1. The endogenous nitrogen losses of men of different ethnic, ecological and socio-economic backgrounds are similar when calculated per unit body-weight or per unit basal energy consumption. The hypothesis that endogenous N losses, adjusted upwards by a factor of 0.30 to equate them with N equilibrium, can be used to derive man's physiological requirements for proteins of high quality, e.g. those of egg and milk, was studied..

2. Men living in Nigeria, accustomed to eat diets which provided mixtures of protein only slightly higher than the ‘safe level of intake’ proposed by the Joint FAO/WHO ad hoc Expert Committee on Energy and Protein Requirements (FAO/WHO, 1973), were found to use absorbed N more efficiently than University of California students who habitually consume diets which supply a great excess of protein over that ‘safe level’..

3. The greater protein-sparing effect of carbohydrates than of fats and oils may play a part in this more efficient use of protein by men living in developing countries. Also, man possesses mechanisms in intermediary metabolism which allow him to adjust to low levels of protein intake..

4. Thus it appears that all apparently healthy men cannot be considered equal in regard to their requirements for protein.

1. A 21 d slaughter trial was done using weanling male rats offered sodium chloride added at 10, 20 and 30 g/kg to a nutritionally adequate, control diet containing 13 g NaCl/kg, or added to the drinking-water at 5, 10, or 15 g NaCl/l. Food and drinking-water with or without NaCl were offered ad lib. and their intakes were measured..

2. NaCl in the food reduced food intake by 10–15%; NaCl in solution reduced food intake only when added at the 15 g/l level; the reduction was 25%..

3. NaCl increased the fluid intake of the rats; for NaCl in the food the increments ranged from 23 to 44%; for NaCl in the drinking-water they ranged from 44 to 229%..

4. Body fat was significantly reduced by 20 and 30 g NaCl/kg added to the control diet, indicating a reduction in the efficiency of fat synthesis. Comparable amounts of NaCl taken in the drinking-water had a negligible effect on fat deposition..

5. It is suggested that NaCl in the food produces hypodipsia, i.e. a failure to drink an optimal amount of water, causing changes in the electrolyte balance which reduce food intake and progressively reduce the efficiency of fat synthesis.

1. Two diets, an all-roughage diet and a high-concentrate diet, were fed at two levels, a low level of estimated 1.5 times maintenance energy requirement and a higher level of estimated two times maintenance energy requirement, to South African Mutton Merino castrated male sheep, aged 13 months and in fairly lean condition at the start of the 93 d experimental period..

2. Body composition and energy retention were determined using the comparative slaughter technique and two series of digestibility and balance studies were done during the course of the experiment. Metabolizability of each diet was estimated and corrected for fermentation heat using the fermentation balance approach..

3. Although there were significantly different rates of energy gain on different diets and feeding levels, fat energy gained (% total energy gained) was similar for the four groups, i.e. 78–80..

4. Regression of energy gain v. corrected metabolizable energy (ME) intake indicated that the maintenance energy requirements of sheep used in this experiment were 310.2 and 302.3 kJ ME/kg body-weight0.75 per d and the values for net utilization of ME for body energy gain were 0.411 and 0.479 with the roughage and concentrate diets respectively..

5. It was concluded that the estimated maintenance energy requirements of sheep obtained in this study are realistic values and that the efficiency of utilization of surplus ME for the two diets did not differ significantly.

1. The nutritional status of children showing no clinical signs of malnutrition, from the University School of Khon Kaen, Khon Kaen province, north-east Thailand and from two villages nearby, was tested. The children were grouped according to their body-weight expressed as a percentage of expected weight-for-height (Harvard standards (Stuart & Stevenson, 1959), as given by Jelliffe (1966))..

2. The differing prealbumin concentrations indicated that nutritional status differed between the groups..

3. The urinary urea: creatinine ratio was significantly lower in the village children compared with the children from Khon Kaen, indicative of the higher dietary protein intake of the latter..

4. α1-Acid glycoprotein and the first ‘post-albumin peak’ (obtained by polyacrylamide gel electrophoresis of serum and containing mainly Gc-globulin, α1-antichymotrypsin and α1-B-glycoprotein) were found to be significantly higher in the village children compared with children from Khon Kaen..

5. The three main proteins of the first ‘post-albumin peak’ from polyacrylamide gel electrophoresis of serum were tested separately using the electroimmunoassay method. There was no significant difference in Gc-globulin between the children from Khon Kaen and the village children. The concentration of α1-B-glycoprotein from those Khon Kaen children whose body-weight was more than 95% expected weight-for-height was significantly lower compared with that of village children. α1-Antichymotrypsin concentration was significantly higher in serum from Khon Kaen children than in serum from village children.

1. The results obtained for 236 Viennese schoolchildren between 11 and 12 years of age indicated that 38% of children had an increased concentration of cholesterol in their serum and 3% had an increased serum triglyceride concentration..

2. The results of the preliminary study suggested that, by extending the dimensions of the screening, further problems, for example the correlation between different ‘risk’ factors and the significance of nutritional habits, might be studied.

1. Food intake and energy expenditure were determined on 500 soldiers drawn from infantry, artillery and engineer units of the Indian army, for 3 months during winter..

2. The units were located in two different regions of India at altitudes varying from sea level to 2300 m..

3. The energy requirements were assessed from the actual food intake as well as from energy expenditure and from the changes in body-weight and skinfold thickness..

4. The nutritional adequacy of the diet was assessed from clinical examination and changes in blood haemoglobin concentration..

5. The mean energy expenditure was found to be 15.39 MJ (3679 kcal) and on this basis the energy requirement was 16.61 MJ (3970 kcal); energy intake was found to be 16.47 MJ (3936 kcal)..

6. The energy contributed by protein, fat and carbohydrate was 0.115, 0.240 and 0.645 of the total intake respectively..

7. There was no significant change in body-weight, blood haemoglobin level and skinfold thickness on this mean daily intake.

1. A study has been made by gel filtration techniques of the soluble copper-and zinc-binding proteins in livers from pigs of different Zn status..

2. The distribution of both Cu and Zn between the three fractions isolated was greatly influenced by the Zn status of the animal. In livers from pigs given a Zn-supplemented diet the proportion of either Cu or Zn found in the fraction with a molecular weight of about 12000 (fraction 3) was a direct function of the total liver concentration of the metal. In livers from pigs given a low-Zn diet, only small amounts of Cu or Zn were present in this fraction, regardless of liver Cu content..

3. These results suggest that Zn may be essential for the stabilization of the metal-binding protein in this fraction.

1. Diets containing different proportions of skim milk and fat, either beef tallow or soya-bean oil, supplemented with fat-soluble vitamins were given to 2-d-old pigs. Each fat source was used in three diets containing approximately 280, 350 and 420 g fat, and 260, 235 and 210 g protein/kg dry matter respectively..

2. The diets were given as a milk containing 200 g solids/l during a 26 d experiment. The pigs were given the diet at hourly intervals according to a scale based on live weight..

3. Increasing the energy content of the diet, with the accompanying decrease in protein content, had no effect on live-weight gain or feed: gain ratio (g feed dry matter/g live-weight gain) (other than a slight reduction in live-weight gain when beef tallow was used), or on nitrogen retention. However, the fat content of the carcass of the 28-d-old pig was increased, and its protein and ash content were decreased..

4. The apparent digestibilities of the fatty acid ranged from 0.96 to 1.00. The faeces from pigs given the soya-bean-oil diets contained some eicosanoic, docosanoic and tetracosanoic acids, presumably of bacterial origin. In general, palmitic and stearic acids were slightly less well digested than oleic and linoleic acids.

1. Thiamin, riboflavin and pyridoxine status of ‘low-income-group’ mothers and their newborn infants was assessed by analysing paired samples of maternal and umbilical cord blood for erythrocyte transketolase (EC 2.2.1.1) (ETK), erythrocyte glutathione reductase (EC 1.6.4.2) (EGR), and erythrocyte aspartate aminotransferase (EC 2.6.1.1) (EAA) activities..

2. The vitamin status of the infants was better than that of the mothers..

3. Most of the mothers and some of the infants had biochemical evidence of thiamin and riboflavin defciency..

4. The pregnant women had a higher EAA activity and also higher stimulation with pyridoxal-5-phosphate than the non-pregnant women of the same community..

5. There was a significant correlation between maternal and umblical blood samples for ETK and EGR activities, but not for EAA activity or any of the coenzyme stimulation tests.

1. The effect on protein quality of treating a commercial rat diet by autoclaving at various temperatures for different periods of time, or by irradiation with 2.5 or 10 Mrd, was studied. True digestibility (TD) and biological value (BV) were measured and the available and total amino acids in the diets were estimated using microbiological and chemical methods..

2. Autoclaving at 121° for 60 min reduced BV, TD and net protein utilization (NPU) more than autoclaving at 134° for 3 min. Availability of amino acids was reduced by both treatments but to a greater extent by autoclaving at 121° for 60 min. Total amino acids were essentially unaffected. Irradiation had no effect on BV, TD, NPU or total amino acids, and the availability of amino acids was also unaffected, with the exception of lysine which was slightly reduced..

3. When the diet was autoclaved at 115 or 121° for 15, 30 or 60 min, or at 134° for 3 min the availability of the amino acids was reduced with increasing time and temperature of treatment. Treatment at 134° for 3 min had an effect on available amino acids similar to treatment at 121° for 15 or 30 min..

4. Ethylene oxide fumigation of the diet caused reduced availability of histidine, methionine and tryptophan but had negligible effect on arginine, leucine and lysine..

5. It is concluded that from a practical point of view irradiation causes least damage to proteins in rodent diets. If such diets are to be autoclaved they should be supplemented with complete protein to counteract amino acid destruction.

1. The observation that thyroid C cell hyperplasia occurred in rats given the iron-deficient diet described by McCall, Newman, O'Brien, Valberg & Witts (1962) prompted a closer study of the preparation and constituents of this diet..

2. It became apparent that there was a discrepancy between the amounts of fat-soluble vitamins in the dietary formulation reported and the supposed final content of the diet. A diet prepared as described by McCall et al. (1962) contains 1000 μg (40000 i.u.) ergocalciferol and 10 μg (14 500 i.u.) retinyl palmitate/kg..

3. An experiment was designed to study the effect of Fe-deficient and Fe-supplemented, high-vitamin-D diets, and an Fe-supplemented, normal-vitamin-D diet, on thyroid C cell volume and serum calcium concentration..

4. Thyroid C cell volumes and serum Ca concentrations were significantly higher in both groups given excess vitamin D than in the group given the Fe-supplemented, normal-vitamin-D diet. It is evident therefore, that hypervitaminosis D was the cause of the morphological and biochemical changes found in rats given the McCall et al. (1962) diet.

1. The thermic effect of a glucose load (50 g) was studied in ten control and eleven obese female subjects, using both direct and indirect calorimetry simultaneously. Experiments were done under conditions of thermal equilibrium (28° and 30% relative humidity)..

2. Thermal balance (heat production measured by indirect calorimetry minus heat losses measured directly) was negative in the control group during the fasting period (heat deficit – 14.2 ± 5.0 kJ/m2 per h), whereas that of the obese group was in equilibrium (+ 1.4 ± 4.8 kJ/m2 per h)..

3. After the glucose load, metabolic rate increased 13.0 ± 1.5 and 5.2 ± 1.3% in the control and obese groups respectively..

4. In contrast to the metabolic rate, total heat losses were not significantly altered in either group after the glucose load. Total heat losses of the obese group were significantly lower than those of the control group throughout the experimental period..

5. During the experiments the amount of heat stored was increased in both groups. Thermal balance in the control group became positive while that of the obese group remained positive..

6. During the fasting period, the control subjects oxidized more carbohydrates (90.4 mg/min) than lipids (68.8 mg/min), whereas obese subjects oxidized more lipids (103.7 mg/min) than carbohydrates (50.2 mg/min). After the glucose load, the oxidation rate of carbohydrates was increased in both groups to 158.1 mg/min in control subjects and 95.6 mg/min in obese subjects..

7. The mean skin temperature of the control subjects was significantly higher than that of the obese subjects and remained higher throughout the postprandial period..

8. These results indicate that: (a) during the fasting period, the energy sources utilized and the thermal balance of the two groups were different; (b) the thermic effect of glucose was less in the obese subjects and, therefore, might be a factor contributing to their low energy expenditure.

1. A number of rumen bacteria isolated because of their ability to deacylate phosphatidyl-choline, were found, in addition, to hydrogenate polyunsaturated fatty acids..

2. The most active lipolytic organisms had an unusual pattern of hydrogenation of dietary fatty acids in that α-linolenic acid was hydrogenated only as far as trans-11,cis-15-octadeca-dienoic acid.