Colo. Rev. Stat. § 35-53-102
It is the duty of the brand inspector, who shall be notified as provided in section 35-53-105, or shall be selected by the board of stock inspection commissioners, to inspect the brands and earmarks of any cattle, horses, or mules to be transported by rail, truck, or other conveyance from any point within this state to any point within or without the state or to be driven out of the state, and to make a report to the state board of stock inspection commissioners, which he shall certify to as correct, of the result of such inspection at least once every thirty days or oftener if in the opinion of the board of stock inspection commissioners it is necessary to do so. It is also the duty of said brand inspector to furnish to any person, firm, association, or corporation, or any agents, servants, or employees thereof, having cattle, horses, or mules destined to be so shipped or driven, a certificate to the effect that he has duly inspected the brands and earmarks of any such cattle, horses, or mules enumerated and designated in the notice furnished such brand inspector.
C.R.S. § 35-53-102