The Determining Size of a Reference Population
For selection a reference population is used as a basis. For this reference population there are animals that are both genotyped and phenotyped. Prediction of genetic values is much more effective and accurate when there are many animals in the reference populations. The statistical relationships are thus more reliable than in a limited database. Genomic assessment is effective if it is regularly fed with abundant, up-to-date information (size and renewal of the reference population).
The reliability of genomic indices is ensured by the very large size of French reference populations. Since 2009, and on the initiative of Allice, the main European selection companies for the Holstein breed have combined to share data concerning their reference populations.
In 2015 the size of the Holstein reference population reached 30,000 bulls which is, in fact, the largest reference population in the world. For the Montbéliarde breed the reference population reached 2650 bulls and 22,000 cows. For the Normande breed there are 2300 bulls and 11,800 cows. Finally for the Brune breed there a little over 6000 bulls.