Analysis of selection signatures in the beef cattle genome

This study aimed to evaluate the impact of selection on the genome structure of beef cattle through identification of selection signatures reflecting the breeding standard of each breed and to discover potential functional genetic variants to improve performance traits. Genotyping data of six beef breeds (Aberdeen Angus, Hereford, Limousin, Charolais, Piedmontese and Romagnola) were used to perform genome-wide scans for selection signatures. The approaches applied were based on an assumption that selection leads to linkage disequilibrium or to a decrease of genetic variability in genomic regions containing genotypes connected with favourable phenotypes. Thus, the selection signatures were analysed based on Wright's FST index, distribution of runs of homozygosity segments in the beef genome and determination of linkage disequilibrium variability between breeds. The number and length of detected selection signals were different depending on the breeds and methodological approaches. As expected due to the breeding goals of analysed breeds, common signals were located on autosomes 2, 6, 7, 13 and 20 close to the genes associated with coat colour (KIT, KDR), muscle development (GDF9, GHRH, GHR), double muscling (MSTN), meat tenderness (CAST) and intramuscular fat content (SCD). But, across the genomes of analysed breeds, unique selection signals were found as well. The subsequent analysis of those single nucleotide polymorphism markers can be beneficial for the genetic progress of studied breeds in future.