Strategies for comparing and combining different genetic and genomic evaluations: A review

Exchange of genetic material within and among national populations has increased rapidly with the development of artificial insemination and frozen embryos. This has increased the need to compare genetic evaluations across populations and ultimately to combine those evaluations for animals of interest. The combination of different sources of information became even more crucial with the development of genomic evaluation. This review summarizes different strategies and algorithms for solving issues related to comparison of methodology for genetic and genomic evaluations and their combination. Reviewed strategies and algorithms for genetic evaluations were categorized as either a post-evaluation or simultaneous combination approach. Post-evaluation approaches make external and internal estimates of genetic merit and their associated reliabilities comparable or combine them after performing external and internal evaluations. Simultaneous combination approaches combine external estimates of genetic merit and their associated reliabilities with internal phenotypic and pedigree data as interval evaluations are calculated. Several of the strategies developed for genetic evaluations were recently adapted for the context of genomic selection, and were mentioned in this paper.