"Genetic variation can be differentiated, within the boundaries of current scientific knowledge, in functional variation and neutral variation. Functional variation includes adaptive and selective genetic variation: these are genetic mutations that play a role in the adaptation of farm animals to their environment (adaptive variation), or that have been under directional selection for traits of agricultural interest in farm animals (selective variation). Neutral variation is genetic variation that has no apparent influence on adaptation or on the traits under selection, and that is inherited along with adaptive and selective variation through linkage, genetic drift and other mechanisms.The estimation of the extent of neutral and non-neutral genomic regions in the genome of farm animals would be of great theoretical interest, contributing to unravel the mysteries of the genome with respect to coding and non-coding sequences, to regulatory regions and to functional and (apparently) meaningless mutations. Estimates of neutral and non-neutral genetic variation would also have great potential for applications in biodiversity studies and in genetic improvement of farm animals. This information would help identify animal breeds or populations at risk of extinction and in quantifying such risk. It would also be helpful in designing conservation programmes of genetic resources of endangered animal breeds or populations. From the perspective of genetic improvement of livestock, the knowledge of the neutral and adaptive/selective components of genetic variation could be used in focusing selection on such variation. In this way, therefore, neutral variation would not passively follow selection for goal traits due to linkage and genetic drift, but could be preserved contributing to the limitation of the rate of inbreeding and the conservation of genetic variability (lower Bulmer effect). More efficient selection schemes for farm animals could thus be designed."