Genomic selection has contributed significantly to the increased rate of genetic gain in EBI, through the more accurate identification of genetically elite males and females. The current rate of genetic gain in EBI is €10/year.
How does genomics work?
Genomics is breeding using DNA to better predict how an animal will perform in the future. DNA is passed from parents to offspring and is therefore central to breeding.
The DNA profile of an animal is analysed and compared to profiles of proven animals in the training population to look for similarities. Performance data, ancestry data and genomic data are combined on the animal itself, generating a more accurate prediction of the animal’s genetic make-up.
Updated genomic training population
To generate genomic evaluations, a training population needs to be established. The training population is a large population of genotyped animals with accurate performance information, such as milk yield or fertility. The associations between DNA and performance measures are then developed from this population.
The DNA profile of an animal is analysed and compared to profiles of proven animals in the training population to look for similarities
Previously, there were around 10,000 informative sires within the Irish Holstein-Friesian training population. The criteria for including animals to this population remained the same since dairy genomics was first launched over 10 years ago.
After several years of research, the size and criteria of the training population has been updated. There are now over 45,000 and 50,000 animals in the training population for milk and fertility traits respectively. Increasing the size of the reference population is essential to ensure genomic predictions are accurate.
Addition of females and multiple breeds
Genotyped females and other dairy breeds such as Jerseys and Norwegian Reds are now included in the Irish training population for the January 2020 evaluations.
Other countries have also started to include informative females into their reference populations. Incorporating females adds a significant amount of information and is a crucial change to genomic predictions.
The addition of genotyped cows with good quality phenotypic data will further increase the accuracy of genomic predictions for traits such as female fertility (Table 1). Dairy genomic evaluations were previously limited to Holstein-Friesians, which don’t have more than 6.25% of any other breed.
There are now over 45,000 and 50,000 animals in the training population for milk and fertility traits respectively
However, the inclusion of multiple breeds to the training population means that genomic evaluations can be published for other dairy breeds, such as Jerseys, Norwegian Reds, Montbeliardes and Ayrshires.
ICBF has developed a system to routinely add male and female genotypes and their records to the training population, which will further increase the reliability of genomic predictions. Another improvement is the continuous genomic blending approach, where the system is constantly integrating an animal’s own performance records with its genomic data. This will result in fewer sudden changes to individual bulls from one evaluation to the next.
Accuracy of predictions
A recent test revealed the accuracy of genomic evaluations is 16-44% more accurate than evaluations made only from non-genomic proofs.
This was based on data from the current evaluations for 262 sires born after 2010 with at least 50 daughters in milk. The accuracy has improved for all traits (Table 1). This clearly shows the benefit of including genotyped cows in the training population.
Impact of improvements on active AI sires
The addition of new data for milk traits to the training population is very similar to the previous information for all Holstein-Friesian sires. For the fertility traits, there is a much larger difference. The impact of adding females to the training population has shifted its distribution, because the females added are more reflective of the current dairy cow population.
The new improvements will change the sire rankings on the active bull list. Table 2 shows the average change for 1,118 active sires on the EBI and the milk and fertility index and associated reliability.
Figure 1 shows the distribution of the change (for example, the central category with the highest sire count (180 sires) are sires that moved between -€12 and -€2 euro). 50% of sires moved between -€23 and +€8. 80% of sires moved between -€46 and €26.
Despite the recent increases in reliability, the EBI of an individual animal can still change over time, as more information gathers. It’s important to minimise the risks associated with genomic selection by using a large team of bulls.
ICBF have updated the size and criteria of animals included in the training population, which will increase the accuracy of EBI and generate greater genetic gain in the future. New updates will have minimal impact on the milk sub-index, but a larger impact on the fertility sub-index. Genomic evaluations are now available for multiple dairy breeds. Improvements to genomic predictions will provide users with more confidence in breeding decisions, especially for young genomically selected bulls.
Genomic selection has contributed significantly to the increased rate of genetic gain in EBI, through the more accurate identification of genetically elite males and females. The current rate of genetic gain in EBI is €10/year.
How does genomics work?
Genomics is breeding using DNA to better predict how an animal will perform in the future. DNA is passed from parents to offspring and is therefore central to breeding.
The DNA profile of an animal is analysed and compared to profiles of proven animals in the training population to look for similarities. Performance data, ancestry data and genomic data are combined on the animal itself, generating a more accurate prediction of the animal’s genetic make-up.
Updated genomic training population
To generate genomic evaluations, a training population needs to be established. The training population is a large population of genotyped animals with accurate performance information, such as milk yield or fertility. The associations between DNA and performance measures are then developed from this population.
The DNA profile of an animal is analysed and compared to profiles of proven animals in the training population to look for similarities
Previously, there were around 10,000 informative sires within the Irish Holstein-Friesian training population. The criteria for including animals to this population remained the same since dairy genomics was first launched over 10 years ago.
After several years of research, the size and criteria of the training population has been updated. There are now over 45,000 and 50,000 animals in the training population for milk and fertility traits respectively. Increasing the size of the reference population is essential to ensure genomic predictions are accurate.
Addition of females and multiple breeds
Genotyped females and other dairy breeds such as Jerseys and Norwegian Reds are now included in the Irish training population for the January 2020 evaluations.
Other countries have also started to include informative females into their reference populations. Incorporating females adds a significant amount of information and is a crucial change to genomic predictions.
The addition of genotyped cows with good quality phenotypic data will further increase the accuracy of genomic predictions for traits such as female fertility (Table 1). Dairy genomic evaluations were previously limited to Holstein-Friesians, which don’t have more than 6.25% of any other breed.
There are now over 45,000 and 50,000 animals in the training population for milk and fertility traits respectively
However, the inclusion of multiple breeds to the training population means that genomic evaluations can be published for other dairy breeds, such as Jerseys, Norwegian Reds, Montbeliardes and Ayrshires.
ICBF has developed a system to routinely add male and female genotypes and their records to the training population, which will further increase the reliability of genomic predictions. Another improvement is the continuous genomic blending approach, where the system is constantly integrating an animal’s own performance records with its genomic data. This will result in fewer sudden changes to individual bulls from one evaluation to the next.
Accuracy of predictions
A recent test revealed the accuracy of genomic evaluations is 16-44% more accurate than evaluations made only from non-genomic proofs.
This was based on data from the current evaluations for 262 sires born after 2010 with at least 50 daughters in milk. The accuracy has improved for all traits (Table 1). This clearly shows the benefit of including genotyped cows in the training population.
Impact of improvements on active AI sires
The addition of new data for milk traits to the training population is very similar to the previous information for all Holstein-Friesian sires. For the fertility traits, there is a much larger difference. The impact of adding females to the training population has shifted its distribution, because the females added are more reflective of the current dairy cow population.
The new improvements will change the sire rankings on the active bull list. Table 2 shows the average change for 1,118 active sires on the EBI and the milk and fertility index and associated reliability.
Figure 1 shows the distribution of the change (for example, the central category with the highest sire count (180 sires) are sires that moved between -€12 and -€2 euro). 50% of sires moved between -€23 and +€8. 80% of sires moved between -€46 and €26.
Despite the recent increases in reliability, the EBI of an individual animal can still change over time, as more information gathers. It’s important to minimise the risks associated with genomic selection by using a large team of bulls.
ICBF have updated the size and criteria of animals included in the training population, which will increase the accuracy of EBI and generate greater genetic gain in the future. New updates will have minimal impact on the milk sub-index, but a larger impact on the fertility sub-index. Genomic evaluations are now available for multiple dairy breeds. Improvements to genomic predictions will provide users with more confidence in breeding decisions, especially for young genomically selected bulls. 
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