The Council on Dairy Cattle Breeding (CDCB) will release these six new direct health traits during April proofs. Click on each individual trait to learn more details about its benefits, reliability and heritability, directly from CDCB.
The traits will be presented as disease resistance. A higher positive value is best – it means an animal is more resistant to the disease. A lower negative value will mean an animal is more susceptible, less resistant to the disease.
For example, let’s take a herd with an average mastitis incidence of 10%. If that herd uses a bull with a PTA of +3.0 for mastitis, we would expect the daughters of this bull to average 7% incidence rate for mastitis. That’s 3% less than the herd average.
Disease incidence rates range from 1.3% for milk fever to 10.2% for mastitis. Economic impact per case of each health event was also estimated, and ranged from $28 cost for ketosis to $197 for a displaced abomasum.
The heritability of these traits is still relatively low, but that doesn’t mean that you cannot make progress by selecting for these traits (read more about the high value of low heritability traits)
Mastitis resistance is also very favorably correlated with somatic cell score. Furthermore, the new health traits show no significant correlations to yield traits, meaning selection for fat or protein yield will not necessarily cause a decrease in health.
As the newly developed health traits are correlated to previously available traits, we have already been making progress in these traits, which you can learn about by reading the genetic guide to healthier cows. The data showed correlations up to 0.39 with productive life, correlations up to 0.47 with livability, and correlations up to 0.59 with DPR.
The data used to evaluate the health traits was collected from producer reported data in US herds, and underwent rigorous data testing to ensure accuracy.
If you have any questions on these new health traits, please feel free to contact me or any member of the PEAK/PD team.