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. 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. 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. 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. The metabolic responses to daily treatment with 1 μg cyanocobalamin were studied in sixteen patients with megaloblastic anaemia due to cobalamin deficiency.

2. The fall in serum iron was sluggish in most patients. The pattern of reticulocyte responses varied widely, the most common being a plateau with suboptimal maximal value.

3. Urinary propionic acid excretion before treatment was normal in two out of six patients. A transient rise during treatment was observed in two patients, possibly owing to demands on coenzyme stores. The fall in urinary propionic acid excretion during treatment was slow.

4. Serum vitamin B12 levels rose during treatment. In two patients an abrupt rise was found, possibly owing to release of stored cobalamin into the circulation.

1. In three experiments sheep were offered a choice of two rations: one high in NaCl (7.5 or 15%) and one low in NaCl. The intake of each ration was recorded when fresh water was freely available, when increasing amounts of NaCl were added to the drinking water and when the amount of fresh water available was restricted.

2. Low levels of NaCl in the drinking water or mild restriction of available water were without effect on the diet selected. At higher levels, total food intake was reduced and the reduction was sustained entirely by the high-salt ration. The intake of the low-salt ration remained the same or increased, so that the selected diet then contained an increased proportion of the low-salt ration. The effects of adding NaCl to the drinking water and of water restriction were similar.

3. It was concluded that sheep with a choice of high- and low-salt rations can partly avoid the stress of saline drinking-water or restricted water supply by changing the proportion of each ration eaten.

1. A laboratory-prepared groundnut flour defatted at room temperature (DGF) was subjected to dry heat or to pressure steaming under varying conditions of time and temperature, and its amino acid composition and nutritive value, the latter assessed by a chick growth test—the gross protein value (GPV) test, were compared with those of some commercial groundnut meals. Trypsin inhibitor activity, available lysine value (ALV) and ‘arachin’ and ‘conarachin’ content and, in some instances, GPV were estimated in the heated samples.

2. The amino acid composition of the DGF and of commercial meals of high, medium and low GPV did not differ markedly, and the GPV of the DGF fell within the range of the three commercial samples.

3. Both dry and moist heat under specified conditions lowered ALV in the DGF and in the ‘arachin’ fractions, but had little effect on the ALV of the ‘conarachin’ fraction.

4. Moist, but not dry, heat rapidly removed trypsin inhibitor activity, and dry, but not moist, heat lowered GPV.

5. Neither ‘conarachin’ content nor trypsin inhibitor activity correlated with GPV in a range of commercial groundnut meals.

6. Dry heat (125. for 5 h) lowered nutritive value and ‘conarachin’ content but did not reduce the amount of total nitrogen soluble in sodium chloride solution.

7. No trypsin-inhibiting activity was found in the testa (skins) but these did exhibit growth-depressant properties for chicks. This property was removed by mild moist heat treatment.

8. ‘Arachin’ isolated from a commercial groundnut meal was valueless as a protein supplement for a cereal ration for chicks; ‘conarachin’ by itself, and mixed with arachin (1:3) was equivalent in GPV to the parent meal.

9. A factor other than those considered here, and possibly unassociated with processing, is primarily responsible for the differences in growth-promoting qualities of the commercial groundnut meals used in this work.

1. The effects of heat treatment on the proteins of the groundnut were studied by examining the electrophoretic patterns of the proteins extracted from samples of a laboratory-prepared groundnut flour after various heat treatments.

2. Marked changes in the electrophoretic pattern of the conarachin fraction were found and these changes correlated with changes in nutritive value.

3. Marked differences were found between the electrophoretic patterns of the conarachin fractions extracted from twenty commercial groundnut meals, and these differences could be correlated with nutritive value.

4. It is suggested that an examination of the electrophoretic pattern of the conarachin fraction could provide a useful and rapid means of determining the nutritive value of a groundnut meal.

1. The effects, on the secretion in milk of fat and its component fatty acids, of supplementing a basal diet low in fat with red palm oil at three levels are reported.

2. The secretion of total fat and of the fatty acids contained in the oil supplement was positively correlated with the dietary intakes, except for linoleic acid which was hydrogenated in the rumen before its absorption and secretion in milk.

3. Evidence for the synthesis de novo of palmitic acid and for the possible depression of intramammary de novo synthesis by high levels of dietary fat is discussed.

1. The dietary intakes of twenty-six women were investigated during their first pregnancy, at 6–8 weeks post-partum and at 6 months post-partum or after the cessation of breast-feeding.

2. Of this group, sixteen subjects were apparently breast-feeding satisfactorily at 6–8 weeks post-partum, as judged by the average weekly weight gain of their infants (202 g).

3. Changes in food consumption and nutrient intake were studied, together with changes in body-weight and activity. The subjects did not consume more calories during pregnancy. It appeared that this was a result of dietary advice received plus some curtailment of activity during pregnancy. There was an increase in intake of nutrients during lactation.

4. Intakes of iron during the third trimester of pregnancy and of ascorbic acid during lactation were 1.9 ± 0.3 mg (16%) and 26 ± 7.3 mg (26%) respectively below the allowances recommended by the (Australian) National Health and Medical Research Council. The significance of these intakes is discussed.

5. No difference was detected in the diets during pregnancy of women who breast-fed compared with those who did not.

1. The first two experiments were similar; pullets were given either a low-manganese diet, 6–7 μg/g, or a high-Mn diet containing an additional 50 μgMn/g; shell thickness as measured by weight per unit area was obtained for the first four and the last four eggs produced during a short laying period and the Mn contents of the first two and last two eggs were determined.

2. Shell thickness was significantly reduced by the low-Mn diet in Expt 1, but not in Expt 2. In both experiments there was an increase in thickness from the first four to the last four shells produced.

3. The Mn content of eggs from birds given the low-Mn diet was significantly lower in both experiments than that from birds given the high-Mn diet. In Expt 1 there was an increase in Mn content from the first to the last eggs laid, but no corresponding change occurred in Expt 2.

4. The differences between the results of the two experiments are discussed; they were probably due to differences in the time for which the experimental diets were given before laying began.

5. In Expt 3 pullets were given the high-Mn or low-Mn diet from about 4 weeks before laying began or the high-Mn diet to the point-of-lay and then the low-Mn diet. Shell thickness was determined in batches of six eggs from each bird at intervals during a 6- to 7-month laying period.

6. Shell thickness was depressed by the low-Mn diet in birds given this diet 4 weeks before laying but not in those given the low-Mn diet from the point-of-lay.

7. In Expt 4 shell thickness was determined on the first thirty eggs laid by four pullets given the high-Mn diet and four given the low-Mn diet from about 4 weeks before starting to lay. The difference between shells from birds given the high-Mn and low-Mn diets just failed to reach significance and there was no significant increase or decrease in the series of thirty shells from each bird, studied in successive groups of six shells.

1. Groups of pullets were given a diet of high (106–107 μg/g) or low (6–7 μg/g) manganese content and killed either before sexual maturity, at the point-of-lay or after a 6- to 7-month laying period. The birds were dissected into six tissue fractions: skeleton, liver, kidney, ovary and oviduct, skin and feathers, and muscle with remaining tissue. Total Mn and concentration of Mn as μg/g dry fat-free tissue were determined for each fraction.

2. There were no differences in live weight attributable to level of dietary Mn, and no differences in egg production.

3. Mean total body Mn varied among groups over a fairly narrow range (528–738 μg), with the exception of birds given the high-Mn diet throughout the experiment, in which the mean was 2319 μg. This represented an increase in Mn content during egg laying of 244%. There was no significant difference in the Mn content of birds given the low-Mn diet whether they were killed at the point-of-lay or after the laying period.

4. The effects of treatment on the weight of Mn in each of the tissue fractions are described. The very large increase in total Mn that occurred during egg production in birds given the high-Mn diet was accounted for largely by the increase in skin and feathers (1072 μg Mn).

5. In general terms, the Mn content of liver, kidney and ovary and oviduct together constituted only just over 10% of total body Mn, the remainder being distributed about equally among skeleton, skin and feathers, and muscle with remaining tissue.

6. There was a close parallel between the concentration of Mn of a tissue and the total weight of Mn it contained except in certain instances when stage of maturity or egg production influenced weight of the tissue.

7. The effects of treatments on the Mn contents of these birds are discussed in relation to the retention of dietary Mn, and the withdrawal from and accumulation of Mn in individual tissues and the whole body.

1. The effectiveness of supplementing a vitamin E-deficient basal diet with levels from 0 to 20 ppm of selenium as sodium selenite, alone and in combination with graded levels of L-cystine, sodium sulphate, L-serine and vitamine E, has been studied in chicks from 1 day of age to 4 weeks. Supplementation with Se at levels up to 1 ppm had maximum beneficial effects on growth and prevention of muscular dystrophy. Levels of Se above 1 ppm were progressively less effective, and, in chicks given supplements of 20 ppm Se, growth and muscular dystrophy were depressed to that found with chicks given the basal diet.

2. Supplementation with L-cystine (0.08% and 0.16%) in combination with Se up to 1 ppm was beneficial, but this effect was progressively suppressed as the amount of Se was increased beyond this level. Supplementation with sodium sulphate (0.08% and 0.16%) or L-serine (0.08% and 0.16%) instead of L-cystine had no influence on the effectiveness of Se at any level of the latter tested.

3. The effectiveness of dietary D-α-tocopheryl acetate, up to 20 mg/kg, for growth and in the prevention of muscular dystrophy was improved by Se at levels up to 1 ppm. Its effectiveness was then progressively reduced as the amount of Se was increased above 1 ppm.

4. It appears that Se at low levels spares L-cystine and vitamin E in the chick, whereas at high levels it increases their requirement for growth and prevention of muscular dystrophy.

1. The true digestibilities of esterified lauric, palmitic, stearic and oleic acids in lard, coconut oil and soya-bean oil were determined by incorporating the [1-14C]-labelled acids into the fats by interestification. The true digestibilities of the labelled fats also were compared with the digestibilities of their unlabelled counterparts, corrected for endogenous fat by the conventional procedure.

2. The true and corrected coefficients of digestibility of each of the fats were in good agreement, but there were significant differences between the true and corrected coefficients for individual fatty acids, particularly for palmitic and stearic acids.

3. The amount of endogenous fat produced with each of the fats calculated from the values found with the labelled fatty acids was greatest when the fat supplement was lard, when a disproportionately high level of palmitic acid was excreted.

4. Evidence was obtained of the extensive hydrogenation of oleic acid in the digestive tract of the pig.

1. After a preliminary period of 2 weeks indoor feeding on hay, two groups of wethers grazed either a timothy pasture or a ryegrass-dominant pasture for 12 weeks. The timothy was particularly low in sodium and chlorine.

2. Within a week of turning out, saliva sodium fell and potassium increased in the timothy group, and by the end of the experiment, the sodium: potassium ratio was 1.9:1. The changes in saliva were not reflected in blood composition. The rate of live-weight gain was similar in both groups of sheep.

3. The results confirm those of a previous indoor experiment and show that timothy supplies insufficient sodium to maintain the normal saliva composition of sheep.

1. Six healthy young women residing in a metabolic unit, but continuing their normal activities, received a uniform diet for 27 days, subdivided into four periods of 6 days and a final collection period of 3 days.

2. The daily food was divided into equal-sized portions; the subjects ate their daily quota as three meals a day in periods 1, 3, and 5 (control), two meals in period 2 (gorging), and nine meals in period 4 (nibbling).

3. The metabolic response of each subject was investigated by measurements of energy expenditure, and by analysis of the food, the urine and the faeces.

4.The subjects showed distinct differences in response, but for most subjects the changes in body-weight and in the metabolism of nitrogen and fat appeared unrelated to the frequency of the meals.

1. In Expt 1, four adult wether sheep were given diets of hay or dried grass in an alternating sequence of feeding treatments. Each treatment period lasted for 20 days and blood samples were taken from the sheep on the last day of each period. When the diet of hay (linoleic: linolenic acid ratio 1.40) was replaced by one of dried grass (linoleic: linolenic acid ratio 0.28), there was an increase in the concentration of linolenic acid and a decrease in the concentration of linoleic acid in the plasma cholesteryl esters and phospholipids. There was an increase in the concentration of stearic acid and a decrease in the concentration of palmitic acid in the plasma triglycerides. Dietary change did not affect the composition of the plasma unesterified fatty acids.

2. In Expt 2, two adult wether sheep, each with a rumen fistula, were given daily intraruminal infusions of 60 g of ‘linolenic’ or ‘linoleic’ acids (both about 70% pure) over a period of 5 days. The infusion treatments were then reversed. Blood samples were taken at the end of each infusion period. Intraruminal infusions of ‘linolenic’ acid increased the concentration of linolenic acid in the plasma cholesteryl esters and phospholipids and increased the concentration of stearic acid in the plasma triglycerides. The infusions of ‘linoleic’ acid increased the concentration of linoleic acid in the plasma cholesteryl esters and phospholipids. No appreciable changes were observed in the composition of the plasma unesterified fatty acids.

1. Groups of chicks were given diets containing four levels of vitamins A and D, 1, 10, 100 and 1000 times the basal level, in all sixteen combinations, with the object of investigating a possible antagonism between the two vitamins.

2. Only diets containing 1000 times the basal level (approx. 1700 times the dietary requirements) of one or both vitamins depressed growth and induced changes in the blood.

3. The packed cell volume was substantially reduced from 4 weeks of age in the chicks given the highest level of vitamin A. It is suggested that this was due to an effect of the vitamin on the fragility of the red cells and thus on their life span.

4. Chicks given the toxic level of vitamin D showed an increase in plasma calcium and a decrease in plasma inorganic phosphorus. The highest level of vitamin A depressed plasma Ca without influencing plasma inorganic P. Increasing amounts of vitamin A given in combination with the highest level of vitamin D caused a progressive increase in the plasma inorganic P.

5. The highest level of dietary vitamin A significantly increased the activity in the plasma of three lysosomal enzymes: acid phosphatase, β-glucuronidase and arylsulphatase. Excess vitamin D given in conjunction with the basal level of vitamin A significantly depressed the plasma acid phosphatase and the activity of this enzyme increased with increasing amounts of vitamin A. Excess vitamin D had no influence on the other hydrolases studied.

6. A marked antagonism between the effects of excessive amounts of the two vitamins occurred only in respect of their actions on the plasma levels of Ca, inorganic P and acid phosphatase, all of which are involved in bone metabolism.