1. Measurements were made of the losses of nitrogen in the faeces and urine of sixty pigs of approximately 33 kg, given dietary regimens comprising twenty-nine combinations of fish flour (0-800 g/d) and maize starch (0–1200 g/d).

2. The results were used to develop a generalized equation describing N retention as a joint function of N intake and starch intake.

3. The protein-sparing effect of starch was exerted in all circumstances. It was greatest when protein intake exceeded 220 g/d but some effect persisted with protein-free diets. With a high protein supply, the increase in N retention per unit increase in dietary starch decreased from 36 mg/g with the first increment to 3 mg/g with the highest attainable starch intake.

4. From the generalized equation the relationships between net protein utilization and protein concentration and food intake could be described as continuous functions. The equations may be of use in comparing the protein values of diets measured under non-standardized conditions.

1. In five experiments with growing female pigs of 38–63 kg, insulin (2 mU/kg per min) and glucose (9–17 mg/kg per min) were infused continuously for 3–7 d. In three further experiments, glucose (9 mg/kg per min) was infused alone for 5 d.

2. In response to the combined infusion, plasma insulin increased 2-7-fold, plasma glucose decreased, on average, by 50% and plasma urea concentration was reduced by 40%. Urinary excretion of urea and nitrogen decreased after the first day of infusion to values averaging 70% of control levels.

3. The infusion of glucose alone provoked only a small increase in plasma insulin. The reduction of urinary urea and of N excretion were approximately 25% of those observed with the combined infusions.

1. Mean daily nutrient intakes of 195 women in the first trimester of pregnancy were assessed by weighed dietary records.

2. In comparison with recommended intakes for non-pregnant women aged 18-55 years (Department of Health and Social Security, (1969), more than two-thirds of the subjects were having insufficient energy, iron and cholecalciferol. Unsatisfactory intakes of other nutrients were not uncommon. In relation to recom mended intakes for the second trimester Department of Health and Social Security, (1969), all mothers were having insufficient cholecalciferol and more than 80 % of mothers had unsatisfactory intakes of energy and Fe.

3. Intakes appreciably lower than those recommended were associated with the following factors: social classes III, IV and V; maternal age under 20 years; smoking ten or more cigarettes daily; vomiting on more than 3 d/week.

1. The B-vitamins in milk from baboons (Papio cynocephalus) at various stages of lactation were measured microbiologically.

2. Mature milk contained, on average (μg/ml): thiamin 0.18, riboflavin 0.74, nicotinic acid 3.2, folate 0.03, vitamin B6 0.70, vitamin B12 0.002, pantothenic acid 2.63, biotin 0.0065.

3. Colostrum contained much less vitamin B6 and pantothenic acid than mature milk; otherwise, there were only slight changes in composition as lactation progressed. Neither these changes, nor the absolute values, resembled those for human or cow's milk.

4. The average daily secretion of B-vitamins in milk represented less than 10% of the mother's dietary intake; that of folate was less than 0.5% of the mother's dietary intake.

5. Baboon milk was calculated to provide infants with approximately the following quantities of B-vitamins (/d): thiamin 0.06 mg, riboflavin 0.25 mg, nicotinic acid 1.1 mg, folate 10 μg, vitamin B6 0.25 mg, vitamin B12 0.7 μg, pantothenic acid 0.9 mg, biotin 2.2 μg.

1. Weanling rats, aged 21 d, given a 40 g casein/kg diet for 25 d were compared with ‘age-matched’ controls given a 200 g casein/kg diet and with ‘weight-matched’ weanling controls.

2. The protein-malnourished rats demonstrated failure of weight gain and linear growth, hypoproteinaemia, hypoalbuminaemia and fatty liver.

3. Autoradiography of the tibia was carried out 24 h after intraperitoneal injection of Na235SO4 (0.1, 1.0, 2.0, 5, 10 μCi/g body-weight). Sections of tibia, humerus and costochondral junction were stained by haematoxylin and eosin, resorcin-crystal violet and picro-fuchsin, Alcian Blue at pH 0.1 and pH 2.5, Alcian Blue at pH 5.7 with magnesium chloride (0.1, 0.7, 1.0 m), and by Alcian Blue after ovine testicular hyaluronidase (EC 3.2.1.35) digestion. The width of the upper tibial epiphysis was measured and the histological and histochemical features of the epiphyses studied.

4. The incorporation of 35SO4 into the epiphyses of the protein-malnourished animals was markedly reduced. The chondrocytes were small and flattened with frequent pyknotic nuclei. The staining characteristics of the cartilagenous matrix was qualitatively similar in all animals. The epiphyses in malnutrition were found to be thin, all zones being affected. The upper tibial epiphyses (mean±sd; μm) were 202 ±46 for the protein-malnourished animals, 367±52 for age-matched controls and 578±40 for weight-matched controls.

5. The changes found resemble those after hypophysectomy and the possible hormonal factors are discussed.