Genomic characterization of Pinzgau cattle: genetic conservation and breeding perspectives

A genome-wide scan of Slovak Pinzgau cattle was prepared for the first time in order to estimate their genetic diversity at a more detailed level compared to previously published studies. The aim of this study was to describe the genetic diversity based on the runs of homozygosity (ROH s ), linkage disequilibrium (LD) and effective population size (N eLD ) using genome-wide data. Moreover, Bayesian clustering algorithms and multivariate methods were used to detect the population structure, potential admixture level and relationship between Austrian and Slovak Pinzgau cattle with respect to a large meta-population consisting of 15 European cattle breeds. The proportion of ROH segments ranged from 0.43 to 1.91% in Slovak Pinzgau, depending on the minimum size of an ROH. The genomic inbreeding coefficients were higher than the pedigree ones possibly due to the limited number of available generations in pedigree data. The observed N eLD was close to the limit value characterizing the endangerment status, based both on genomic and pedigree data. Population structure within analyzed breeds based on the Wright’s F ST index, Nei’s genetic distances, and unsupervised as well as supervised analysis has been established. Overall, these analyses clearly distinguished populations based on their origin. A detailed analysis of the introgression of each breed into the Pinzgau breeds prepared using a Bayesian approach showed that the contribution of Holstein cattle in Austrian as well as Slovak Pinzgau was larger than contribution of beef breeds. A possible reason is the recent usage of Holstein sires to increase milk production. There are considerable differences between well-defined regions that clearly distinguish Austrian and Slovak Pinzgau, despite their close common history. Generally, the breeding program of Austrian Pinzgau is more focused on meat production than Slovak Pinzgau, which was clearly reflected in the obtained autozygosity islands. Considering the genetic establishment of Slovak Pinzgau population the genetic potential of the breed is insufficiently used. On a long term, more global breeding program including very close populations will be more efficient providing higher genetic progress and diversity. Established methodology how to distinguish genealogically close populations on high-throughput molecular information based of Slovak and Austrian Pinzgau can be proposed as general for analysis of differences in all highly related breeds.