Changes in the Economic Breeding Index (EBI) are set to come into effect today (Tuesday, September 23) which will result in a major change in a herd's EBI figure.

The Irish Cattle Breeding Federation (ICBF) in partnership with Teagasc have updated the dairy and beef evaluations.

ICBF said the changes "are designed to make the indexes (EBI, Replacement, Terminal and Dairy Beef Index (DBI), more accurate and relevant to today’s farming conditions".

It also outlined that "continuous improvement in the EBI is essential for Irish dairy farmers to breed the most profitable and resilient cows for the future".  

Following research work by ICBF and Teagasc, a number of changes will be introduced to the EBI in the latest evaluation published today.

Farmers will see changes to their individual animals in their EBI profile, EBI reports and the animal search.

The three key changes to the EBI will include a base population change on milk and fertility sub-index, updates to economic values on all traits and new models applied to the health and management sub-index.

The EBI is calculated by assessing key traits that impact the profitability of dairy cows and these traits are grouped into categories such as milk production, fertility, calving performance, beef production, maintenance, and health.

Each trait is assigned an economic value based on its impact on farm profitability and the genetic merit of an animal for each trait is assessed using breeding values.

The EBI is then calculated by summing the economic values and the genetic merits for all traits to give the overall EBI figure.

Based on the latest data regarding economic values and costs of milk production in Ireland, Teagasc has updated the economic values in the Moorepark dairy systems model (MDSM), which are used in the formulation of the EBI.

These updates account for rising input costs, such as increased feed and fertilizer prices, higher output prices and future market projections.

The updates to the economic model are as follows:

Costs have risen: feed €370/t, fertiliser €550/t, labour €17/hour;
Milk price is forecast at 40c/litre (incl. VAT) with a protein-to-fat ratio of 1.7:1;
The heifer growth cost has been moved to the Maintenance Sub-Index which was previously accounted for in the Beef Sub-Index;
These updates mean some sub-indexes (especially Beef and Maintenance) will change to reflect higher beef value and feed costs.

Overall, the impact of the economic values update and base change has had very little change on the relative emphasis which can be seen below.

In genetic evaluations, a base is simply the reference group that all animals against are compared to and each cow or bull’s genetic merit, or Predicted Transmitting Ability (PTA), is measured relative to this base group.

Over time, the genetic potential of herds improves due to selective breeding and so today’s cows are, on average, genetically superior to the older base population of cows.

To reflect the genetic improvements made in milk production and fertility in the Irish dairy herd, the base cow against which EBI is measured has been updated as part of the September 2025 evaluation.

The previous base cow related to cows born in 2005, first calved and milk recorded milk recorded in the 2007- 2009 period.

The new base will use cows born in 2015, first calved and milk recorded in the 2017-2019 period, which is more reflective of the actual genetics in the national herd.

The 2015 genetic base for production and fertility traits are as follows:

The updated base will result in each animal’s EBI reducing by €97.

All cows' EBI will reduce, but this in turn does not necessarily mean that each cows genetic merit has deteriorated.

Within this €97 decrease, a €45 decrease in the milk sub- index will occur as the change in milk yield PTA is -74kg, -7kg fat, -5.6kg protein, -0.07% fat and -0.05% protein.

The fertility sub-index will also drop by €52 as the the calving interval PTA has increased by 2.66 days and the survival has decreased by 1.33%.

This keeps evaluations up to date with today’s cows, but it doesn’t change the ranking of bulls or cows as even though the PTA figures for all animals shift up or down, they all shift by the same amount.

The heifer rearing cost has been moved to the Maintenance Sub-Index which was previously accounted for in the Beef Sub-Index and has increased the maintenance sub-index from 4% to 8%.

The original maintenance sub-index would include 100% of the cost to maintain a cow whereas the new sub-index will be 63% cost to maintain cow and 37% cost to grow heifer which would have previously been included in the cull cow.

The inclusion of heifer rearing costs in the maintenance sub-index amalgmated with the inflation of costs from feed to fertiliser has increased the weighting of maintenance in the EBI, essentially rewarding lighter cows that can still produce good levels of milk solids.

A cow with a maintenance sub-index of €0 will now have a liveweight of 600kg. A cow that would've previously had a maintenance sub-index of €16 will now have a maintenance sub-index of €29 for a cow weighing 550kg.

The formula for new predicted liveweight is 601.67 + (New_maint_SI x -1.7349). For instance, a herd with €15 maintenance, 601.67 + (€15 x -1.7349) = 575.6.

All genetic evaluations are periodically reviewed and both the health and management genetic evaluations have been recently revised.

For lameness and mastitis, records from multiple lactations are now used, so cows with repeated cases are better reflected in the evaluations.

When it comes to temperament, the scale has been simplified from 5 points to 3 points, making it quicker and easier to score a cow, with no con

For locomotion scores, the linear locomotion scoring is now used to help predict overall health, giving a clearer picture of mobility issues.

When it comes to better data checks and calculations, there has been an improvement in the way information is cleaned and analysed, so the results are more reliable.

ICBF also believe that their latest international 'single-step genomic' method that combines pedigree and DNA data in one step will lead to more accurate evaluations.

While the figures will look significantly different initially, in general, aside from the base change, most herds will see minimal changes to their herd EBI.

Combining the economic changes with the base change, farmers will see a reduction of approximately €83 on each animal with avaerage decreasing from €194 to €111.

On the ICBF Active Bull list, the current EBI of the 100 bulls will go from €325 to €243, a decrease of €82 with 79 of the bulls still remaining in the top 100 Active Bull List.

The majority of bulls in the Active Bull List will have a negative milk kg PTA and over 60% of the herds will will be negative for milk kg as ICBF said that "milk PTA is a good predictor of milk litres but it's not a good predictor of of milk solids or milk value" and the "milk sub-index is a very good predictor of milk value".