1. Concentrations of the amino acids in the plasma of blood from the portal vein and hepatic vein and in the liver of fed rats and rats starved for 1 d or 3 d were measured. The 1 d values were compared with the equilibrium concentrations of the amino acids found in the perfusion medium during perfusion of livers from rats starved for 1 d.

2. The measurements of portal–venous differences in amino acid concentrations confirmed the idea that postprandially and during starvation most of the amino acids flow from extrahepatic tissues to the liver but also showed that during starvation tryptophan, cystine, ornithine, valine, leucinc and isoleucine flow in the opposite direction, from liver to extrahepatic tissues.

3. The blood levels of the non-essential amino acids fell markedly during starvation while those of the essential ones tended to be maintained. This contrasts with the pattern of changes known to take place in rats and man given low-protein diets. In the liver, changes in amino acid concentrations were generally related to those in the blood but not strictly parallel. The relative changes in amino acid concentrations in blood and liver indicate that as starvation progresses the concentrative ability of the liver is enhanced for most of the amino acids which are taken up and that the increased output of those which are released is also due to changed membrane transport.

4. The changes in plasma amino acid concentrations in the blood passing through livers of rats starved for 1 d were, except for tryptophan and perhaps cystine, consistent with the extracellular changes found during perfusion of livers form rats straved for 1 d, indicating that the perfused liver influences concentrations of extracellular amino acids substantially as it does in vivo.

5. The results suggest of mechanism wherby the liver may control the maintenance of the essential amino acids during starvation.

1. Measurements of the concentrations of amino acids in the plasma of blood from the portal vein and hepatic vein in the livers of rats made diabetic with streptozotocin or alloxan and starved for 1 d were compared with similar measurements from normal rats starved for 1 d.

2. The concentrations of many of the amino acids in the blood plasma were lower in the streptozotocin diabetic rats than in the normal animal while the liver concentrations tended to be increased. This suggests that there is enhanced concentration of these amino acids by the liver in diabetics, as is also found in starvation, which is probably due to factors other than the direct absence of insulin.

3. The direction of flow of the groups of amino acids into and out of the liver was unchanged in the diabetic compared with the normal rat except that the output of tryptophan was abolished, and that of the branched-chain group was abolished in alloxan diabetes though apparently enhanced in streptozotocin diabetes. The rates of movement of amino acids in both directions appeared to be increased in the streptozotocin diabetic animals.

4. The changed amino acid pattern in the alloxan diabetic rats was to some extent similar to that of the streptozotocin diabetic rats but the changes were more difficult to interpret, perhaps because of side-effects of alloxan on tissues including liver.

1. Monozygous twin cattle with permanent rumen fistulas were used to measure the rate of degradation of casein and ovalbumin. One twin was used as a control and the other had protein administered by fistula about 4.75 h after eating a standard ration.

2. Casein was rapidly degraded with a half-life in the range 5.6–21.5 min, with the formation of peptides, free amino acids and finally ammonia. Up to 43% of the casein nitrogen was found as ammonia in the rumen fluid. Most of the amino acids present in casein were found in the free state in the rumen fluid to an extent of less than 7%, but valine, leucine, isoleucine and lysine were present as 25, 27, 21 and 38% respectively of the amounts present in the casein administered.

3. When acid-hydrolysed casein was given, ammonia was rapidly formed, the maximum amount found in the rumen being equivalent to 39% of the casein N. The individual amino acids were rapidly broken down except for valine, leucine, isoleucine and lysine of which synthesis in addition to degradation may occur.

4. Ovalbumin was degraded slowly with a half-life of 175 min, which was reduced to 132 min by feeding the cattle with ovalbumin for 5 d. Ammonia was produced slowly.

5. When added together the two proteins were degraded in the rumen independently at their own rates.

6. δ-Amino-n-valeric acid was produced in large quantity when casein or casein hydrolysate was degraded in the rumen.

1. In the wild, red grouse live largely on heather, a high-fibre (25%), low-protein (7%) food. Digestibility trials were carried out under semi-natural conditions, with magnesium as a digestibility marker. Two trials were done, one in autumn and one in spring.

2. Digestibility of the dry matter varied from 21 to 30% and metabolizable energy from 1.1 to 1.6 kcal/g. These variations were inversely related to intake and could partly be accounted for by facultative variations in holocellulose and lignin digestion.

3. Digestion of soluble carbohydrates, protein (measured as α-amino-nitrogen) and holocellulose varied between trials according to the initial concentration in the food. The digestibility of soluble carbohydrate was high (78–83%) in autumn (16% in food) and low (61–66%) in spring (11% in food) and that of protein was relatively low (24–31%) in autumn (6% in food) and high (42–48%) in spring (7% in food). Digestibility of crude fat was 30–33% for four birds and 20% for one bird.

4. By comparison with poultry, voluntary intake of dry matter was very high relative to body-weight and intake of energy appeared to be adequate. None the less, all birds lost weight during the trials, presumably for reasons other than energy shortage.

5. Urate excretion increased in parallel with body-weight losses, but formed only 2% of the total N output at low weight losses, in which event the main nitrogenous compounds in the droppings were α-amino N (presumably largely from undigested protein), ammonium salts and ornithuric acid.

6. The ornithuric acid was presumably a detoxication product of prolignins and possibly tannins and other polyphenols. Its excretion by grouse corresponds to the excretion of hippuric acid by ruminants.

1. The intestinal absorption of [11,12 3H2] retinyl acetate was studied in five apparently normal children, eight children with respiratory infection and three with gastroenteritis.

2. The absorption of vitamin A was significantly lower in children with respiratory infection or gastroenteritis than in normal children.

3. In the light of these observations, it is suggested that repeated attacks of infections may significantly contribute to the prevalence of vitamin A deficiency in children of poor communities.

1. The body composition was determined of forty-one fetuses of different gestational ages born to mothers belonging to a low socio-economic group of the population.

2. With increasing gestational age the water content fell from 88% at 28 weeks to 76% at term; the fat content increased from 2.1% to 11.2% and the protein content increased from 6.9 to 9.3%.

3. The changes in body composition were more closely related to body-weight than to gestational age.

4. The calcium, Phosphorus and magnesium contents of the body per unit fat-free weight progressively increased with gestational age, and at term the values appeared to be considerably lower than those reported in the literature. The Ca:P ratio was constant at different body-weights.

5. The body iron content per unit of fat-free weight increased marginally with increasing gestational age. The value was almost 30% lower than the values reported from elsewhere.

6. It is suggested that chemical composition and nutrient stores of the developing foetus can be considerably influenced by the state of maternal nutrition.

1. Liver composition and hepatic nutrient stores in foetuses born to mothers belonging to a low socio-economic group of the population were determined.

2. The contribution by the liver to body-weight and the concentration of water and nitrogen in liver at different gestational ages were relatively constant.

3. Total iron and copper contents of the liver were in the normal reported range but the ferritin content was considerably lower in the present investigation.

4. Hepatic stores of vitamin A, vitamin B12 and folate were lower than the values that have been reported elsewhere.

5. It is suggested that inadequate stores of iron, vitamin A, vitamin B12 and folate in these infants may predispose them to the early development of some deficiency diesease.

1. Diets containing varying levels of crude protein (CP) in the range 9.5–18.5% with and without supplements of diammonium citrate (DAC) as a source of non-protein nitrogen (NPN) were given to 160 growing chicks from 2 to 4 weeks of age, and their livers were assayed for glumate dehydrogenase (GDH) activity.

2. Growth rate and total liver protein were increased by raising the protein level from 9.5 to 18.5% CP. Chicks receiving 9.5 or 12.5% CP were heavier when they had also received 1.94% DAC. At 18.5% CP the addition of 3.88% DAC depressed growth.

3. GDH activity per unit liver weight and total GDH activity increased with dietary protein level but there were no consistent responses to DAC supplements. It was concluded that liver GDH activity did not provide a useful index of the utilization of NPN.

1. Fatty acid levels were studied in the tissues of 1-week-old calves receiving maize oil (in filled milk) with and without supplementary α-tocopherol. The calves that were not given vitamin E developed muscular dystrophy.

2. Decreased amounts of linoleic acid and increased amounts of arachidonic acid were found in nearly all the lipid fractions of skeletal muscles, hearts, livers and kidneys of vitamin E-deficient calves. The concentration of the polyunsaturated fatty acids beyond arachidonic acid remained about the same in both groups. There was a significant decrease of 20:2Ω6 fatty acid in the phosphatidy1 choline, phosphatidy1 ethanolamine and free fatty acid fractions in the livers and kidneys of vitamin E-deficient calves.

3. It is suggested that vitamin E has an inhibitory effect on the desaturating but not on the chain-elongation enzymes of microsomes in the liver and kidney.

4. Maize-oil feeding had only a slight effect on erythrocyte fatty acid composition, and the erythrocyte haemolysis test was negative even in the vitamin E-deficient animals.

1. The effect of methionine supplementation upon pancreatic trypsin, chymotrypsin, pancreatopeptidase E and amylase of chicks given raw and heated soya-bean diets (RSD and HSD) was studied before and after fasting.

2. Statistical analysis of the ratios of amylase to pancreatopeptidase E, trypsin and chymotrypsin in each individual chick revealed that methionine supplementation consistently increased the ratio of amylolytic to proteolytic enzymes. This phenomenon was most marked in the fasted RSD group, less in the fed RSD and fasted HSD groups and least in the fed HSD group.

3. The results are discussed in relation to methionine metabolism in chicks given RSD and HSD supplemented with trypsin inhibitors.

1. The influence of diets, particularly dietary carbohydrate, on the development of the intestinal disaccharidases of the chick was studied.

2. The maltase activity in the small intestine was similar in groups of 25-d-old chicks that had been fed, from hatching, on diets containing either starch, glucose, maltose, sucrose, or a mixture of 50% glucose + 50% lactose, as the source of carbohydrate. The sucrase activity in the small intestine was also similar in the different groups, as was the palatinase (the enzyme that hydrolyses palatinose, i.e. 6-o-α-D-glucopyranosyl-D-fructose) activity. The maltase activity in the large intestine of the group receiving the starch-containing diet was significantly increased. The lactase activity in the large intestine was significantly higher in the group receiving the 50% glucose + 50% lactose and in the group receiving glucose than in the other groups. Body- weights were similar with all the diets.

3. The fasting of chicks for a period of 3 d caused a marked decrease in the activity of the disaccharidases and in the protein content of the homogenates of the small intestine.

4. The maltase activity was similar in the small intestine of chicks that had been fasted for 3 d and subsequently given diets containing either starch, glucose, maltose, sucrose or fructose for 5 d. The sucrase activity, the isomaltase activity and the palatinase activity were also similar in the small intestine of the chicks given the different diets. Feeding with a fat-free or protein-free diet did not affect the development of disaccharidases in the small intestine, but feeding with a carbohydrate-free diet resulted in reduced disaccharidase activity.

5. The results suggest that, in the chick, dietary carbohydrate is necessary for the development of the disaccharidases but the form of the carbohydrate is not important. None of the sugars tested had a specific effect on a particular disaccharidase.

1. Rats were given stock chow diets containing several levels of calcium cyclamate to study the effects on growth and on some metabolites in liver and blood.

2. Levels up to 1% in the diet produced diarrhoea without affecting body-weight. At a level of 3% in the diet, body-weight was decreased by 12% in 8 weeks.

3. No changes were noted in liver protein, lipid and RNA-P and serum protein and lipid. 14CO2 excretion during the 1st hour after [14C]glucose administration also remained unchanged.

4. Adult rats weighing 500 g were given, at a restricted intake, a diet with variations in its fat and cyclamate contents.

5. During 15 weeks, the animals given the fat-supplemented diet plus cyclamate lost twice as much weight as controls without cyclamate and also excreted 20% more 14CO2. When the food intake was further restricted for 15 weeks weight losses in all groups were the same.

6. Serum lipid and free cholesterol concentrations were lowered in the cyclamate group. 14CO2 excretion for this group was 35% higher than for controls, indicating increased metabolic activity.

7. Concentrations of aspartate, glutamate, lactate, succinate, malate and glycerol-I-phosphate in liver were within normal limits. There were indications of decreased levels of lactate and succinate in cyclamate-fed rats which could be associated with aerobiosis and increased metabolic activity.

1. Groups of newborn calves were fed on liquid diets which had fat contents ranging from 0.2 to 17% (dry- weight basis) and which provided linoleic acid in amounts ranging from 0.01 to 0.7% of the calorie intake. Two commercial milk replacers, high in fat (17–18%) and linoleic acid (3.4 and 5.0% of calories) were also given. All diets were given for at least 65 d.

2. Except for reduced feed utilization associated with the two diets lowest in fat (0.2 and 0.4%), the calves developed normally, without signs of essential fatty acid deficiency.

3. The polyunsaturated fatty acid content of erthrocytes and plasma phospholipids and cholesteryl esters rose rapidly during the first few days on all diets. At 65 d, these concentrations were higher than at birth and appeared generally to be related to the linoleic acid intake. However, in the low dietary linoleic acid range, the fat content of the diet also seemed to exert some influnce. In no instance was there any indication of the appearance of 20:3ω9, which is observed in other species under conditions of essential fatty acid deficiency.

4. Some of the experimental diets were given to weanling rats. There was a rapid fall in the polyunsaturated fatty acid content of erythrocyte lipids and plasma phospholipids and cholesteryl esters, accompanied by the appearance of 20:3ω9.

5. These results suggest that calves on liquid diets have apparently a very low requirement for essential fatty acids.

1. Energy expenditure determinations have been made on thirty-two soldiers newly arrived in the warm humid climate of southern Malaya. Ergometer cycling was investigated as well as everyday activities such as lying, sitting, riding in a trunck, abultions, buildings a jungle camp and walking with loads over four different routes.

2. The inter-individual variation in the gross energy expenditure (kcal/min and kJ/min) of each activity has been compared with the variation in energy expenditure standardized for body-weight, surface area and lean body mass. Standardization for body size did not consistently or effectively reduce the coefficients of variation of energy expenditure.

3. The gross energy expenditure of most activities was significantly correlated with bodyweight, surface area or lean body mass but the correlation coefficients were not of a high order, suggesting that less than 41% of the inter-individual variation in energy expenditure was accounted for by variation in body size.

4. The energy expenditure of walking at various speeds over both firm and uneven terrain was related to the square of the walking speed and the total weight of the man and his equipment (correlation coefficients 0.89–0.92, P < 0.001).

1. Serum β-lipoprotein and cholesterol have been measured in children ‘at risk’ to severe protein-calorie malnutrition and in others with kwashiorkor or marasmus. β-Lipoprotein was estimated by an immunological technique. In children recovering from kwashiorkor, serum triglyceride estimations and lipoprotein electrophoretic separations were also carried out.

2. β-Lipoprotein concentrations did not fall significantly until serum albumin concentration was less than 2.5 g/100 ml; cholesterol concentration fell before β-lipoprotein.

3. In frank kwashiorkor, serum β-lipoprotein concentration was reduced by about 30%, whereas cholesterol and triglyceride concentrations were reduced by about 50% in comparison with apparently normal children. Electrophoretic evidence showed that serum α-lipoprotein concentration was also reduced or absent altogether. Marasmic children had normal serum concentrations of β-lipoprotein and the other lipid components measured.

4. The metabolic significance of this degree of reduction in serum β-lipoprotein concentration in the pathogenesis of the fatty liver of kwashiorkor has been discussed. It was concluded that, in Ugandan children with serum albumin concentrations below 2.50 g/100 ml, the β-lipoprotein concentration was probably insufficient for normal mobilization of fat from the liver and the children could therefore be considered susceptible to the development of a fatty liver.

5. The recovery from kwashiorkor was marked by a rapid rise in serum β-lipoprotein concentration and hypertriglyceridaemia but a slower rise in cholesterol concentration. This confirmed the results of previous investigations.

1. Fasting serum cholesterol and triglyceride, and post prandial insulin secretion and lipaemia were measured in human subjects in a metabolic ward, who were given an ordinary diet (diet 1) in which the sucrose was isocalorically replaced by starch (diet 2) or vice versa. The subjects were nine healthy normolipaemic adult males. In eight of these subjects the effect of sucrose calorie reduction (diet 3) on fasting serum lipids was also studied.

2. When starch replaced sucrose, there were no singnificant differences in fasting serum lipid concentrations or immunoreactive insulin or in the insulin response and alimentary lipaemia after a standard mixed breakfast.

3. Serum triglyceride concentration fell and cholesterol concentration rose during the period of sucrose (and calorie) restriction.

4. After lunch and supper on the first two diets (when different carbohydrates were given) the lipaemic response was larger and the insulin response smaller after meals containing sucrose.

5. Thus, there was no difference between concentrations of fasting serum lipids when starch replaced sucrose at 23% total calories, but the concentrations of serum triglycerides were higher after individual mixed meals containing sucrose.

6. There were no significant differences in the fatty acid patterns of serum lipids on the different diets.

1. Pre- and post-prandial metabolic rates were measured in twelve malnourished Jamaican infants.

2. On admission to hospital, minimal increase in postprandial metabolic rate were found, whereas during the recovery phase when growth was rapid, inreases in postprandial metabolic rate of up to 38% occurred.

3. After recovery only the five children who were still gaining weight at a rate of more than 4 g/kg body-weigh. d continued to show a substantial increase in postprandial metabolism.

4. A highly significant correlation was found between growth rate and the increase in postprandial metabolic rate.

5. Marked differences existed in the respiratory quotient measured 4 h after the last meal, the values being low on admission and high during the phase of rapid growth.

6. After a test meal, the respiratory quotient rose sharply both innewly admitted and in recovered children, but fell slightly when the children were studied during the phase of rapid growth.

1. Radioactive calcium has been used to study the placental transfer of Ca in ewes at three stages of gestation.

2. At each stage virtually all the radioactive Ca injected into a foetus was still present 5–6 h later and little or none was found in the mother or in a twin foetus if present.

3. It was concluded that there is neither exchange of Ca between foetal and maternal pools nor transfer from foetus to mother. Passage of Ca across the placenta of the ewe is therefore a one-way process.

4. The rapidly exchangeable Ca pool of the foetus tended to increase in size with the stage of gestation and was found to contain only about half of the total Ca of the foetal soft tissues.

5. Two methods for calculating the rate of accretion of Ca into the foetal skeleton have been applied. The results obtained from these calculations suggested that rates of foetal bone accretion also increased with the stage of gestation. Accretion per unit foetal weight, however, remained fairly constant irrespective of age or number of foetuses present.

6. Bone accretion rates calculated from the results of the present work were very similar to the rates obtained previously for transfer of Ca across the sheep placenta, indicating that resorption of Ca from bone is negligible in the foetus.

1. Two pairs of Friesian steers were changed from ad lib. to restricted intake of a pelleted barley diet and were maintained on this latter intake for periods of 18 or 25 weeks. The restricted level of intake was 70 g/kg0.73 and was adjusted weekly according to individual live weights. The daily allowance was given in three equal feeds during day-time.

2. After an initial period of 9 weeks on the restricted diet, during which all four animals were kept free of rumen ciliate protozoa, one member of each pair was given an inoculum of rumen ciliates. Eight weeks later, the ciliate-free member of the younger pair of steers was similarly inoculated. Observations were made on the rumen bacterial and protozoal populations and on changes in rumen pH and volatile fatty acids (VFA) throughout each treatment period. The concentrations of urea and haemoglobin in blood and of glucose and amino acids in plasma were examined on one occasion in each animal.

3. In the absence of ciliates, restriction of intake resulted in rumen pH values and molar proportions of VFA similar to those normally encountered on an ad lib. intake of a barley diet. A decrease in bacterial numbers and certain minor changes in bacterial types were observed on changing from ad lib. to restricted intake but the resultant population under ciliate-free conditions was basically the same as that found later in the faunated animals. In culture, organisms of the genus Bacteroides were predominant.

4. Large populations of rumen ciliates were established in each animal inoculated. Relative to the ciliate-free periods, the presence of ciliates resulted in an increase in rumen pH, a reduction in total VFA concentration and a decrease in the ratio of propionic to butyric acid in rumen fluid. It is concluded that these changes are a direct effect of ciliate activity.

5. Conditions within the rumen remained more stable from day to day when large ciliate populations were present than when ciliates were absent. In one animal, spontaneous fluctuations in ciliate number were accompanied by corresponding changes in rumen pH and VFA proportions.

6. Significant differences were observed between faunated and ciliate-free animals in the concentration urea in blood and of glucose in plasma; only minor differences were noted in blood haemoglobin and plasma amino acid concentrations.