1. The fatty-acid composition of the plasma total lipids of children with kwashiorkor and of healthy infants was determined by gas–liquid chromatography. Breast milk from Yoruba mothers, and traditional weaning foods, were also analysed for fatty acids, and for protein, fat and carbohydrate.

2. Evidence of essential fatty acid (EFA) deficiency was obtained in the children with kwashiorkor. The proportions of linoleic and arachidonic acids were reduced in the plasma lipids, whereas the endogenous eicosatrienoic acid showed a marked increase. The triene:tetraene ratio had the abnormally high value of 1·08. These changes were consistent with the prolonged ingestion of suboptimal amounts of linoleic acid.

3. Breast milk was of good quality, with a particularly high concentration of retinol. The milk was also rich in linoleic acid, and was thus discounted as a factor in the development of EFA deficiency, but the weaning foods were found to provide substantially less than the minimum recommended intake of 1% of the total energy as linoleic acid.

4. The maize pap with which the children with kwashiorkor had been fed for several months before the appearance of acute symptoms provided almost 7% of the energy as protein, but only 1·21 MJ (290 kcal)/kg. To satisfy energy requirements, it would have been necessary to consume 3–4 kg of the pap each day.

5. It is concluded that the protein deficiency which leads to the development of kwashiorkor in the Yoruba community arises from a very severe restriction in energy intake rather than from the consumption of foods very low in protein at adequate or excessive levels of energy intake.

1. The availability of iron added to dried skim milk and to maize–soya-bean–milk mixture (CSM) was measured by whole-body counting in thirty clinically healthy children and compared with the availability of Fe from ferrous ascorbate alone.

2. The mean absorption of Fe added as ferrous sulphate to a test meal of dried skim milk was 9·5% when the test meal was given as a sweetened drink. When maize meal was added to the dried skim milk to produce a porridge the mean absorption of the supplementary Fe was reduced to 6·3%. The mean absorption of Fe given as ferrous ascorbate alone was 59·6%.

3. These results differed from those reported for indirect tests done with animals in which the absorption of inorganic Fe added to milk-based feed preparations for infants was substantially greater than that of dietary Fe.

4. The mean absorption of Fe added as ferrous fumarate to a test meal of maize–soya-bean–milk mixture was 6·0%, whereas that of Fe given as ferrous ascorbate alone was 63·5%.

5. The amount of supplementary Fe added to maize–soya-bean–milk mixture (USA Department of Agriculture specification) was considered to be adequate.

1. Metabolic balance studies of zinc, copper, cadmium, iron, molybdenum and selenium were made on four young New Zealand women, using brilliant blue and chromic oxide as faecal markers.

2. Zn, Cu, Cd and Fe concentrations in foods, faeces and urine were measured by atomic absorption spectrophotometry, whereas Mo was determined spectrophotometrically with dithiol and Se fluorimetrically with diaminonaphthalene.

3. The dietary intakes of Zn, Cu and Fe were similar to those reported in the USA and the UK, whereas those of Cd, Mo and Se were less. The subjects ate a diet consisting of foods normally consumed by New Zealand women.

4. For each subject there was little variation in the urinary output of each element for three 6 d periods. Day-to-day variation was small for each subject. The individual variation in urinary output of each element among the subjects was smaller when expressed as a ratio of intake, except for Mo.

Retentions were small for Zn, Cu and Fe, all elements which are poorly absorbed. Balances of Se, Mo and possibly Cd were in equilibrium.

1. Studies were made of the effects of food supplements varying in carotene and calcium content on the nutritional status of children aged 2–6 years. Three groups of children who were given a dietary supplement for 6 months and a fourth group of controls were investigated. The supplement was the fermented food dhokla, made of wheat and Bengal gram (Cicer arietinum L.) (group 1) or dhokla with added greens (group 2) or dhokla with added greens (fenugreek) and lime powder (a mixture of CaO, Ca(OH)2 and CaCO3) (group 3).

2. Studies were made of the effects of the above supplements on height, weight, skeletal status as judged by increments in bone age and cortical thickness of the second metacarpal bone and femur, and biochemical status as judged by the composition of blood (haemoglobin), serum (protein, albumin and vitamin A) and urine (creatinine, nitrogen, thiamin, riboflavin and vitamin C).

3. All the groups given the supplement were found to be superior to the controls as judged by these criteria. The size of the increment generally increased from group 1 to group 3 and the differences were most marked for bone age and cortical thickness.

4. The results suggested that (a) calcium deficiency is a crucial factor in the aetiology of skeletal retardation in young children and (b) that at the levels of calcium (560 mg) and phosphorus (980 mg) consumed, and with liberal exposure to sunlight, a dietary supply of vitamin D may not be a crucial factor for skeletal development in young children.

1. The effect of feeding sheep at two different frequencies (once hourly and once daily) on the flow of digesta, dry matter, and starch to the duodenum was assessed by fitting sheep with re-entrant cannulas in the proximal duodenum and giving them, at each feeding frequency, rations differing in the particle size of the roughage component.

2. Frequent feeding resulted in a less variable daily pattern of flow of digesta and a significant increase (P < 0·01) in the total daily volume flowing to the duodenum. Altering the particle size of the ration did not affect the flow of digesta at either feeding frequency.

3. The pattern of flow of dry matter followed very closely that of the flow of digesta, but there was a significant (P < 0·001) interaction between feeding frequency and particle size of the ration which affected the flow of starch to the duodenum. As a result, more starch entered the duodenum when both the frequency of feeding and the particle size of the ration were increased.

1. Eleven obese subjects fasted for 24 d, by which time their serum albumin concentration had fallen significantly. 125I-labelled albumin was injected on day 7 of fasting to allow study of albumin metabolism.

2. Although no significant alteration occurred in either the intravascular content or the absolute catabolic rate of albumin between days 7 and 24 of fasting, the mean values for both content and catabolic rate were significantly lower than values determined in eight normal subjects.

3. A corresponding fall occurred in the absolute ‘synthesis+transfer’rate.

1. Gas exchanges on eleven steers with a mean weight of 273 kg, fasted for 96 h, were obtained over time intervals of 5·76 min in a confinement-type respiration chamber, when the animals were either standing of lying, or engaged in the act of standing or lying.

2. In all, 751 observations were analysed and these included twenty-four associated with the act of standing, forty-eight with the act of lying and the remainder approximately equally divided between standing and lying.

3. When lying, the heat production was 72·2 kJ (17·2 kcal)/kg fasted weight per 24 h and when standing, 85·7 kJ (20·5 kcal)/kg fasted weight per 24 h; an increase when standing of 18·7%. The double act of standing and lying was associated with an increase in heat production of 11·3 kJ (2·7 kcal)/100 kg fasted weight and while the act of standing was energetically more costly than the act of lying, the difference between the two was not significant.

4. The results are discussed in relation to earlier estimates.

5. Confinement-type respiration chambers of the type described by Turner & Thornton (1966), which have a fast response time and monitor the changes in chamber air frequently, are ideally suited to the detection of short-term changes in metabolic rate such as occur with changes in posture.

1. The effects of chronically raised body temperature on lipid metabolism were studied in groups of 3-month-old British (Shorthorn × Hereford) and Zebu (Africander × British) bull calves. Calves in control groups at ambient temperature were pair-fed to calves housed in a climate room.

2. In control groups, concentrations of plasma cholesterol and phospholipid were significantly higher and the excretion of fatty acids 14:0, 16:0 and 18:0 was lower in the Zebu than in the British calves.

3. In the climate room the constant daily environmental temperature required to maintain an increase in rectal temperature of 1·3° was 33° for British and 38° for Zebu calves. Changes in respiration rate, water metabolism and nitrogen metabolism associated with hyperthermia were similar in both breeds.

4. Hyperthermia in all animals was associated with lowered plasma concentrations of cholesterol and phospholipid and increases in the ratio of free to total cholesterol. It was without effect on the circulating concentrations of non-esterified fatty acids and about twice the amount of fat was excreted without change in its fatty acid composition.

5. The results showed that, when control of normal body temperature was lost, increased rectal temperature led to similar metabolic changes in animals of both breeds.

1. In the first of three experiments four sheep received chopped (C) and pelleted (P) hay by mouth (m) or rumen fistula (f) in the four combinations shown below. Feed eaten by mouth was offered ad lib. from 09·15 to 16·00 hours; feed was given by fistula at 09·00 hours in amounts equal to half of total intake (i.e. by mouth and by fistula) on the previous day. Daily dry-matter intake (g/kg metabolic live weight, W0·75) was as follows: treatment CmCf, 51·5; CmPf, 74·5; PmCf, 57·8; PmPf, 85·7. The corresponding dry-matter digestibility coefficients were 0·59, 0·56, 0·57 and 0·53.

2. The intention was that the difference in intake between CmPf and PmCf should provide a measure of palatability, since the animals digested the same composite diet but ate different components of it. For the comparison to be valid the two treatments had to promote equal rates of digestion, but measurements of rumen fill and of rate of passage of digesta suggested that Cf was digested more slowly than Cm.

3. In Expt 2, each form of hay was given entirely by mouth or partly by fistula. Daily dry-matter intake (g/kg W0·75) was as follows: Cm, 45·5; CmCf, 42·4; Pm, 80·4; PmPf, 79·2. In this experiment there was less evidence of Cf being digested more slowly and hence depressing intake.

4. The conclusion drawn from these two experiments is that fistula feeding in its present form is not a suitable technique for measuring the relative palatability of feeds differing considerably in physical structure. However, the technique might be improved if food given by rumen fistula to one animal was previously masticated by, and collected from the oesophageal fistula of, a second animal.

5. In Expt 3, the effects of sudden changes from a composite diet to either C or P, or from C to P or vice versa were measured in sheep receiving food by mouth only. The patterns of intake suggested that total intake might be partially determined by feed palatability.

1. Allantoin excretion was determined in forty-four rats; twenty-four rats were 21 d old and twenty were 90 d old. The animals received ad lib. for 11 d diets that contained varying amounts of protein from casein and from gluten. Urinary allantoin excretion was determined during the last 3 d of the period.

2. The amount of allantoin excreted in both young and adult animals was independent of the diet consumed and was related to metabolic weight (W in kg0·73) and rate of gain in body-weight (ΔW in g/d), also to body nitrogen content (N in g0·73) and rate of gain in body N (ΔN in mg/d), according to the equations allantoin (mg/d) = 60·54 W0·73 + 2·12ΔW, and allantoin (mg/d) = 5·45 N0·73 + 0·071ΔN.

1. A simple two-compartment physical model was assembled with the aim of simulating passage of marker through the reticulo-rumen, small intestine, and caecum and proximal colon of sheep. Passage of marker through the whole digestive tract and the hind-gut were also simulated with a computer and methods of describing such results were compared.

2. The same mathematical equation applied equally well to the passage of a single injection of marker through the model and whole digestive tract of sheep. The magnitude of a rate-constant, reflecting in theory the retention time of marker in the caecum and proximal colon, was accurate for the model but larger than expected for the sheep. Modifications of the model are discussed which might account for the greater complexity in the biological system.

3. The average time available for digestion in the entire gut can be described with R or t and that for the intestinal tract distal to the abomasum with Ri or with a similar measurement ti. The magnitudes of these values and of rate-constants and a transit time of marker in the intestines, derived from the concentration curve of marker excretion in faeces, are closely related. The times for peak concentration of marker in faeces, for 5 and 50% excretion and the 80–5 % excretion time were found to be of limited usefulness in describing the results of rate of passage experiments with sheep.

1. Three groups of sheep receiving 400, 800 and 1200 g lucerne chaff/d in equal hourly meals were killed. The large intestines were removed and divided into segments 15 cm long to provide information on the amounts and dry-matter contents of digesta and on the rates of passage of digesta and absorption of water along the large intestine.

2. With increasing intakes of food, increases were observed along the entire large intestine in the amounts of wet digesta present, in the transit rates of digesta and in the rates of absorption of water. The mean retention time of digesta in the large intestine decreased with increasing food intake, being 1737, 1056 and 692 min respectively.

3. Four patterns of sodium and potassium concentrations in digesta water along the large intestine were found.

1. Twelve Friesian bull calves were weaned at 5 weeks and reared to approximately 18 weeks of age on diets consisting mainly of concentrates containing 209 (HP), 169 (MP) or 130 (LP) g crude protein/kg dry matter. Hay was removed from the diet when the calves reached 10 weeks of age.

2. In relation to metabolic body size, daily dry-matter intake rose rapidly until the calves were about 9 weeks old and then tended to level off at between 80 and 100 g dry matter/kg0·73.

3. After adjustment for treatment differences in concentrate intake, the live-weight gains of calves given diets HP or MP were significantly greater, both from 1 to 12 weeks and from 1 to 16 weeks of age, than those of calves given diet LP.

4. Digestibility trials made twice on each calf, when given solely the concentrate diet and when live-weight gain was about 1 kg/d, showed no differences in dry-matter digestibility, but the apparent digestibility of crude protein increased with the protein content of the concentrate mixture. The true digestibility coefficient of dietary protein was estimated to be 0·880, with no difference between diets. Metabolic faecal nitrogen excretion was estimated to be 3·43 g N/kg dry matter ingested.

5. At the mean intake of digestible energy/kg0·73, N balance was significantly greater with diets HP and MP than with diet LP. Endogenous urinary N excretion was estimated to be 220 mg/kg0·73 and the apparent biological value of protein was 0·851 when diet LP was given.

6. The results confirm the importance of a balanced relationship between energy and protein intakes in the diet of the rapidly growing calf. It is concluded that the crude protein content of the diet can be reduced to below 172 g/kg dry matter, and possibly as low as 153 g/kg, for calves of 122 kg live weight to achieve weight gains of 1 kg/d, when given an all-concentrate diet. This lower protein level would be expected to result in the maximum efficiency of utilization of the dietary energy and protein.

1. The effect of fortification of rice with lysine and threonine (at levels of 2 g and 1 g/kg respectively) on the growth of preschool children was assessed in feeding trials at a residential orphanage and a village day-care centre.

2. In the first trial, the children at the orphanage were offered a diet based on rice, to provide the recommended allowances of protein and energy. For the children in the experimental group, the rice was fortified with lysine and threonine for the 6 months of the trial.

3. Statistically significant differences in final height and weight were not observed between the children in the control and in the experimental groups.

4. The children in the control group grew at optimal rates.

5. In the second trial, the diet provided approximately 80% of the daily energy and protein intakes from rice and was offered ab lib. at four meals a day in the orphanage and at three meals a day in the day-care centre.

6. In the orphanage, most children are enough of this high-bulk diet to ensure an adequate energy intake. The children given the fortified rice and those who served as controls grew at very satisfactory rates.

7. At the village centre most of the children were unable to eat enough food to achieve an adequate intake of energy. The children given the fortified rice did not grow taller than those given unfortified rice.

8. Fortification of rice with lysine and threonine did not improve rates of growth of preschool children.

1. The dietary intake, and urinary, cutaneous and faecal loss of water, sodium, potassium and iron have been studied in young men living and performing moderate work in a hot climate. The dietary intakes of K and Fe were lowered during part of the study.

2. The subjects were already somewhat acclimatized to heat; further acclimatization was achieved when they were performing work, and this was assessed in terms of the increase in their rate of sweating.

3. The subjects tended to be in marginally negative Na balance, partly owing to lowered Na intakes. Intakes and outputs of K were in balance. Losses of K in sweat amounted to 15% of intake when the dietary level was reduced.

4. The subjects were slow in adapting to changes in Fe intake, 8 d being an insufficient period for adaptation after their intake had been halved. Losses of Fe in sweat were approximately 0·3 mg/d, or one-third of the estimated requirement for absorbed Fe.

5. It is concluded that Fe losses in sweat could be a significant factor in Fe depletion if dietary Fe was low or unavailable, as there was no evidence that a low intake and absorption affected sweat losses.

1. Information was sought concerning the long-term fate of orally and intravenously administered [75Se]selenomethionine and [75Se]selenite in rats.

2. Urinary and faecal radioactivity was assayed during the 1st week and whole-body radio-activity was determined weekly for 16 weeks. Rats were killed at intervals for analysis of 75Se tissue distribution.

3. Intestinal absorption after oral administration was estimated to be 91–93% for selenite and 95–97% for selenomethionine.

4. Urinary excretion of absorbed [75Se]selenite was greater than that of [75Se]selenomethionine during the 1st week.

5. After the 1st week, whole-body retention diminished exponentially at a similar rate in rats given either selenomethionine or selenite. Except for the erythrocytes, 75Se content of individual tissues also decreased exponentially.

6. It appears that, after an initial period, 75Se from either selenomethionine or selenite is metabolized similarly, suggesting that Se from both potential dietary sources is ultimately incorporated into the same metabolic pool.

1. Two adult wether sheep were maintained on a diet of hay and two on a diet of dried grass for 3 weeks before starvation for a period of 10 d. Urinary excretion of the following acids was determined when the animals were fed and when they were fasted: total diethyl ethersoluble acids of hydrolysed and unhydrolysed urine, hippuric acid, benzoic acid and phenylacetic acid. By the 5th day of fasting, urinary output of all acids had attained stable levels that did not change during the remaining starvation period. The output of all urine fractions except phenylacetic acid declined rapidly during the first 4 d of fasting: phenylacetic acid output by all sheep increased to a maximum during the first 4 d of fast and then declined to stable values (0·42–0·73 g/24 h) which were greater than those observed when the sheep were fed. It is concluded that prolonged retention of food and microbial residues in the digestive tract is responsible for the large output of phenylacetic acid in the urine of fasted sheep.

2. Solutions of casein which supplied between 6·3. and 26·5 g nitrogen/24 h were infused into the rumens (fifteen experiments) or abomasums (sixteen experiments) of eight adult wether sheep. Ruminal infusions of casein caused increments in the urinary excretion of diethyl ethersoluble acids and phenylacetic acid. Both these increments were described by linear regression equations (P < 0·001), the coefficients of which showed that 284 ± 44 and 220 ± 21 mg benzoic acid equivalent were excreted as diethyl ether-soluble acids and phenylacetic acid respectively per g casein N infused. The phenylacetic acid excreted was equivalent to 95% of the phenylalanine of the infused casein. No increments in urinary benzoic acid were observed. One sheep scoured when it was given an abomasal infusion of casein. This was the only animal to show any increment in urinary aromatic acids when casein was infused into the abomasum.

3. When four sheep were given two rations containing an excess of carbohydrate as sugarbeet pulp or rolled barley, 11 and 16% respectively of their phenylalanine intakes were excreted in the urine as phenylacetic acid. When the same sheep were given two rations containing an excess of N as linseed meal or field beans, 51 and 59% respectively of their phenylalanine intakes appeared in the urine as phenylacetic acid.

4. Methods for the determination of creatinine, and of benzoic, phenylacetic, 3-phenylpropionic, cinnamic, hippuric and phenaceturic acids are described.

5. It is suggested that the amount of phenylacetic acid excreted in the urine is a measure of the equilibrium occurring in the rumen between catabolism of phenylalanine and reutilization of the products of catabolism for phenylalanine synthesis.

1. Homogenates of mucosa from bovine small intestine hydrolysed isomaltose slowly.

2. The enzyme exhibited maximum activity at pH 6·0–6·2 and possessed a Km value of 9·1 mM.

3. Isomaltase and maltase activities showed a similar pattern of distribution along the small intestine; activity was higher in the jejunum than in the ileum, the lowest activity being in the duodenum.

4. Neither activity changed markedly with age.

5. The disaccharidase activities (maltase, isomaltase, trehalase, lactase and cellobiase) of the small intestine were found in the sediment when homogenates were centrifuged at 100000g.

6. Heat inactivation studies suggested that there was one enzyme which hydrolysed trehalose, one enzyme which hydrolysed isomaltose, one enzyme which hydrolysed lactose and cellobiose and that the hydrolysis of maltose was brought about by more than one enzyme.