Implementation of single-step genetic evaluation in Poland

In April 2025, Centre for Genetics of Polish Federation of Cattle Breeders and Dairy Farmers (CGen) implemented single-step genomic evaluation for Polish Holstein-Friesian population. The process of implementing the new evaluation system started in December 2024 when CGen became the official provider of dairy genetic evaluations in Poland calculating selection indexes based on breeding values estimated by the National Institute of Animal Production in Balice using a two-step approach. To increase the accuracy of breeding value estimations, CGen developed single-step pipelines using BLUPF90 family of programs. In January 2025 conventional EBVs for all traits were submitted for Interbull test run and successfully passed the evaluation. Next, the results of genomic evaluations were submitted for GEBV test and also passed for all traits. In April 2025 single-step evaluation results were officially published for the industry. In this paper we share the experience from the work undertaken to implement the single-step approach in Poland. The changes to the genetic evaluation models are highlighted. The methodology implemented for the integration of external information (MACE proofs) in single-step evaluations is discussed and results presented. Technical aspects of implementation are also discussed including model running times for individual traits. Highlights from the validation work undertaken are also included. The most noticeable impact on genetic evaluation results of the transition from the two-step evaluation system to the single-step method was increase in reliabilities. For example, for production traits, reliability increased by 12 percentage points for bulls and 10 percentage points for cows. The most significant improvement was observed for longevity, with a reliability increase of 40 percentage points for bulls and 35 percentage points for cows. The new system also demonstrated substantial improvement in the correlation between Polish and international breeding values, as estimated by the Interbull Centre. The most noticeable improvement was for longevity, where correlation increases with some countries reached 46 percentage points.