1. Thirty-nine children suffering from protein–calorie undernutrition were classified into nineteen with kwashiorkor, twelve with marasmus and eight with nutritional oedema according to history, physical findings and laboratory investigations. Liver biopsy samples from these patients were extracted with lipid solvents and the phospholipids were fractionated into phosphatidylcholine, ethanolamine and serine, and sphingomyelin.

2. The total liver phospholipids were found to be reduced in kwashiorkor and the reduction was mainly in the phosphatidyl ethanolamine fraction. The decrease in phosphatidyl ethanolamine was probably due to an observed reduction in free serine content. The ethanolamine phosphatase activity of the liver was found to be high in kwashiorkor.

1. Young rats were kept on a 6% casein diet for 4–7 weeks and then either killed or returned to a stock diet. Control rats were given a stock diet.

2. Argininosuccinate lyase (EC 4.3.2.1, L-argininosuccinate arginine-lyase) was assayed in liver, and amino acid activating enzymes were assayed in liver and muscle of rats after depletion and while they were refed on the stock diet. Levels of enzymes were compared with those in the control rats.

3. Amino acid activating enzymes were markedly increased in liver at the end of the depletion period, but returned almost to normal levels after 4–6 days of refeeding. In muscle the enzyme levels were not decreased after depletion, but began to rise after 4 days of refeeding.

4. Argininosuccinate lyase activity in depleted female rats was about half that in control rats and rose again slowly on refeeding. Male rats were hardly affected by depletion.

5. It is suggested that these enzyme changes play a part in the adaptation of the rat to a reduced protein intake.

1. When chicks were given a fat-free casein–gelatin diet and, after 2 weeks of age, 0·15% silver acetate in the drinking water, they were found to have colourless exudates mainly in the pectoral region and partly in the peritoneal and pericardial spaces. Vitamin E and selenium, separately and together, failed to prevent this condition. Vitamin E was required together with methionine to prevent the condition. Methionine itself induced green staining of a few of the exudates.

2. When lard was added to the casein–gelatin diet and the chicks were also given Ag, some green exudates were found in addition to the colourless ones. Addition of vitamin E or Se or both prevented the green exudates, but raised the incidence of colourless exudates. Methionine enhanced the green exudate condition, but again when combined with vitamin E prevented both types of exudate.

3. A similar condition characterized by colourless exudates was induced by giving chicks diets based upon gelatin, yeast BPC, α-protein (with extra salts) or α-protein with gelatin. A torula yeast diet induced green exudates and haemorrhages.

4. All the basal diets, which were deficient in sulphur amino acids, produced dystrophy of the breast muscle. Four of these diets contained no fat. Some diets also induced dystrophy of the gizzard. Vitamin E and Se protected against both these lesions. Methionine was protective in all except the torula yeast diet.

5. Ethionine induced muscular dystrophy in chicks given a vitamin E-deficient diet adequate in sulphur amino acids. Additional methionine or vitamin E was protective, but cystine was not. Ethionine also produced a small incidence of green exudates and slight haemorrhages. This condition was prevented by vitamin E but not by methionine. The liver damage due to ethionine was not prevented by vitamin E, methionine or cystine.

6. Liver necrosis was induced in rats by giving them an 8·3% casein diet and Ag, 130–1000 ppm, in the drinking water or the diet. Necrosis was produced even in the absence of dietary fat. Vitamin E and DPPD (N,N′-diphenyl-p-phenylenediamine) prevented necrosis, but adenine sulphate (0·25%), methionine (0·15%) and IONOX 330 (2,4,6-tri-(3′,5′-di-tert.-butyl-4′-hydroxybenzyl) mesitylene) did not. Se, 0·05 ppm, protected against 130 ppm Ag, but 1000 ppm Ag overcame the protective effect of 1 ppm Se. Similarly, 3 ppm cyanocobalamin was partly protective against 130 ppm Ag, but not against the higher concentration. Gold chloride (1000 ppm Au) had a mildly necrotic effect against which vitamin E did not protect. Neither copper sulphate (500 ppm Cu) not arsanilic acid (70 ppm As) induced liver necrosis.

7. A high intake of Se (20 ppm as sodium selenate) was necrogenic in rats given a 10% casein diet; vitamin E and methionine did not protect. Vitamin E and cystine raised the low incidence of an exudative condition found in rats given 20 ppm Se. Methionine opposed this action of vitamin E.

8. It was concluded that exudative diathesis in chicks could be resolved into a simple exudative condition and a superimposed haemorrhagic condition. Ag is a pro-exudative factor. Vitamin E and Se are also pro-exudative for chicks given the casein–gelatin–lard–Ag treatment. Torula yeast, methionine, lard, Ag (with lard) and ethionine are all pro-haemorrhagic factors. Se and Ag have an antagonistic relationship in rats and chicks; in chicks, however, Se synergizes with Ag when the supply of methionine is limited.

1. Groundnut flour plus lysine, fed to young rats at a high level as their sole source of protein supported weight gain and nitrogen retention equal to that on what has been considered the ‘ideal’ egg protein diet. For every 100 metabolizable kcal of the groundnut diet that were consumed, 41 came from the dietary protein and there was a net retention of protein equivalent to 14·5 kcal.

2. The predicted retention of protein according to the equations of Miller & Payne (1961) for this methionine-deficient protein source, given a score of 56 by FAO (1957), would have been equivalent to only 6·1 kcal and, whatever the level of such a protein in a diet, the maximum predicted retention would be equivalent to no more than 8·5 kcal, or 60% of the best expected with egg as the protein source.

3. Feeding a lysine-deficient protein source, wheat gluten, at high levels also gave a greater N retention than had previously been predicted.

4. It is concluded that the Miller & Payne (1961, 1963) equations can greatly under-estimate the performance to be obtained from feeding poor proteins at high levels. A revised equation (P. R. Pane, Private communication) predicts much higher results under these conditions.

1. The same six high-protein diets that were fed to rats (Carpenter & Anantharaman, 1968) have now been fed to chicks.

2. The net nitrogen retention by chicks, per 100 kcal consumed, was for each diet greater by 20–50% than the retention by rats. For a diet based on a mixture of commercial protein concentrates the NDpCal % was 19·1 (± 0·18); this value greatly exceeded the theoretical maximum of 14·6 obtained from the equations of Miller & Payne (1963).

3. Although groundnut protein plus lysine has a calculated chemical score of only 56, chicks receiving this at a high level retained N at the same rate (NDpCal % of 17·5–17·9) as those receiving a diet which included egg protein at the level (26% of the dietary ME) predicted to be optimal for them.

4. The ‘endogenous + metabolic’ losses of N were in almost the same proportion to metabolic size for chicks as for rats.

1. Examination of the digesta from all regions of the avian digestive tract showed that volatile fatty acids (VFAs) were present in greatest concentration in the caeca and that they comprised mainly acetic, propionic and butyric acids.

2. All droppings contained VFAs but they were present in highest concentration in those of caecal origin. Caecectomy was followed by a marked reduction in the total output of VFAs.

3. Birds 14–20 weeks of age had similar concentrations of VFAs along the tract and similar numbers and distribution of micro-organisms.

4. Portal blood contained all the VFAs found in the digestive tract whilst peripheral blood contained only acetic and formic acids.

5. The almost complete absence of VFAs from the tract contents of germ-free birds showed that the VFAs normally present in the tract were of microbial origin.

6. The presence of similar levels of acetate in the peripheral blood of conventional and germfree birds indicated that circulating acetate was mainly of endogenous and not microbial origin.

7. The significance of VFAs as an energy source is discussed.

1. Fifty-one pregnant fine-wool Merino ewes were slaughtered at intervals during pregnancy. The gravid uteri were dissected and were separated into uterus, membrane and fluid, and foetus fractions, which were analysed separately for water, nitrogen, ash, fat, calcium, phosphorus, sodium and potassium content.

2. Uteri from twenty-one similar non-pregnant ewes were also analysed for these constituents.

3. A number of relationships between the composition of the gravid uterus minus the composition of the uterus taken from non-pregnant sheep, and time from conception were calculated.

4. The rate of nutrient deposition was calculated from these relationships and estimates were made of the nutrients utilized for pregnancy.

1. The purpose of this paper is to propose the measurement of scalp hair diameter as a useful index of protein synthesis in the management of cases of malnutrition.

2. Observations on scalp hair from ten control infants showed that each hair tapered very gradually towards its free end.

3. Observations on scalp hair from twenty-six infants with kwashiorkor showed that each hair narrowed towards the follicle; the effect was statistically significant.

4. After I month's treatment for kwashiorkor, scalp hair thickened towards the follicle and the effect was statistically significant.

5. Serial measurements of the greatest diameter at 0·5 mm intervals along the hair shaft had a main trend which was related to nutritional history.

6. The period of time over which narrowing of the hair shaft took place was calculated from the rate of hair growth and the serial diameter measurements: this time was always longer than the history of kwashiorkor.

1. Total lipids were extracted from digesta obtained from the rumen, abomasum and upper small intestine (jejunum) of each of four slaughtered sheep. The lipids were fractionated into unesterified fatty acids, neutral lipids and phospholipids and the proportional contribution of each fraction to the total fatty acids was determined.

2. The contribution made by phospholipids to the total fatty acids in the digesta showed a marked increase in the samples from the small intestine compared with those from the rumen and abomasum. This increase was apparently due to the presence of biliary phospholipids.

3. Total lipids and conjugated bile acids were extracted from sheep bile, the lipids were fractionated and their fatty-acid composition was determined. Phospholipids predominated and these consisted mainly of phosphatidylcholine, together with some lysophosphatidylcholine.

4. Both phospholipids contained significant amounts of unsaturated C18 components which could account, at least in part, for the previously reported increament to the proportion of these acids in the digesta when it enters the upper jejunum.

5. The overall fatty acid compositions of the two biliary phospholipids were very similar and, in common with other naturally occurring phosphatidylcholines, the fatty acids present in position 2 of the phosphatidylcholine of bile were found to consist almost entirely of unsaturated components.

6. Total lipids and conjugated bile acids were extracted from samples of digesta obtained from three sheep with cannulas in different positions in the jejunum. Analysis of the lipids indicated that biliary phospholipids, in particular phosphatidylcholine, underwent progressive hydrolysis in the intestinal lumen.

7. The distribution of conjugated bile acids, unesterified fatty acids and phospholipids between the solid (particulate) and liquid (micellar) phases of the intestinal digesta was determined. These chyme constituents were, for the most part, associated with the particulate matter and thus, at any given time, it appears that only a small fraction of the total fatty acids is available for absorption in micellar form. It is suggested that the micellar solubilization of fatty acids may be facilitated by the presence of lysophosphatidylcholine.

1. Three sheep, each of which was fitted with a rumen cannula and with two pairs of reentrant cannulas in different parts of the small intestine, were used in this study. They were fed on dried grass cubes or hay plus linseed meal and oats: an aqueous solution of polyethylene glycol (PEG) was infused continuously into the rumen.

2. Total lipids were extracted from samples of the chyme entering and leaving the different lengths of the small intestine embraced by the respective cannulas. The lipids were fractionated into unesterified fatty acids, neutral lipids and phospholipids and the contribution of each fraction to the total fatty acids was determined. The samples were also analysed for their PEG content, thus affording an index of the extent to which water had been absorbed from each particular length of intestine.

3. From the above findings and a knowledge of the flow-rate of the digesta, the uptake of unesterified fatty acids and the degree of dissimilation or uptake, or of both, of esterified fatty acids was calculated.

4. The results indicated that, by the time the digesta reached the ileum (i.e. the distal half of the small intestine), the uptake of fatty acids was almost complete, as was also the hydrolytic release of esterified fatty acids.

5. Though there were no gross differences in the overall composition of the unesterified and esterified fatty acids in different parts of the small intestine, it appeared that C18 mono-unsaturated acid, the principal unsaturated unesterified acid, was absorbed somewhat more efficiently than were the major saturated acids (palmitic acid and stearic acid).

1. The quality of the protein in five high-protein mixtures intended for human consumption and made from materials that are available in Chile is reported.

2. The ingredients were fish flour, bread, wheat (Triticum sativum Lam.) flour, roasted whole wheat flour, a wheat flour made from a variety of durum wheat (T. durum Desf.), skim milk and sunflower presscake, mixed in different proportions.

3. The net protein utilization when fed to rats in diets at the 10% level of protein calories gave values in the range 66–76, which compare well with that (67), found for Incaparina, an all-vegetable mixture produced by the INCAP Group and used in Colombia, and are higher than the values (55 and 56) obtained for Peruvitas, which are mixtures made up basically from cottonseed and quinoa reinforced with dried skim milk.

4. The protein values of the mixtures, expressed as net dietary protein calories %, were calculated from their biologically determined net protein utilization (operative), and gave values that ranged from 10·5 to 12·8, which are higher than the recommended values in diets for infants and toddlers.

1. The flow of digesta to the abomasum and through the duodenum and terminal ileum was measured over 24 h periods in sheep. Pelleted diets of concentrates, principally composed of barley, and of poor-quality hay were given. The seven Scottish Blackface ewes studied were all fitted with rumen cannulas, and in addition two had simple abomasal cannulas, one a re-entrant abomasal cannula, two re-entrant duodenal cannulas, and two re-entrant ileal cannulas.

2. Paper impregnated with chromium sesquioxide was given twice daily by rumen fistula. The amounts of dry matter, starch, cellulose, total nitrogen and energy passing through the abomasum, duodenum and ileum and the amounts excreted in the faeces were measured. The flows of digesta were adjusted to give 100% recovery of chromium sesquioxide and the extent of digestion in various parts of the alimentary tract was calculated using these adjusted values. Concentrations of glucose in the blood and of volatile fatty acids (VFA) in the rumen were also measured.

3. For the concentrate diet, 69% of the digestible dry matter disappeared in the stomach (reticulo-rumen, omasum and abomasum), 17% in the smail intestine and 14% in the large intestine. Values for disappearance of digestible energy were 72% in the stomach, 23% in the small intestine and 5% in the large intestine. Of the 298 g starch fed daily only 6–35 g passed through the abomasum or duodenum and only 1–4 g reached the terminal ileum. The cellulose in the diet was poorly digested.

4. For the hay diet, 67% of the digestible dry matter disappeared in the stomach, 22% in the small intestine and 11% in the large intestine. Values for disappearance of digestible energy were 81% in the stomach, 7% in the small intestine and 12% in the large intestine. Of the 33 g of starch consumed daily, from 5 to 13 g passed through the abomasum or duodenum. The cellulose in the hay was 59% digestible and virtually all this digestion took place in the stomach.

5. The concentration of VFA and the proportion of propionate in the rumen fluid, 2·5 h after feeding, were considerably greater on the concentrate diet than on the hay diet, but diet had little influence on the concentration of blood glucose.

6. The importance of the small amount of starch passing to the sheep's small intestine is discussed.

1. Two young steers, aged approximately 6 months and each fitted with a rumen and an abomasal cannula, were used to measure the flow of digesta to the abomasum over periods of 24 h. A diet of concentrates, at two levels, and a diet of hay cubes were given to the steers. Paper impregnated with chromium sesquioxide was inserted into the rumen twice daily.

2. The amount of digesta passing to the abomasum and the output of faeces were measured and the values were adjusted to give 100% recovery of chromium sesquioxide. Measurements were also made of concentrations of plasma glucose, of volatile fatty acids (VFA) in both the rumen and abomasal fluid, and of rumen fluid volume and outflow.

3. About 60–80% of the digestible dry matter and of the digestible energy of both diets disappeared from the forestomach (reticulo-rumen and omasum). The amounts of starch flowing through the abomasum differed little between diets and ranged from 29 to 77 g daily.

4. The volume of rumen fluid did not differ consistently between diets, but the outflow of fluid from the rumen was considerably higher when hay was given.

5. Diet had little influence on plasma glucose but affected the concentrations and molar proportions of VFA in the rumen fluid, and to a lesser extent in the abomasal fluid.

1. In a balance study with young chicks estimates of nitrogen retention were made by a balance method and by a body analysis method.

2. N retention appeared to be about 15% greater by the balance method when no allowance was made for N in alimentary tract contents. Allowance for tract contents reduced the difference to about 13%.

3. Only about one-third of the discrepancy could be accounted for interms of the possible sources of N loss investigated.

4. About a quarter of the difference was due to loss of N on drying the droppings before analysis and another tenth to loss of N on freeze-drying minced chick tissues.

5. No appreciable loss of ammonia could be detected from chickens and excreta under conditions prevailing in the balance trial. The efficiency of digestion of feathers, uric acid and droppings from birds appeared to be complete by the Kjeldahl method employed.

6. A difference of about 8% could therefore not be explained.

1. ‘58Co’cyanocobalamin was given by stomach tube to Wistar albino rats aged between 6 h and 24 days. The fraction of the dose absorbed was assessed by measuring the amount retained by the animals after 7 days, by total body counting.

2. Rats up to 4 days old absorbed about 90% of the test dose, compared with a mean of 83% at the age of 8 days, 66% at 16 days and 47% at 24 days.

3. The proportion of the test dose absorbed did not appear to be affected by starvation for up to 24 h, by increasing the dose from 0·05 ng to 0·25 ng/g body-weight, or by giving the ‘58Co’cyanocobalamin mixed with rat's milk.

4. The results support earlier suggestions that newborn rats absorb vitamin B12 by a different mechanism from that in adults.

1. Details are given of modifications to standard pH measuring equipment enabling it to be used to record continuously the pH in the bovine rumen for up to 4 weeks. The operation of the apparatus and examples of its use are presented.

1. Numbers of erupted primary teeth were counted in young children in four rural villages in The Gambia. The ages of all children were precisely known, and their heights and weights were measured.

2. The majority of children were recorded as having an even number of teeth. The number of primary teeth present in children of given age varied widely. Up to 18 months of age, the Gambian children lagged behind American and European children in number of erupted teeth.

3. From the distributions, it appears that a child having no teeth is unlikely to be over 12 months of age, and one with all primary teeth is unlikely to be under 20 months. Between these dental limits, estimates of age from the number of primary teeth present are likely to be accurate to ± 3 or 4 months.

4. Children who were tall or heavy for age tended to have more teeth than those who were short or light. Thus, children with delayed dentition would be systematically assessed as younger than true chronological age.

5. There was, however, no evidence that slow growth was associated with prolongation of the total period of dental eruption, nor that seasonal variations in rate of growth were associated with similar variations in rate of tooth eruption.

1. Thirty-six nitrogen-balance measurements were made on children recovering from malnutrition. Two types of diet were used: a high-protein diet providing from 1·25 to 6·0 g protein/kg per day which supported normal growth, and a low-protein diet providing 0·75 g protein/kg per day on which the children were approximately in N balance. Both diets provided 120 kcal/kg per day.

2. The size of the labile protein pool was estimated from the N lost on changing from a high- to a low-protein diet. After the change of diet a new equilibrium was reached in about 3 days.

3. Labile protein, as defined above, represented about 1·2% of the total body protein on changing from 6·0 to 0·75 g protein/kg per day, and about 0·2% of total body protein on changing from 1·5 to 0·75 g protein/kg per day. The magnitude of the labile protein pool did not appear to be related to the nutritional state of the child.

4. It is concluded that the labile protein pool is not a reservoir which can be filled, but that losses of N which occur on reducing the protein intake of an infant reflect a lag in metabolic adjustment.