1. Total lysosomal hydrolase activities were measured in liver, gastrocnemius muscle and plasma of malnourished and normal rats between 3 and 8 weeks of age.

2. Concurrently, the DNA and protein contents of the livers and muscles were determined.

3. Increased amounts of acid hydrolase activities were found to be associated with subnormal protein: DNA ratios in the tissues of malnourished rats.

4. It was concluded that lysosomal enzymes may be involved in protein catabolism during malnutrition.

1. The effect of ammonia concentration on microbial protein production was determined in continuous-culture fermentors charged with ruminal contents obtained from steers fed on either a protein-free purified diet, a maize-based all-concentrate diet, or a forage–concentrate (23:77) diet. Urea was infused into the fermentors to maintain various concentrations of ammonia in the incubating mixtures.

2. Under nitrogen-limiting conditions, microbial protein yield measured as tungstic acid-precipitable N (TAPN) increased linearly with supplementary urea until ammonia started to accumulate in the incubating ingesta. Increasing the ammonia concentration beyond 50 mg NH3-N/l had no effect on microbial protein production.

3. The molar proportions of volatile acids produced were not affected by the level of urea supplementation. Total acid production was decreased slightly under N-limiting conditions, but not to the same extent as microbial protein production.

4. Estimated yield of microbial dry matter/mol ATP produced averaged 15·6 when non-limiting N as urea was provided with the purified diet.

5. These results suggest that addition of non-protein N supplements to ruminant rations are warranted only if the prevailing concentration of ruminal ammonia is less than 50 mg NH3-N/l ruminal fluid.

1. Experiments were conducted to determine the effects of the supplementation of carbohydrate-deficient fatty acid-based (FA) diets with 18·7, 37·5, 75, 150 and 300 g maize starch (MS)/kg on the growth and metabolism of the growing rat. Further, the effects of fasting on rats given the FA diet were compared with those given the high-carbohydrate (CHO) diet. Due to the significant decrease in food consumption of rats given the FA diet, the effects of pair-feeding the CHO and the FA diet were also investigated.

2. The isoenergetic replacement of fatty acids with increasing amounts of MS in the FA diet given to rats increased their weight gain and concentration of glucose in their plasma. These increases, however, tended to level off for weight gain and glucose concentration, respectively, at about 18·7 g and 75 g MS/kg diet. The same type of replacement decreased the concentration of ketones in the plasma but the decrease levelled off at the high concentration of 300 g MS/kg diet. Activities of liver glucose-6-phosphatase (EC 3.1.3.9) and glucokinase (EC 2.7.1.2) decreased and increased respectively with increasing concentration of maize starch in the diet. These changes tended to level off at concentrations of about 75–150 g MS/kg diet.

3. Fasting for 18 h decreased the concentration of glucose in plasma of both the FA- and the CHO-fed rats, while fasting of the CHO-fed rats depressed the concentration of glycogen in the liver but did not influence that of the FA-fed rats. Pair-feeding the CHO diet to the FA diet produced similar weight increases during the 8-week experimental period.

1. The development of vitamin B12 deficiency, as indicated by the serum and liver vitamin B12 levels and the excretion of methylmalonic acid, was studied over a 2-year period in baboons (Papio cynocephalus) given a diet deficient in vitamin B12. The effects of partial hepatectomy and the inclusion of either ampicillin or sodium propionate in the diet on the rate of development of the deficiency were also studied.

2. The baboons had previously been fed on a mainly vegetarian diet. Their serum vitamin B12 levels were less than 100 ng/l and the mean liver vitamin B12 concentration was 0·56 μ/g. Similar serum and liver vitamin B12 levels were found in baboons given a purified diet supplemented with 1 μg vitamin B12/d, and marked increases in the serum and liver vitamin B12 levels occurred when the daily intake was increased to 2 μg.

3. The serum vitamin B12 levels decreased to less than 20 ng/l in all baboons given a vitamin B12-deficient diet.

4. The liver vitamin B12 concentration also decreased in all baboons given a deficient diet. At 9 months the lowest levels (0·20 μ/g) were found in partially hepatectomized baboons but subsequently baboons given the diet containing ampicillin had the lowest levels (0·11 μ/g).

5. The excretion of methylmalonic acid after a valine load was found to be inversely related to the liver vitamin B12 concentration. In the early part of the study, partially hepatectomized baboons excreted the highest amount but subsequently baboons given a diet containing ampicillin excreted the highest amount.

6. Increased formiminoglutamic acid excretion after a histidine load was observed in two baboons given a vitamin B12-deficient diet and in both baboons the liver folic acid concentration was low.

7. No haematological or neurological symptoms of the vitamin B12 deficiency were observed.

1. Excessive amounts of food (70% greater than ad lib. intake) introduced into the gastrointestinal tract of young chicks were efficiently digested and caused increased growth resulting mainly from lean body substance and partially from fat deposition, more efficient energy utilization than the ad lib.-fed controls, increased relative weights of the crop, proventriculus, intestine, liver and abdominal adipose tissue. Pancreas relative weight was not changed and that of the gizzard was reduced.

2. The treatment also caused changes in blood plasma composition. Free fatty acid, trigly-ceride, α2-, β- and γ-globulin and pre-β-lipoprotein concentrations increased.

3. Fasting for 30 h caused higher body fat losses and lower body protein losses in the force-fed chicks than in the ad lib.-fed chicks.

4. The effects of over-feeding on body and blood plasma composition and differences found in these measurements during starvation are discussed.

1. Force-feeding of young chicks for 15 d increased kidney arginase (EC 3·5·3·1) activity threefold. Fasting for 30 h decreased this activity by 50%.

2. Liver xanthine dehydrogenase was slightly increased after force-feeding and decreased following fasting.

3. The specific activities of two pentose-phosphate-cycle enzymes were not significantly affected by force-feeding, but glucose-6-phosphate dehydrogenase (EC 1.1.1.49) decreased following fasting.

4. The over-all secretion of digestive enzymes increased parallel to the increase in food consumption. Therefore, despite an increased absolute weight of the pancreas and intestinal chyme, specific activities were the same in the force-fed and ad lib.-fed groups, except for a higher activity in intestinal amylase.

5. Fasting did not affect the pancreatic enzymic activities.

1. Parenteral administration of pyridoxal 5′-phosphate (PALP) to riboflavin-deficient rats increased the non-FAD component of erythrocyte riboflavin.

2. Pyridoxaminephosphate oxidase (EC 1.4.3.5) activity in the livers of riboflavin-deficient animals was only 15% of that of controls. PALP concentration in blood, liver and brain was not affected. Deficient animals had higher levels of pyridoxine in liver.

3. Human subjects with lesions of the mouth responded to treatment with either riboflavin or pyridoxine.

4. PALP concentration of human blood was not affected by administration of riboflavin but was markedly increased by pyridoxine.

5. Erythrocyte glutathione reductase activity (EC 1.6.4.2) in humans was increased and in vitro stimulation of the enzyme with FAD was decreased by treatment with riboflavin, but not by treatment with pyridoxine.

1. The object of the experiments was to estimate the maintenance requirements for lysine and leucine by a radioactive method. Rats were given a single dose of 14C-labelled lysine or leucine and groups of animals were killed after 15, 20 and 30 d.

2. After 20 d the specific radioactivity (SR) of protein was approximately the same in liver, muscle and viscera; it was somewhat lower in skin. Once uniform SR is achieved, the rate of loss of radioactivity is a measure of the rate of endogenous loss of the amino acid.

3. The rate of loss between 20 and 30 d was measured in two ways: from the daily output of expired 14CO2, and from the decrease, over the 10 d interval, of the total amount of radioactivity retained in the body.

4. For the first 15 d after administration of the labelled amino acid, all rats were given a low-protein or low-amino acid diet on which body-weight was maintained constant. For the second 15 d period some rats were kept on this diet; others were transferred either to a protein-free diet or to a diet lacking the specific amino acid (lysine or leucine) which had been administered in the labelled form.

5. The fractional rate of amino acid loss in the different experiments ranged from 1.5 to 3.5%/d, being greatest with the protein-free diet. The absolute rates of loss were calculated from measurements of the total lysine and leucine content of rats.

6. The best estimates of the rate of endogenous amino acid loss obtained in this way, expressed as mg/kg0.75 per d were: lysine 136, leucine 80. These estimates are higher than most estimates of maintenance requirements obtained by growth or nitrogen balance methods and possible reasons for these discrepancies are discussed.

1. Fifteen ‘constitutionally’ obese subjects, eleven hyperlipidaemic subjects of mixed-type and fourteen normal subjects were studied.

2. With a reduction in energy intake (range 3.3–4.2 MJ) for 21 d, there was no change in the levels of plasma total cholesterol (TC) and triglyceride (TG) of obese subjects, but the free fatty acid levels increased. However, in hyperlipidaemic subjects there was a reduction in levels of TC and TG with no increase in levels of free fatty acids.

3. There was a significant increase in the serum ketone levels of obese subjects but not in those of hyperlipidaemic subjects. The reduction of the respiratory quotient to a value of 0.7 was more rapid in the obese than in hyperlipidaemic subjects.

4. After administration of a fat load (0.5 g/kg gross body-weight) there was no change in plasma TG levels in obese subjects but there was an increase in those of normal subjects.

5. After administration of a glucose load (1 g/kg ideal body-weight) there was a significant reduction in plasma TG levels in obese subjects but no change in those of hyperlipidaemic subjects.

6. Hyperlipidaemic subjects eating their normal diet were found to have a hydroxybutyrate: acetoacetate ratio three- to fivefold that of obese and normal subjects.

7. These results suggest that obese subjects have an increased ability to store fatty acids, to mobilize them quickly and to generate fatty acid metabolites in the form of ketone bodies, while these same metabolic functions are reduced in hyperlipidaemic subjects.

1. A metal-binding fraction with a molecular weight of about 12000 in calf and sheep liver has been characterized as a metallothionein-like protein.

2. The combined concentrations of copper and zinc in the fraction (as μg/g liver) are a direct function of liver Zn concentration.

3. The relative proportions of Cu and Zn in the fraction are dependent on the Cu: Zn ratio in the liver.

4. These findings may be relevant to the mutual interaction between Cu and Zn.

1. A study has been made by gel-filtration techniques of the soluble copper- and zinc-binding proteins in livers from calves and sheep of widely differing Cu and Zn status.

2. Cu and Zn generally occurred together in three main fractions, with approximate molecular weights of > 75000, 35000 and 12000, and Zn also in one other fraction with molecular weight about 65000. The distribution of the metals between these fractions was variable and dependent on both the Cu and Zn status of the animals.

3. Zn was usually absent from the low-molecular-weight fraction in Zn-deficient or high-Cu livers, with Cu also being absent in the former instance.

4. The fraction with molecular weight of 35000 was tentatively identified as hepatocuprein. It generally accounted for only 4% of the total hepatic Cu except in Cu-deficient livers.

5. The possible relationship of these findings to the mutual antagonism between Cu and Zn is discussed.

1. Weanling (24-d-old) male rats were maintained at their body-weight for 1 month by restricting the intake of their normal diet. The animals were then rehabilitated for 0, 3, 7, 10 or 16 d. Control animals were given an unrestricted diet and some killed at the same body-weight as the experimental animals and others at the same age.

2. The forebrain, cerebellum, brain stem, heart, lungs, liver, spleen, kidneys, testes, and three sections of the alimentary tract were weighed, and DNA, RNA and protein contents were determined in the brain parts and liver.

3. During rehabilitation the weight of the body, corrected for the weight of the gut contents, showed a rapid gain between 7 and 10 d, which was synchronous with a rapid gain in weight of the testes.

4. The weight of the majority of organs relative to body-weight was maintained during both undernutrition and rehabilitation, the most marked exceptions being the stomach, which increased in relative weight during undernutrition, and maintained a high relative weight during rehabilitation, and the spleen, which lost weight during undernutrition, and on rehabilitation gained weight very rapidly to achieve a high relative weight.

5. The weight of the forebrain fell during undernutrition, due to a loss of water, and the weight of the brain stem rose. In the forebrain, DNA and the protein: DNA ratio were unchanged throughout, whereas a marked loss of RNA occurred during undernutrition, which was restored during rehabilitation.

6. The weight of the liver remained unchanged during undernutrition, despite increases in the amounts of DNA and protein. The amount of liver RNA decreased during undernutrition, but on rehabilitation showed an immediate and rapid increase. The variables measured in the liver were normal relative to body-weight, within 10 d of rehabilitation.

7. It is suggested that the growth occurring on rehabilitation is a balanced response to a single stimulus, partly mediated at the cellular level by RNA.

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. 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. 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 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. 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.