1. Germ-free (GF) and conventional (CV) rabbits wearing collars to prevent coprophagy were fed an autoclaved diet with added cellulose. Their faecal excretion was analysed to determine nutrient digestibility.

2. Clearly distinguishable hard faeces were excreted by the GF rabbit only if the diet contained at least 15% cellulose. Unlike CV rabbits, the GF rabbits did not consume their soft faeces even when permitted to do so. Soft faeces made up a larger proportion of the total output of GF than of CV rabbits. Food intake and total dry-matter excretion per kg body-weight were similar in both groups.

3. Although digestibility of dry matter was similar in the two groups, in the GF rabbits there was a higher digestibility of crude fat and true protein and a lower digestibility of crude fibre and nitrogen-free extract. GF rabbits excreted a higher percentage of ingested calcium and phosphorus in the urine than did CV rabbits.

4. The results suggest that intestinal microbes, even without the enhancing effect of coprophagy, aid in the digestion of carbohydrate by rabbits. The greater faecal excretion of crude fat and true protein by CV rabbits could result from poorer digestion and absorption, but could also represent nutrients synthesized by microbes from simpler materials. The reingestion of faecal crude fat and true protein might therefore improve the quality of the total nutrient intake. The results suggest ways of assuring an adequate dietary intake by GF rabbits in the absence of contributions from an intestinal microflora.

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. 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. 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. 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. 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. 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. The uptake of lipid by the small intestine of the pig was examined by the perfusion of a segment of the jejunum with radioactively labelled lipid in vivo. The rate at which lipid was presented to the small intestine under specific dietary regimes was also examined by means of re-entrant fistulas in the duodenum and jejunum.

2. The capacity of the small intestine to absorb micellar lipid, prepared in vitro or isolated from intestinal contents, was much in excess of the normal rate of flow of fat into the small intestine.

3. There was little uptake of lipid when emulsions of oleic acid were examined, suggesting that the absorption of particulate fat is probably of little importance in pigs.

4.No specificity in the removal of fatty acids from their mixed micellar solutions was observed.

1. Young rats were given, for 9 weeks, vitamin E-deficient diets containing either 20% or 10% casein, with and without a dietary supplement of 350 ppm D-α-tocopheryl acetate. For the next 5 weeks the casein content of the low-protein diets was decreased to 7%.

2. The low-protein diets induced severe growth depression.

3. The dialuric acid-induced haemolysis test showed that the rats given the 20% casein vitamin E-deficient diet were depleted of vitamin E, but that the rate of depletion on the lowcasein diet was slower.

4. Haemoglobin levels were slightly decreased by the 10% casein diets after 9 weeks, but this difference was not found after 14 weeks, comparing 20% and 7% casein. Dietary vitamin E had no effect on haemoglobin levels or erythrocyte counts.

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. 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. 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. 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 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 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.