Unknown parent groups unwanted behavior in traditional evaluations
As communicated in our August “CDCB changes to evaluation system” (https://www.uscdcb.com/cdcb-changes-to-evaluation-system-august-2018/), a modification to the traditional evaluation procedure that creates the unknown parent groups (UPG) was applied to prevent Guernsey from not having separate UPG. In the routine checks to the evaluations that will be published on August 7th, we discovered that the change in the parameter that fixed the problem for Guernsey, had also caused the generation of separate groups (instead of combining them automatically with unknown sires of cows) for parents of sires in the other breeds. As a consequence, the resulting new groups for parents of sires involved few animals and many years / group. This means the groups are not incorrect in their values, but the estimates for those years/groups are less accurate than the ones used in the April evaluation. This issue affects mostly the traditional PTAs of ungenotyped animals with incomplete pedigree, with only minor effect on genotyped animals (except for those with missing parents). We apologise for the inconvenience and we ensure we’ll reinstate the previous situation in the next triannual evaluation.