The disclosure relates to an agent when used to prevent or treat a perinatal disease in an adult female cow, the agent comprising at least one of cashew nut shell liquid, which may be a cashew nut shell itself, heat-treated cashew nut shell liquid, which may be a heat-treated cashew nut shell itself, anacardic acid, cardanol, and cardol. The perinatal disease is selected from hypocalcemia, fatty liver, ketosis, abomasal displacement and combinations thereof. The disclosure also relates to a feed for the same purpose and a method of preventing or treating perinataa disease in a ruminant using this agent.