Breed Improvement
EPDs: Moving to a North American Evaluation Jeff Hyatt – CSA Research Coordinator
S
ome of you may have noticed that the Canadian Simmental Association (CSA) EPDs have changed and with that the base for the EPD calculation has also been changed. This is indeed the case as the CSA recently entered into a North American evaluation with the American Simmental Association (ASA). As a result, the CSA EPDs are now directly comparable with the ASA numbers.
The reason being that some of an animal’s genetic information can be predicted with all of the CSA’s current DNA tests.
The following shows the percentile rankings for the top 1% and 95% for both the new and old EPDs so you can access the ranges of a given EPD.
There has been very little change to some of the EPDs; with calving ease the average has decreased somewhat and the range has broadened slightly. Some other EPDs however have changed more such as weaning weight or milk. The reason for some of the changes is due to ASA’s formulas being different from those used in the CSA’s old evaluations while others are due to the base adjustment which was made to allow comparisons to other breeds. The EPDs are still as valuable, they are just evaluated slightly differently. Regardless of how the EPDs are calculated we must remember that the accuracies are also important to consider. When an animal is young, their EPD accuracy is very low; a low accuracy EPD will provide a general idea of what the animal may provide in a specific trait. As the animal has more progeny with recorded data that same animal will have higher accuracy EPDs which will provide a better indication of the genetic potential that animal may contribute. As genomic information is included into the EPD evaluations, animals that are tested will have more accurate EPDs with fewer progeny.
A good example of this is two full sibs ER BIG SKY 545B and ER MACKFRID 550B, who upon their first evaluation would have had very similar EPDs. These two bulls have extremely accurate EPDs now, in the 0.90+ category. BIG SKY had only two EPDs not in the top 2% or bottom 10%; MACKFRID on the other hand had a more balanced set of numbers. As you can, see you may not be able to discern what an animal’s progeny will do at a low accuracy but you will have a general idea. In the next EPD evaluation (Spring 2014), genetic testing information will greatly help to increase the EPD accuracy for young animals so that you can have a better indication of that animal’s worth.
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9/24/2013 11:04:42 AM