This is probably one of the most common questions about the Euro-Star system. ICBF has a large database which receives information about animals on a daily basis. Data such as calving surveys, weights, carcass records and death dates are sent to ICBF from farmers, weight recorders, DAFM, marts, factories, etc. This data is then evaluated six times per year which results in updates to the Euro-Star index values of animals. These updates are what cause stars to change on animals.

Take a farmer that submitted weights on their cows and calves last Autumn as part of the BEEP-S programme. This weight data is used in the evaluation of a number of traits such as maternal weaning weight (milk) and cow liveweight. Weights were submitted for 20 cows and their 20 calves. The ICBF evaluation looks at these animals as a contemporary group. Each cow and calf’s performance is compared to the 19 other cows and calves in the group. It is not compared with the performance of animals in a neighbour’s herd as those animals could be managed very differently. The animals that are performing well in the group will generally see a rise in their Euro-Star figures and those performing poorly will see a drop.

We’ll pick out 2 cows from the herd and look closer at their performance. Cow 289 was one of the lightest cows in the herd at 640kg but her calf had one of the highest average daily gains (A.D.G.) at 1.48 kg/day giving it an adjusted 200-day weight of 341kg. This gave a cow/calf weaning efficiency % of 53% (calf’s weight as a % of the cow’s weight). Cow 285 was one of the heaviest cows in the herd at 775kg and her calf had one of the lowest ADG’s at 1.21 kg/day giving it a 200-day weight of 287kg. This gave a cow/calf weaning efficiency % of 37%. Table 1 details the performance of both cows.

Table 1. Performance of cows 285 and 289 on calf weight, cow weight and weaning efficiency

Both cows were 5th calvers, both of their calves were male and sired by the same stock bull, so neither cow had an advantage over the other e.g. one cow had a bull calf and the other a heifer calf. At the next evaluation, cow 289 will likely see an increase in her Replacement Index while cow 285 will see a decrease. Cow 285 will get the benefit of a higher liveweight on carcass weight and cull cow weight though. Table 2 details the likely direction of movement on the Replacement Index and the relevant traits based on the weight data submitted.

Table 2. Effect of weight data on both cows on their Replacement Indexes and the relevant traits influenced by cow and calf weights.

While cow 285 will lose out on milk and cow liveweight, she will gain on the carcass weight and cull cow weight traits. Her overall Replacement Index will likely drop though as milk and cow liveweight have a higher value in the index.

The Index and trait values will change for an animal in most evaluations but this does not necessarily mean that the stars will change. The current across breed ‘cut-off’ to be 5-stars on the Replacement Index is €118 (see table 3). Using cow 285 in our example, she had a Replacement Index of €135. The poor weight data recorded saw this drop to €120. Her index value will have dropped, but she would still be 5-stars as she is still above the €118 cut-off to be a 5-star. Cow 289 had a Replacement Index of €165 which increased to €182 based on her favourable performance. Again, her index has changed but she is still 5-stars.

Table 3. Euro-Star percentiles (cut-offs) based on the March 2023 evaluation.

Index and trait values move based on the data ICBF receives on animals and they will continue to move in the future. The Dublin footballers won 6 All-Irelands in a row from 2015-2020. At their peak they were undoubtedly the best team in the country and were ranked accordingly. We are now in 2023 and the Dublin team’s performances have waned, while other teams have improved and are now rightly ranked ahead of Dublin. The same principle applies to the Euro-Star Indexes. ICBF will continue to evaluate and rerank animals based on the latest available data.

For more information on interpreting the Euro-Star Indexes, please contact the HerdPlus office on 023-8820452 or [email protected]