Abstract: System for determining supplementary feed rations for dairy cows, which comprises the steps of:(a) recording in a hand-holdable microprocessor-based recorder (1) information relating to the cow identity of each of a plurality of cows which are to use a milking parlor,(b) entering information relating to the cow identity of each cow actually entering the parlor for a milking session, the recorder being programmed to validate the entered cow identities with the recorded cow identities,(c) entering respective milk yields in relation to respective validated cow identity entries,(d) after a milking session, connecting the recorder to a master unit (30), and(e) causing the master unit to read the information in the recorder as to milk yield Y for each identified cow and enter this information into a central processor programmed to compute a value of feed concentrate ration (R) for each cow according to an algorithm having the general form: R=V(Y-M+L(t)+C), where M, L(t) and C are values for "maintenance +", lactati