The main object of the present investigation was to test the inference from the results of previous trials that a diet composed substantially of cereal and weatings, with a small percentage of lucerne meal or grass meal, and supplying 7% of white-fish meal up to 90 lb. live weight and no protein supplement at all thereafter, should provide all the protein needed for the maximum rate of growth in bacon pigs and the production of carcasses of satisfactory quality, when fed at the rates shown in the feeding chart in Table 3.Two separate trials were carried out, and both the individual-feeding and group-feeding techniques were employed. In Trial I the control treatment A supplied the standard allowances of high-protein supplement, consisting of 10% of white-fish meal from weaning to 150 lb. live weight, and 5% of extracted soya-bean meal from 150 lb. to slaughter at about 200 lb. The white-fish meal in the rations of the pigs on treatment B was restricted to 7% up to 90 lb. live weight, and from this stage onwards the high-protein supplement was entirely omitted from the diet. The rest of the diet in both treatments consisted of barley meal and weatings, with a small percentage of lucerne meal, care being taken also to safeguard the animals against mineral deficiencies.