The most recent evaluation of the Irish Cattle Breeding Federation (ICBF) Active Bull List has seen another major re-ranking.

This time last year, there was quite a bit of controversy among farmers as one of the most popular bulls in the country had his Economic Breeding Index (EBI) drop like a meteor.

Tankardsrock Teak (FR7929), who previously held the top position on the ICBF Active Bull List, had his ranking dropped to 201st in spring 2025.

The decline was largely attributed to a reduction of €73 in his Fertility Sub-Index, which also impacted his Carbon Sub-Index, decreasing it by €8.

Now under the May 2026 evaluations, Tankardsrock Teak, who is the sire to a large portion of dairy animals in Ireland, sits at 435 on the Active Bull List.

2026 Active Bull List

If we go back to March 2026, when many farmers were flicking through catalogues for the upcoming breeding season, Cityhill Lincoln SRM was the top ranked bull.

Two months on and following the May 2026 evaluations, he has falling to 22nd on the list, which is still a great position but a major re-ranking.

Oldcastletown Mojo held the second position, but he has now fallen to 44th.

Aghernbridge Borocco SRM who was in third, has now made his way to 16th.

In fact, Candrew Freedie 2040 SRM is the only bull who kept his place in the top 10 since March, albeit dropping one position (8th-9th).

The updated top 20 bulls on ICBF's Active Bull List as of May 26 are as follows:

How do proofs fluctuate?

So how do bull proofs fluctuate so much and so quickly?

Bulls typically end up on the Active Bull List with a Genomic Proof (GS).

Young and full of hybrid vigour, they can quickly climb into competition with the best of the best bulls.

When they get to this position, they quickly sire plenty of off-spring.

Data from the off-spring born the following spring quickly becomes available, and is added to the bulls EBI, moving him from a GS bull to a a Daughter Proof (DP-Irl) bull.

This can affect their ranking in terms of reliability, genomics, and other predictor traits, which are correlated throughout the EBI, for example, Milk Kilograms (Milk Kg) is used as a predictor trait for Calving Interval and Survival.

Therefore if a bull's off-spring is doing poorer than predicted, he will quickly drop through the rankings as data is made available.

When we see bulls drop so far and so fast, it acts as a good reminder to have large bull teams when it comes to breeding and not over-rely on one or two bulls.

No more than 15% of heifer replacements should come from any single bull. This strategy spreads risk and ensures a more balanced herd.