The present invention relates to a method for providing an animal population having an essentially identical metabolome comprising compiling an animal population being of essentially the same age, keeping said animal population for a time period sufficient for acclimatization under the following housing conditions: (i) constant temperature, (ii) constant humidity, (iii) physical separation of the animals of the animal population, (iv) feeding ad libitum, wherein the food to be fed is essentially free of chemical or microbial contaminance, (v) drinking libitum, wherein the drinking liquid is essentially free of chemical or microbial contaminance, (vi) constant illumination period, and providing the animal population after said time period. Further, the present invention relates to methods for the identification of a compound which effects the metabolome of an animal, or methods for the identification of a marker for such compounds. Moreover, the present invention encompasses methods for the identification of such compounds or markers thereof comprising metabolically analyzing a sample from at least one animal of an animal population.