Cow Reference Population – Benefit for Genomic Evaluation System and Farmers

Abstract Cow reference population is a tool to introduce genomic selection for new traits within a manageable time. Furthermore it is an instrument to control the bias in more and more pre-selected bull reference populations. Whole herd genotyping by farmers for management purposes becomes more and more popular. This results in cow reference populations for classical traits. Beside this several projects are set up in Europe by breeding organizations to support this trend and collect data especially on new traits. The German Holstein herdbook organizations introduced the project KuhVision in June 2016 to achieve a reference population of 120.000 cows from whole herd genotyping within 3 years until June 2019. The goal of 550 participating herds with average 200 milking cows was reached already at the beginning of 2017. Meanwhile over 50,000 cows are in milk and provide phenotypes. First results after adding 20,000 cows to the EuroGenomics bull reference population show improvement of gEBV reliability for all routinely evaluated traits (see Alkhoder et al, 2017). The benefit of whole herd genotyping for dairy farmers management is demonstrated by the prediction power of young stock gEBV (not including own performance information) for differences in later phenotypic performance. The phenotypic difference e.g. in 305d milk production of 1st lactation between the bottom 25% for gEBV milk kg (-440kg) and the top 25% (+909kg gEBV) was 1,495 kg milk (8,340 versus 9,835 kg). Even for low heritable traits like fertility and calving traits differences in young stock gEBV correspond to big variation in phenotypic performance. These results encourage additional farmers to start whole herd genotyping outside the project. Therefore there is a realistic chance to establish whole herd genotyping on a commercial base parallel to and after the project even adding more cows to the reference population than the 30,000/year expected from the 550 farms in the project.