By Melvin Kuhn and Paul VanRaden
Data for daughter pregnancy rate (DPR) now excludes known embryo donors. A donor cow's pregnancy may be greatly delayed while embryo recoveries occur. Thus, a donor cow's own fertility is difficult to observe, and her fertility records are excluded for the lactation in which embryo donation begins and for all subsequent lactations. Specifically, fertility records of donor cows are not used if the birth date of the earliest embryo transfer progeny occurs before the cow's own next fresh date. Embryo donation in subsequent lactations could not be determined because some embryos may be frozen. Reporting of embryo transfer occurs when progeny are registered or grade daughters freshen, although earlier reporting will be possible in the future using format 5. Longevity data of embryo donors has been excluded from productive life calculations with similar procedures introduced in February 2002. Embryo recipients will continue to receive credit for their pregnancy rates because recipient identification was not recorded. Because of the low heritability for DPR, changes to predicted transmitting abilities were small for most animals. However, most progeny-tested bulls are born by embryo transfer. Exclusion of fertility records for their dams increased the parent averages of most Holstein bulls by more than .2 and increased the predicted transmitting abilities (PTA's) of active AI bulls by nearly .2 on average. Published reliabilities for DPR decreased for some animals because of the exclusion of donor dam records, and because some final lactation records previously were incorrectly coded as confirmed not pregnant for cows that actually had no fertility information. Closer examination of data and cooperation with data providers is leading to an improved fertility database.
By Jan Wright
Interbull evaluations of type traits for Ayrshire bulls were released as official for the first time this run. Determination of whether the Interbull or domestic evaluation is official is based on the trait udder support.