5 Jan 2024 - NTM Unlocked #2
Reading and understanding NTM and our proofs isn’t as tricky as it sounds.
To make it as easy as possible, we show the Estimated breeding values (EBVs) for NTM’s 15 main traits based on an average index of 100 – the typical animals in the base population. For NTM itself, the average is equal to 0.
Remember: the average bull has an NTM of 0 and breeding values of 100. This is the typical representative of the breed.
However, simply relying on averages can be misleading. Considering the standard deviation solves this issue, as we can determine the spread of the values around the average. This way, we can see what is normal, what is excellent, and what is not so good.
To explain this, let’s look at the indices' distribution. Also, keep in mind that proofs generally range from 70 to 130.
The bell-shaped curve shows a plot of normal distribution, and each band has a width of 1 standard deviation. In our system, 1 standard deviation equals 10 units.
The index distribution shows that 1 deviation represents 68% of the animals with breeding values between 90 and 110 and -10 to +10 for NTM.
Moving further away from the mean – 2 deviations to each side – 95% of the animals have breeding values between 80 and 120. For NTM, it would be those with -20 to +20.
Animals with a proof over EBV 120 and an NTM over +20 are the top representatives of the breed, as they are among the best 2.5%. They are elite specimens and, compared with other international indices, are similar to a US bull at +2.00 (PTA Type) and 108 in the Dutch proofs.
