Single Step

07
avril
2021

Neue Überschrift

Information on the switch to the single-step method for Fleckvieh and Brown Swiss

23-07-2014 Panorama See braunvieh-fleckvieh horizontal ©

Ten years after the introduction of the genomic selection in 2011, a new big step is done now with the proof run for the Fleckvieh and Brown Swiss breed: the estimation method is switched from the two-step to the single-step system. In the following, we would like to give you some background information.

What does single-step mean?

Until now, the breeding values of all male and female animals had been calculated after the two-step method: in the first step, conventional breeding values were calculated using performance and pedigree data. In the second step, those were combined with the information from genotyping to calculate genomic breeding values. Now with the single-step breeding value estimation, genomic enhanced breeding values are calculated for all animals in one step (“single step”) and there are no conventional and genomic direct breeding values anymore. Performance, pedigree and genotype data are considered simultaneously in one proof run.

Why was the system changed?

The reason is that, according to the latest state of science, the single-step method enables a still more precise prediction of the breeding values and thus leads to higher reliabilities.

A major advantage of single step is the inclusion of the genotypes of female animals. In the last years in Germany and Austria, more and more genotypes of female animals have become available which are now included in the breeding value estimation (250,000 for Fleckvieh, 50,000 for Brown Swiss). The training sample is not only formed by proven old sires now, but also by genotyped cows with performance data.

Another great advantage of the new method is that the calculation of breeding values for health traits with low heritabilities like early fertility disorders or cysts becomes possible with higher reliabilities.

For Brown Swiss, from now on the information of foreign daughters from MACE is considered.

What are the consequences of the switch to single-step?

As already mentioned, the reliabilities of many breeding values will rise substantially with the April sire proof run. The involving of the female genotypes will also cause substantial changes of the breeding values of individual animals. The positive point to be stressed here is the better differentiation of half sibling groups. So far, the sons of top sires were often very close together. Now, a clearer differentiation is assured by the consideration of the cow family in the breeding value estimation.

Conclusion

Due to the switch to the single-step method, the quality of the breeding values will increase. You will notice substantial changes in the ranking of the bulls and in the breeding values of the individual animals in the April proof run. However, the important thing is: the calculation of the breeding values changes, but their interpretation stays the same! This means that the figures in the sire catalogue are to be red and interpreted in exactly the same way as before the switch to single-step.

Furthermore, you should keep in mind that the ranking by GZW (TMI) is just a first overview. For the best possible success on your farm, you should always consider the individual traits which are especially important for breeding progress on your farm. We will be pleased to assist you with the selection of the perfect sires for your special needs.

If you have any further questions, please feel free to contact us!

 

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