1. The fasting metabolism of twenty-seven animals, nine Brahmans, nine Africanders and nine Hereford × Shorthorns was measured after fasts of 96 h duration. Urine was collected over successive 24 h intervals and gas exchange was determined 96–103 h after the last meal.

2. Urinary urea decreased and creatinine increased throughout the fasting period. There was no difference between breeds in the urinary excretion of nitrogen, urea and creatinine on the 4th day of fasting (72–96 h). Excretion of nitrogen, urea and creatinine increased by 259, 197 and 45 mg/kg increase in fasted weight and by 8.9, 7.6 and 0.91 mg/kcal increase in fasting metabolism respectively. Protein oxidation accounted for 25.6, 21.7 and 22.7% of the fasting heat production of Brahman, Africander and Hereford × Shorthorn cattle respectively, values which were not significantly different.

3. The breeds differed in fasting metabolism per kg fasted weight ( P < 0.05) and in fasting metabolism adjusted for fasted weight (0.05 < P < 0.10), mainly owing to lower values for the Brahmans. The respective values for the Brahmans, Africanders and Hereford × Short-horns were 20.7, 25.2 and 24.1 kcal/kg (86.6, 105.4 and 100.8 kJ/kg) and 5.856, 6.947 and 6.600 Mca1/24 h (24.50, 29.07 and 27.61 MJ/24 h) at a fasted weight of 277 kg. The variation in fasting metabolism between animals within breeds, expressed as a coefficient of variation, was 13.7%.

4. The results are discussed in relation to published estimates of fasting metabolism, possible reasons for the breed difference and the relation of fasting metabolism to heat tolerance.

1. Copper deficiency was induced in newly hatched chicks by feeding on a milk-based diet for 12 d; effects of supplementation with ascorbic acid were studied.

2. Cu deficiency alone resulted in 30% mortality from aortic rupture. This was associated with a 20% increase in total acid mucopolysaccharides in the aorta, manifested as an increase in chondroitin sulphate and a relative decrease in hyaluronic acid. Cytochrome oxidase activity of liver and heart was less than half that of the controls.

3. Supplementing the Cu-deficient diet with 0.5 % L-ascorbic acid increased mortality to 40%, raised total aortic acid mucopolysaccharides to a higher level, and increased liver iron by 36%.

4. Supplementing the control diet with ascorbic acid decreased liver Cu by 30% and significantly reduced total aortic acid mucopolysaccharides.

5. The enhancement of the Cu-deficiency effect by ascorbic acid probably results from interactions between ascorbic acid and absorption or metabolism of Cu; untoward effects of supplementing the control diet with ascorbic acid may be interpreted as manifestations of ascorbic acid toxicity per se.

1. Sheep confined topens and given a cobalt-deficient ration which supplied about 30μgCo/d required for maintenance of normal growth rate a Co supplement approaching 40 μg administered per os daily; for maintenance of what appeared, under the conditions of the experiments described, to be the maximum vitamin B12 status of a sheep, namely 3 ng vitamin B12/ml serum and 1.4 μg vitamin B12/g liver tissue, a supplement of between 0.5 and 1.0 mg Co/d per os was necessary.

2. For maintenance of normal growth rate the minimum daily requirement for vitamin B12 of sheep given the Co-deficient diet was about 11μg: about 5 μg absorbed from the gut and about 6 μg injected parenterally.

3. Extrapolation of the linear regression obtained by plotting the amount of vitamin B12injected/d against concentration of vitamin B12 in the liver tissue of a sheep indicated that to attain a concentration of 1.4 μg vitamin B12/g liver (wet weight) injection of 34 μg vitamin B12/d was necessary.

4. Comparison of the relative effects on body-weight of the administration of 100 μg vitamin B12/dper os and 3.12 μg vitamin B12/d by injection to sheep given the Co-deficient diet indicated that the efficiency of absorption of the vitamin from the gut was < 3%.

5. Loss of appetite, the first symptom of vitamin B12 deficiency to appear in the sheep, occurred when the concentration of vitamin B12 in the liver was reduced to about 0.1 μg/g wet weight.

6. In sheep given a supplement of 1 mg Co/d per os neither production in the rumen nor absorption from the gut but rather capacity for storage limited the concentration of vitamin B12 in the liver.

7. Following treatment to restore the vitamin B12 status of a sheep whose stores of the vitamin had been depleted, there was a linear negative correlation between the increase in the concentration of vitamin B12 in the liver and the concentration prior to treatment.

8. Following withdrawal of treatment from a sheep whose stores of vitamin B12 were adequate, there was a linear positive correlation between the rate of depletion of vitamin B12 from the liver and the concentration prior to cessation of treatment.

9. The concentrations of vitamin B12 in the serums of sheep given the Co-deficient diet, and given a supplement of 1 mg Co/d per os 0.5 h after feeding, remained relatively stable over the period 0–7 h after feeding; maximum concentration occurred 7–8 h after feeding.

10. Under the conditions of the experiments described a significant linear regression existed between concentration of vitamin B12 in the liver of a sheep and the logarithm of the concentration in the serum.

1. The effect of riboflavine deficiency on in vivo incorporation of [2–14C]glycine into proteins of liver homogenates and its subcellular fractions has been studied on rats maintained on a 16 % protein diet.

2. Riboflavine deficiency did not seem to affect the in vivo incorporation of [2–14C]g1ycine into proteins of liver homogenates. But riboflavine deficiency caused increased and reduced invivo incorporation of [14C]amino acid into mitochondrial and microsomal proteins, respectively.There was no significant change in the in vivo incorporation of [14C]amino acid into proteins ofnuclear, ribosomal and soluble fractions in riboflavine deficiency.

3. Riboflavine deficiency caused enhanced and reduced proportions of liver mitochondrial and microsomal proteins, respectively.

4. The results are discussed as suggestive of enhanced and reduced protein synthesis in the mitochondrial and microsomal fractions, respectively, of riboflavine-deficient rats.

1. Urinary excretions of creatinine (Cre) and hydroxyproline (OHPr) were measured in two groups of children: (a) 24 h collections in male and ‘spot’ samples in female marasmic infants throughout the course of treatment, and (b) ‘spot’ samples in underprivileged pre-school children at home. Results were related to certain somatic measurements and in some instances to some dietary factors.

2. Analysis of 24 h samples taken at intervals throughout 120 d of treatment showed a steady rise towards normal levels from very low initial values of OHPr. There was no corre-lation with age or body-weight on admission, nor of OHPr excretion through recovery with increase in height. Excretion of Cre also increased during recovery but the trend was more erratic. There was no relation to initial weight deficit or age but mean Cre excretion through recovery did correlate with rate of increase in weight. Values of Cre excretion at different stages of recovery expressed in terms of weight or height differed somewhat from those reported by others. The possible significance of these findings is discussed.

3. High correlations of the OHPr index according to Whitehead (1965) determined on 6 h and 24 h collections provided evidence for the representative nature of ‘spot’ samples.

4. Partial correlation analysis of body-weight and urine volume in relation to Cre excretion (mg/24 h) showed that the former (r = 0.719) had a greater influence than the latter (r= 0.485).

5. In a subgroup of eleven marasmic infants aged 3–5 months multiple linear regression analyses of OHPr and Cre excretion on somatic and dietary factors revealed no consistent correlations.

6. Periods of lowered OHPr and Cre excretion were frequent but in only half of the instances were they related to intercurrent infection.

7. A high correlation was found between changes in excretion of OHPr and of Cre throughout recovery.

8. An appraisal was made of the OHPr index according to Whitehead (1965). On the basis of the considerable influence that age was shown to have on this index during the preschool period an OHPr index (age-adjusted) was suggested for use.

9. The OHPr index (age-adjusted) determined on ‘spot’ samples from underprivileged preschool children at home and from marasmic infants during recovery was shown to be closely correlated with a modified ‘index of thriving’ based on somatic measurements.

10. The value of Cre and OHPr determinations in the study of severely malnourished children during recovery and in the detection of mild undernutrition is discussed in the light of these experimental results.

1. Two wethers fitted with permanent rumen cannulas were used to study the effect of two mineral supplements, Na2HPO4 and a 1:1 mixture of Na2CO3 and NaHCO3, on the buffering system in the rumen of sheep given a pelleted roughage-concentrate diet.

2. Measurements were made of rumen pH, buffering capacity value (β), total volatile fatty acids (VFA), CO2 and inorganic phosphorus concentrations as well as rumen cellulase activity.

3. The addition of either mineral supplement to the diet significantly (P < 0.001) increased the rumen pH values during the critical post-feeding period, there was a difference of only 0.5 pH unit between the minimum and maximum pH values.

4. Both mineral supplements significantly increased the concentrations of CO2 in the rumen fluid and rumen cellulase activity. They resulted in a general reduction in total VFA concentrations. It is suggested that this may possibly arise from increased absorption of VFA associated with increased CO2 tension in the rumen fluid.

5. The Na2HPO4 supplement significantly ( P < 0.001) increased the β values in the pH range 6–8, whereas the bicarbonate supplement contributed to raising the β values in the pH range 5–6.

6. The bicarbonate supplements raised cellulose digestibility from 39.7% for the control diet to 45.6% and the addition of Na2HPO4 further raised the digestibility to 51.1%. It would appear that low rumen pH impairs rumen cellulase activity and this could be offset by the addition of mineral supplements.

1. A combination of balance and isotope techniques has been used to study calcium metabolism in ten sheep at different stages of pregnancy, and the results have been combined with earlier results obtained during lactation to show the variations in Ca metabolism which occur during the whole reproductive cycle.

2. Transfer of Ca to the foetuses during pregnancy and to the milk after parturition rose rapidly from the 65th day of gestation and reached a maximum at parturition or shortly afterwards.

3. Although the rate of absorption of Ca from the intestine increased steadily throughout pregnancy it was insufficient to meet the full requirements of late pregnancy and early lactation. During this period, the extra Ca was supplied by increased bone resorption.

4. The maternal Ca balance became negative during pregnancy, the net daily loss of Ca reaching a maximum in early lactation.

5. In late lactation the maternal Ca balance became positive enabling the animals to replenish their skeletal stores.

6. There was no marked change in the demands for Ca at parturition and the connexion between this observation and the pathogenesis of milk fever is discussed.

7. Rates of transfer of Ca to the foetus during pregnancy are compared with estimated values of other workers.

1. The concentrations of volatile fatty acids (VFA) in the rumen and caecum were compared when sheep were given barley or dried grass. The molar proportions of VFA in the caecum resembled those in the rumen except that the proportions of isobutyric and isovaleric acids were higher in caecal than in rumen fluid indicating an extensive breakdown of protein during fermentation in the caecum.

2. The capacity for starch digestion in the large intestine was studied in two sheep receiving dried grass. Starch was infused into the caecum, the amount given increasing by daily increments of 20 g until 300 g daily were infused. Infused starch in excess of 138 g daily largely appeared in the faeces, indicating a limited but substantial capacity for starch fermentation in the large intestine. The infusion caused a marked increase in the molar proportion of butyric acid.

3. Determinations made with a single sheep showed that the infusion of starch into the caecum caused large changes in the microflora, and species similar to Butyrivibrio became prevalent. The viable count on a starch medium was increased by 83 % by starch infusion.

4. The infusions of starch increased the excretion of nitrogen in the faeces from 5.8 to 9.0 g daily. Using a fractionation procedure it was shown that when 100 g of starch were fermented in the large intestine the 'bacterial and endogenous debris' nitrogen increased by about 1.0 g. When starch was given orally to two sheep the increase in this fraction was about 0.4g nitrogen/100 g starch digested.

5. It is suggested that dietary factors that cause changes in the site of fermentation from the rumen to the caecum will render less microbial nitrogen available to the host animal per unit of carbohydrate fermented and decrease the apparent digestibility of nitrogen.

1. Eighty-eight Nigerian village children aged 1–12 years were involved in this study.

2. A food consumption survey on each child was carried out for 7 consecutive d; iron, folic acid and calorie intakes were calculated from food composition tables.

3. Samples of the children's diets (cooked) were collected and analysed for moisture, total nitrogen and ascorbic acid content.

4. Blood samples were assessed for haemoglobin and haematocrit values.

5. Calorie, protein and folic acid intakes were low for all age groups; iron and ascorbic acid intakes were adequate.

6. There was no incidence of severe anaemia. Only 10% of all the eighty-eight children had a haemoglobin concentration below acceptable levels and only about 8 % of all the eighty-eight children had haematocrit values below acceptable level.

1. Fifty-two pregnant women in a village were divided into three groups, A, B and C, and were given the following supplements: A, iron in the form of 200 mg ferrous sulphate daily; B, Fe(as group A) and 5 mg of folic acid daily; C, Fe and folic acid (as group B) plus an antimalarial drug.

2. Blood samples were collected each week and assessed for haemoglobin and haematocrit values.

3. Dietary intakes of Fe and folic acid were calculated for both pregnant and non-pregnant women. Results revealed that Fe intake was adequate and Fe deficiency not common. The supplement of Fe increased the haemoglobin levels.

4. Folic acid intake was low and intake probably fluctuated during the year because of seasonal changes in the dietary folic acid.

5. About 28% of patients, during their first attendance, had haematocrit values below normal. Folic acid supplements increased these values.

1. An experiment is reported in which groups of six lambs were fed two basal diets supplemented at three levels with a mixture of sodium and calcium acetates.

2. The basal diets were given in amounts that provided equal intakes of digestible organic matter and crude protein. One contained 85 % of concentrates (Hc), the other 40% of concentrates (Lc). Rumen contents from a sheep receiving diet Hc contained a lower molar proportion of acetate and higher proportions of propionate and butyrate than when diet Lc was given.

3. The calculated metabolizable energy of the basal Hc diet was utilized more efficiently than that of the basal Lc diet, for promoting empty body-weight and carcass-weight gains.

4. On both basal diets, lambs receiving the diets supplemented with acetate made greater live-weight, empty body-weight and carcass-weight gains than lambs given unsupplemented diets. The responses of weight gain to increasing levels of acetate were linear.

5. The responses to acetate were greater when it was given with the Hc diet than with the Lc diet. This effect was most marked for live-weight gain (P < 0.001), intermediate for empty body-weight gain (P < 0.05), but not significant for carcass-weight gain. This order of effects was in part due to a greater weight of alimentary tract tissue, and its contents, in lambs fed the Hc diet supplemented with acetate.

6. It is concluded that under certain circumstances the energy of acetate may be utilized less efficiently than energy from propionate or butyrate.

1. Isotope dilution techniques were used to measure the rates of entry and oxidation of glucose, acetate, palmitate, stearate and oleate in fed and fasted (16 h) pigs.

2. Glucose entry rates measured in eight fed and five fasted (16 h) pigs were 20.6 and 8.0 mg/min per kg0.75 (mean values) respectively. The entry rates in fed pigs were lower than the calculated rates of glucose uptake from the alimentary tract, and the validity of glucose entry rates determined under these conditions is discussed.

3. Acetate entry rates were unrelated to the fibre content of the diet, and acetate produced from endogenous metabolism was the main contributor to total acetate production.

4. Increased rates of entry and oxidation of palmitate, stearate and oleate were observed in fasted pigs.

5. Glucose production in fasted pigs was inhibited by raising the concentration of blood glucose. Infusion of insulin in the fed pig caused a decrease in glucose production and a simultaneous reduction in the mobilization of free fatty acids. When blood glucose concentrations fell below about 55 mg/100 ml the release of free fatty acid into the circulation was restored.

1. The nutritive value of solubilized wool protein prepared by dissolving finely ground wool in sodium sulphide-sodium sulphite solution followed by precipitation with 40 % acetic acid has been tested by incorporating it into protein-free diets containing the amounts of vitamins and minerals required by weanling rats.

2. At the level of 10 % (w/w) of the diet, solubilized wool protein failed to support growth in weanling rats, but when the diet was fortified with histidine, methionine and lysine a protein efficiency ratio of up to 1.8 was obtained. The effect of the addition of lysine was marginal. Similar results were obtained with solubilized wool protein prepared from dyed wool suiting material.

3. Apart from the methionine content, which varied from 0.49 to 0.66 g/100 g protein, the contents of the essential amino acids in the solubilized wool protein generally met the requirement of the FA0 (1957) provisional pattern, although in many of the preparations the levels of isoleucine and lysine were marginal. The tryptophan content was not determined. Supplementation of the solubilized wool protein with lysine to the level of 6–10 g/100 g protein slightly enhanced the nutritive value.

1. 64Cu as copper chloride in aqueous solution was given by intraperitoneal injection to rats varying in age from a few hours to 14 weeks. The isotope was allowed to circulate in the body for 24 h.

2. The amount of gamma radioactivity present in the brain and blood was measured and the percentage of the initial dose present was calculated. It was shown that the brain 64Cu activity reached a maximum around the 16th day of life and that the blood showed a steady decrease in the 64Cu activity per g from birth to maturity. Measurements were also made on the liver and kidney.

3. The excretion of 64Cu in the urine and faeces in 24 h was also studied. Approximately 30% of the isotope was excreted in that time, mostly in the faeces.

4. A limited number of experiments in three different age groups were carried out to discover whether changes in specific activity of the isotope given to rats had a significant effect on the percentage of 64Cu taken up by the brain and blood. No such effect was seen.

1. Young rats were fed on diets containing heated or unheated soya-bean flour.

2. Feeding unheated soya-bean flour decreased concentrations of vitamin B12 in liver, kidneys and blood serum, urinary excretion of sulphate and concentration of reduced glutathione in liver. Blood glutathione level and urinary excretion of methylmalonic acid and formimino-glutamic acid following loads of propionate and histidine, respectively, were increased.

3. Supplementing a diet of unheated soya-bean flour with vitamin B12, had no effect on the level of reduced glutathione in the liver. Adding methionine to this diet decreased excretion of methylmalonic acid and the level of glutathione in blood.

4. The activity of liver methyl-tetrahydrofolate: L-homocysteine S-methyltransferase was not affected by the nature of dietary soya-bean flour nor by supplementation with vitamin B12

5. It is concluded that heat-labile substances present in soya-bean flour induce metabolic changes which can bring about an increased requirement for vitamin B12, and a deficiency of sulphur-containing amino acids.

1. The effect of addition of a mixture of two non-essential amino acids (NEA), namely alanine and glutamic acid, to milk proteins on nitrogen retention and the biological value of the proteins was determined in a group of six girls aged 10–11 years.

2. The mean daily intakes of milk protein by the children on three diets (1, 3 and 5 ) were 1.41, 1.10 and 0.70 g/kg body-weight. The quantities of NEA added daily to the three diets were 0.97, 0.49 and 0.97 g/kg body-weight respectively.

3. Addition of NEA did not bring about any significant increase in N retention in the children. The addition of NEA to milk proteins significantly decreased the biological value of the proteins.

1. The effects of the introduction into the diet of natural fats rich in individual fatty acids or of simple triglycerides on the composition of blood lipids and of milk fat in the sow were investigated.

2. Replacement in the diet of a mixture of animal, vegetable and marine oils by a single natural fat had varying effects on the concentrations of plasma lipid fractions, whereas replacement of tallow by simple triglycerides, with few exceptions, increased the concentrations of all fractions.

3. When butyric or caprylic acids were present in the diet there was no detectable transfer of those acids to plasma triglycerides, and there was only a limited transfer of dietary erucic acid. An increase in the dietary concentration of other acids (ranging from capric to linolenic) was associated with an increase in the content of the acids in the plasma triglycerides. For saturated fatty acids the response to dietary changes was at a maximum for myristic acid.

4. The effects on the composition of milk fat reflected the changes in the composition of the plasma triglycerides, except during the feeding of cottonseed oil when there were marked decreases in milk fat of palmitoleic and oleic acids and corresponding increases in palmitic and stearic acids which were not observed in the plasma triglycerides. Also, during the feeding of coconut oil, capric acid was present in the plasma triglycerides but not in milk fat, and the increases in the plasma triglycerides of lauric and myristic acids were much more marked than the corresponding increases in milk fat.

1. A chemical and biological evaluation of the protein content of some leaves and leaf extracts from the eastern region of Nigeria (Biafra) has been made: most were from cassava (Munihot utilissima).

2. The protein content of the leaves was from 3 0 to 40% (expressed as percentage of leaf dry matter). The concentrations of essential amino acids were adequate, except for methionine. The biological criteria, true digestibility (TD) and biological value (BV), showed that the digestibility was from 70 to 80%, whereas BV varied from 44 to 57%, depending on the methionine content.

3. Adding methionine to a diet of cassava leaves raised BV from 49 for the leaves alone to 80 for the mixture. This relationship clearly shows that cassava leaves contain too little available methionine. An investigation into the true availability of the amino acids showed that this is somewhat variable, and only 60% of the methionine is available.

4. The BV of cassava leaves combined with Norwegian dried cod showed a mutual supplementation effect.