Expanding Australian sheep genomic reference population

Allele frequencies play a crucial role in multi-breed genetic evaluations by enabling the construction of a breed-adjusted genomic relationship matrix (GRM), which can be derived from a genomic reference population. This study aimed to update the Australian sheep genomic reference population for a combined Terminal and Maternal LAMBPLAN genetic evaluation. The analysis incorporated genotypic data from sheep across maternal, terminal, shedding, and Merino breeds, as well as smaller breeds and composite populations. Population structure analysis identified 27 genetic clusters among terminal, maternal and shedding breeds and five clusters within Merino sheep. The findings demonstrate that genomic data and unsupervised clustering methods can improve breed composition accuracy and facilitate a comprehensive multi-breed genetic evaluation, reducing the need for strictly straight-bred reference populations.