1. In pregnancy, severe hypoproteinaemia, cirrhosis and anaemia, plasma free α-amino nitrogen (FαAN) was found to be lowered. The non-essential:essential amino acid ratios, determined by paper chromatography, were increased in hypoproteinaemia and anaemia.

2. The erythrocytic FαAN content increased in early hypoproteinaemia and values lower than normal were found in severe hypoproteinaemia. There was also a rise in anaemia, which was due to increased cellular non-essential amino acids.

3. The leucocytic FαAN was reduced in all hypoproteinaemic states. The increased FαAN values in patients with thyrotoxicosis demonstrated that, in catabolism, leucocytic uptake of amino acids is increased. The non-essential:essential amino acid ratios were decreased in cirrhosis, possibly due to poor biosynthesis of non-essential amino acids by the liver.

1. Effect of glucose infusions on the rate of gluconeogenesis, as indicated by changes in the irreversible loss of plasma glucose, synthesis of glucose from ruminal propionate or fixation of blood bicarbonate into glucose, has been examined in sheep.

Sheep, feeding at hourly intervals, received intravenous infusions of [U-14C]glucose, NaH14CO3, or [6-3H]glucose, infused simultaneously with an intraruminal infusion of [2-14C]propionate. Glucose (4–144 mg/min) was infused intravenously at a single rate or at two different successive rates of equal duration. The glucose infusions were over a 6 h period and followed estimates of pre-infusion kinetic measurements.

2. The infusion of glucose suppressed endogenous glucose production in direct proportion to that infused for sheep given diets of lucrene or wheat. The maximum rate of suppression recorded was equivalent to about 50–60% of the endogenous production rate of glucose.

Transfer rates of carbon-14 from blood bicarbonate or ruminal propionate to plasma glucose were reduced during glucose loadings. The results indicate that administration of glucose was more effective in suppressing the synthesis of glucose from substrates other than ruminal propionate.

3. The percentage of glucose carbon derived from blood bicarbonate was lower in sheep given wheat than in sheep given lucerne. It was suggested that this difference may have been due to absorption of glucose from the alimentary canal of sheep on the former ration. Approximately 8% of the wheat starch may have escaped fermentation and been absorbed as glucose in these animals.

1. Short-term effects of infusions of propionate, amino acids and butyrate on gluconeogenesis, as indicated by changes in the irreversible loss of plasma glucose, synthesis of glucose from ruminal propionate or fixation of blood bicarbonate into glucose have been examined in sheep given their daily ration in twenty-four equal portions at hourly intervals.

Sheep received intravenous infusions of [6-3H]glucose usually, in combination with [U-14C]glucose or NaH14CO3 or with intraruminal infusions of [2-14C]propionate. Substrates were infused over a 3–7 h period and followed estimates of pre-infusion kinetic measurements.

2. It was demonstrated that intraruminal and intramesenteric vein infusions of sodium propionate and intra-abomasal infusions of casein hydrolysate stimulated gluconeogenesis. Glucose synthesis showed a linear response to the infusion of these substrates, which varied from 0·35–6·35 mmol propionate/min and 50–160 mg casein/min.

3. The increment in the measured production rate of propionate in the rumen was consistently less than the rate of addition of propionate to the rumen.

4. Intramesenteric vein infusions of sodium butyrate at successive rates of 0·25 and 0·50 mmol/min produced only an initial transient increase in plasma glucose production. Since the rate of glucose synthesis from ruminal propionate was not altered, it was suggested that butyrate initiated glycogen mobilization.

1. Four feeding trials were made to investigate relations between diet and protozoal population in the rumen.

2. When a ration containing no concentrate was used, the number of entodiniomorphs decreased rapidly. The number of entodiniomorphs increased with the amount of concentrate. Rice straw, which was used as a sole source of roughage, was not always necessary for protozoa to survive in the rumen.

3. The type of diet affected the holotrich population to a much smaller extent than the entodiniomorph population.

1. Groups of rats were maintained from weaning on magnesium-deficient (30 mg Mg/kg) and control (460 mg Mg/kg) diets.

2. Mg deficiency for a period of more than 3 months resulted in sterility of both males and females.

3. A Mg deficiency of less than 3 months caused abortions or resorptions in utero of foetuses in pregnant females before other physical signs appeared.

4. Mg deficiency during lactation rendered the survival of young rats uncertain. The mother rat died of exhaustion if she did not devour her litter.

5. The growth of surviving young rats born of Mg-deficient mothers was noticeably retarded when they were nursed by mothers receiving the Mg-deficient diet.

1. The method of Sukhatme (1970b), which takes into account the interrelationship between dietary protein and energy, has been applied to the dietary survey results collected during the nation-wide Nutrition Survey of West Pakistan. It was found that most of the protein deficiency that occurs in Pakistan is conditioned by energy deficiency. The incidence rises from 13 to 40% when cases conditioned by energy deficiency are taken into account. Protein deficiency as such exists in only 2% of families compared with 11% of families which are deficient in both protein and energy. These findings indicate the magnitude of the protein problem in Pakistan.

2. In view of these findings, it is obvious that, unless the energy need is met, increased protein production will not help much to improve the situation and may be a costly approach to the solution of the protein problem in Pakistan.

1. Techniques were devised for the operation of a new small-scale gnotobiotic rat unit.

2. The unit was then used to compare the cariogenicity of sucrose and glucose under carefully controlled conditions in the presence of a single strain of a streptococcus, as gnotobiotic experiments by other workers had given conflicting results.

3. Streptococcus IB-1600 was implanted into thirty-four rats, which were then fed on high-sugar diets under gnotobiotic conditions for 5 or 8 weeks from weaning. The level of caries was significantly higher on the sucrose than on the glucose diet, but there was no significant difference in the extent of soft coronal dental plaque.

1. The haematological status of Ayrshire bull calves reared on fat-supplemented skim milk from about 17 d of age has been examined. The calves were moderately anaemic after an 11-week experiment and it was shown that their performance was related to their blood haemoglobin concentration.

2. The relative availabilities of iron from FeSO4, ferric citrate, ferric-ethylenediaminetetra-acetate and iron phytate were compared at a supplementary dietary concentration of 30 μg Fe/g. No significant differences were noted between the three soluble Fe sources but the Fe of the insoluble iron phytate was less available.

3. The decreases in blood haemoglobin concentrations in all calves were greatest in the early weeks of the experiment. In calves given supplementary Fe, however, there was generally an improvement in haematological status after 6 weeks. Plasma Fe concentrations fell to 0·20 μg/ml in the most deficient animals. Total Fe binding capacities averaged about 10 μg Fe/ml in the later stages of the experiment.

4. Some of the calves were copper-deficient, and in some animals the effects of dietary Cu supplementation on both Cu and Fe metabolism were studied. About 50% of the supplementary Cu was retained in the livers of the calves.

5. A dietary intake of 40 μg Fe/g milk powder appears to be sufficient to prevent all but a very mild anaemia, provided the Fe is presented in soluble form.

1. The pool size, space and rate of irreversible loss of glucose were estimated with primed infusions of [U-14C]glucose in reindeer cows within 6 h of being taken from outdoor pens or from free grazing in the field.

2. In conjunction with primed infusions of [U-14C]glucose, single injections of [3-3H]glucose were also used to estimate pool size, space, transfer rate, and turnover time of glucose.

3. Except in a period of severe undernutrition, the concentration of glucose in plasma was higher (range 0·76–1·40 mg/ml) than that recorded for other ruminants.

4. The size of the glucose pool (range 8–35 g) varied in parallel with plasma glucose concentration and was generally distributed in a space in excess of the extracellular fluid volume.

5. The lowest rates of irreversible loss of glucose (approximately 1·7 mg/min per kg0·75) were measured when cows were in mid pregnancy and when available food was scarce; the highest rate (5·5 mg/min per kg0·75) was found in cows during mid summer.

6. Changes in irreversible loss and transfer rate of glucose are interpreted in relation to changes in body composition (estimated in a parallel study), subjective assessment of available food and factors known to control glucose metabolism in other ruminants.

7. The difference between glucose transfer rate and rate of irreversible loss of glucose was used as an index of the rate of resynthesis of glucose from products of glucose catabolism. The rates of glucose resynthesis were highest during a period of rapid growth (4·52 mg/min per kg0·75 or 45% of the glucose transfer rate) and in mid and late pregnancy (respectively 4·14 and 4·28 mg/min per kg0·75 or 71 and 59% of the transfer rate).

1. A group of ten Ugandan children were given, ad lib., under supervision, the traditional home diet and their intakes of energy and protein and changes in body-weight and concentrations of serum albumin compared with those of a similar group of nine children fed on a milk-based diet with the same protein concentration.

2. The energy and protein intakes of the children fed on the home diet were significantly lower than those of the children fed on the milk-based diet, as was their rate of weight gain and serum albumin regeneration.

3. The significance of the findings is discussed in relation to the low intakes of energy and protein and the hypoalbuminaemia found in Ugandan preschool children.

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 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. 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. 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. 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.