The invention concerns a method for determining a characteristic describing the intestinal microbiota for an animal and/or a human being, in which method an animal and/or a human being is fed with a fodder/food; the number of two or more microorganisms in the intestine is determined; and the characteristic describing the intestinal microbiota is calculated as a ratio of the number of microorganisms. The invention also concerns methods for monitoring, development and promoting the intestinal microbiota, the well-being of an animal and/or a human-being, the intestinal health, the nutrition of an animal and/or a human being, the productivity and/or fodder utilization ratio of an animal, as well as the use of the characteristic and the use of the method for developing a fodder, a nutriment, a fodder and nutritional additive, a preparation and a pharmaceutical supporting the well-being, and a nutritional program.