1. Body-weight, body height, knee width, wrist width and skinfold measurements were made on males (n 139) and females (n 167) in three age-groups (20–22, 25–27 and 30–32 years). Percentage of body fal was calculated from skinfold thicknesses using regression equations according to Durnin & Womersley (1974), Three indices of relative weight were calculated: W/H2, W/Hp and W/Ŵ, where W is body-weight, H is body height, p is the exponent that made the index of relative weight independent of height and W is the weight, estimated from body height and frame size.

2. The standard error of the estimate of body-weight was only reduced by 5% in males and by 13% in females when, in addition to body height, knee width was taken into account.The addition of wrist width did not improve the accuracy of estimation of body-weight in either sex. Therefore in further analyses W was estimated from body height and knee width. In the present population the exponent p was 1·7 in males and 1·6 in females.

3. The correlations between the percentage of body fat and the indices, W/H2, W/HP, and W/Ŵ, were all very similar, being approximately 0·8 in both sexes.

4. A positive relationship was observed between percentage of body fat and knee width in females, which may be explained by an artifact of measurement.

5. In conclusion it can be stated that the accuracy of estimation of percentage of body fat was not improved when the index of relative weight was adjusted for knee width or wrist width in the present population. The W/H2was the most preferable of the three indices which were calculated.

1. The proportions of lymphocyte subpopulations (by rosette tests) and the serum antibody levels (using haemagglutination techniques) were estimated in malnourished and well fed Nigerian children before and up to 21 d after immunization with tetanus toxoid or measles virus vaccine.

2. Significantly diminished (P < 0.01) mean percentage T lymphocyte levels and considerably higher mean percentage null cell levels were observed in the malnourished children before immunization with either of the vaccines.

3. There was comparable in vivo increases in percentage T lymphocytes in malnourished and control children following the administration of each antigen.

4. The mean percentage B lymphocyte levels were similar in the control and malnourished children before and after the immunization.

5. There was a slight depression in the tetanus antibody levels (P > 0.2) but a significant diminution (P < 0.01) in measles virus antibody concentrations in the malnourished children.

6. Rise in mean percentage T lymphocytes corresponded with the elevation in mean tetanus antibody levels in both malnourished and control children following tetanus toxoid immunization. This was however not the situation in the malnourished children following immunization with measles virus.

7. The observed depressed T lymphocyte number in malnourished children may in practice affect their handling of antigens such as measles virus in vivo.

1. Rat pups were undernourished during the period of the brain growth-spurt by feeding their mothers a low-protein diet from the third day post partum.

2. The pups were killed on days 5,6,9,12,16,20 and 24 post partum, and their brains were analysed for protein, DNA, glycosides and glycoproteins. The activities of four enzymes involved in neurotransmission, and in the synthesis of glycolipids and myelin were also measured. Results of the analyses were compared with those obtained for pups that were suckled by well-nourished dams.

3. The brains of the undernourished pups contained substantially less protein and DNA; gangliosides and glycoproteins were also reduced.

4. All four enzymes showed lower peak activities in the nutritionally deprived animals, and the attainment of peak activity was retarded by several days.

5. These results suggest that undernutrition imposed during the brain growth-spurt leads to a deficit in the glial cell population and thus in the capacity to form myelin, and reduced deveiopment of cellular processes.

1. Newly weaned 21-d-old male rats were given isoenergetic diets containing 200, 100 and 50 g protein/kg for 7, 14, 28 or 70 d. The mid-jejunum was removed from the rats and a micrometric analysis of the mucosa was made. The following measurements were made: number of villi/mm2, vilius dimensions, villus surface area, crypt depth, crypt: villus, the number of cells/crypt in metaphase arrest per h.

2. Comparisons were made between animals of the same age but on different diets, and animals on the same diet but of different ages. The latter comparison gave information on the effect of protein deficiency on the pattern of maturation of each feature of The villus or crypt studied.

3. The effect of protein deficiency was not consistent at each stage of maturation. For instance villus height was decreased when compared with the controls following 28 d on a protein-deficient diet but not after 7 or 70 d.

4. The only measurement to be unaffected by protein deficiency was the number of villi per unit area.

5. In general the 50 g protein/kg diet had a more pronounced effect than the 100 g protein/kg diet. Protein deficiency delayed maturation by either slowing or inhibiting changes seen in normal maturation.

6. In rats given 50 g protein/kg diet, although the villus surface area did not increase as the rats matured there were increases in epithelial cell production rate and number of crypts per villus.

1. Ryegrass (Lolium multiflorum cv. RvP) silage was given to twelve Friesian steer calves (initial live weight (LW) 106 kg) at 2·3 kg dry matter (DM)/calf per d, alone, or with a supplement of fish meal at 50(FM1) or 100(FM2) g/kg silage DM per d.

2. The rate of flow of nutrients into the duodenum was measured using a dual-marker technique. Glucose irreversible-loss rates and the contribution of propionate to gluconeogenesis were measured using continuous infusions of [U-14C]glucose and [2-14C]propionate.

3. Amino acid flow into the duodenum was significantly (P < 0·01) increased from 238 g/d on the control treatment to 319 g/d on FM2, but there was no response to FM1 (P > 0·05).

4. Glucose irreversible loss rate remained constant with an average value of 1·86 mg/min per kg LW.

5. Neither the percentage of glucose synthesized from propionate (average 30) nor the percentage of propionate converted to glucose (average 45) was significantly altered by treatment (P > 0·05).

1. Five monotocous and twoditocous Scottish Blackface ewes with indwelling catheters in an umbilical artery and vein of one foetus only and in both maternal jugular veins were used.

2. Experiments were conducted over a period of 2 d when [I4C]urea was infused intravenously over 9 h into either the mother or foetus, separate days being used for each infusion. Two series of experiments were completed, one in well-nourished and the other in undernourished sheep at 125–141) and 138–143 d of gestation respectively.

3. Plasma urea specific radioactivities of the mother and infused foetus at plateau were used to determine the urea flux-rates within and between mother and foetus. The mean rate of foetal urea production (Ffo) was 1.45 and 1.63 mg/min per kg foetus in well-nourished and undernourished ewes respectively. The corresponding rates of maternal urea production (Fmo) were 0.49 and 0.37 mg/min per kg live weight respectively and there was a close correlation between the rate of maternal urea disposal (Fom) and the dietary nitrogen intake.

4. The values of Ffo were used to calculate the maximum potential for foetal gluconeogenesis from deaminated amino acids. These calculations were compared with published information on the over-all rates of foetal gluconeo genesis in well-nourished ewes.

5. The foetal entry rate of urea expressed on a body-weight basis was high, approximately 8.5 times that of the mother, but it was a threefold overestimate of Ffo. The maternal entry rate was 1.3 times Fmo and the significance of this in relation to assessing differences in urea entry rates in pregnant and non-pregnant sheep is discussed.

1. Five pregnant sheep, with indwelling catheters positioned for withdrawal of maternal right-atrial and foetal arterial blood, were exposed for 2 h to neutral and to cold (– 1° and wool-clipped) environmental temperatures. Acute maternal cold exposure increased the concentrations of glucose, glycerol and non-esterified fatty acids in maternal plasma and increased the concentration of glucose in foetal plasma, but not glycerol or non-esterified fatty acids. The concentration of corticosteroids in maternal piasma increased. The concent ration of corticosteroids in foetal plasma did not change but the concentration of insulin increased.

2. Thirteen pregnant sheep were housed at thermoneutrality and thirteen similar, sheep fed the same amount of food, were clipped and exposed to cold during the last 5– 6 weeks of pregnancy. Chronic maternal cold exposure increased the birth weight of both single and twin lambs.

3. It is concluded that exposure of pregnant sheep to cold can alter the partition of some nutrients between mother and foetus in favour of the foetus, and it is suggested how this may be brought about.

1. An in vitro preparation was used to measure rates of oxygen consumption, Na+, K+-ATPase-dependent respiration, [14C]phenylalanine incorporation and tyrosine release of skeletal (stenomandibularis) muscle from 10-21 -d-old (three) and 7-month dairy (three) calves and control (CDM; four) and extreme double-muscled (EDM; two) calves.

2. Rate of oxygen consumption was greatest (P < 0.001) for muscle from 10.21-d-old dairy calves and lowest (P < 0.05) for CDM calves.

3. Ouabain (10−6 M) caused a 40% inhibition of muscle respiration.

4. Na+, K+-ATPase-dependent respiration was similar for muscle from all calf groups except 10-21-d-old dairy calves which had a value 26% greater (P < 0.001) than that of older dairy calves.

5. Na+, K+-ATPase-independent respiration was 16% greater (P < 0.001) for muscle from 10.21-d-old than that of older dairy calves while muscle from EDM calves had a value 11 % greater than that of CDM caives.

6. The rate of [14C]phenylalanine incorporation was greater (P < 0.05) for muscle from 10-21-d-old dairy than from older dairy calves, similar between older dairy and CDM calves, and decreased (P < 0.05) for EDM calves.

7. Rate of tyrosine release was greatest (P < 0.05) for muscle from CDM and EDM calves: both dairy groups had similarly low rates of muscle tyrosine release.

8. The energy estimated to be required for peptide bond synthesis accounted for 2.0–3.3% of the O2 consumption of the muscle preparations.

1. Groups of adult colostimized chickens were given diets with and without dietary fibre in the form of bagasse or wheat straw. The fibrous materials were analysed for their contents of cellulose, hemicellulose and lignin. The digestible energies (DE) and metabolizable energies (ME) of these diets were measured by a balance method.

2. Groups of germ-free and conventional chicks aged 4 weeks were given diets with and without penicillin or with and without graded levels of wheat straw as a source of fibre and the ME of these diets were determined.

3. The incorporation of the forms of dietary fibre tested reduced the DE and the ME of the diets in adult conventional chickens and the ME in young germ-free and conventional chicks. Both DE and ME were reduced in proportions that suggested that the dietary fibre present was acting largely as an inactive diluent of the dietary energy and was not affecting the absorption of other nutrients. In the young germ-free and conventional chicks, there was a linear relationship between the proportion of wheat straw in one diet and the reduction in me.

4. Dietary penicillin did not alter the ME of the diet in either the germ-free or the conventional environments.

5. The reduction of ME with incorporation of wheat straw was less in conventional than in germ-free chicks. It is suggested that this may be due to the ability of chicks with a gut flora to obtain a small amount of energy from wheat straw.

1. Experiments were carried out to establish the conditions required for the measurement of the availability to chicks of biotin in feed ingredients by a bioassay based on the response of blood pyruvate carboxylase (EC 6.4.1.1; PC) activity.

2. Reference diets were formulated which gave a linear response in blood PC activity at 3 weeks of age over a wide range of supplemental dietary biotin concentrations.

3. Dietary protein concentration was found to affect blood PC activity. Hence purified ingredients in the reference diets were wholly or partially replaced by the test ingredients so that all diets in each assay contained the same amounts of protein, fat and metabolizable energy. Comparison of the blood PC activities of birds$ given the test diets with those given biotin-supplemented reference diets provided a measure of the available biotin content of the test ingredient.

4. Bioavailabilities of biotin were found to vary widely in the cereals and vegetable-protein sources tested.

1. Pigs (sixteen/diet) were weaned at 2 d of age and given liquid diets (200 g dry matter/1) during a 26 d experiment. The pigs were fed on a scale based on live weight. Dried skim-milk was the only source of protein in diet U and was partially or totally replaced by a soya-bean isolate (diet B) or a concentrate (diets C and D). Soya-bean protein provided 500, 700 or 350g/kg total crude protein (nitrogen × 6·25) in diets B, C and D respectively.

2. Performance was similar for diets B and D, but poorer than that of pigs given diet U. The apparent digestibility and retention of N of these diets was similar. Pigs given diet C scoured severely and twelve died.

3. Protein digestion was studied in pigs given diets U, B and D, killed at 28 d of age, at the termination of the feeding experiment. The dry matter content and proportion of N in the digesta in the stomach were reduced in pigs given soya-bean protein. Pepsin concentrations in digesta and stomach tissue were unchanged.

4. The concentrations of trypsin and chymotrypsin in the pancreas were greater in pigs given the soya-bean protein concentrate compared with milk protein, but only the increase in trypsin was significant (P < 0·01). Digesta from the small intestine of pigs given the soya-bean-protein isolate contained less chymotrypsin (P < 0·05). There were no differences in the proportion of non-protein-N in the total N in the digesta, suggesting that proteolysis of the milk and soya-bean proteins were equally efficient by 28 d of age.

1. Male weanling rats were given for extended periods diets containing gum arabic or wheat offal or various offal fractions. The fractions included two lipid fractions, a water-soluble extract and a modified-acid-detergent (MAD)-fibre extract. The diets contained either low concentrations of aflatoxin B1 (induced rats) or were free from this source of aflatoxin (non-induced rats). The distribution of 14C was then studied after the rats received 14C-labelled aflatoxin B1 in their feed. Blood plasma concentrations of triglycerides, and total cholesterol were also measured.

2. Gum arabic and wheat offal accelerated the rate of passage of 14C through the small intestine and wheat offal very considerably decreased retention time in the large intestine. Both fibre sources increased faecal bulk. However, only wheat offal decreased liver and urinary accumulation of 14C and the effect could be explained entirely by the MAD-fibre fraction of wheat offal.

3. The possible induction of either microsomal enzymes unrelated to the production of mutagenic aflatoxin metabolites, or of extramicrosomal enzymes is discussed; but it is concluded that the main effect brought about by wheat offal on the toxicity and carcinogenicity of aflatoxin can be attributed to a direct influence of the MAD fibre fraction of wheat offal on the intestinal absorption of aflatoxin B1.

4. The relevance of these conclusions to drug safety studies is discussed, because comparable studies may yield differing results, despite a use of diets having the same nutrient composition but differing ingredient composition.

1. Total entry, irreversible loss and recycling rates of glucose were measured in four non-pregnant female Shetland ponies before and after a 24 h fast by the continuous intravenous infusion of a mixture of [U-14C] glucose and [2-3H]glucose.

2. The post-fasting fall in the concentration of glucose and the rise in the concentration of ketones in plasma were not significant.

3. After fasting, the total entry rate fell from 1·44±0·11 (n 4) to 1·19±0·12 mg/min per kg body-weight (P > 0·01) and irreversible loss fell from 1·36±0·10 (n 4) to 1·05±0·10 mg/min per kg body-weight (P > 0·02). Recycling rate did not change significantly.

4. In one pony the intravenous infusion of glucose at rates of 0·52, 1·0 or 1·64 mg/min per kg body-weight had no appreciable effect on endogenous glucose production whereas in a second pony, similarly fed, total entry was depressed by 43% and irreversible loss by 54%.

5. Irreversible loss of glucose in the horse is similar to that of many other species.

1. The regulation of the utilization of dietary tryptophan, nicotinamide and nicotinic acid as precursors of the nicotinamide nucleotides has been studied in groups of rats fed on diets providing only one of these precursors at a time, in amounts adequate to meet their requirements for nucleotide synthesis.

2. The concentration of nicotinamide nucleotides in the liver of rats receiving a high-tryptophan diet was 56% higher than in animals fed on a diet providing a minimum amount of tryptophan, together with nicotinic acid or nicotinamide. The excretion of N1-methyl nicotinamidc was three times higher in the tryptophan-fed animals than in the other two groups.

3. The concentration of quinolinic acid in the liver was significantly higher in animals receiving the high-tryptophan diet than in the other two groups; that of nicotinic acid was highest in those animals receiving the nicotinic-acid-containing diet. The concentration of nicotinamide was highest in the livers of those animals receiving the high-tryptophan diet, and lowest in those receiving the nicotinic-acid-contaning diet.

4. The values of the Michaelis constant Km of nicotinamide deamidase (nicotinamide amidohydrolase. EC 3.5,1,19) and nicotinamide phosphoribosylltransferase (nicotinamide nucleotide: pyrophosphate phosphoribosyltransferase, EC 2.4.2.12) were approximately equal, and approximately one-tenth of the concentration of nicotinamide was in the liver. This suggests that both these enzymes normally function at their maximum rate, and a change in the availability of nicotinamide would not affect the rate of its incorporation into nucleotides.

5. The maximum rate of reaction (Vmax) of nicotinamide deamidase was twice that of nicotinamide phosphoribosyltransferase; this suggests that unless compartmental or other factors are involved, the major route of nicotinamide utilization will be by way of deamidation.

6. The Km of nicotinate phosphoribosyltransferase (nicotinate nucleotide: pyrophosphate phosphoribosyltransferase, EC 2.4.2.11) was less than twice the concentration of nicotinic acid in the liver, so that a change in the availability of nicotinic acid might be expected to lead to a small change in the rate of its utilization.

7. The Km of quinolinate phosphoribosyltransferase (nicotinate nucleotide: pyrophosphate phosphoribosyltransferase (carboxylating) EC 2.4.2.19) was approximately 100 times greater than the concentration of quinolinic acid in the liver, so that any change in the availability of quinolinic acid would be expected to lead to a considerable change in the rate of its utilization. The Vmax of quinolinate phosphoribosyltransferase was relatively low, so that under conditions of high tryptophan flux, some accumulation of quinolinic acid might be expected. This was observed in animals receiving the high-tryptophan diet.

8. It is concluded that it is unlikely that the utilization of quinolinic acid, arising from tryptophan. for the synthesis of nicotinamide nucleotides is regulated, but that control over tissue concentrations of nucleotides is achieved by hydrolysis of NAD to nicotinamide. Incorporation of nicotinamide into nucleotides seems to be strictly limited by the activity of the enzymes involved.

1. Bipolar electrodes were permanently implanted on the gastric antrum, and on the different portions of the small intestine of each of eleven healthy adult cats receiving one meal daily. All parts of the feline gut exhibited, as in several other species, regular slow waves and alternate periods of quiescence and electrical spiking activity during the recording sessions lasting from 10 to 30 d.

2. Patterns of electrical activity characteristic of this species were identified. Both the amplitude and frequency of the antral slow-wave were related to the presence cf superimposed spike bursts during fasting decrease in the antral slow-wave frequency and increase in the length of the duodenal plateau of slow waves after the daily meal were related to its nature.

3. In fasted state, the electrical spiking activity of the small intestine occurred as fused spike bursts of large amplitude potentials migrating slowly over short distances only 24 h after feeding. They are interspersed with short periods of irregular spiking activity.

4. These findings suggested that, except the distal part of the small intestine which showed an activity which resembled partially the migrating myoelectric complex observed in other species during the fasting state, the motility patterns of the digestive tract in the cat were not comparable to those observed in the dog or sheep. In the cat, mixing of the contents seemed to result from more or less regular spiking activity allowing their propulsion distally. The propagation over distances varying from 200 to 1000 mm of nine to eighteen daily fused spike bursts in the fasting state remains unclear but they are related to the digestive function in accordance with the displacement aborally of their origin in a prolonged fasting condition.

1. Pancreatic juice was collected from six pigs of 48 kg initial weight fitted with a collection catheter in the pancreatic duct and a return catheter in the duodenum.

2. Measurements of flow and composition of the juice were made during 24 h periods after adaptation to isonitrogenous diets based on barley, wheatings and fish meal (diet BWF) or starch, sucrose, casein, maize oil and cellulose (diet SSC), given in a change-over design. Measurements were also made during the periods of adaptation to a change from one diet to the other.

3. Mean flow-rates for pigs adapted to diets showed a highly significant four-fold difference between diets; values were 4962 ml/d for diet BWF and 1273 ml/d for diet SSC. The hourly volumes of juice were very variable and showed no clear response to feeding and no consistent diurnal pattern for either diet.

4. There were no significant differences between diets in the specific activities of the proteases. Average values were (units/nig protein) trypsin. (EC 3.4.21.4) 29·6, chymotrypsin (EC 3.4.21.1) 7·7, carboxypeptidase A (EC 3.4.17.1) 0·65, carboxypeptidase B (EC 3.4.17.2) 1.6. The total output of each tended to be higher with diet BWF than with diet SSC. The specific activities and tolal outputs of α-amylase (EC 3.2.1.1) and lipase (EC 3.1.1.3) were significantly higher for diet BWF than for diet SSC; specific activities for the two diets respectively were: (units/mg protein) α-amylase 95·6 and 42·3, lipase 59·0 and 14·5.

5. The higher daily volume of juice with diet BWF was associated with significantly (but only slightly) higher levels of both sodium and potassium, compared with diet SSC.

6. The results are discussed in relation to previous studies on digestion at this Institute, in which pigs with intestinal cannulas were given the same diets.

1. Digesta were collected from twenty-two pigs, of 40 kg mean live weight, and fitted with single re-entrant cannulas in either the duodenum, jejunum or ileum.

2. Three approximately isonitrogenous diets were given to the pigs; their main constituents were: barley, fine wheat offal and white fish meal (diet BWF); starch, sucrose, maize oil, cellulose and either groundnut (diet SSG) or casein (diet SSC).

3. The activities of pepsin, chymotrypsin and trypsin were measured every hour in duodenal digesta during 24 h collection periods. Chymotrypsin and trypsin were also measured every hour in jejunal digesta and every 6 h in ileal digesta, during 24 h collection periods.

4. The mean total pepsin activities in the duodenal digesta during 24 h collection periods (units for a 40 kg pig given 1·7 kg diet) were: 7764400 (diet BWF), 6078400 (diet SSG), 5801 600 (diet SSC).

5. The mean total chymotrypsin activities (units for a 40 kg pig given 1·7 kg diet) in digesta in the duodenum, jejunum and ileum respectively were: 62920, 59560, 21 880 (diet BWF), 78240, 68400, 24680 (diet SSG). 75280, 76120, 6160 (diet SSC).

6. The mean total trypsin activities (units for a 40 kg pig given 1·7 kg diet) in digesta from the duodenum, jejunum and ileum, respectively were: 256840, 362840, 77600 (diet BWF), 211 200, 205280. 46720 (diet SSG) 325720, 428560, 13600 (diet SSC).

7. It was calculated that the total weights of pepsin, chymotrypsin and trypsin in duodenal digesta in 24 h periods were between 6·2 and 7·1 g. This represents 20–25% of previously published estimates of the amounts of endogenous protein in this part of the gut.

1. Balance trials with respiration measurements were performed with twelve rats and twelve pigs given either low- or high-crude-fibre diets. There were six collection periods with the rats over a live-weight range of 86–264 g and three collection periods with the pigs over a live-weight range of 30–55 kg. Measurements were made on the influence of microbial activity in the digestive tract on digestibility and nitrogen and energy metabolism. Dietary inclusion of the antibiotic Nebacitin was the method used to reduce the microbial population.

2. The microbial activity in the hind-gut (μmol ATP/g air-dry contents) of antibiotic-treated rats was reduced to approximately one-tenth of that of untreated rats.

3. Live-weight gain was not significantly affected in either species by a reduction in the microbial activity, in spite of a reduction in dry matter digestibility in animals with reduced microflora.

4. For rats on low-crude-fibre diets, a reduction in microflora reduced digestibility of all nutrients and energy and metabolizability of digestible energy by approximately 5·4%. All differences were highly significant. On high-crude-fibre diets the decrease was approximately 5·9%. In pigs on both crude fibre levels, the digestibility was also influenced by the level of microflora, but the pattern was somewhat different from that obtained with rats, with the Nebacitin treatment increasing the digestibility of N slightly, and the digestibility of fat markedly.

5. Retained N in rats reached a maximum when the rats were approximately 60 d old and thereafter decreased with increasing age. However, for pigs daily N retention increased with age. The retained N:digested N value decreased linearly with age in the rats, but varied little with age over the range (104–146 d) studied in the pigs.

6. The metabolizability of gross energy (metabolizable energy (ME): gross energy) was significantly reduced with an increase in crude fibre level and by the addition of Nebacitin.

7. Retained energy (RE) in relation to ME (RE:ME), was not significantly affected either by level of microbial activity or by crude fibre.

8. The ratio, RE as fat (RF):RE as protein (RP) increased as the animals grew. In the rat experiment there was a tendency for RP to be higher for animals with normal microflora than for animals with reduced microflora for both crude fibre levels.

9. With rats, the regression analyses indicated that the energy requirement for maintenance could be influenced by both the level of microbial activity in the digestive tract and by the level of fibre in the diet. The net availability of ME for maintenance and growth by rats averaged 0·72 for all treatments.

10. The net availability of ME for growth in the pigs averaged 0·65 for all treatments.

1. Addition of supplemental choline to a biotin-deficient diet decreased the biotin status of chicks and increased mortality from fatty liver and kidney syndrome (FLKS).

2. Mortality was also increased by dietary supplementation with a mixture of other B-vitamins, excluding biotin, and was highest when the choline and B-vitamin supplements were combined.

3. The occurrence of sudden death syndrome (SDS) was unaffected by dietary biotin concentration.

4. A previously unreported condition was observed in which birds died showing post-mortem signs characteristic of both FLKS and SDS and whose occurrence was related to the biotin status of the chicks.