Dr. Andrew Cromie:

In the genetic evaluations, we are comparing like with like on the day. It is based on the average on the day. The average calving interval is 400 days, but there could be an animal at 430 days and another at 370. Deputy Aylward's herd might be at 370 days but the point is the genetic differences for individual bulls. We could see progeny from a particular bull in Deputy Aylward's herd at 390 days compared to his herd average of 370. That is how genetic evaluation works.