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. 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 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. 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. 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. 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.