Colo. Rev. Stat. § 35-43-102
Animals which are usually branded may be branded on either side with the owner's brand. No evidence of ownership by brands shall be permitted in any court in this state unless the brands are recorded as provided in section 35-43-105. Each drove of cattle or sheep which may be driven into or through any county of this state shall be plainly branded or marked with one uniform brand or mark. The cattle shall be so branded with the distinguishing ranch or road brand of the owner as to show distinctly in such places as the owner may adopt. Sheep shall be marked distinctly with such mark or device as may be sufficient to distinguish the same readily, should they become intermixed with other flocks of sheep owned in the state. Any such owner or person in charge of such drove being driven into or through the state who fails to comply with the provisions of this article shall be fined not less than fifty dollars nor more than three hundred dollars.
C.R.S. § 35-43-102