Mo. Rev. Stat. § 276.010

Any stockyards in the state of Missouri, maintained for the purpose of receiving cattle, hogs or sheep to be bought, sold or exchanged, is hereby declared to be a public market, and any person, firm or corporation maintaining such public market, or any person, firm or corporation buying, selling or exchanging any cattle, hogs or sheep at such public market, shall, in maintaining, or in buying, selling or exchanging at such public market, be subject to the provisions of sections 276.010 to 276.080.