Genomic selection in practical application
When genomic selection is completely introduced in the Norwegian Red (NR) breeding program, available bulls will be selected based on genomic breeding values calculated when they are calves.
Phased implementation of genomic selection means big changes in the NR breeding program, especially when compared to the very intense progeny test program used in the past. In our past progeny testing program, semen from young bulls was distributed across Norway and used for about 40% of all matings. Elite sires were used on about 60% of the Norwegian population and these elite sires were selected from the young bulls when their daughters had phenotypic information on important traits.
Selection of the best elite bulls will change under genomic selection as we will no longer need to wait on progeny information to select the elite sires to be used across the Norwegian population. The top Norwegian Red elite bulls to be used in Norway will be selected based on genomic breeding values.
With genomic selection, elite bulls are selected based on a breeding value calculated using the single-step genomic evaluation method. Like in other populations, genomic breeding values will have lower reliability compared to our highly reliable breeding values from the progeny testing program in the past. As a consequence we will use an increased number of elite bulls each year compared to the number of elite sires used in the past progeny testing program.
In the past progeny testing approach, we used from 10 to 12 elite bulls each year selected based on their progeny test results. With genomic selection, we expect to use approximately 50 elite sires each year. This larger number of sires will help control inbreeding in the NR population and to spread risk over a larger number of animals.
In cattle the reduced generation interval from the use of genomic selection has a great impact on genetic progress. Elite bulls in the genomic selection program will be the same age as young bulls in our previous progeny testing program. Thus, the generation interval is approximately halved compared to a progeny test program and this contributes to the increase in the genetic gain.
Increased frequency of genetic evaluations
Historically Geno has calculated 3 to 4 genetic evaluations each year. With the new genomic selection program, breeding values will be calculated much more frequently.
Optimal genetic contribution
To keep control of inbreeding in the NR population, it is important to have a good method for the selection of elite bulls. This is especially important for genomic selection where changes occur quickly. The selection of the bulls, the number of bulls selected for use and the amount of use for each bull within the population will be critical.
"Optimal genetic contribution" selection considers inbreeding and genetic change simultaneously. It is the method that will be used by Geno to select the best bulls and their level of usage while maintaining full control of inbreeding.
Large gains in the form of a shorter generation interval
Bulls that are selected on the basis of genomic information will have breeding values with lower accuracy (or reliability) compared to breeding values based on progeny testing. However, we have a big advantage for genomic selection in terms of a shorter generation interval. In total, genomic selection will provide faster genetic progress.