1. The absorption of iron from 59Fe-labelled maize and soya-bean preparations was measured by whole-body counting in forty-two apparently healthy Jamaican infants and compared with the absorption of ferrous ascorbate.

2. The mean absorption of Fe from maize was 4·3% and from soya beans baked at 300°, 9·4%, compared with 28·5% for ferrous ascorbate. In a group of children given boiled soya beans the mean absorption of Fe was 2·8%, and of ferrous ascorbate 16·7%.

3. There was much variability between replicate tests made on the same child at intervals of 1–2 weeks.

4. The absorption of food Fe was not increased in children who were considered to be anaemic (haemoglobin less than 100 g/l) or Fe-deficient (serum Fe less than 500 μg/l and saturation of total Fe-binding capacity less than 15%).

5. The poor availability of Fe in maize meal, which is a staple food of children in Jamaica, is probably an important cause of the high prevalence of Fe-deficiency anaemia.

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. A method is described for measurement of portal blood flow in the sheep by the principle of continuous thermal dilution produced by injection of cool saline into the portal circulation at 1 mg/s for 30 s.

2. In most animals phlebitis developed only around the catheter in the right ruminal vein. This affected their appetite and condition after surgery. When all catheters were introduced into the anterior mesenteric veins there was no phlebitis and appetite postoperatively was normal.

3. Portal blood flow in six out of nine sheep was 33–34 mg/kg body-weight per min in the morning before feeding. After a meal of dried grass it increased during the period about 2–6 h later.

4. Total heat production and oxygen consumption of the digestive tract were estimated from portal blood flow and arteriovenous differences in temperature and oxygen concentration. When the heat production of the digestive tract was increased by 1·77 kJ/min by the inclusion of a heating element in the rumen, estimated total heat production increased, on average, by 1·73 kJ/min.

5. During the period 2–6 h after a meal of dried grass, portal venous temperature rose, on average, by 0·7°, visceral O2 consumption did not alter significantly, but total heat production rose by 1·19 kJ/min.

6. These initial results suggest that the heat of fermentation can be determined in vivo. In these experiments it was about 10 kJ per 100 kJ digestible energy consumed.

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. Phospholipds were studied in the heart muscles, skeletal muscles and livers of seven Ayrshire calves which received vitamin E-free maize oil (in filled milk) with and without supplementary α-tocopherol from 1 week old for 17 d. The calves that were not given vitamin E developed muscular dystrophy.

2. Decreased amounts of cardiolipin and increased amounts of sphingomyelin were found in the skeletal muscles of vitamin E-deficient calves. There was a significant decrease of phosphatidyl choline in the livers of vitamin E-deficient calves.

3. The decrease in cardiolipin concentration confirmed the electron-microscopical picture (reported elsewhere) of preferential destruction of mitochondria in muscular dystrophy of calves.

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. A liquid diet is described for the supply of ethanol to rats with a constant proportion of energy equivalents from different sources. In this diet, a protein-enriched, dry, milk powder is used as the protein source.

2. The diet was used in a two-group experiment lasting for 80 d in which the rats were fed ad lib. The consumption was 120 ml/d per rat in the control group, whereas in the ethanol-consuming group the consumpton was only 40 ml/d per rat at the start of the experiment and rose to and remained at 80 ml/d per rat after 20 d.

3. The control group grew normally. In the ethanol-consuming group, there was an initial loss of body-weight; after 20 d there was some increase in body-weight but growth was slower than in the control group. The smaller food intake in the ethanol group was not wholly caused by the lower body-weight.

4. The free and total activities of acid phosphatase (EC 3·1·3·2) and β-glucuronidase (EC 3·2·1·31) were estimated in the liver after 10, 20, 30, 40, 60 and 80 d. Neither the free nor the total activity of acid phosphatase changed significantly during the experiment. The ratio of free activity to total activity increased significantly after 20–40 d of treatment with ethanol. The free and total activities of β-glucuronidase were significantly increased after 10 d of treatment with ethanol, but this difference could not be shown after prolonged treatment.

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.

1. The effect of short-term and long-term feeding (0–80 d) with a liquid diet containing ethanol on the activity of rat hepatic enzymes related to lipogenesis has been evaluated. Carbohydrates were isoenergetically substituted for ethanol in the control animals.

2. The maximum concentration of triglycerides in the livers was reached after about 30 d, when it was almost three times as high as in the control animals. The activity of malic enzyme (EC 1·1·1·40) and ATP citrate lyase (EC 4·1·3·8) decreased significantly in the ethanol group, compared with the control rats, within 10 d and remained low during the rest of the experiment (80 d). After 20 d, the acetyl-CoA synthetase (EC 6·2·1·1) activity increased significantly in the livers of the ethanol-fed rats but fell subsequently to values similar to those in the livers of the control rats. Thus, despite a pronounced increase in the amount of triglyceride in the livers of rats on a liquid diet containing ethanol, there was a dramatic decrease in the activity of the enzymes (malic enzyme and citrate lyase) involved in lipogenesis.

3. The almost unchanged activity of acetyl-CoA synthetase shows that the utilization of acetate, produced when ethanol is oxidized, is not stimulated by long-term feeding with ethanol. The involvement of citrate lyase in various postulated shuttles for the transport of reducing equivalents across the mitochondrial membrane and the role of malic enzyme in the microsomal ethanol-oxidizing system are discussed.

1. The main products of fermentation of 1,2-propanediol were n-propanol and propionic acid, but variable amounts of acetic acid and carbon dioxide were also formed. The concentrations of an intermediate propionaldehyde increased and then decreased.

2. A tentative scheme is suggested, showing that 1,2-propanediol is first dehydrated to propionaldehyde, which is then reduced to n-propanol. The scheme also explains the formation of propionic and acetic acids and shows how the metabolism of 1,2-propanediol is related to that of rhamnose.

3. Experiments with samples of rumen contents from animals on various diets showed that 1,2-propanediol was metabolized most rapidly when the animals were given molassed sugar-beet pulp. The rates of dissimilation of the diol increased with the concentration of rumen contents and with the concentration of substrate.

4. The dissimilation of 1,2-propanediol by rumen micro-organisms resulted in an increased uptake of hydrogen. The metabolic hydrogen, arising from the inhibition of methane production by chloroform, appeared to be better utilized than the gaseous hydrogen.

5. Oxygen gas did not affect the utilization of 1,2-propanediol, but the diol increased the uptake of oxygen by the rumen contents. The hydrogen and carbon balances were better when 1,2-propanediol was incubated anaerobically than in the presence of oxygen.

1. Nucleic acids introduced into the rumens of calves, or incubated with calf, sheep or cow rumen contents in vitro, were rapidly destroyed.

2. The degradation products formed were separated and identified by means of column chromatography on Sephadex G-10 Dextran gel and thin-layer chromatography on cellulose.

3. In vitro, RNA was rapidly (within 1 h) converted into ultrafilterable oligo-and mono-nucleotides, nucleosides, purine and pyrimidine bases. After 4 h, only the bases xanthine, hypoxanthine and uracil remained, having increased at the expense of the other constituents.

4. DNA gave similar products but with a much greater proportion of ultrafilterable oligoand mono-nucleotide material which remained as a major component even after 4 h. The only bases present in appreciable amounts were thymine, hypoxanthine, uracil and xanthine.

5. The same products accumulated temporarily in vivo, after addition of RNA or DNA to the rumens of calves, and were found also, in small amounts, in corresponding samples of duodenal digesta. The products disappeared from the rumen at a greater rate than could be accounted for by transfer to the duodenum.

6. Cell-free preparations from calf rumen fluid contained enzymes which converted RNA and DNA into products which appeared to be ultrafilterable oligonucleotides.

7. When ground hay was incubated with whole rumen contents the nucleic acids in the hay were degraded to a mixture of nucleotides, nucleosides and bases, almost as readily as were pure nucleic acids.