Disclosed is the use of a cashew nut shell liquid, a heat-treated cashew nut shell liquid, anacardic acid, cardanol, or anacardic acid and cardanol in the manufacture of an agent to control a disease caused by a Clostridium bacterium. Also disclosed is the use of a cashew nut shell liquid and/or anacardic acid in the manufacture of an agent to promote weight gain in livestock other than ruminant. Also disclosed is a method of promoting weight gain in livestock other than ruminant, comprising feeding to the livestock other than ruminant a weight gain promoting agent or feed comprising cashew nut shell liquid and/or anacardic acid.
