In a concrete example some principles of the economy of milk collection are being applied to the S.C. Sud-Lait (SL, Recogne). This is not at all an exhaustive study of this subject. On the contrary, this study is limited to the aspect of minimizing the routes covered by milk transports. First, the models are expressed in tons-kilometers (TKm). The conversion into real costs (BF) shows the main problem of the milk receiving centres (RC) and of transferring milk into larger tankers in view of transporting it to the milk processing centres (PC) of Recogne and Dison. First of all, however, the authors deal with some preliminary notions in order to define the problem properly.