The changes affecting farming, operating between local and global, are important concerning milk processing. How these changes express themselves locally? What consequences concerning strategies of processing firms and concerning livestock farming systems? Developing diachronic studies we analyze interactions between marketing strategies of milk processing factories, livestock farming systems and consequences of these changes at local scales. Comparing contrasted situations (France, South America, Vietnam and Senegal), we found mostly two contrasted dynamics: (1) a process of globalisation (concentration of operators, increasing importance of long food chains, location of farms in high productivity areas, intensification of farming practices); (2) a process of strengthening relationship between product and local specificity (emphasizing local image and the link between product and the 'terroir', handicraft processes of transformation), increasing of local marketing channels, farming practices valorizing a diversity of local resources. Intermediating between production and distribution, dairy factories are at the core of these two dynamics. We will present the methodologies employed to characterize the studied situations. From examples we will illustrate how these two dynamics are emerging and operate. We will discuss then how in a same place complementarity, tensions or exclusions may appear between these two dynamics.