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Why EBI values of genomic sires have slumped by an average of €39


Evaluation of almost 1m more fertility records from the 2017 calving season added to an 15pc increase in the size of the sire reference population, has contributed to the downward adjustment in the EBI values of genomic sires by an average of €39 in new active dairy bull list for the coming breeding season.

Having delayed the release of the listing to include the latest statistics from calvings in 2017, ICBF brought forward the quarterly review due be published in May, which has been included in the release.

Topping the listing is the Co Kilkenny bred, Ballinteskin Arnold, bred by William Duggan, Hugginstown, a 59pc holstein, with EBI €259,  combining €49 for milk, €207 for fertility and €33 for calving in the sub indexes.

Second is Nextgen YKG Candy 493, another 59pc Holstein,  bred in the Teagasc Moorepark Herd with an EBI €282, including €67 for milk, €164 for fertility and €33 for calving in the sub indexes.

The breding body points out that the listing contains a number of notable improvements compared to previous years, in time for the current breeding season,  which had not been anticipated for release until the next evaluation due in May 2017. 

These include the inclusion of 2-year old bulls on the listing for the first time (due to these bulls now having their first official evaluation for calving difficulty based on calves born just this Spring), more accurate genomic proofs for AI sires due to a number of improvements having being made by ICBF and Teagasc to the genomic evaluation system over the past 4 months and a 15% increase in the size of the sire reference population against which the genomic prediction equations are generated as well as the inclusion of almost 1m more fertility records from the 2017 calving season to date and updates to the genomic evaluation systems and software from which the evaluations are generated.

The average drop of €39 in EBI is equivalent to about two days in calving interval and 1% for survival and has been based on the weighted average reduction in EBI value for the 285 GS sires that are currently available in ‘Active AI’.

ICBF points out that some bulls will drop more and others less than this average figure, depending primarily on how the sires of these young GS bulls are performing on farms. 

“The impact will be seen most in bulls that have a genomic “only” proof or a genomic component to their fertility proof (blended proof). These are generally the younger GS bulls, born in 2015 and 2016.

Whilst the average drop is €39, the average ranking of bulls is staying very similar (with a correlation of 95% between the new evaluation and the last official evaluation), indicating that only a very small number of bulls are re-ranking significantly”.

The listing is dominated with young Genomically Selected (GS) bulls, with a total of 68 of the total 75 bulls being these young GS bulls. In addition the listing is almost completely dominated by Irish bred bulls (74 out of the 75 bulls are Irish bred), “reflecting the very significant investments that Irish owned AI companies have made in the national breeding program over the past 8 years, since the first introduction of genomics in 2009”.

The reliability of bulls has increase as a result of the above improvements the genomic evaluation system, with latest analysis indicating an increase in average reliability from 60% for Spring 2016 listing, up to 63% for bulls on the Spring 2017 listing.

Online Editors