5 Jan 2024 - NTM Unlocked #11
In NTM, there are eight traits covering cows' health, reproduction, and lifespan – all these traits together have a 45% weight in the total merit index (NTM).
The Udder Health index has a weight of 17% for VikingJersey, 11% for VikingHolstein and 9% for VikingRed.
The Udder Health index is strongly correlated with NTM. For VikingHolstein, that number is 29%, and it also has a strong correlation with Longevity (44%), General health (28%), Udder conformation (26%), and Daughter fertility (23%).
The Udder Health index describes the bull’s daughters’ genetic ability to resist mastitis, and it includes breeding values for udder health in the first three lactations.
The data behind the Udder Health index is the records on clinical mastitis made by veterinarians. Cell count (first three lactations) and udder conformation (fore udder attachment and udder depth from the 1st lactation) are used as indicators of udder health.
What makes the Udder Health index unique is that in the Nordic countries, we register actual disease cases and don’t just rely on indicator traits, like Somatic cell count (SCC).
SCC alone is not a good enough predictor for improving mastitis resistance. The correlation between SCC and clinical mastitis is around 0.6, so they are not really the same trait. Therefore, registrations of clinical mastitis are a more accurate breeding value base.
Official registrations are done for 90% of cows in Denmark, Sweden and Finland. That results in a high reliability of breeding values for udder health.
