After the sheriff has received notice of the taking up of any stray, and the ownership not having been established, the sheriff shall advertise such stray in the area where taken up, and shall cause the stray to be delivered to a public livestock market and shall sell or cause such stray to be sold at such a market, to the highest bidder for cash. Such advertisement shall be at least seven days before sale date, and such sale date shall be at least 21 days after the date the stray was reported to the sheriff.