C.R.S. § 35-56-105

All auctioneers, commission merchants, and other persons who keep a place or stand for publicly vending horses, mules, and horned cattle, or any of them, in a book kept for that purpose, shall keep a true and faithful record of all the animals purchased or sold by them, or under their control, which record shall contain a brief description of the animal, including its age, value, marks, brands, and date of purchase and sale, and the name and residence of the seller and purchaser in each case.