Approaches for investigating genome variability in cattle

Aim of the present thesis is to study the genetic variability of cattle breeds farmed in Italy. These were selected in order to represent different origin, selection history and production aptitudes. The variation at genome level was investigated by using three approaches that allow for disentangling different aspects of the genetic difference between animal populations. One approach checked the difference between two breeds by using a modification of the Fstmetric methodology, developed in order to make the signal pattern more readable through a local regression smoothing and to identify outlier signals based on statistical evidence. This study was focused a identifying genomic regions that harbor genes involved in the differences between dairy and beef cattle. Then a multi-breed investigation was performed based on the comparison between allele frequencies under the hypothesis of the binomial distributions. The research was mainly aimed at looking for genes shared between breeds grouped according to production aptitudes. Finally a third study was carried out to analyse the structural differences in the genome by investigating the variation of the distribution of ROH between breeds. Relationships between runs of homozygosity features and inbreeding coefficients have been investigated within and between breeds.