A means for determining the nutritional requirements of an industrial animal is provided. The objects can be achieved by identifying an mRNA the expression of which changes before and/or after a change in physiological condition in an industrial animal by comparing mRNA expression data obtained before and after the change in physiological condition, identifying a metabolic pathway of which the expression changes before and after the change in the physiological condition on the basis of the identified mRNA, and identifying a metabolite that is highly required by the industrial animal before or after the change in physiological condition on the basis of the identified metabolic pathway.
