The present invention relates to a bile salt adjuvant for animals for improving fat utilization efficiency in the bodies of the animals, and to animal feed comprising same. More particularly, the present invention relates to a bile salt adjuvant for animals comprising sodium stearoyl-2-lactylate. The adjuvant is used in animal feed to improve fat utilization efficiency in the bodies of livestock when ingested by said livestock, thereby reducing the amount of fat required to be used in animal feed and improving productivity.