Conservation & local programs

Genomic diversity and population structure in Nordic Red Dairy Cattle populations

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Abstract

VikingRed (VR) and Norwegian Red (NR) are the predominant red dairy cattle populations in the Nordic countries, representing distinct but closely related breeding programs. The VR breeding program, coordinated by VikingGenetics, integrates Danish Red, Finnish Ayrshire, and Swedish Red cattle within a joint genomic selection program across Denmark, Sweden, and Finland. The NR population, managed by Geno SA in Norway, has been developed independently, with similar breeding objectives and comparable selection intensity. Both breeding programs are supported by long-standing national recording and evaluation systems, which have enabled early adoption of genomic selection and a shared emphasis on production efficiency, health, and functional traits. Intensive selection within relatively small breeding populations, together with historical gene flow between the VR and NR populations, has likely influenced patterns of genetic diversity and relationships among individuals, yet the extent and nature of these changes have not been comprehensively assessed. This study investigates the population structure and genomic diversity of VR and NR using medium-density SNP genotype and pedigree data representing both historical and active breeding animals. Analyses focus on quantifying genetic connectedness and identifying potential substructure within and between the populations.Population structure is analyzed using principal component analysis (PCA) and ADMIXTURE to assess differentiation and admixture patterns, complemented by analyses of genomic diversity, relatedness, and population differentiation. Genetic differentiation between populations is further quantified using Wright's fixation index (FST). Together, these analyses provide an overview of current genetic composition and reveal how historical selection, gene flow, and population management have shaped the genomic structure of each population. Genetic relatedness between VR and NR was quantified using pedigree-based mean kinship among bulls used in the breeding programs between 2008 and 2024. Mean kinship between the two populations was low (0.010), indicating limited recent genetic relatedness between the breeding programs. Within-population kinship was higher in VR (0.033) than in NR (0.016), partly reflecting differences in pedigree depth between the two populations, with NR having shallower pedigrees than VR. Despite shared historical origins and similar breeding objectives, the two populations appear to remain weakly connected at the pedigree level. This pattern suggests that increased genetic exchange or partially coordinated breeding strategies could contribute to maintaining genetic diversity in both populations. This study provides new insights into the genetic composition and substructure of VR and NR. Identifying genetic clusters and their characteristics will support the development of sustainable breeding strategies for admixed populations. Understanding the degree of genomic connectedness between the populations will help optimize reference population design and ensure balanced genetic contributions in joint genomic evaluations. Collectively, the findings will support sustainable genetic improvement and the continued competitiveness of Nordic red dairy cattle populations in the Nordic region and beyond.

Keywords: 2026

How to Cite:

Tenhunen, S., Sørensen, L., Thomasen, J., Kargo, M. & Uimari, P., (2026) “Genomic diversity and population structure in Nordic Red Dairy Cattle populations”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2285476. doi: https://doi.org/10.31274/wcgalp.23721

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