Mich. Comp. Laws § 287.122

Sec. 2. A dealer, broker, agent, or livestock trucker shall not engage in or carry on the business of buying, receiving, selling, exchanging, transporting, negotiating, or soliciting the sale, resale, exchange, transportation, or transfer of any animals within the state unless the person is licensed as provided in this act. A dealer, broker, agent, or livestock trucker is responsible for acts performed or contracts made by any person employed by the dealer, broker, agent, or livestock trucker in buying, receiving, selling, exchanging, transporting, negotiating, or soliciting the sale, resale, exchange, transportation, or transfer of livestock.