A number of major enhancements were implemented in the December 2022 Single-Step BREEDPLAN analysis as provided to Angus Australia and New Zealand Angus. These are outlined below:

• Updated adjustment factors and genetic parameters: A complete re-estimation of genetic parameters for traits reported in the Single-Step BREEDPLAN analysis as provided to Angus was completed this year, with a particular focus on carcase traits. As the current genetic parameters were estimated in 2013, the latest parameter estimates are based on a significant increase in performance records, especially slaughter-endpoint traits and net feed intake. As a consequence, the parameters that were implemented in the December 2022 evaluation will better represent the population of animals with performance records. These updated parameters relate to the main multi-trait analysis only: genetic parameters for calving ease, docility and structural traits were not updated.
• Revised Docility analysis: Previously, the Docility analysis only included animals with a temperament score plus 2 generations of pedigree, meaning that many animals did not have a Docility EBV. The revised analysis now uses the pedigree file from the main multi-trait analysis and the CE analysis, to ensure that potentially all animals in the BREEDPLAN evaluation have all EBVs available (including Docility).
• New accuracy software: The volume of genomic information used in the Single-Step BREEDPLAN analysis as provided to Angus was reaching a point where the algorithm used in the calculation of accuracy was becoming inefficient in terms of time and computer memory requirements. A much-improved algorithm has been developed to more effectively incorporate SNP effects, representing a major advancement in the analytical software used in the Single-Step BREEDPLAN analysis as provided to Angus. This new software was implemented in December 2022.
• Updated parameter files for Index calculation: These were needed to ensure the calculation of indexes reflected the changes in parameters used in calculating EBVs.
• Changed approach to using imported EPDs: As of December 2022, EPDs will no longer be updated for American Red Angus animals represented in the Single-Step BREEDPLAN analysis as provided to Angus. Updated EPDs will still be used for Canadian Angus (Black and Red) and American Angus (Black) animals represented in the Single-Step BREEDPLAN analysis as provided to Angus.

Changes in EBVs, accuracy and index values are to be expected as a consequence of these enhancements to the Single-Step BREEDPLAN analysis as provided to Angus. A number of test evaluations with these enhancements in place were completed over the last few months with outcomes of this testing presented to both Angus Australia and NZ Angus.