1. Serial measurements of total body potassium were made in children while they were malnourished and as they recovered. Initially, there was a low total body potassium which rose slowly and reached the normal levels of 45 m-equiv./kg at 3–4 weeks after admission to hospital.

2. The early stages of recovery were divided into three phases. In the first 5 days of treatment, retention of potassium served to correct a true potassium deficiency and the amount of potassium retained during this phase was related to the initial level of total body potassium. There was no relationship between serum potassium and total body potassium. There was indirect evidence that antecedent diarrhoea was an important factor in the production of potassium depletion.

3. In the next phase—the lag phase—potassium was retained in relation to deposition of new body tissue.

4. In the phase of rapid growth, potassium was also retained in the amount appropriate for deposition of new tissue.

5. After the repair of the acute potassium depletion, potassium retention was always correlated with the protein intake.

1. Chicks were reared to 3 weeks in a germ-free or conventional environment on diets containing 50% raw or heated soya-bean meal. Body-weights and pancreas weights were determined and the proteolytic and amylolytic enzymes in the pancreas were measured. In one experiment the contents of the intestinal tract were analysed for their content of nitrogenous compounds.

2. The growth of chicks given raw soya was depressed below that of controls given heated soya, and the growth depression was significantly greater in the conventional compared with the germ-free environment.

3. The pancreases of chicks given raw soya were significantly larger than those given heated soya. The degree of enlargement was similar in both environments. The concentration of α-amylase was lower in the enlarged pancreases, but the total amount per pancreas was similar to that in the normal pancreases. Conversely, the concentration of proteolytic enzymes was the same or greater in the enlarged pancreases, which had significantly greater total content of proteases than did the normal pancreases.

4. There was evidence of impaired protein digestion in the birds given the raw soya diets. Their gut contents contained larger amounts of insoluble matter, with higher nitrogen content, and the soluble fraction contained more nitrogen present as ‘protein’, with correspondingly less ‘peptide’ and ‘amino acid’, than did similar samples from birds given heated soya. No differences were observed in this respect between germ-free and conventional birds.

5. It was concluded that the gut microflora exacerbated the growth-depressing effect on chicks of raw soya meal. Possible explanations are advanced.

1. The absorption of the amino acid components of two protein-containing test meals has been studied in six healthy volunteers. One meal contained 15 g of milk protein and the other contained 15 g of gelatin. In a control experiment a meal was given which contained a negligible amount of protein.

2. The subjects were intubated with a single lumen tube; then each meal was swallowed and intestinal residues were obtained from known levels. The amino acid composition of the intestinal contents was compared with that of the original meal. Correction was made for net water shifts by reference to a non-absorbable marker compound (polyethylene glycol 4000).

3. The results showed that at least 70–75% of the milk protein test meal had been absorbed when the sampling holes were 230 cm from the nose. It is suggested, however, that most, if not all, of the meal had been absorbed when the sampling holes were 140 cm from the nose.

4. Amino acids were absorbed at rates proportional to their concentrations in the meal.

5. Gelatin, a protein known to be relatively resistant to enzymic hydrolysis, was poorly absorbed from the region of the small intestine under study.

6. Estimates of the amount of endogenous protein secreted in response to the test meals ranged from z to 8 g, equivalent to 13–53% of the protein containing test meals.

7. The absorption of certain amino acids, e.g. the dicarboxylic amino acids, was more rapid than was expected; glutamic and aspartic acids are absorbed slowly from a mixture of amino acids, both in vitro and in vivo.

1. Intestinal contents, collected from the human jejunum after a test meal (milk-protein, gelatin or low-protein) were fractionated by centrifugation and gel filtration on G-75Sephadex. The fractions were hydrolysed and the proportion of the total amino acid in each fraction was determined. The amino acids were measured with an EEL Amino Acid Analyser.

2. The free amino acid concentrations were determined in samples of the contents of the small intestine collected from various levels after the three types of test meal.

3. Intestinal contents collected from two levels of the jejunum after a milk-protein meal, were incubated in vitro at 37° for periods up to 80 min and the rates of release of the individual free amino acids were determined.

4. There was a rapid breakdown of the proteins of the test meals to fragments of molecular weight under 5000. The further breakdown (during incubation in vitro) to free amino acids was sufficiently rapid to account for the absorption in the free form of arginine, lysine, tyrosine, valine, phenylalanine, methionine and leucine. It was not rapid enough to account for the absorption of glycine, threonine, serine, the imino acids or the dicarboxylic amino acids in the free form.

5. The free amino acid concentrations in the intestinal lumen bore very little relationship to the concentrations in hydrolysates of the test meals or to those in hydrolysates of the intestinal contents. Many of the free amino acids in the intestinal samples were present in approximately equimolar concentrations.

6. It is suggested that experiments in which amino acid mixtures, simulating a dietary protein, are fed to experimental animals to determine the rates of amino acid absorption do not present a true picture of the events in the small intestine following the ingestion of a protein meal.

1. Isoalloxazines were characterized and measured in the caecum of two conventional rabbits kept on an adequate diet, two rabbits on the same diet from which vitamin B2 (ribo-flavine) had been omitted and five germ-free rabbits which were also on the adequate diet.

2. Riboflavine (up to 12mg) unaccompanied by any of its degradation products was found in the caecum of germ-free rabbits and 8–9 μg per ml were found in their urine.

3. Hydroxyethylflavine (4–5 mg) accompanied only by traces of riboflavine was found in the caecum of conventional rabbits.

4. There was about 1% ash in the contents of each of five germ-free and two conventional caecums.

5. The five germ-free caecal contents averaged 22.4% of the animal's body-weight. For four conventional animals this figure was only 10.5%.

6. In the caecum of each of two conventional rabbits kept on a diet deficient in riboflavine neither riboflavine nor hydroxyethylflavine was found but there was somewhat less than 1 mg of a yellow-fluorescing material of low RF value in each caecum.

7. The results are discussed in relation to the authors' previous reports on metabolites of riboflavine.

1. Emulsions with egg phosphatides of nine synthetic triglycerides (tributyrin, tricaprylin, tripelargonin, tricaprin, trilaurin, trimyristin, tripahitin, triisostearin, triolein) and of rapeseed oil and a proprietary emulsion of cottonseed oil were given as continuous infusions into the jugular vein of lactating sows. The effects of the infusions on the concentration and composition of blood plasma lipids and on the composition of milk fat were determined.

2. The infusions did not affect the concentrations in blood plasma of cholesterol, phospholipid or cholesterol esters, but there was a tendency for the concentration of plasma triglycerides to be increased which was most pronounced for the infusions of longer-chain triglycerides. The fatty acid composition of the plasma triglycerides was not altered by the infusion of tributyrin, except that there was an increase in the content of oleic and a decrease in that of linoleic acid. With other infusions the composition of the plasma triglycerides was altered towards that of the infused material and the effect was more marked for the longer-chain triglycerides, with the exception of triisostearin.

3. The changes in the composition of the milk fat reflected those in the composition of plasma triglycerides, with two exceptions. The infusion of tripalmitin was associated with an increase not only in the palmitic acid content of milk fat but also in the palmitoleic acid content. Also, the changes in the content in milk fat of eicosenoic acid and, more especially of erucic acid during the infusion of rapeseed oil were much less than the corresponding changes in the plasma triglycerides.

1. The nature of the complexes of zinc, manganese and copper which occur in ryegrass has been examined as part of a study of the availability of these metals to ruminants.

2. Ryegrass labelled with 66Zn was produced by water culture. A large proportion of the Zn could be extracted with aqueous ethanol and with water. The remainder of the Zn was liberated on peptic digestion and on treatment with a fungal cellulase.

3. The aqueous ethanolic extract was examined by a combination of gel filtration and thin-layer chromatographic and electrophoretic techniques. The results showed the presence of closely related complexes of Zn of low molecular weight. These were of limited stability and their behaviour was dependent on pH.

4. The value of electrophoresis in free solution as a fractionation technique for the soluble forms of Cu, Zn and Mn from ryegrass was demonstrated. Soluble Mn from was found to exist in a single cationic, perhaps non-complexed form, whereas several anionic Cu and Zn complexes were present in closely related forms.

1. The mean retention time of stained food residues was longer in sheep maintained on a chopped straw ration than in sheep maintained on a chopped lucerne ration.

2. Infection of sheep with 1500 infective Oesophagostomum columbianum juveniles was associated with increased mean retention times.

3. The extent to which the mean retention times were increased was associated with the diet and mode of infection of the sheep.

4. It was noted that an increase in mean retention time following infection was associated with a general decrease in food intake per kg live eight0.75.

5. The results are discussed in relation to the pathogenesis and survival of O.columbianum infections in sheep.

1. Children attending a boarding school in the New Guinea highlands, and receiving a protein-deficient diet of sweet potato and taro showed, when compared with village children, a progressive retardation of growth which was related to the number of years at school.

2. Feeding of supplementary protein resulted in a dramatic acceleration of growth in both height and weight, whereas the feeding of extra calories produced an increase in only weight and skinfold thickness.

3. This response to protein feeding appears to be greater than previously reported in the literature.

1. Regular estimations of dietary intake, body-weight, skinfold thickness, blood pressure and pulse rate, and serum lipids were made in twenty-four members of an Antarctic expedition over 1 year.

2. The mean levels of serum total cholesterol, phospholipids, and triglycerides were 198.5 ±4.85 mg/100 ml, 221.4±5.73 mg/100 ml and 120.9±13.53 mg/100 ml respectively.

3. A positive correlation was found between the total intake of fat expressed as calories and the following serum lipid levels: total cholesterol, β-cholesterol, and the cholesterol:phospholipid ratio. Significant positive correlation was also found between the latter serum levels and fat when expressed as a percentage of the total food intake.

4. This correlation has not been found in small groups before, and is due to the fact that each estimation was the result of several assessments made over 1 year.

5. The survey suggests that the personal serum cholesterol level may be dependent upon the habitual total intake of dietary fat and the percentage of the total calories supplied by fat.

1. Bovine plasma albumin (BPA) containing approximately 14% moisture, when heated for 27 h at 115° suffered an appreciable loss of cystine and a small loss of lysine; at 145° all the amino acids except glutamic acid and those with paraffin side-chains, showed considerable losses. Isoleucine also showed some loss through racemization to alloisoleucine.

2. BPA heated at 115° evolved H2S; at 145° other sulphur compounds were released as well, all coming from the breakdown of cystine. Possible mechanisms for this are discussed.

3. Ammonia was also liberated from BPA heated at 115°. The degree of correlation of lysine binding in different proteins with ammonia liberation and amide changes has led us to suggest that the main reaction of ε-amino lysine groups is with amide groups of asparagine and glutamine. Reaction of ε-amino groups with carboxylic groups is thought to be less important.

4. Model experiments have shown that a reaction between amide groups and the e-amino group of lysine in proteins can occur at practical drying temperatures.

5. Reactions of the ε-amino group of lysine with destruction products of cystine is also considered to be partially responsible for the lysine binding in heated proteins.

1. Information was obtained on the activity and food intake of ninety-two boys and 186 girls aged 16–19 years over a period of 7 days. Seventy-four boys and 132 girls were students, and eighteen boys and fifty-four girls were employed.

2. Each subject recorded daily activity on a chart divided into squares corresponding to 5 min, using a code letter for each type of activity. The amounts of all foods and beverages consumed each day were recorded in a food diary.

3. The energy expenditure of each subject was estimated from selected values for the energy cost of each activity. The intakes of calories and nutrients were calculated from tables of food composition.

4. It was found that the subjects spent very little time in strenuous physical exertion. There were slight differences between the age-group and the occupation groups, but between 78 and 80% of the total time was spent in bed or seated, 14–20% in very light to light physical activity and only 1.5–4.4% in any activity greater than walking at an even pace.

5. The group means for estimated energy expenditure in kcal, with their standard deviations, were: schoolboys aged 16–17, 2780 ± 250; employed boys aged 16–17, 2890±240; schoolboys aged 18–19, 2710±280; employed boys aged 18–19, 2749±270; schoolgirls aged 16–17, 2030±170; employed girls aged 16–17, 2140±240; schoolgirls aged 18–19, 2040±190; trainee teachers aged 18–19, 1900±140; employed girls aged 18–19, 2070±160.

6. Group means for the intake of kcal were: schoolboys aged 16–17, 3040±540; employed boys aged 16–17, 2730±520; schoolboys aged 18–19, 3110±450; employed boys aged 18–19, 2700–170; schoolgirls aged 16–17, 2140±420; employed girls aged 16–17, 1910±310; schoolgirls aged 18–19, 2400 ± 310; trainee teachers aged 18–19, 2020 ± 330; employed girls aged 18–19, 2030±440

7. The employed girls aged 16–17 had lower intakes of calories and all nutrients than the schoolgirls of the same age.

8. No correlation was found between the weight and calorie intake of individual subjects, nor between their calorie intake and energy expenditure during the time interval studied. The results indicated that for these Australian subjects, calorie balance was not achieved over a period of a few days. This is in accord with evidence of workers in other countries.

9. The findings suggest the need for further studies on the nutritional status of Australian employed girls aged 16–17.

1. Assessments were made of the energy expenditure and food intake of five boys and four girls aged between 16 and 20 years.

2. The subjects recorded their activity over a 7-day period and weighed and recorded their food intake over the same period. The energy expended by them in performing specific activities, such as sitting, standing and walking, was measured by indirect calorimetry. The total daily energy expenditure of each subject was then counted. (Values were selected from the litera ture for the energy cost of the activities which we did not measure.)

3. The following range of values was obtained for the energy cost per min of various activities: sitting, 1.0–1.8 kcal, standing, 1.2–2.0 kcal; walking, 2.0–7.5 kcal; office work 1.1–1.9 kcal; laboratory work 1.4–2.3 kcal; playing table tennis, 4.6 kcal; riding a bicycle, 3.6–6.0 kcal; running, 5.2–7.5 kcal.

4. The means and standard deviations for daily energy expenditure and for calorie intake, respectively, expressed in kcal, of the individual subjects were: for the boys 2677±184 and 3348±668, 2285±91 and 2652±418, 2730±263 and 2985±625, 2638±338 and 2379±204, 2594±244 and 3150±692; for the girls 1939±234 and 2340±524, 2261±175 and 2064±376, 2131±148 and 2011±389, 2104±171 and 2454±469.

5. There was no correlation between the daily energy expenditure and calorie intake of any subject, nor was there any relation between the weight of individual subjects and either their total energy expenditure or calorie intake.

6. It is concluded that more precise methods of measuring the energy expenditure and calorie intake of individual subjects would need to be used in order to determine if there is any correlation between these two variables over short periods.

7. The results of this study tend to confirm the findings of other workers that calorie balance is only achieved over periods longer than 7 days.