News
‘Blended’ estimated breeding values for increased model adequacy and predictivity
Researchers from Wageningen University & Research, Animal Breeding and Genomics (WUR-ABG) developed an integration procedure to integrate publishable sires’ international estimated breeding values and their associated reliabilities computed from pedigree-based or single-step international beef cattle evaluations into national evaluations to obtain ‘blended’ estimated breeding values.
The Italian pedigree-based national evaluation was used as a case study to validate the integration procedure. Their results were published in Genetics Selection Evolution.
International evaluations allow the comparison of animals’ estimated breeding values (EBV) across countries. This gives breeders the possibility to choose from a larger panel of elite bulls which better meet their selection objectives. In addition, considering relatives that are recorded in other countries, international evaluations increase the accuracy of bulls’ EBV and reduce the potential bias of national estimated breeding values (EBVNAT) for foreign bulls.
Integrating international estimated breeding values
International and national evaluations can use different sources of information to calculate EBV, which can lead to differences between the international EBV (EBVINT) and the EBVNAT. Consequently, choosing one of these EBV results in losing the information that is contained in the discarded EBV. To overcome this issue and use all the information that is available, an integration procedure can be applied to integrate the EBVINT and its associated measure of precision (e.g., its reliability) into the national evaluation, resulting in a ‘blended’ EBV.
“Our objectives were to define and validate a procedure that enables participating countries to integrate publishable sires’ EBVINT that are computed using either a pedigree-based or a single-step international evaluation, into a national evaluation to obtain a blended EBV,” says Renzo Bonifazi, researcher at Wageningen Livestock Research (WLR). “We used data for weaning weight of Limousin cattle from countries participating in Interbeef evaluations and the Italian national dataset as a case study to validate the adequacy of the integration procedure and the predictivity of the resulting blended EBV.”
Increased model adequacy and higher predictivity
The one-animal-at-a-time integration procedure proposed by the researchers resulted in blended EBV that are in close agreement with full EBVINT. “We showed that the proposed integration procedure increased the model adequacy for EBV of publishable sires, while giving a similar or higher predictivity for EBV in their domestic offspring,” says Renzo. “An additional advantage of this procedure is that it is computationally inexpensive and its application to existing national evaluations is straightforward since it does not require any specific software.”
About Interbeef
Interbeef is a working group of ICAR (International Committee for Animal Recording) that aims to develop and promote national and international evaluations of beef cattle. The project leading to these results has received funding from the Interbeef Working Group, the International Committee for Animal Recording – ICAR (Utrecht, the Netherlands), the International Bull Evaluation Service (Uppsala, Sweden), and the Irish Cattle Breeding Federation (ICBF, Link Road, Ballincollig, Co. Cork, Ireland).