Updated publication reference for PubMed record(s): 30208024. Pig breeds have different attitude to traits like growth rate, carcass composition and reproduction parameters as well as other traits. These traits considered as external traits or end phenotypes are the outcome of complex biological processes and interactions. The main goal of pig breeding programs and the basis for crossbreeding is finding a balance between these traits. In pig production, Large White and Duroc breeds are commonly used to optimise respectively fertility and growth ability and differ on several production traits, indeed the first breed as a high fertility characters whereas Duroc is used as terminal sire for her growth performance and good carcass quality traits. In this study, we have used a quantitative label-free LC-MS proteomics approach to characterise and compare the liver proteome of two heavy Italian pig breeds, Italian Duroc and Italian Large White to identify difference due to their different genetic background. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 703094.