30 April 2011

4 minute read

The implementation of genomic evaluations in Ireland has been very successful and the uptake of the genomically selected (GS) bulls has been encouraging with dairy producers using several bulls as recommended to reduce the risks.

“Initial results on how the technology is working are promising and the introduction of genomic evaluations will generate greater genetic gain in the future,” the Irish Cattle Breeding Federation’s Francis Kearney told delegates at the 2010 British Society of Animal Science’s annual conference, held at Queen’s University, Belfast.

The implementation of genomic evaluations in Ireland has been very successful and the uptake of the genomically selected (GS) bulls has been encouraging with dairy producers using several bulls as recommended to reduce the risks.

“Initial results on how the technology is working are promising and the introduction of genomic evaluations will generate greater genetic gain in the future,” the Irish Cattle Breeding Federation’s Francis Kearney told delegates at the 2010 British Society of Animal Science’s annual conference, held at Queen’s University, Belfast.

“Research work is now underway to increase the size of the training population, by incorporating multiple-trait across country evaluations (MACE), to improve the accuracy of genomic estimated breeding values,” he added.

Genomic selection in Holstein-Friesian dairy cattle was launched in Ireland in February 2009. Dr Kearney and his team set out how to both implement and monitor the uptake of genomic estimated breeding values (GEBVs) in Ireland for spring 2009.

“We also outline the results of the first group of Holstein-Friesian bulls that were selected on GEBVs compared to their progeny test proofs obtained in the August 2009 evaluations,” he said.

The training population was made up of just over 1,000 Holstein-Friesian bulls, genotyped using the Illumina Bovine50 Beadchip. And the uptake of the use of genomically selected (GS) bulls was assessed on 349,000 AI insemination records collected via technician handhelds from January to June 2009.

Initial results on the predictive ability of genomic selection was assessed by looking at the correlation of the daughter proven estimated breeding values (EBV) to the direct genomic values (DGVs), the GEBVs, and the parent average proof for 35 young test sires used in the 2006 national progeny test programme, and who received a daughter proof in the August 2009 evaluation. These bulls were marketed in spring 2009’s breeding season as GS bulls with no daughter information.

“And after consultation with representatives from the Irish dairy industry it was decided to publish GEBVs of individual bulls without progeny on the list of active bulls for the spring 2009 breeding season,” said Dr Kearney.

“Bulls included on the active bull list had to have sufficient progeny born to have reliability for direct calving difficulty of ≥50 per cent in the country of origin. Also the reliability of the GEBV for economic breeding index (EBI), had to be ≥35 per cent.

In 2008, prior to the introduction of genomic evaluations, each sire on the active bull list had to have a reliability of EBI of ≥58 per cent. Compared to 2008, the average EBI of the bulls on the list was higher, but the reliability was lower,” he added.

“In addition, younger sires replaced sires that had occupied the list for many years, but the number of bulls with daughters in Ireland decreased. The usage for the daughter proven bulls with daughters in Ireland (DP-IRL) was the highest at 37 per cent of inseminations with GS bulls accounting for 34 per cent, and proven bulls but with no Irish daughters (DP-INT) at 29 per cent. The mean number of bulls used per herd was 3 for DP-IRL bulls, 2.7 for DP-INT bulls and 4 for GS bulls.” The very positive uptake of GS bulls can be attributed to the difference in genetic merit between these bulls and the daughter-proven bulls. The weighted average EBI of the GS bulls was €69 – more than one standard deviation (€62) ahead of the DP-IRL bulls. The weighted average across all three groups of bulls used in 2009 was €38 more than the bulls used in 2008.

“In terms of the predictive ability of genomic information the correlation between parent average and daughter proofs were consistently lower than those of the GEBV and the DGV. At this stage the DGVs are the best predictors of progeny performance however one must recognise the limitations of this analysis due only 35 bulls being included in this comparison, the average reliability of the sires is 80 per cent, and the daughter records are not completed lactation records,” said Dr Kearney.
Presented to the British Society of Animal Science Annual Conference, April 12 to 14, 2010, Queen’s University, Belfast. Full details: Kearney JF, Cromie A and Berry DP: “Implementation and first year results on the use of genomic selection in dairy cattle in Ireland.”