1. Digestibility of maize stalk from Troyer Reid (Tr) maize and its isogenic mutant (bm1) was studied by suspending nylon bags containing ground tissue in the rumen of a fistulated steer. The animal was given a grass hay–concentrate (5:3) diet or a maize silage–grass hay–concentrate (4:1:3) diet.

2. The digestibility of the organic matter of the mutant maize stalk was greater than that of the normal maize stalk.

3. Adaptation of the rumen to maize silage increased the organic-matter digestibility of the maize stalk.

4. Lignin content was determined by two methods, namely organic matter insoluble in 72% sulphuric acid (method of the Association of Official Agricultural Chemists, 1960) (AOAC-lignin) and the organic matter lost from the ligno-cellulose complex (represented by acid-detergent fibre) by oxidation with potassium permanganate. The AOAC-lignin concentration was twice the permanganate-lignin concentration, but the amount of lignin estimated by both methods showed a significant negative relation to organic-matter digestibility. The AOAC-lignin concentration was greater in Tr than in bm1 maize but the permanganate-lignin concentration in Tr was slightly lower than in bm1.

5. There was an irregular relationship between the amount of lignin extractable with dimethylformamide (DMF) and digestibility of organic matter due to the solution of some of the DMF-lignin during digestion. The loss of lignin was greater from the mutant maize stalk tissue than from the parent maize stalk tissue.

6. The chemical composition of DMF-lignin determined by analysis showed a significant correlation between the syringealdehyde, p-hydroxybenzaldehyde and vanillin concentrations, and digestibility of organic matter.

7. Higher concentrations of both phenolic aldehydes and acids were found in the less digestible Tr material than in the bm1 stalk tissue.

1. Sheep given 400 and 1200 g lucerne chaff/d in equal hourly meals were infused continuously with the complex 51Cr EDTA into the rumen for 5 d and then slaughtered. The retention times of 51Cr EDTA along the small intestine and the apparent quantities of water absorbed in the small and large intestines were calculated.

2. The apparent quantities of water absorbed for the 400 and 1200 g food intakes were 5844 and 13110 ml/d in the small intestine and 2101 and 8520 ml/d in the large intestine respectively.

3. The mean total retention times of 51Cr EDTA in the small intestine were 136 and 91 min for the sheep given 400 and 1200 g/d respectively. The marker was retained up to seventeen times longer in the ileal than in the duodenal or proximal jejunal segments.

1. Metabolic alterations related to protein catabolism were studied in rats in transitional states induced by changing from a low-protein (LP) (50 g casein/kg) diet to a high-protein (HP) (250 g casein/kg) diet.

2. Twenty-four hours after the diet was changed, the rats showed a more rapid increase in live-weight gain than controls that had been fed on the HP diet throughout. On the 5th day after the diet change, their increase in body-weight had returned almost to the control rate. Food and therefore nitrogen intakes on the 1st and 5th days after the change in diet were the same as those of the controls. It seems likely therefore that the initial high rate of live-weight gain is an indication of a metabolic adaptation which occurred on the LP diet and which did not fully return to normal until the 5th day after the change of diet.

3. N balance was higher 24 h after the change in diet than in the controls, owing to a reduction in total urinary N and in urea excretion, but when measured on the 5th day it was similar in both groups.

4. Carcass N determination showed that, after 7 d on the LP diet total-, trichloroacetic acid (TCA)-soluble- and TCA-insoluble-N contents (in terms of mg/g rat) were all slightly lower than control values but they had almost returned to normal 5 d after the diet change. There was a significant increase in the TCA-soluble-N content after 24 h on the HP diet to a value greater than the control value.

5. Proteolysis was measured in vitro by incubation of liver slices and diaphragms under anaerobic conditions. With liver slices it was significantly lower 24 h after the diet change than in control rats. On the 5th day it was significantly higher than 24 h after the diet change but had not quite reached the control level. In the diaphragm, proteolysis was also lower 1 d after the diet change, and had not increased at all by the 5th day.

6. Ureogenesis in the liver was reduced significantly 24 h after the diet change and it had almost returned to the control level on the 5th day. On the other hand, arginase (L-arginine amidinohydrolase; EC 3·5·3·1) activity was significantly lower 24 h after the diet change and did return completely to the control level on the 5th day.

7. These results show that the initial increased N balance and reduced N excretion were due to enzymic adaptation to the LP diet, the reduced N excretion being attributable to reduction in hepatic urea production.

1. A new product of the bacterial degradation of riboflavin has been isolated from fermentations in vitro of mixtures of either rumen bacteria or caecal bacteria with excess of the vitamin.

2. This product has been identified as 7,8-dimethyl-10-carboxymethylisoalloxazine and has also been shown to occur in the urine of ruminants and man.

3. The bacterial formation of this compound is compared with the bacterial formation of other isoalloxazines previously identified in similar incubation mixtures, and is discussed in relation to the factors influencing the mode of degradation of riboflavin.

1. The riboflavin metabolite, 7,8-dimethyl-10-formylmethylisoalloxazine, has been shown to be reduced to the corresponding alcohol, 7,8-dimethyl-10-(2′-hydroxyethyl)isoalloxazine, by an enzyme present in the soluble fraction of liver and kidney.

2. The enzyme is present in these organs in a number of species but is especially prevalent in the tissues of ruminants. It appears to be different from the normal hepatic alcohol dehydrogenase in that it uses NADPH rather than NADH as cofactor.

1. Details of a chemical method, using acetic acid and sodium nitrite, for determining ‘available lysine’ in plant materials are given. An analytical procedure was used which distinguished lysine from ornithine; the latter was liable to arise in the course of the deamination and hydrolysis procedure.

2. The experimentally determined ‘available lysine’ contents of various samples of leaf-protein concentrates showed significant positive correlations with previously reported values for their biological value and true digestibility. ‘Available lysine’correlated significantly with total lysine liberated by direct acid hydrolysis.

1. There were statistically-significant relationships between the concentrations of vitamin B12 in the livers of rats and their urinary excretion of methylmalonic acid, both before and after the intraperitoneal injection of sodium propionate.

2. The effects of diets based on raw and heated soya-bean flour (SBF) on the growth rates, urinary excretion of methylmalonate and hepatic vitamin B12 were compared in normal and vitamin B12-depleted rats.

3. When female weanling vitamin B12-deficient rats were put on to the raw SBF diet they lost weight and became moribund after 3 weeks, even when the diet was supplemented with vitamin B12. Male adult vitamin B12-deficient rats lost weight but showed no other signs of severe vitamin B12 deficiency.

4. Stock weanling male rats were fed on raw SBF diets with or without added vitamin B12. The diets were given alone and supplemented with either methionine or a mixture of methionine, valine, threonine and tyrosine. The rats still did not grow as well as those fed on diets containing heated SBF. However, there was some evidence of increased methylmalonate excretion and lower hepatic concentrations of vitamin B12 in the rats fed on the raw SBF diets.

1. The vitamin B12 content of items of diet and of meals was measured after they had been prepared for consumption.

2. There was poor agreement between the vitamin B12 contents of meals estimated by measurements on meal homogenates and the contents estimated by calculations involving the weights and vitamin B12 contents of items.

3. The average amount of vitamin B12 absorbed per d from a hospital diet was found to be 1.7 μg.

1. The effect of dietary copper deficiency on the distribution of Cu, zinc and iron between plasma, various soft tissues and bone was investigated in weanling male rats.

2. The concentration of Cu decreased in plasma, liver, kidney and femur, and the concentration in plasma correlated with that in all three organs. The total amount of Cu in the liver was reduced over the whole depletion period and a net loss from kidney also occurred over a shorter period, indicating that liver and, to a lesser extent, kidney both provide a mobilizable reserve of Cu.

3. Animals in galvanized cages developed Cu deficiency more rapidly than similar rats in stainless-steel cages owing to Zn aggravating the depletion. Zn accumulated in the liver and femur of Cu deficient rats, particularly when they were housed in galvanized cages.

4. Cu-deficient animals accumulated Fe in the liver, but had reduced concentrations in plasma, kidney and spleen. The hypertrophy of the heart and bone-marrow observed in Cu-deficient rats appeared to be secondary to the anaemia resulting from this impaired mobilization of hepatic Fe.

1. Young female Wistar rats were fed for 18 d on diets containing dextrose, 43 dextrose equivalent (DE) glucose syrup, fractions of 43 DE glucose syrup of high and low molecular weight or sucrose.

2. All rats gained weight and showed no gross external abnormalities or significant dental caries scores.

3. The concentrations of cholesterol, triglycerides, free fatty acids and glucose were determined in samples of liver and serum. Generally, these values tended to increase with increasing molecular weight of dietary carbohydrate in the order dextrose, glucose syrup fraction of low molecular weight, and glucose syrup fraction of high molecular weight.

4. Rats given the high-molecular weight glucose syrup fraction were found to have caecums twice the normal size.

1. Three groups of rats of different mean weights were given a diet of milk treated with hydrogen sulphide and supplemented with copper-free minerals and vitamins. Also divided into three groups of similar weights were rats given the same diet supplemented with 500 μg Cu/week and stock rats which were given a commercial diet.

2. In a second experiment eight adult female rats were given the Cu-deficient diet for 2 weeks before mating and during pregnancy, and in a third experiment were mated and immediately after mating were given the Cu-deficient diet or the Cu-supplemented diet.

3. Cu deficiency reduced the growth rate of younger rats but had a much less marked effect on the weight of more mature rats. Achromotrichia appeared at 5 weeks; diarrhoea, with the faeces frequently containing undigested blood, and subcutaneous oedema were terminal changes. Deaths occurred in the youngest group of rats after 9 weeks and later in heavier, older rats.

4. Histological changes were seen in livers, spleens, testes and epididymes but not in blood vessels or bones.

5. Pups were not born to mothers given the deficient diet before mating, and the pups from mothers given the deficient diet only during pregnancy were born dead or showed congenital abnormalities.

6. Foetal and liver Cu concentrations for the various groups of animals are given.

7. Maintenance of the foetus appears to be the biological process most susceptible to Cu deficiency in the rat.

1. A feeding trial with children suffering from kwashiorkor was conducted in which the winged bean (Psophocarpus palustris Desv.) was used as the major source of protein in the diet.

2. Seventy-two children who had been admitted to hospital with moderate or severe kwashiorkor were included in the study. The experimental diet, prepared from a mixture of two parts of the winged beans and three parts of maize flour, enriched with a small amount of skim milk, was given to twelve children with moderate and twenty-four children with severe kwashiorkor. Equal numbers of children with similar clinical, somatometric and biochemical measurements received a control diet in which most of the protein was provided by skim milk. Both groups of children had a supplementary meal of ‘poto-poto’of negligible protein content, which supplied an extra 100–120 kJ per kg per d. The diets were introduced after the children had overcome the most acute phase of the illness during which a routine diet based on skim milk and calcium caseinate had been given. Both diets supplied 4 g protein and 435 kJ per kg body-weight and were given to the children, on the average, for 30 d.

3. The experimental diet was well accepted and tolerated, and all children made good clinical progress. The rates of gain in weight were slightly less in the experimental groups than in the children who received the control diet. Although the differences were not statistically significant, they were more marked in children whose weights were between 61 and 75% of standard (classified as second degree kwashiorkor). With both diets, mean daily weight gains were significantly higher in children with severe kwashiorkor than in those with moderate kwashiorkor.

4. The increase in total serum protein and the decrease in the amino acid ratio determined 2 weeks after admission were more marked in children given the control diet. At the end of the experimental period, however, the differences between the groups in these two measurements, as well as in values for haemoglobin concentration, protein fractions and the hydroxyproline index were no longer significant.

5. The high nutritive value and the pleasant, sweet taste, even in the raw state, are the main advantages of the winged bean. These should outweigh the disadvantage that its skin is tough and more difficult to remove than that of the soya bean.

1. Rats were given a low-protein (10 g/kg) diet for 16 weeks and the changes occurring in their serum amino acids were studied; during this time a full picture of protein-energy malnutrition was manifested. Groups of rats were killed at intervals of 4 weeks.

2. Food intake decreased gradually from the 4th to the 8th week, then increased slightly from the 9th to the 11th week, and then decreased again.

3. The body-weight of the rats fell progressively from the 1st week on the low-protein diet, remained stationary from the 10th to the 13th week, and then decreased again during the last 4 weeks.

4. The ratio of non-essential to essential amino acid was not correlated with the severity of protein deficiency.

5. The ratios between some individual amino acids were compared with these ratios in control rats during the 4-week periods of protein deficiency. The ratio of serine+glycine to threonine was always significantly higher in the protein-deficient than in the control rats.

1. The composition of the milk of Chinchilla chinchilla chinchilla was determined throughout lactation in twenty-eight chinchillas. The amino acid pattern of the protein and the fatty acid composition of the milk were determined, and the effect of three different diets on the milk composition was studied.

2. The milk contained (g/kg): 64–80 protein, 108–156 fat, 17 lactose and 10 ash.

3. Paper and polyacrilamide gel electrophoresis showed four additional protein fractions that are not apparent in bovine milk protein.

1. Rats were raised on a low-fat diet containing 6 g fat/kg. Females of the second generation were bred and only 11% of their pups survived to weaning age compared with a 66% survival for control pups. Pups were killed 8–12 h after birth and their tissues were analysed.

2. Pups in the low-fat group had smaller body, brain and liver weights than control pups; the lipid contents of body, brain and liver were also significantly less.

3. In the liver triglycerides from the control group the C20 and C22 polyenoic fatty acids constituted 33% of the total fatty acids. The liver triglyceride concentration in the low-fat group was lower and the concentration of the long-chain polyenoic fatty acids in this fraction was 20% of the control value. The milk fatty acids from the low-fat group contained only 33% as much of the C18 to C22 polyenoic fatty acids compared with the control group.

4. In the brain lipids from the low-fat group, changes in the fatty acid composition were less marked than in the liver lipids. In these experiments there were only small amounts of 20:3ω9 in the tissue lipids; the ratio to 20:4ω6 was less than 1.

5. These changes are discussed in relation to the influence of dietary lipids on tissue growth especially of lipid-rich tissues such as the brain.

1. The reproductive performance of rats reared from weaning on a moderately protein-deficient (LP) diet containing 80 g casein/kg, or on a control diet (HP) containing 250 g casein/kg has been studied. Although the rate of growth was reduced in LP animals, these rats eventually achieved the same adult weight and appearance as the controls.

2. Weight gain during the first 2 weeks of gestation was similar in the two dietary groups, but during the 3rd week HP rats gained twice as much weight as the LP animals.

3. Viable litters were produced by 78% of the HP rats mated but by only 33% of LP rats. Most of the offspring which died did so during or soon after birth; so the perinatal mortality for the offspring of LP rats was 73% compared with only 26% for control rats. After the first few days of life, the chance of survival of HP and LP offspring was similar.

4. At birth the mean body-weight of the offspring was 5.4 g for HP offspring and 4.7 g for LP offspring. However, the mean body-weight at birth of viable offspring was similar whether they were from HP or LP rats (HP 5.6 g; LP 5.3 g). At weaning, HP offspring weighed 31.2 g and LP offspring only 13.3 g.

5. When the HP diet was given to LP rats at parturition, the viable offspring achieved a weaning weight of 31.5 g, but there was no decrease in the perinatal mortality.