Total merit indexes – NTM vs. JPI

Total merit indexes like NTM (Nordic Total Merit), JPI, TPI NM$ index, PLI, BPI among others are important genetic selection tools. The indexes differ by the traits covered and by the weight allocated to the specific traits.
Let’s look at the traits included in JPI and NTM and compare the weights of different traits for Jersey. 

NTM places 53% of the total weight on health and reproduction traits, while JPI puts only 27%.NTM has some traits that are not covered by JPI being: Hoof health (2%), General health (6%), Calving direct (2%), Youngstock survival, calf survival in the early and late rearing periods (4%).

Daughter fertility has similar weights in JPI and NTM, both being at 11% weight while Udder health and Calving maternal have higher weight in NTM. It is important to note that Udder health index in NTM is based on the registrations of clinical mastitis – direct selection, while JPI has SCS as an indirect selection tool. JPI has higher weight on longevity, as JPI does not have most of the health traits that are included in NTM, so Longevity is used as indirect selection tool for better health in JPI.
As for production, JPI has higher weight on Production 53%, while NTM has lower weight on Production traits - 35%
If we move on to conformation and workability traits, JPI has a higher weight on these than NTM. In JPI Frame (7%), Udders (12.8%), Feet & Legs (0.2%) conjoined have a weight of 20%. In contrast NTM puts 6% weight on Udders, and 3% on Feet & Legs, while having no weight attached to Frame. However, NTM also considers Milkability and Temperament in its index with a conjoined weight of 5% - These traits are not included in JPI.
 Trait
 NTM
VikingJersey
 JPI
 Production
 35
 53
 Daughter Fertility
 11
11 
Calving Direct 
 2
Calving Maternal 
 Udder Health / SCS
19 
General Health 
Hoof Health 
 2
Longevity 
 4
6 (PL) + 4 (LIV) 
 Youngstock Survival
 4
 -
 Frame
 0
 7
Feet & Legs 
 3
 0.2
 Udder
 6
 12.8
 Milkability
 4
 Temperament

All in all, NTM for VikingJersey includes 13 main traits, while JPI covers 7 main traits. NTM has an increased weight on multiple health, and reproduction traits compared to JPI, and this group of traits has high economic importance for achieving profitable and sustainable dairy production.

With higher weight placed on health and reproduction traits, while focusing on direct selection in general, and for health traits in particular, NTM is a much stronger and more reliable tool for commercial dairy farmers, as NTM delivers the well-balanced breeding goal for improving production, health, reproduction and functional conformation.

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