Farm Ireland
Independent.ie

Tuesday 6 December 2016

New fertility index to hit rankings of Jersey bulls

Published 01/11/2011 | 05:00

A new fertility index looks set to hit the rankings of Jersey AI bulls when it is introduced before the end of the year.

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The new index is a revamp of the existing calculation which attempts to evaluate a cow's inherent ability to go back in calf.

The ICBF geneticists behind the new index said that it would improve the reliability of fertility scores for bulls and provide them earlier in the case of young test bulls.

The ICBF board is due to meet in a fortnight to decide whether to go ahead with the incorporation of the new index into the bull rankings due in December.

However, there may be some resistance from Jersey breeders when they find out that Jersey bulls will effectively be the only breed to see the new index reduce their EBI scores.

ICBF data suggests that Jersey bulls will see their fertility indexes drop by €13, while Norwegian Red bulls will see theirs increase by €13.

Friesian bulls will rise by €11 on average, Montbeliards will be up by €12 and Holsteins will increase by €1.

As a result Norwegian Red bulls will jump €26 in overall EBI ahead of their Jersey counterparts.

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Part of the reason the new index affects Jerseys so severely is because the negative correlation that was being factored in against milk yield for fertility will be diluted.

Instead, the number of calving intervals being included is being increased from three to five. In addition, the number of inseminations before a cow goes in-calf is also being included.

Data

"The use of handheld computerised recorders by AI technicians has revolutionised the amount of data that we can capture for analysing," said ICBF's Francis Kearney.

"While there is a 0.97 correlation between the old and the new indexes, some bulls will find themselves being re-ranked.

"It will also allow us to get a better handle on the effect that heterosis is having on the data that is coming from crossbred animals.

"But the movement of bulls between the different breeds is what we would have expected. Jerseys were never inherently more fertile than other dairy breeds but Norwegian Reds have been bred specifically for fertility for the past 20 years."

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