Metabolic studies were carried out on nine male infants to investigatethe digestibility and utilization of some of the nutrients of the Milk-substitute 5410, there by ascertaining whether those nutrients could satisfy their requirements. From the results of the chemical analyses of the foods and excreta of the infants, statistical treatment of the records on the fre- quency of defecation, the amount and form of the stools, and the growth rate of the infants, it was possible to evaluate the apparent energy utilization of the milk-substitute.The ages of the infants at the beginning of the experiment were 37-77 days, and 6-7 months at the end. The experiment was divided into five periods: in the first and second periods the infants were fed alternately with the milk-substitute and powdered whole milk diet; in the third and fourth periods the diets were the same as the first and second but supplemented with cod liver oil concentrate (sbout 1500 1. U. vitamin A and 500 I. U. vitamin D per day). In the fifth period the protein content of the milk-substitute was raised from 16.6% to 22.6%, supplemented also with cod liver oil. In periods when the infants were fed with the milk substitute alone, the number of defecation was significantly less and loose stools fewer than in the milk diet period. Introduction of cod liver oil tended to reduce the dry weight of the feces. When the milk-substitute with higher protein content was given, the number of defecation increased and occurence of diarrhea was more frequent but not more so than during the cow's milk powder period.From the statistical analyses of the results, it was found that the digestibility of protein and carbohydrate of the milk-substitute was significantly lower than that of cow's milk powder but that of fat was higher. Introduction of cod liver oil increased the digestibility of protein, fat, carbohydrate and crude fibre. There was no significant difference between the availability of energy of the milk-substitute and cow's milk powder, the former being 90.9% while the latter 91.7%.The growth curves of the nine infants showed that the higher the food intake, the higher the growth rate. The caloric intakes of eight infants were 100-120 kcal per kilogram of body weight per day and their growth rates were almost identical. The caloric intake of one infant was consistently below 100 kcal per kilogram of body weight per day and his growth rate was significantly lower. It may be concluded, therefore, that when the Milk-substitute 5410 is given to infants supplying 100-120 kcal per kilogram of body weight per day, would be adequate for normal growth.

Previous feeding experiments on infants have shown that the growth promoting effect of the milk-substitute 5410 was comparable to that of hu- man milk or a milk powder diet. In order to know more about the biochemical and physiological properties of this mixture, nine male infants were put in serial metabolic studies with respect to the digestion, nitrogen, calcium and phosphorus utilization of this soybean product.The age of the infants were 37-77 days at the beginning of the experiment, and 6-7 months at the end. The infants were fed with the milk-substitute and a milk powder diet in alternative periods each of which lasted 2-4 weeks. In the first and second periods the infants were fed milk powder or milk-substitute alone, while in the third and forth periods the same diets were supplemented with concentrated cod liver oil, and in the fifth period the infants were fed with another soybean product similar to mixture 5410 but with higher protein content.The digestibility of protein and the absorption of nitrogen, calcium and phosphorus of mixture 5410 were significantly lower than those of the milk powder diet. However, the nitrogen retention were the same during these two dietary periods (191 and 196 mg per kilo per day). The calcium and phosphorus retention were signigicantly lower during periods without cod liver oil (24 and 24 mg per kilo per day) but improved markedly after supplementation (58 and 36 mg per kilo per day).On the average, each infant received from the milk-substitute 4.3g of protein per kilo per day. The amount of calcium ingested was 850 mg per day; it seems to be that supplementation with cod liver oil is necessary for adequate calcium retention at this level of intake.Raising the protein content of the milk-substitute by further addition of soybean powder may increase the nitrogen retention, but it tends to lower the absorption and retention of calcium and phosphorus due to increased amount of fecal excretion.