Mo. Rev. Stat. § 430.170
The owner or keeper of any stallion, jack or bull may advertise the terms upon which he will let any such animal to service, by publication thereof in some newspaper of the county where such animal is kept, for sixty days during the season of each year, or by printed handbills conspicuously posted during such period, in four or more public places in said county, including the place where such animal is kept; and the publication or posting as aforesaid of the terms of such service shall impart notice thereof to the owner of any female animal served by such stallion, jack or bull during any such season; and in all actions and controversies in respect to the foal or other product of such service, the owner of such female animal so served shall be deemed to have accepted and assented to said terms, when so advertised and published or posted as provided herein.
§ 430.170, RSMo