A new calculation model increases the reliability of genomic breeding values by an average of 11 percent

The single-step method makes better and more efficient use of all available information. Moreover, the number of markers has been further expanded. The development of new software and the increased processing power of computers has made this possible.

The single-step method meets all of Interbull’s requirements. This was also extensively tested by comparing the daughter breeding values achieved of a large number of bulls with the genomic breeding values calculated using the new method. This revealed that the new genomic breeding values were closer to the daughter breeding values achieved than the genomic breeding values calculated using the old method.

The increase in the reliability of genomic breeding values is not the same for all traits. For the breeding value lifespan, for example, the reliability increases from 56 to 78 percent (+22%), for the breeding value hoof health from 39 to 68 percent (+29%) and for the breeding value feet and legs, from 64 to 80 percent (+16%).

The increase in reliability is shown in the table for a number of key traits. The reliability of the NVI increases by 9 percent to 69 percent. For production and overall conformation breeding values, with the single-step method reliability increases to approximately 80 percent, for many health and management traits, to 60 to 70 percent.

From December, CRV will also use the new calculation model to estimate the genomic breeding values of female animals. This will also increase the reliability of the genomic breeding values of female young animals. Dairy farmers can therefore select and make mating decisions based on a higher level of reliability. This will result in faster genetic progress in their herds. Dairy farmers who have the DNA of their female animals tested, will obtain better information than previously.

Introducing the single-step method brings more benefits. For example, from December, genomic breeding value estimates for the traits udder balance, robot habituation and a number of fertility problems and metabolic disorders will be available. The new calculation method will also make the introduction of new traits easier.

As a result of the introduction of the new calculation method, the genomic breeding values of young bulls and female young animals may change more than usual in the December index run, which will be a one-off. These relatively significant changes are purely due to the new calculation method and will not occur again in later index runs. On the contrary, higher reliability will actually make breeding values more stable. In particular, the transition from genomic breeding values of young bulls to breeding values based on daughter performance will be accompanied by fewer changes.

CRV is excited about the introduction of the single-step calculation method, which further improves the reliability of genomic breeding values. This higher level of reliability helps dairy farmers to make even better breeding choices on both the male and female side, which will further accelerate genetic progress.

• The new calculation system increases the reliability of the genomic breeding values by an average of 11 percent.

• The reliability of lifespan increases by an average of 22 percent and the reliability of hoof health by an average of 29 percent.
• Genomic breeding values are now also available for robot habituation, udder balance, fertility problems and metabolic disorders.
• In the future, unexpected fluctuations in breeding values will be less common. Also, the fluctuation in breeding values from genomic to breeding values based on daughter information will be smaller.
• The new calculation system will have very little impact on the breeding values of daughter-tested bulls.
• Dairy farmers that have the DNA of their calves tested, can make better selections and better mating decisions.

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