How to understand the 5 Total Merit Indexes

Different traits and weights into the 5 Total Merit Index
 

The graph shows the composition of the 5 Total Merit Index (TMI).

For genotyped animals:

• gNVI is the Total Merit Index used in  Netherlands-Flanders,
• gNTM is the TMI used in Denmark, Sweden and Finland,
• gISU is the TMI used in France,
• gPF is the TMI used in Poland,
• gICO is the TMI used in Spain.

Several categories of traits can be distinguished: production, type, growth, workability, and functional traits including calving, health, longevity and fertility. Depending on countries and breeding goals, these categories of traits might be introduced with different weights into the definition of each Total Merit Index (TMI).

The values & ranges of TMI look different from one scale to another
 

Ranges of values for Total Merit Index on the 5 scales.

We can't compare Total Merit Index (TMI) from one scale to another: weight given to traits are different because breeding goals differ from one country to another, 

However, all TMI can be caracterized by two values: average and standard deviation. For example, 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 have an average of 100 and a standard deviation of 110.

As you can see from the graph, average and standard deviation are all different on the 5 scales (Dutch, Nordic, Polish, French and Spanish). However, how to read the Total Merit Index 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.
• 95% of the Holstein population evaluated in the three Nordic countries has a NTM between -20 and 20.
• 66% of he Holstein population evaluated in the three Nordic countries has a NTM between -10 and 10.
• Bulls with a NTM below -20 belongs to the bottom 2.5% of the Holstein breed in Denmark, Sweden and Finland. 

Similarly:

• Bulls with a NVI over 170 belongs to the top 2.5% of the Holstein breed in the Netherlands - Flanders.
• Bulls with a PF over 120 belongs to the top 2.5% of the Holstein breed in Poland.
• Bulls with an ISU over 120 belongs to the top 2.5% of the Holstein breed in France.
• Bulls with an ICO over 3594 belongs to the top 2.5% of the Holstein breed in Spain.