---
title: "4.2 A unique identification system for animals is essential"
canonical: "https://wiki.groenkennisnet.nl/space/TAB/283377703/4.2%20A%20unique%20identification%20system%20for%20animals%20is%20essential"
format: markdown
---
A pedigree only has a predictive value when a unique and reliable identification system is used in a breeding program. At birth each animal should get a unique identification number and its parents should be known without any doubt.
In many breeding programs the pedigree is checked with genetic markers (see example in this chapter). A second requirement is that measurements (phenotypes) on animals (e.g. height of withers, milk production etc.) are combined with the correct identification number. Mistakes in a pedigree and mistakes in the attachments of data to animals in the recording system are disastrous for the predictive value of pedigrees.
The parents of an animal have an additive genetic relationship of 0.5 and the grandparents of 0.25. The shorter the distance between an ancestor and the animal itself, the more valuable are traits of the ancestor in predicting traits of the animal at stake. In the past, herd books started with pedigree registration and pedigree checking to guarantee the buyers of breeding material that the traits of an animal could be derived from the traits of its ancestors.
In addition to the additive genetic relationship with the ancestors more additive genetic relationships between animals can be used in animal breeding. An animal may have full sibs with recorded traits: the additive genetic relationship among full sibs is 0.5. On average, they share 50 per cent of their DNA supplied by their parents. Half sibs share on average 0.25 of their DNA (they have the same dam or the same sire) and this additive genetic relationship of 0.25 with its half sibs might be also valuable for predicting the traits of a (young) half sib. Full or half sibs do have an additive genetic relationship of 0.5 with their common parent and are often used to establish the breeding value of one of these parents. Even offspring in later generations, granddaughters and grandsons with and additive relationship of 0.25, are used to establish the breeding values of their grandparents. In conclusion: it is worthwhile and very informative to extend the pedigree of an animal in a scheme where, in addition to the ancestors, also full and half sibs and offspring are situated. This gives a full picture from all the relatives that might provide information for the estimation of the breeding value of the animal at stake.