PROBLEM TO BE SOLVED: To provide a muscle potentiator for husbandry animals and a muscle potentiating method.SOLUTION: A muscle potentiator contains 20 wt.% or more of &bgr；-1,4-mannobiose which can be obtained by action of mannan catabolic enzyme on a natural product containing mannan such as palm kernel meal, copra meal, coffee bean lees, sesame lees, guar gum and locust bean gum or on mannan extracted from such a natural product. In a method, &bgr；-1,4- mannobiose is digested so as to potentiate a muscle of a husbandry animal and the like.
