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The objective of this study was to analyse the level of pedigree and genomic inbreeding in a herd of the Norik of Muran horses. The pedigree file included 1374 animals (603 stallions and 771 mares), while the reference population consisted of animals that were genotyped by using 70k SNP platform (n = 25). The trend of pedigree inbreeding was expressed as the probability that an animal has two identical alleles by descent according to classical formulas. The trend of genomic inbreeding was derived from the distribution of runs of homozygosity (ROHs) with various length in the genome based on the assumption that these regions reflect the autozygosity originated from past generations of ancestors. A maximum of 19 generations was found in pedigree file. As expected, the highest level of pedigree completeness was found in first five generations. Subsequent quality control of genomic data resulted in totally 54432 SNP markers covering 2.242 Mb of the autosomal genome. The pedigree analysis showed that in current generation can be expected the pedigree inbreeding at level 0.23% (ΔFPEDi = 0.19 ± 1.17%). Comparable results was obtained also by the genomic analysis, when the inbreeding in current generation reached level 0.11%. Thus, in term of genetic diversity both analyses reflected sufficient level of variability across analysed population of Norik of Muran horses.

The aim of this study was to analyse the genome-wide distribution of runs of homozygosity (ROH) segments in the genome of Norik of Muran horse and to identify the regions under strong selection pressure. Overall, 25 animals genotyped by the GGP Equine70k chip were included in the study. After SNP pruning, 54479 SNPs (75.72%) covering 2.25 Gb of the autosomal genome were retained for scan of ROH segments distribution. The ROHs were present in the genome of all animals and covered in average 13.17% (295.29 Mb) of autosomal genome expressed by the SNP loci. The highest number of ROHs was identified on autosome 1 (404), while the lowest proportion of autosome residing in ROH showed ECA31 (38). The footprints of selection, characterized by SNPs with extreme frequency in ROHs across specific genomic regions, were defined by the top 0.01 percentile of signals. Overall, nine genomic regions located on seven autosomes (3, 6, 9, 11, 15, 23) were identified. The strongest signal of selection showed three autosomes ECA3, ECA9 and ECA11. The protein-coding genes located within these regions suggested that the identified footprints of selection are most likely consequences of intensive breeding for traits of interest during the grading-up process of the Norik of Muran horse.