Application of genomic tools to breeding and to genetic structure studies in livestock populations

This work is organized into a general introduction, four chapters of experimental contributions and general conclusions. Chapter 1 contains the general introduction, aiming to provide a synopsis about genetic application in animal science. Two main topics were debated in this thesis, modern genomic tools applied in animal breeding and animal biodiversity. The first two experimental contributions (Chapters 2 and 3) concerned animal breeding programs, particularly the first and the last step: variance components and breeding values estimation, respectively. The contribution about variance components estimation was the result of my abroad period at the University of Georgia (USA). Chapter 3 deals with the estimation of heritability and genomic breeding values for milk fatty acid profile. Regarding the animal biodiversity, two researches were carried out analyzing both cattle and sheep breeds farmed in Italy. Several statistical approaches were used to identify selection signatures in livestock. Chapter 4 analyzed genetic diversity among five cattle breeds: two purebreds and three crossbreeds raised in Sardinia. In the Chapter 5, in order to highlight genome regions that can differentiate livestock production, selection signatures were investigated among different productive aptitudes in the Italian ovine stock. Finally, the general conclusions reported in Chapter 6 offered a short overview of the main results obtained during the PhD.