6 Total Merit Indexes under EuroGenomics
On the EuroGenomics website six different Total Merit Indexes (TMI) are shown: ISU, ICO, NVI, NTM, PF and RZG, originating from France, Spain, The Netherlands-Flanders, Denmark-Sweden-Finland, Poland and Germany respectively.
Within the TMI, several categories of traits can be distinguished like production, conformation, growth, workability, and functional traits including calving, health, longevity and fertility. Depending on country and breeding goal, these categories of traits are introduced with different weights into the definition of each TMI. Therefore, it’s impossible to directly compare TMI from one scale to another.
The below image shows the composition of the 6 TMIs under Eurogenomics:
How to understand the Total Merit Indexes
Although TMIs cannot be directly compared to each other, they are all characterized by two values: average and standard deviation, which help to interpret the TMI. The figure below gives an overview of averages and standard deviations (σ) for the six TMIs under EuroGenomics Cooperative:
As can be seen in the figure, NTM breeding values on the Nordic scale have an average of 0 and a standard deviation of 10. PF breeding values on the Polish scale however have an average of 100 and a standard deviation of 10.
Even though the average and standard deviation is different between TMIs, how to interpret the TMI scores is always the same:
- Bulls with a NTM over 20 belongs to the top 2.5% of the Holstein breed in Denmark, Sweden and Finland.
- Bulls with an ICO over 3912 belongs to the top 2.5% of the Holstein breed in Spain.
- 95% of the Holstein population evaluated in The Netherlands has a NVI between -174 and 174.
- 66% of the Holstein population evaluated in Poland have a PF between 90 and 110.
- Bulls with an ISU below -56 belong to the bottom 2.5% of the Holstein breed in France.
- Bulls with an RZG over 124 represent the top 2.5% of the breed in Germany.