1. Albumin, α1-, α2-, β- and γ-globulin fractions were demonstrated in serum from control and copper-depleted rats, but no quantitative difference was found in the distribution of the proteins between the two groups of animals. Both the total number of leucocytes and the number of polymorphonuclear leucocytes increased during copper depletion.

2. Plasma copper content was found to be superior to whole blood copper content as an index of the copper status of rats at intermediate stages of depletion. The copper content of erythrocytes was found to be unaffected even in the severely depleted animals; this explains, in part, the poor response of whole blood copper content to intermediate stages of depletion.

3. A single dose of orally administered copper was reflected in the plasma copper content of depleted rats about 12 h after dosing. No similar rise was observed in control animals, and the extent of the response was not increased by increasing the dose of copper.

4. It is suggested that plasma copper response to a single oral dose of copper sulphate may provide a useful method for the detection of subnormal copper status in individual farm animals without the necessity of determining breed norms.

1. A comparative study of the iodine and calcium contents of diets in areas of Ceylon where goitre is endemic and non-endemic was carried out.

2. The iodine content of food grown in non-endemic areas was, in most instances, considerably higher than in endemic areas.

3. In endemic areas the daily average intake per person per day was well above the allowance of 100–150 μg recommended by most workers. The critical level of total daily iodine intake below which goitre becomes endemic in Ceylon was 400 μg. Possible reasons for this higher need of iodine are discussed.

4. Addition of iodine to cooking salt has been used successfully to combat endemic goitre in many countries. The amount of iodine added is based on the degree of endemicity and the amount of salt consumed per person per day. It is suggested that the more important criteria which should determine the amount of iodine added to cooking salt are the dietary iodine content, the daily total intake of dietary iodine and particularly the level of iodine below which goitre becomes prevalent.

1. Thirty-nine children suffering from protein–calorie undernutrition were classified into nineteen with kwashiorkor, twelve with marasmus and eight with nutritional oedema according to history, physical findings and laboratory investigations. Liver biopsy samples from these patients were extracted with lipid solvents and the phospholipids were fractionated into phosphatidylcholine, ethanolamine and serine, and sphingomyelin.

2. The total liver phospholipids were found to be reduced in kwashiorkor and the reduction was mainly in the phosphatidyl ethanolamine fraction. The decrease in phosphatidyl ethanolamine was probably due to an observed reduction in free serine content. The ethanolamine phosphatase activity of the liver was found to be high in kwashiorkor.

1. The presence of transaminase activity in rumen contents has been demonstrated. The level of activity varied with time after feeding and was influenced by the nature of the diet.

2. Rumen contents from a sheep given a diet containing casein showed greater transaminase activity at 2 h than at 6 h after feeding. Conversely, with a diet containing urea and maize, the activity was higher at 6 h than at 2 h after feeding.

3. The greater part of the transaminase activity of rumen liquor was associated with the fraction containing protozoa and food residues while the cell-free fraction contained no transaminase activity under the experimental conditions.

1. Three experiments using sixty individually fed, enzootic pneumonia-free Large White pigs on experiment from 9–11 weeks of age to 200 lb live weight are described.

2. Information was obtained on the effect of different dietary concentrations of aflatoxin B1 on the performance of the pigs, on various biochemical measurements and on the histology of the livers and kidneys.

3. Reduced growth rate and loss of appetite were the main adverse effects observed, their extent being positively related to the dietary level of aflatoxin B1. No marked clinical signs were seen, mortality was very low and there was little or no effect on the feed conversion efficiency of the animals.

4. No evidence for any adverse interaction between aflatoxin B1 and the presence in the diet of a supplement of copper sulphate providing 250 ppm Cu was apparent from either the performance, biochemical or histological results obtained. It was concluded that the few isolated reports of toxicity in growing pigs fed diets containing a supplement of 250 ppm Cu were unlikely to have been the result of the unsuspected presence of aflatoxin B1 in the feedingstuffs used in the diets.

5. Aflatoxin B1 tended to increase the serum alkaline phosphatase level, the concentration of Cu in the kidneys, and liver weight and to reduce the liver vitamin A concentration. No other consistent differences in the measurements made were observed.

6. The extent of the total pathological abnormality observed in the livers and kidneys was closely related to the level of aflatoxin B1 in the diet.

1. Young rats were kept on a 6% casein diet for 4–7 weeks and then either killed or returned to a stock diet. Control rats were given a stock diet.

2. Argininosuccinate lyase (EC 4.3.2.1, L-argininosuccinate arginine-lyase) was assayed in liver, and amino acid activating enzymes were assayed in liver and muscle of rats after depletion and while they were refed on the stock diet. Levels of enzymes were compared with those in the control rats.

3. Amino acid activating enzymes were markedly increased in liver at the end of the depletion period, but returned almost to normal levels after 4–6 days of refeeding. In muscle the enzyme levels were not decreased after depletion, but began to rise after 4 days of refeeding.

4. Argininosuccinate lyase activity in depleted female rats was about half that in control rats and rose again slowly on refeeding. Male rats were hardly affected by depletion.

5. It is suggested that these enzyme changes play a part in the adaptation of the rat to a reduced protein intake.

1. Variation in endogenous nitrogen metabolism was determined by giving eleven healthy men, aged 17–22, a diet supplying daily only 6 mg N/kg body-weight. Eight subjects were given the diet for 7–10 days and three other subjects were given it for 16 days.

2. Body cell mass (BCM) was calculated from whole-body 40K in ten subjects and basal metabolism was determined in seven subjects during the ‘protein-free’ period. Urine was analysed daily for N and creatinine, and faecal N was measured in pooled samples. Plasma free amino acids, serum albumin and protein were measured in preprandial morning blood samples at the beginning and end of the study.

3. BCM did not change during the ‘protein-free’ period and accounted for 48% of the total body-weight. Basal calorie expenditure amounted to 48 ± 5 kcal/kg BCM per day.

4. Mean daily endogenous urinary N excretion in the eight subjects given the ‘protein-free’ diet for 7–10 days was 36·6 ± 3·0 mg N/kg body-weight, 79·4 ± 4·4 mg N/kg BCM and 1·6 ± 0·2 mg N/basal kcal. Endogenous faecal N excretion was 9·9 ± 1·1 mg N/kg body-weight and accounted for 20% of the total endogenous loss. Results obtained with three other subjects given the diet for 16 days were similar.

5. Plasma essential amino acids were reduced, glutamic acid, alanine and glycine increased, and the ratio of essential to non-essential amino acids decreased after 7 or 10 days of ‘protein-free’ diet.

6. The loss of endogenous N per basal kcal and of faecal N per kg body-weight was lower than the values assumed in the factorial approach to protein requirements by the FAO/WHO (1965) Expert Group on Protein Requirements.

1. The ingestion of doses of up to 6 g sodium tungstate (56 mg W/kg body-weight) by goats was found to diminish the amount of xanthine oxidase secreted in their milk so that, in some samples, the enzyme became undetectable. This effect occurred whether the goats were eating a semi-synthetic or a conventional diet.

2. Tungstate ingestion by goats did not affect the concentration of riboflavine in their milk.

3. The ingestion of sodium tungstate by young goats for 3–5 months diminished the amount of xanthine oxidase in their livers.

4. When given in early lactation to two cows, doses of sodium tungstate (up to 20 g) diminished the titre of xanthine oxidase in their milk with no concomitant effect on the yields.

5. Much later in lactation the milk phosphatase of these two cows was poorly correlated with milk xanthine oxidase. Reasons for this are discussed.

6. Under anaerobic conditions, with xanthine as substrate and triphenyl-tetrazolium chloride as hydrogen acceptor, neither molybdate nor tungstate affected the xanthine oxidase activity of cow's or goat's milk in vitro. Molybdate in vitro did not enhance the very low titre of human milk.

1. The variability in the purchase and consumption of vitamin C in the diet of people living in the United Kingdom has been studied using the Annual Reports of the National Food Survey Committee and new observations gathered independently.

2. The sources of variability examined have been family household composition, social class, seasonal and week-to-week sampling variation.

3. The distribution of mean household daily intakes of vitamin C approximates closely to a log-normal distribution. Assuming this to be so, it may be calculated that about one-quarter of households have vitamin C intakes averaging less than the 30 mg/person per day recommended by the British Medical Association Committee on Nutrition to provide a good margin of safety. Households with intakes below 20 mg/person per day may average 5% of the total. These percentages fall during the late summer and rise correspondingly in the remainder of the year.

4. Allowing for the many uncertainties involved, it is suggested that up to 10% of households and an even greater proportion of individuals may have a vitamin C intake that is permanently below 30 mg/person per day.

1. An attempt has been made to compare the nutritive value of beef from intensively reared animals with that from more extensively reared stock.

2. The difficulties of such a comparison are described and the consequent limitations of this experiment specified.

3. It was found that samples of longissimus dorsi and superficial digital flexor muscles showed no significant differences between intensively reared and extensively reared animals in their content of moisture, intramuscular fat, protein, non-protein nitrogen, iron, thiamine, riboflavine, or nicotinic acid.

4. The longissimus dorsi muscles had more non-protein nitrogen and more nicotinic acid, but less iron and less riboflavine, than the superficial digital flexor muscles.

5. There was less vitamin A and less carotene in samples of liver from intensively reared animals than in comparable samples from extensively reared animals.

1. A previous dietary survey has reported some very low calorie intakes in a farming community in rural Jamaica. Subsequently, ten subjects were specially selected on the basis of being very poor and underfed and individual dietary surveys were carried out in their homes for 7 days.

2. The accuracy of the dietary surveys was tested in a metabolic ward by feeding the subjects with the same meals as were recorded in their homes. Body-weight, calorie and nitrogen intakes, and urinary and faecal N outputs were measured.

3. Basal metabolic rates and the calorie expenditure during sleep were measured to investigate whether any metabolic adaptations to the low calorie intakes had occurred. The calorie cost of performing a standard step-test was measured and compared with that of well-fed control subjects to find out if there were differences in physical efficiency.

4. Nine of the subjects were found to be thinner than the average person of the same age and sex in their district, and were considerably thinner than the average American.

5. Five of the dietary surveys were thought to have given a correct picture of the normal dietary pattern. The remaining five surveys were unsatisfactory.

6. In the five correct surveys, calorie intakes were 61, 69, 72, 78 and 98% of the FAO recommended requirements.

7. No clear-cut evidence of an adaptive change in basal metabolic rate was found.

8. Few calories were available for physical exertion and there was an apparent increase in the physical efficiency of work.

1. When chicks were given a fat-free casein–gelatin diet and, after 2 weeks of age, 0·15% silver acetate in the drinking water, they were found to have colourless exudates mainly in the pectoral region and partly in the peritoneal and pericardial spaces. Vitamin E and selenium, separately and together, failed to prevent this condition. Vitamin E was required together with methionine to prevent the condition. Methionine itself induced green staining of a few of the exudates.

2. When lard was added to the casein–gelatin diet and the chicks were also given Ag, some green exudates were found in addition to the colourless ones. Addition of vitamin E or Se or both prevented the green exudates, but raised the incidence of colourless exudates. Methionine enhanced the green exudate condition, but again when combined with vitamin E prevented both types of exudate.

3. A similar condition characterized by colourless exudates was induced by giving chicks diets based upon gelatin, yeast BPC, α-protein (with extra salts) or α-protein with gelatin. A torula yeast diet induced green exudates and haemorrhages.

4. All the basal diets, which were deficient in sulphur amino acids, produced dystrophy of the breast muscle. Four of these diets contained no fat. Some diets also induced dystrophy of the gizzard. Vitamin E and Se protected against both these lesions. Methionine was protective in all except the torula yeast diet.

5. Ethionine induced muscular dystrophy in chicks given a vitamin E-deficient diet adequate in sulphur amino acids. Additional methionine or vitamin E was protective, but cystine was not. Ethionine also produced a small incidence of green exudates and slight haemorrhages. This condition was prevented by vitamin E but not by methionine. The liver damage due to ethionine was not prevented by vitamin E, methionine or cystine.

6. Liver necrosis was induced in rats by giving them an 8·3% casein diet and Ag, 130–1000 ppm, in the drinking water or the diet. Necrosis was produced even in the absence of dietary fat. Vitamin E and DPPD (N,N′-diphenyl-p-phenylenediamine) prevented necrosis, but adenine sulphate (0·25%), methionine (0·15%) and IONOX 330 (2,4,6-tri-(3′,5′-di-tert.-butyl-4′-hydroxybenzyl) mesitylene) did not. Se, 0·05 ppm, protected against 130 ppm Ag, but 1000 ppm Ag overcame the protective effect of 1 ppm Se. Similarly, 3 ppm cyanocobalamin was partly protective against 130 ppm Ag, but not against the higher concentration. Gold chloride (1000 ppm Au) had a mildly necrotic effect against which vitamin E did not protect. Neither copper sulphate (500 ppm Cu) not arsanilic acid (70 ppm As) induced liver necrosis.

7. A high intake of Se (20 ppm as sodium selenate) was necrogenic in rats given a 10% casein diet; vitamin E and methionine did not protect. Vitamin E and cystine raised the low incidence of an exudative condition found in rats given 20 ppm Se. Methionine opposed this action of vitamin E.

8. It was concluded that exudative diathesis in chicks could be resolved into a simple exudative condition and a superimposed haemorrhagic condition. Ag is a pro-exudative factor. Vitamin E and Se are also pro-exudative for chicks given the casein–gelatin–lard–Ag treatment. Torula yeast, methionine, lard, Ag (with lard) and ethionine are all pro-haemorrhagic factors. Se and Ag have an antagonistic relationship in rats and chicks; in chicks, however, Se synergizes with Ag when the supply of methionine is limited.

1. Iron metabolism was studied during lactation in the rabbit by the intravenous injection of 59Fe in order to measure plasma Fe turnover, Fe transfer to the milk and Fe absorption by the suckling young.

2. Although the plasma and red cell volumes were elevated in the lactating animal a significant increase of plasma Fe turnover was not demonstrated.

3. Between 2.5 and 11.5% of the injected dose of 59Fe appeared in the milk during the following 2–3 weeks. Secretion into the milk continued for at least 2 weeks, and the specific activity of Fe was higher in milk than in plasma, suggesting that the mammary gland contained a pool of Fe, with a low turnover rate from which milk Fe was derived. On the average, 150–315 μg Fe were secreted in the milk per day.

4. Almost all the 59Fe ingested by suckling rabbits, either in milk or sodium chloride solution, was absorbed.

5. It is concluded that in the rabbit the relatively small increase of body Fe which occurs during suckling is entirely due to the limited supply of Fe available in the milk. The high concentration of Fe-binding protein present in rabbit milk did not appear to aid Fe transfer into the milk or to affect Fe absorption by the young.

1. Pigs, held by undernutrition to a weight of about 5.5 kg till they were a year old, were then rehabilitated on an excellent growing ration, and killed when they were fully mature.

2. Undernutrition of this degree of severity delayed the growth and development of the teeth, but relatively less than that of the body or the jaws.

3. The teeth became abnormally sited and the shape of the mandible changed.

4. During rehabilitation, some of the crowns and most of the roots of the molar teeth failed to reach their proper size.

5. Some of the molar teeth remained permanently impacted and out of alignment.

6. The fine structure of the teeth, particularly of those parts formed during the period of undernutrition, was still abnormal when the animals were killed.

1. Groundnut flour plus lysine, fed to young rats at a high level as their sole source of protein supported weight gain and nitrogen retention equal to that on what has been considered the ‘ideal’ egg protein diet. For every 100 metabolizable kcal of the groundnut diet that were consumed, 41 came from the dietary protein and there was a net retention of protein equivalent to 14·5 kcal.

2. The predicted retention of protein according to the equations of Miller & Payne (1961) for this methionine-deficient protein source, given a score of 56 by FAO (1957), would have been equivalent to only 6·1 kcal and, whatever the level of such a protein in a diet, the maximum predicted retention would be equivalent to no more than 8·5 kcal, or 60% of the best expected with egg as the protein source.

3. Feeding a lysine-deficient protein source, wheat gluten, at high levels also gave a greater N retention than had previously been predicted.

4. It is concluded that the Miller & Payne (1961, 1963) equations can greatly under-estimate the performance to be obtained from feeding poor proteins at high levels. A revised equation (P. R. Pane, Private communication) predicts much higher results under these conditions.

1. Two experiments were carried out with non-pregnant ewes in which individual drymatter intake (DMI) and total water intake (TWI) were measured. TWI was closely correlated with DMI; TWI/unit DMI was higher for silage than for cubed dried grass and with both foods water intakes were higher than with long hay.

2. Twelve ewes were fed on silage and twelve on hay from the 9th to the 19th week of pregnancy. TWI/unit DMI of each feed doubled during this period. Another twenty-four ewes were fed on silage from the 14th to the 20th week of pregnancy. TWI/unit DMI was positively related to litter size.

3. Fifteen ewes were fed on hay from the 4th week of pregnancy until the 7th week of lactation. Milk yield was estimated weekly. Six non-pregnant ewes were controls. TWI/unit DMI for the seven twin-bearing and the nine single-bearing ewes in the last 4 and 3 weeks of pregnancy respectively was significantly higher than that of the six non-pregnant ewes. In the control group TWI/unit DMI was closely related to environmental temperature. In the first 4 weeks of lactation TWI/unit DMI was greater than the sum of TWI/unit DMI of the non-pregnant ewes plus the water in the milk.

4. The results supplement those used by the Agricultural Research Council (1965) to assess the water requirements of sheep.