14.1.3 Importance of variation between breeds (2024)

The key question in these developments is: what proportion of the genetic variation lies between breeds? If this parameter is typically small then it may be expected that the variation within breeds should be utilized in selection programs to overcome weaknesses in traits when they arise. If the between breed variation is large then it may be realistic to consider crossbreeding. This is an important reason to be alert on the chance of extinction of breeds.

Example: At the moment a lot of breeders of Holstein Friesian cattle start crossbreeding with Swiss, German, French and Scandinavian dual purpose breeds to improve the health and fitness traits of their cattle. They experience a deterioration of these traits and do not expect that they can stop this process when they continue pure breeding with Holstein Friesians. The French and Scandinavian breeds do have better health and fitness traits and in stable (rotation) crossbreeding systems these traits get an additional boost from heterosis.

When the required livestock production has to adapt quickly to new challenges, then the variation between breeds might be of great help. Therefore conservation of breeds with a diversity of traits is a rational and important strategic response to the uncertainties in production circumstances and market developments today.

Broadly it appears that variation between breeds accounts for approximately half of the total genetic variation within a species. In formula form:

Recently, genomic research gave a lot of evidence that differences in genetic diversity between breeds exists within species. Several studies indicate that rare breeds or non-mainstream breeds have some unique genetic diversity not present or no longer present in the main stream breeds.