1. Lysozyme activity was estimated in plasma and leucocytes of twelve children suffering from kwashiorkor, thirteen children with ocular signs of vitamin A deficiency and ten apparently normal children acting as controls.

2. The results showed that the activity of lysozyme in leucocytes was significantly reduced in children with kwashiorkor and in vitamin A-deficient children. Following therapy, the levels of the enzyme in leucocytes were restored to normal.

3. The initial enzyme activity in the plasma of both groups of children did not differ significantly from the control value, and was not significantly changed after treatment.

4. It is suggested that the decreased activity of lysozyme is one of the factors responsible for diminished resistance to infection generally observed in malnourished children.

1. The capacity of animals to conserve branched-chain amino acids was assessed during 3 weeks on a protein-free (PF) diet in groups of female rats at three stages of development, i.e. at weaning (35 g), in a period of rapid growth (85 g) and at maturity (200 g).

2. Leucine and valine oxidation was assessed by monitoring the evolution of 14CO2 from a tracer dose of the [1-14C]-labelled L-amino acid given intragastrically. Activities of the L-leucine:2-ketoglutarate aminotransferase (EC 2.6.1.6) and α-keto acid dehydrogenase enzymes in leucine and valine metabolism were also determined in muscle and liver at weekly intervals.

3. All three groups of rats given a normal protein intake excreted the same proportion of the dose of labelled leucine and valine. In rats given PF diet there was a consistent reduction in 14CO2 output from both L-[1-14C]leucine and L-[1-14C]valine, but valine was not conserved as efficiently as leucine.

4. Muscle dehydrogenase responded to a PF diet in all three groups of rats, but the most marked changes occurred in the youngest group. In addition, there was a decrease in hepatic dehydrogenase activities for leucine and valine catabolism in the weanling group; in older animals there was little change in the α-keto-isovalerate, but a consistent decrease in the activity of the α-keto-isocaproic acid dehydrogenase. The difference in the responsiveness of the dehydrogenases, therefore, matched the difference between leucine and valine oxidation rates in vivo.

5. Weanling animals responded rather more efficiently than the older animals to the need to conserve amino acids and there was no evidence of a poorly developed system for adapting to PF intake at this early stage of development.

6. Despite reduced catabolism of the amino acids, aminotransferase activities in liver and muscle rose in the first 1–2 weeks on a PF regimen. Aminotransferase activity as such is unlikely to control acid oxidation.

1. A low-digestibility ryegrass hay was fed to sheep and the effect of supplementation with dried red clover on animal production and digestion was examined. Comparisons were made using other supplements containing (a) barley (isoenergetic with clover supplement), (b) barley and decorticated groundnut meal (isoenergetic and isonitrogenous with clover supplement), (c) barley, groundnut meal and mineral salts (containing an equivalent level of digestible energy, apparently digestible crude protein and minerals to those of the clover supplement).

2. Dry matter intake, digestibility of organic matter and live-weight gain were higher with clover supplemented hay than with hay alone, and the live-weight gain response to clover supplementation was comparable with the concentrate diet (supplement c), which supplied an equivalent level of digestible energy, crude protein and minerals.

3. The utilization of digestible energy for live-weight gain was significantly higher (P < 0.05) for clover than for hay, hay plus barley, and hay plus barley and groundnut meal. The utilization of the clover – hay mixture was similar to that of the hay plus concentrates and minerals and tended to be higher than that of the concentrate diet without minerals, although the difference was not significant (P < 0.05).

4. There was no significant difference between hay and clover diets in the proportions of volatile fatty acids found in the rumen, although there was a shift from acetate to butyrate production with the two diets containing groundnut meal.

5. The apparent digestibility of nitrogen for both hay and clover was low, but intake and retention was markedly increased with clover.

6. The intake and retention for all the minerals studied was better for the clover-supplemented hay and all-clover diets than for the hay diet, and the availability of sodium, potassium, magnesium, calcium and phosphorus was higher. The availability and retention of Na, K and Mg with the clover-supplemented hay diet were slightly lower than the mineral-supplemented diet, while those of Ca and P were higher.

1. Using a double-lumen tube jejunal perfusion system, the rate of glycine absorption from a glycylglycine solution (50 mmol/l) was measured in three groups of Zambian African subjects: in fifteen subjects there was no evidence of an infection (normal group); in eleven there was acute bacterial pneumonia and five had a chronic systemic infection.

2. Differences between the mean absorption rates for the three groups were not significant.

3. Glycine absorption rate has been shown previously to be increased in subjects with acute bacterial pneumonia. The present result provides further evidence that glycine and glycylglycine use separate transfer mechanisms in man, and suggests that dipeptide absorption rate is influenced to a lesser extent than that for free amino acids by systemic stimuli.

1. To assess the part played by the microflora in the digestion of proteins, the amino acid composition of the excreta and the apparent and true digestibilities of individual amino acids were measured in germ-free (GF) and conventional (CV) chicks.

2. Three diets were used: diet 1, nitrogen-free; diet 2,280 g protein/kg as (g/kg): casein 80, gelatin 100 and freeze-dried egg albumen 100 and diet 3,280 g protein/kg as diet 2 but with heat-damaged instead of freeze-dried egg albumen. Half of the GF and half of the CV chicks received the N-free diet in the first 7 d of test and the other half of each group received either diet 2 or diet 3. In the second 7 d test period those chicks which had been given the N-free diet received either diet 2 or diet 3 while those which had been given protein diets received the N-free diet. Total amino acids were measured in hydrolysates of the soluble and insoluble fractions of the excreta collected in the last 3 d of each test period.

3. The amino acid composition of the soluble fraction of the excreta of chicks given either diet 2 or diet 3 differed markedly from that of chicks given the N-free diet. The amino acid composition of the insoluble fraction of the excreta of chicks given diet 2 was similar to that of chicks given the N-free diet, whereas that of chicks given diet 3 was markedly different and resembled egg albumen in composition.

4. In the soluble fraction of excreta from CV chicks given diets 1 and 2 the proportions of threonine, serine and glucosamine were lower and those of methionine, leucine, isoleucine and phenylalanine were higher than in those from GF chicks, particularly on diet 1. In the insoluble fraction of excreta from CV chicks given these two diets, compared with GF chicks, there were lower proportions of serine and proline and higher proportions of cysteic acid and lysine, the latter particularly with diet 1.

5. Lower proportions of threonine, serine and glucosamine were also observed in the soluble fractions of excreta from the CV chicks given diets 1 and 3, compared with GF chicks, whereas the proportion of glutamic acid was higher. With these two diets the insoluble fraction from CV chicks contained a higher proportion of alanine. In each instance the environmental effect was greater with diet 1.

6. No effect of environment on either apparent or true digestibility of individual dietary protein amino acids was demonstrated, with the exception of threonine in diet 2, the true digestibility of which was higher in GF than in CV chicks.

7. It was concluded that the gut microflora of the chick had little influence on the digestion of the proteins in the diets tested, but may serve an important role in the degradation of endogenous proteins and the recycling of N.

1. Pigs were fitted with re-entrant duodenal cannulas anterior to the pancreatic duct, and total collections of digesta were made for 12 h periods.

2. Maize–soya-bean diets were made from maize which had been harvested with a dry-matter content of 770 g/kg and either dried, preserved with acetic or propionic acid or ensiled naturally. The pigs received two meals of these diets/d at 12 h intervals, and the amount of digesta flowing through their cannulas was measured.

3. Between 4.5 and 5.25 l of digesta flowed through the cannulas in the 12 h collection period, 0.9 of the total 12 h flow passed through the cannulas in the first 9 h with the dry-maize diet and 0.8 with the acid-treated-maize diets.

4. The mean total dry matter intake was 358 g/meal, and 304 g dry matter passed through the duodenal cannulas in the 12 h collection period. The corresponding intake and flow of nitrogen (g/12 h) was 11.1 and 9.6, and for chromic oxide 1.13 and 0.94.

5. The pigs consumed 205 g starch (total α-linked glucose polymers)/meal, and 1.5 g free glucose/meal. Only 110 g starch and 4.1 g free glucose reached the duodenal cannulas, suggesting that digestion and absorption of up to 92 g glucose had taken place anterior to the pancreatic ducts.

1. Digestion of grass lipids and pigments in the rumen of the sheep has been studied during starvation and following the administration of 14C-labelled grass.

2. Both galactolipids contained in chloroplasts are rapidly degraded, although mono-galactosyldiglycerides disappear faster than digalactosyldiglycerides. It was concluded that rumen micro-organisms are mainly responsible for this degradation, although grass itself also contains enzymes which can degrade galactolipids.

3. Rumen contents can degrade added 14C-labelled mono- and digalactosyldiglycerides in vitro at a rate sufficient to account for the disappearance of galactolipids in the intact rumen. The initial enzyme attack is probably a successive deacylation to give monogalactosylglycerol and digalactosylglycerol.

4. Most of the chlorophyll pigments are rapidly converted into phaeophytins by loss of magnesium. A small proportion of chlorophyll a and more of chlorophyll b remains intact even after 24 h starvation. On the other hand, about half the phaeophytin undergoes further rapid decomposition to yield phylloerythrin.

5. Although the grass phospholipids are extensively degraded, β-carotenes and many non-polar compounds, e.g. steroids, appear to undergo little change in the rumen.

1. A study of the food intake, during a period of 7 consecutive days, was made on 192 boys and girls, aged 14 years, attending Glasgow schools in 1964. A similar study was done in 1971 on 419 boys and girls of the same age. The children came from all the various socio-economic backgrounds and were subdivided into four social groups.

2. The heights and body-weights of the groups studied in 1964 and 1971 were similar but the percentage contribution of fat to the body-weight had increased in the boys.

3. Between 1964 and 1971 there had been a decrease in the mean energy intake of both boys and girls of between 0.8 and 1.0 MJ (200–250 kcal)/d. A similar proportionate decrease had also occurred in the protein, fat, carbohydrate, calcium and iron contents of the diet. However, no individual had a very low intake of protein.

4. Only the boys of the poorest social group (4) showed a lower intake of nutrients than the other groups. There were almost no differences between the girls from the different socio-economic groups.

5. Eating school meals did not affect levels of total energy and nutrient intake.

6. The proportion of energy and nutrients derived from different food groups did not appear to have appreciably altered in the two surveys, although the amount of milk drunk had become less. Fish, eggs and cheese contributed surprisingly little to the diet.

7. The combination, in both sexes, of a reduction in energy intake in 1971 compared to 1964, together with, for the boys, an increased body fat content, could be accounted for by a marked reduction in physical activity.

8. Although a comparison of the energy intake of the fattest and of the thinnest boys showed no clear differentiation, there was a consistently lower energy intake, in all social groups, by the fattest girls (‘fattest’ 7.07 MJ (1690 kcal)/d; ‘thinnest’ 9.23 MJ (2207 kcal)/d).

9. These and other recent results suggest that the national (UK) recommended energy requirements, at least for this group, are too high.

1. A procedure for sampling digesta from within the omasal canal of sheep given a variety of roughage diets was used to enable comparison to be made of the composition of effluent from the reticulo-rumen with that of rumen fluid.

2. Concentrations of protozoa in effluents, relative to a soluble marker continuously infused intraruminally, were usually less than 20% of corresponding rumen fluid concentrations. It was estimated that the amount of protozoal nitrogen leaving the rumen represented less than 2% of dietary N.

3. Passage of volatile fatty acids (VFA) from the rumen in effluent was less than 75% of that indicated by rumen concentrations.

4. A continuous, in vitro fermentation system was developed, in which outputs of protozoa were comparable with in vivo outputs.

1. Twelve commercial samples of high-protein feeding-stuffs, six of them fish meals, were used for a study of the reproducibility of chemical, microbiological and biological assay values for individual amino acids. Comparisons were also made of results obtained by different methods for the same amino acid.

2. For lysine there was quite good agreement between the results from the different laboratory tests for ‘available’ lysine. The values for ‘total’ lysine were, on average, 10 % higher than those for ‘available’ lysine.

3. For methionine the correlations between the chick assay and each of the laboratory tests were similar.

4. The results from the ‘total protein efficiency’ test of over-all protein quality, using chicks, showed a close correlation with the results of lysine or methionine assays according to which of the two amino acids was most deficient.

5. The results with tryptophan were difficult to interpret and no recommendations could be made as to procedures suitable for general use.

6. Although most of the present samples proved to be of good quality, only screening of a much larger number of samples will reveal to what extent commercial protein concentrates of low availability are still liable to come onto the market.

1. Simple extracts of raw navy (haricot) beans (Phaseolus vulgaris L.) known to be toxic to conventional Japanese quail (Coturnix coturnix japonica) have been fractionated and tested for toxicity by feeding to this species.

2. Of the various fractions obtained during the biochemical purification of the phytohaemagglutinin, only those possessing agglutinating activity were found to be toxic.

3. The final purification stage yielded an homogeneous protein with both agglutinating and toxic properties.

1. Measurements were made, at 6 h intervals, of urinary nitrogen output and of the activity of some hepatic enzymes in the rat during adaptation from one level of dietary protein to another. The enzymes measured were arginase (EC 3.5.3.1), argininosuccinate lyase (EC 4.3.2.1), argininosuccinate synthetase (EC 6.3.4.5), glutamate dehydrogenase (EC 1.4.1.2) and alanine and aspartate aminotransferases (EC 2.6.1.2 and EC 2.6.1.1).

2. Completeness of urine collection, which was essential for these experiments, was checked by recovery of injected [131I]iodide.

3. When the dietary protein content was reduced from 135 to 45 g casein/kg, the urinary N output and the activities of the hepatic enzymes reached their new steady-state levels in 30 h. The reverse adaptation, from 45 to 135 g casein/kg, was also complete in 30 h.

4. The rate of change of enzyme activity and the final activity as percentage of initial activity were very similar for all six enzymes, suggesting a common control mechanism. The calculated half-lives of the enzymes were of the order of 7 h, which is very much shorter than those found by previous workers.

5. There was no simple relationship between the activity of the urea cycle enzymes and the amount of N excreted. When an equal amount of gelatin was substituted for casein the N output was doubled but there was no change in the activity of the liver enzymes.

6. The results suggest that the activity of the urea cycle enzymes depends in part on the amount of N available for excretion after the demands for synthesis have been met. The enzymes, however, appear to be present in excess so that an increased N load was not necessarily accompanied by an increase in enzyme activity.

1. The effects on gastric secretion of altering the amount and type of food eaten were examined in sheep with fundic abomasal pouches and in sheep which also had the antral region of the abomasum isolated into a pouch or removed (antrectomy). Secretion, which was continuous in all preparations, was collected over 24 h periods, and daily determinations of its acid and pepsin concentrations were made for periods of up to 10 weeks.

2. Experimental diets consisting of chaffed lucerne, meadow and wheaten hays were fed on ad lib. or restricted regimens.

3. Raising and lowering the dry matter (DM) intakes of lucerne chaff increased and decreased respectively the volume, acidity and acid and pepsin outputs (volume x concentration of acid or pepsin) of fundic pouch secretion.

4. Increases of 27–64% in the amount of lucerne chaff eaten, after changing from restricted to ad lib. feeding, were followed by increases in the volume (19–66%), acid concentration (4–10 mequiv. H+/l, 3–9%) and acid output (18–76%) of pouch secretion.

5. With DM intakes of mixed lucerne and wheaten chaffs between 88 and 107% of those of lucerne, the secretion from the pouches was reduced to 45–88% of the volume and 39–77% of the acid output observed with the lucerne diet. Acid concentration was least affected, being unchanged in one series of observations and decreased by, at the most, 13 mequiv. H+/l (12%) in another. Reverting to a diet of lucerne chaff reversed these effects: the volume was increased by 30–49%, acid concentration by 2–15 mequiv. H+/l (2–14%), acid output by 38–68% and pepsin output by 30–43% although the intake of DM was the same or 6% less than that on the wheaten chaff mixture.

6. Secretion was greater when animals ate lucerne chaff than when they ate meadow chaff.

7. The changes in secretion according to diet were obtained in animals with antral pouches and antrectomy as well as in those with only fundic pouches.

8. It is argued in discussion that the markedly different abomasal secretions on different diets arise from abomasal stimulation due to the nature rather than the amount of digesta entering it and that although the pyloric antrum contributes to these changes it is not essential for their occurrence.

1. The Knoop test of hardness applied to samples of finger nails from 334 healthy and 147 malnourished individuals showed statistically significant differences in the mean hardness of the nails of the two groups.

2. The hardest nails were those of Filipino infants and children suffering from protein-energy deficiency. The softest nails were those of children in Guatemala recovering from protein-energy deficiency. Ranking of hardness appeared to be related to the severity and duration of protein-energy depletion.

3. In children up to 12 years of age, hardness did not appear to be influenced by the age, sex, and racial origins of individuals or the environmental conditions to which nail specimens were exposed.

4. Further studies are required to correlate hardness with clinical, biochemical and anthropometric measurements of nutritional status during protein-energy deprivation and during recovery. The causes of the differences in hardness need to be explored.