Genome-Wide Homozygosity in Italian Holstein Cattle using HD SNP Panel

High throughput genotyping techniques allow to identify long and uninterrupted stretches of homozygous genotypes named runs of homozygosity (ROH). The objective of this work was to calculate ROH in Italian Holstein Friesian bulls in order to identify genomic regions potentially under selection. A total of 2,993 bulls were genotyped using medium and high density SNP panels. A total of 161,566 and 67,915 ROH were detected using 54K and 777K panels respectively. The average number of ROH per animal was 77.2±9.5 (54K) and 74.2±15.2 (777K). Regions with a high occurrence of ROH were identified in several chromosomes. Of particular interest was a ROH hotspot identified on BTA26, where several genes involved in the metabolism of the mammary gland map. ROH could be used to detect genomic regions involved in traits of economic importance