1. Total body water (TBW) was measured using tritiated water in sixty-five children. The measurements were distributed throughout rehabilitation in order to define the effect of changing energy intakes.

2. Oedematous children had a high TBW which decreased to the normal range during loss of oedema providing they were not receiving more than maintenance amounts of energy during this period.

3. Marasmic children who had not received greater than maintenance amounts of energy had a normal TBW.

4. Treatment with a high-energy diet was associated with an initial increase in TBW.

5. The possible mechanisms for this phenomenon are discussed.

1. Statistical analyses were carried out on results obtained under strictly-controlled conditions in metabolism stalls with forty-one different rations fed to 127 adult non-pregnant dry cows, and with fourteen other different rations fed to thirty-five adult non-pregnant lactating cows that had calved 2–6 months earlier and whose daily milk production ranged from 11 to 20 kg.

2. Correlations between calcium digestibility and values for the sum of the alkaline ions sodium and potassium minus the sum of the stable acid ions chloride, sulphate and phosphate were calculated for all fifty-five experimental diets.

3. The results showed that the excess of the anions over the cations, in rations maintaining a positive Ca balance but not in rations allowing a negative Ca balance, increases the absorption of Ca from the intestine. Phosphorus, not alone but with chloride and sulphate, is the most important component of this effect.

1. Pigs, each surgically prepared with a Thiry-Vella jejunal loop were used to study the absorption of calcium and inorganic phosphate from the intestine.

2. The loops were perfused daily for 6–8 h with a nutrient solution and absorption from the perfusate was measured.

3. The technique employed minimized atrophy of the jejunal mucosa and enabled the measurement of hourly or daily changes in absorption rate of components of the luminal fluid.

4. No differences were observed when polyethylene glycol (PEG; molecular weight 4000), [14C]PEG or 51Cr-EDTA were used as markers of net water movement.

5. Increasing the concentration of Ca in the perfusate resulted in the demonstration of a two-component relationship between net absorption rate of Ca and intraluminal Ca concentration. An initial rapid absorption rate from 0 to 4 mm was found, then a slower rate from approximately 5 mm upwards which did not saturate at the highest concentration tested (25 mm).

6. Increasing the concentration of phosphate in the perfusion solution increased the net absorption of phosphate from that solution. Although a two-component system, similar to that for Ca, was not evident, net absorption of phosphate was not saturated at the highest concentration tested (50 mm).

7. The absorption of Ca was unaffected by the presence of phosphate in the solution but Ca (2.5 mm) enhanced the absorption of phosphate.

1. An investigation was made to determine the value of tissue enzymes as indices of protein nutrition.

2. Sheep were given a reduced protein intake for 6 weeks, whereupon some were given a protein supplement for 1 week and then the sheep were refed their initial diet. In the first experiment sheep were taken from pasture and given a reduced protein intake for 6 weeks whereupon some were given a protein supplement for 1 week and then all the sheep were grazed on pasture. In the second experiment sheep were fed on lucerne (Medicago sativa) chaff ad lib. in place of grazing before and after the period of reduced protein intake during which one group was also fed on molasses. Again, another group was given a protein supplement for 1 week after 6 weeks on the reduced protein intake.

3. As a result of reduced protein intake there were significant (P < 0.01) changes in the liver in the content of DNA, protein: DNA, arginine synthetase (combined activity of argininosuccinate synthetase (EC 6.3.4.5) and argininosuccinate lyase (EC 4.3.2.1)), aspartic aminotransferase (EC 2.6.1.1), glutamic dehydrogenase (EC 1.4.1.2), arginase (EC 6.5.3.1) and tyrosine aminotransferase (EC 2.6.1.5).

4. There were few consistent changes in muscle in the levels of DNA, protein:DNA, creatine kinase (EC 2.7.3.2) and aspartic aminotransferase.

5. The feeding of molasses to one group tended to reduce the change in DNA level but still resulted in significant changes in the enzymes.

6. It is suggested that the levels of arginine synthetase, aspartic aminotransferase and DNA in liver could be useful indices of protein status.

A method of estimating volatile fatty acid (VFA) production in the rumen in non-steady-state conditions was proposed. Laboratory models indicated that good estimates of total production over a complete feeding cycle could be obtained even when a wide range of production rates and volume changes occurred during the experiment. But estimates of instantaneous production rates might have contained large errors unless some attempt was made to match the infusion rate of labelled VFA to the rate at which VFA was produced in the rumen.

1. Four pregnant sows were used to study lysine requirements by means of the interpretation of values for plasma amino acid and blood urea. Diets containing graded levels of dietary lysine were fed at the rate of 1.82 kg/d.

2. Plasma lysine remained at a low level up to 6.4 g dietary lysine/kg (dry matter basis) and then increased sharply with further increases in lysine intake.

3. Blood urea levels decreased when the dietary lysine content was increased to 6.4 g/kg and then increased at higher dietary lysine concentrations.

4. Both criteria of response indicated that the lysine requirement of the pregnant sow given 1.82 kg diet/d during the later stages of pregnancy does not exceed 10.00 g/d.

1. Studies were done on the effects of giving calves two types of concentrate diet, both in a liquid form from an open pail or in a dry pelleted form, on the closure of oesophageal groove, body-weight gains and the digestibility of rations.

2. Twenty-four Holstein calves were used in an experiment by dividing into two groups of twelve calves each. The ‘dry-fed’ group (DFG) was given a pelleted concentrate, F1, from 25 to 42 d of age, and then given another type of pelleted concentrate, F2, from 43 to 87 d of age, and again given F1 from 88 to 112 d of age. The ‘liquid-fed’ group (LFG) was given from a pail a liquid suspension of the equivalent amount of the same concentrates as those fed to DFG calves, for the same periods. F1 contained skim milk and glucose with lower levels of maize and soya-bean meal than F2 which did not contain skim milk or glucose; F1 and F2 were both supplemented with 10 g methionine/kg and also supplemented with lysine at 5 and 10 g/kg respectively. All calves were allowed free access to roughage, and digestibilities were measured at 12 and 16 weeks of age.

3. Wet weights of reticulo-rumen and abomasal tissues (% whole stomach weight) were respectively 69.8 and 17.6 in DFG, and 59.0 and 26.4 in LFG at 42 d of age; at 87 d of age, the corresponding values were 68.0 and 16.3 in DFG, and 52.8 and 36.6 in LFG, and further, LFG had significantly more developed caecums and large intestines as well as significantly less developed reticulo-rumens and omasums than DFG.

4. Free amino acid patterns in plasma did not vary in DFG, but varied in LFG in response to the change in diet from F1 to F2 and to the difference between diets in lysine supplementation.

5. Feeding F1 in a liquid form and F2 in a dry form significantly improved calf gains. The intake of roughage in DFG exceeded that in LFG especially when F2 was fed.

6. The digestibility of diethyl ether extracts did not vary with feeding procedures, but that of crude protein (nitrogen × 6.25) was significantly higher in DFG independent of the type of diet. Digestibilities of dry matter and N-free extracts were significantly higher in LFG for F1, while higher in DFG for F2. The digestibility of acid-detergent fibre did not differ significantly between groups at 12 weeks of age, but was significantly higher in LFG at 16 weeks of age, suggesting a possible compensatory contribution of the large intestine to the digestion of fibre in LFG.

7. The efficiency of liquid feeding of a concentrate diet to ruminants compared with that of dry feeding is discussed.

1. Food intake and rates of protein, lipid and energy deposition during growth were measured for lean and congenitally obese (fatty) Zucker rats offered from 34 d of age to slaughter at 66 d of age, one of six semi-synthetic diets containing casein (C) in the following amounts (g C/kg): 40C, 100C, 150C, 300C, 500C and 700C.

2. In Expt 1, groups of four male rats were offered each diet to appetite. The digestibility of dietary protein and metabolizability of dietary energy were determined. Total carcasses were analysed for protein, energy and lipid at 34 and 66 d of age. The results showed that, given diets containing 300C or above, both fatty and lean males regulate food intake so as to sustain a maximal rate of protein deposition. This maximal rate was greater in males than in females, and the sex difference was more marked in lean rats. Diets containing less than 300C did not permit maximal protein deposition and, in this instance, both sexes and phenotypes showed a similar reduction in food intake and protein deposition. The rate of deposition of body lipid did not appear to be controlled in either phenotype.

3. In Expt 2, fatty and lean rats were pair-fed diets 100C and 500C. Carcass composition at 66 d of age confirmed that obesity in the fatty rat was not due to hyperphagia but to an abnormal pattern of energy utilization between fat deposition (too much), and protein deposition and heat production (too little).

4. In Expt 3, fatty and lean, male and female rats were given diets 100C and 500C to slaughter at 66 d of age. The carcasses were analysed into different parts by weight, and according to protein and lipid contents of viscera, pelt and subcutaneous fat, and empty carcass. Fatty rats stored approximately 0.53 of their protein in the empty carcass, lean rats approximately 0.65.

5. The results confirm that food intake in the Zucker rat is intimately related to the capacity of the animals for protein deposition, but this capacity differs between sexes and between phenotypes, and the distribution of body protein in the fatty rat eating ad lib. is not that of a normal rat.

1. The effect of daily supplements of 20–30 mg inorganic iron as ferrous sulphate on the growth, activity and haematological status of preschool children was studied for 3.5, 7 and 12 months and compared to that of children who served as controls. All children were given their daily requirements of energy and protein. In addition, they received 5 μg cyanocobalamin and 200 μg folic acid.

2. Fe supplementation increased the haemoglobin, serum Fe and percentage saturation of transferrin and reduced the unsaturated Fe-binding capacity significantly compared to corresponding values for the controls.

3. Height and activity were unaffected by Fe supplements.

4. Of the children 45% had haemoglobin values below 110 g/l at the end of 7–12 months of Fe supplementation.

1. Rats bred from vitamin B12-depleted dams were fed on a vitamin B12-deficient diet for 12–15 months and developed a severe vitamin B12 deficiency, as judged from methylmalonic acid excretion and tissue vitamin B12 levels at slaughter. Control rats were supplemented with vitamin B12 in the drinking-water.

2. Neurological signs were recorded after 7 months but the motor nerve conduction velocities remained normal. Neuropathological examination revealed mild changes in the peripheral nerves but no changes in the central nervous system.

3. The amounts of total lipids and phospholipids were normal, but in all examined tissues the proportions of pentadecanoate (C15 fatty acid) and heptadecanoate (C17 fatty acid) were considerably increased in vitamin B12 deficiency.

4. 3H2O was incorporated to the same extent into the fatty acids of nervous tissue from vitamin B12-deficient and control rats after 48 h. Less 3H was found in the liver fatty acids of the vitamin B12-deficient rats.

5. Neurological dysfunction can be demonstrated in the vitamin B12-deficient rat; the relation of the biochemical and neuropathological changes to the neurological signs needs further study.

1. Digesta were collected from twenty-three pigs, initially of 30 kg live weight, and fitted with single Ash re-entrant cannulas in either the duodenum, jejunum or ileum. A further twenty-four pigs were used in a conventional digestibility trial.

2. The diets contained: barley, fine wheat offal, white fish meal, minerals and vitamins (diet BWF); starch, sucrose, maize oil, cellulose, minerals, vitamins and either groundnut (diet SSG) or casein (diet SSC).

3. The flow-rates of dry matter (dm), ash and water were measured hourly in the duodenum and jejunum, and every 6 h in the ileum during 24 h collection periods. Faeces were collected during 5 d periods.

4. Marked increases in the flow rates of each of the digesta components after feeding each diet were observed in the duodenum and jejunum, but not in the ileum. The total flow in 24 h periods was much lower in the ileum than at the other sites.

5. Values for the ratio, dm output:intake for dm outputs from the duodenal, jejunal or ileal cannulas, and in faeces, in 24 h periods were respectively 0.94, 0.81, 0.28 and 0.22 for diet BWF; 0.96, 0.76, 0.20 and 0.15 for diet SSG; 0.96, 0.73, 0.08 and 0.04 for diet SSC. The corresponding values for ash were: 1.47, 1.65, 0.74 and 0.53 for diet BWF; 1.28, 1.34, 0.59 and 0.51 for diet SSG; 1.63, 1.35, 0.50 and 0.26 for diet SSC. The corresponding values for water were: 3.49, 3.41, 0.88 and 0.18 for diet BWF, 2.75, 2.80, 0.80 and 0.08 for diet SSG and 2.61, 1.87, 0.23 and 0.01 for diet SSC.

1. Pigs growing from 20 to 60 kg live weight were given diets based on barley, weatings and fish meal, or starch, sucrose and groundnut meal or starch, sucrose and casein. Seventeen pigs were fitted with single re-entrant cannulas in the duodenum (posterior to entry of bile and pancreatic ducts), jejunum or terminal ileum and twenty-four non-cannulated pigs were used in a conventional digestibility trial.

2. The amounts of calcium, phosphorus, magnesium, sodium and potassium passing through the reentrant cannulas and amounts excreted in the faeces were measured. These values were used to calculate the direction and extent of net movements of the five elements through the walls of the four parts of the digestive tract anterior to the collection sites.

3. The small intestine was the principal site of Ca and P absorption but there were differences between the diets in the relative importance of the regions anterior and posterior to the mid-jejunum.

4. Secretion of small amounts of Mg occurred in the anterior small intestine; the ileum and large intestine were the principal sites of net absorption.

5. There was a large net secretion of Na anterior to the duodenal cannulas and further secretion into the anterior small intestine with each diet. There were marked differences between diets in the amounts secreted but the ileal Na concentration was the same in each instance. Absorption occurred in the ileum and large intestine.

6. Secretion of small amounts of K was evident anterior to the duodenal cannulas and net absorption occurred in both parts of the small intestine with each diet.

1. Seven pigs of 30 kg initial live weight were fitted with re-entrant cannulas in the terminal ileum. Each was fed, in succession, four purified diets having cellulose and sodium levels (g/kg) of 30 and 2.7, 30 and 0.9, 90 and 2.7 or 90 and 0.9, respectively. Collections of digesta (24 h) and 3 or 4 d collections of faeces were made.

2. There was a greater throughput of ileal digesta with the high-cellulose diets than with the low-cellulose diets, mainly due to increased water content, and there was a concomitant reduction in the net absorption of Na from the small intestine. The immediate response to reduced Na intake was increased secretion of Na into the gut lumen anterior to the terminal ileum; this was more pronounced with the high-cellulose diet. Na concentrations in ileal digesta were very similar for all four diets.

3. The apparent absorptions of calcium, phosphorus, magnesium, potassium and zinc were reduced by the high-cellulose diets. In each instance this was due to reduced absorption posterior to the terminal ileum.

1. Blood pyruvate carboxylase (pyruvate-CO2 ligase (ADP-forming); EC 6.4.1.1; PC) activities in young chickens and turkeys given low-biotin diets supplemented with biotin at graded levels were studied in three experiments.

2. In both species PC activity was related positively to the supplemental biotin level. The relationship was sigmoid and maximum activity was attained with supplemental levels above those required to give maximal growth response.

3. Enzyme activity decreased between 2 and 4 weeks of age but remained almost constant thereafter.

4. Activity in chicks was not affected by alterations in the fat or protein content of the diet.

5. Changing poults from high to low and from low to high supplemental biotin levels resulted in reversals in the levels of enzyme activity.

6. It is concluded that blood PC activity is a promising new criterion for assessing the biotin status of young chickens and turkeys.

1. A calorimeter for the continuous measurement of heat production and heat loss in the human subject, for at least 24 h, is described. The calorimeter operated on the heat-sink principle for direct calorimetry and an open-circuit system for indirect calorimetry.

2. Sensible heat loss was measured using a water-cooled heat exchanger, and the temperature of water entering the heat exchanger was controlled to maintain a mean temperature gradient of zero across the chamber walls.

3. Evaporative heat loss was determined from ingoing and outgoing wet-and-dry bulb temperatures and air flow-rates.

4. Problems associated with the calculation of evaporative heat loss and the estimation of the volume of incoming air in open-circuit systems are considered.

5. The calibration, limits of accuracy, sources of error and experiments with subjects are discussed.

1. Pelleted diets containing concentrates and 0, 200, 400 or 600 g chopped straw/kg were fed ad lib. for 5 h daily to four cows. Concentrations of various energy-yielding metabolites were measured in samples of rumen fluid and jugular blood taken before feeding and at intervals after food was offered.

2. After feeding, the pH of rumen fluid decreased rapidly and the total concentration of volatile fatty acids (VFA) increased; the changes were greatest in the diet containing no roughage. The changes were essentially complete by 135 min at approximately the time feeding stopped. Rumen lactate concentrations were always low and increased significantly only in cows given no roughage.

3. There were highly significant relationships between the peak rumen acetate concentration after a meal and the apparent digestibility of the dry matter of that meal, and the amount of material in the rumen at the end of a meal. The latter relationship resulted in there being no difference between treatments in the total amount of acetate present in the rumen after feeding.

4. In the blood, concentrations of acetate, propionate, β-hydroxybutyrate (BHB) and lactate all increased after feeding. The increase was prolonged and maximum values were rarely reached before 4–5 h. The highest concentrations of acetate and BHB were found in cows given 200 g roughage/kg and were twice as great as those in cows given no roughage; lower concentrations were found in cows given 400 or 600 g roughage/kg. This information, together with the rumen concentrations of acetate and butyrate, was interpreted as indicating an inhibition of VFA absorption from the rumen of cows given no roughage.

5. Plasma glucose concentrations decreased rapidly for 4 h after feeding, the decrease being greatest in cows given 200 g roughage/kg. Non-esterified fatty acid concentrations also decreased after feeding 200 and 0 g roughage/kg rations, but concentrations were not high at any time.

6. It is concluded that chemical changes in the rumen correspond to feeding behaviour much more closely than changes in blood and therefore any chemostatic regulation of food intake probably occurs at the former site, with acetate playing a major role. Monitoring energy balance at tissue level is likely to be mediated hormonally, with insulin an important factor.

1. Urinary and faecal excretion of single oral doses of 1 mg selenium or 0.1 mg Se as selenomethionine (Semet-Se) in solution were studied in two women. Most of the Se was absorbed and little was eliminated in the urine (0.05–0.22 dose).

2. The results have been compared with those from an earlier study (Thomson, 1974) on the same two women after similarly sized doses of sodium selenite (selenite-Se) in solution. Although selenite-Se was almost as well absorbed as Semet-Se more was excreted in the urine (0.41–0.85 dose).

3. Repeated dosing with 1 mg selenite-Se on five consecutive days in one of the women indicated that 1.1 mg had been retained.

4. Twenty patients with muscular complaints from Tapanui (South Otago, New Zealand), a low-Se soil area, ingested 0.5 mg selenite-Se daily for 20 d. Blood Se increased rapidly to almost twice the initial concentration but reached a plateau well below most values reported for residents outside New Zealand. No difference in blood Se concentration was found between those who did or did not report improvement.

5. Spasmodic medication with selenite-Se by some residents near Lincoln (Christchurch, New Zealand) for periods of up to 10 years or more had increased the blood Se somewhat.

1. The daily intake of selenium by three subjects was supplemented with 100 μg Se as selenomethionine (Semet-Se) or sodium selenite (selenite-Se)/d for 10–11 weeks, or with 65 μg Se as in mackerel (Scomber japonicus) (fish-Se)/d for 4 weeks.

2. Urinary and faecal excretion of Se was measured and also Se concentration in whole blood, plasma and erythrocytes. Measurements on blood were made at intervals after supplementation had ceased.

3. Selenite-Se was not as well absorbed (0.46 of the intake) during the first 4 weeks as Semet-Se (0.75 of the intake) and fish Se (0.66 of the intake).

4. Blood Se increased steadily with Semet-Se, from 0.08 to 0.18 μg Se/ml, but more slowly with selenite-Se, reaching a plateau in 7–8 weeks at 0.11 μg Se/ml. Plasma Se increased more rapidly with Semet-Se than with selenite-Se, so that initially with Semet-Se plasma Se was greater than erythrocyte Se.

5. Daily urinary excretion increased with all forms of supplement, with initially a greater proportion of absorbed selenite-Se being excreted than Semet-Se or fish-Se. A close relationship was found between plasma Se and 24 h urinary excretion. The findings suggested that there was a rapid initial excretion of presumably unbound Se then a slower excretion of residual unbound, loosely bound or bound Se.

6. Total retentions of 3.5 mg selenite-Se and 4.5 mg Semet-Se were large when compared with an estimate of body content of 6 mg Se, derived in another paper (Stewart, Griffiths, Thomson & Robinson, 1978). Retentions of Semet-Se and fish-Se appeared to be reflected in blood Se, whereas for selenite-Se, blood Se reflected retention for only a short period after which Se appeared to be retained without altering the blood Se. This suggested that Semet-Se and selenite-Se were metabolized differently.

7. A double blind-dosing trial with 100 μg Semet-Se was carried out for 12 weeks on twenty-four patients with muscular complaints in Tapanui, a low-Se-soil area. Blood Se increased in the experimental group (from 0.067 to 0.143 μg Se/ml); clinical findings were not conclusive and will be presented elsewhere.

8. Blood Se was measured in New Zealand residents before travelling to Europe or to North America. On return their blood Se was increased, and depending upon the period of time spent outside New Zealand some values reached concentrations found in visitors and new settlers to New Zealand.

9. The results from these studies and the earlier studies of single and multiple dosing have been used to look at the various criteria in use for assessing Se status of subjects. It is suggested that plasma Se be used in preference to 24 h urinary excretion, and in addition to whole blood Se and glutathione peroxidase (EC 1.11.1.9) activity.

1. New Zealand White (NZW) rabbits were given, between 4 and 8 weeks of age, a range of diets, based on oats and fish meal, containing from 104 to 255 g crude protein (nitrogen × 6.25; CP)/kg to establish the level of CP below which growth was retarded.

2. In three experiments each diet was fed to four animals and food intake, growth and N balance were measured over 4 weeks. Body analysis was also carried out after two of the experiments.

3. The rates of food intake and growth of animals increased with dietary CP concentration until a CP concentration of approximately 150 g/kg diet had been reached. Beyond this there was little further improvement. N balance studies showed that once this dietary concentration of CP had been reached, there was a reduced rate of N retention.

4. Good agreement was found between N retention measured by balance methods and by body analysis: body composition showed a tendency towards an increase in fat and a decrease in N as the dietary protein concentration was reduced.

5. Microbial protein produced in the caecum and eaten during coprophagy, was found to supplement the dietary protein by approximately 2 g CP/d, or by only 0.1 of a normal dietary intake of CP.

6. In the second part of the study NZW rabbits were offered, between 5 and 8 weeks of age, diets based on oats containing 150 g CP/kg. The protein supplied by oats was supplemented with maize gluten, gelatin, groundnut meal, casein, soya-bean meal or fish meal.

7. Rabbits offered diets containing casein, soya-bean meal and fish meal gained 40–50 g/d similar, to animals given a well-balanced control diet, while those given diets containing maize gluten, gelatin or groundnut meal gained approximately 30 g/d. This indicated that amino acid balance in dietary protein was important to the growing rabbit.

8. In later experiments, diets based on cereals and groundnut meal supplemented with varying amounts of lysine and methionine were offered during a 3-week post-weaning period in order to assess requirements for those limiting amino acids.

9. The addition of both lysine and methionine improved growth rates. The minimum requirements for normal growth were found to be 6.2 g methionine+cystine and 9.4 g lysine/kg diet.