The milk proteome changes due to many factors, such as lactation, individual, health status, processing, and species differences. The objective of the work described in this thesis was to increase our understanding of the dynamics of proteome in human and farm animal milk, and its contributions on the improvement of infant formula. This study shows that milk proteome not only differs qualitatively and quantitatively but also differs in their changing rate over lactation between species, especially for immune-related proteins. In addition, milk proteome shows different stability under different processing within and between species. It is concluded that although milk proteome differs between species, the function of milk proteins is essentially the same for all newborns, in providing nutrients and immunity for their growth and development. Both enriching specific milk proteins and mild processing of milk proteins should be considered for the improvement of infant formula.