upon the duties of such office, such commissioner shall take and subscribe an oath of office to faithfully and honestly discharge the duties of such office to the best of such commissioner’s knowledge and ability, and shall file the same with the secretary of state. The animal health commissioner shall serve at the pleasure of the secretary of agriculture and the animal health board.