Selecting the nutrition for an animal or animal group comprises performing a diagnostic test to obtain first data. A data base that comprises first data relating a genomic analysis of a bodily fluid or tissue sample from an animal to a physiological condition and optionally the genotype of the animal is accessed. A data base that comprises second data relating to effects of nutrition on genomic analysis is accessed. The first and second data are processed with input data defining the physiological condition and optionally the genotype of the animal or animal group to derive the nutrition for an animal or animal group.