1. Three experiments involving sixty-two growing-finishing pigs from 28 to 90 kg body-weight were conducted to investigate the effect of environmental temperature on the thiamin requirement of growing-finishing pigs. Three temperatures (20°, 30° and 35°) were used.

2. Under these experimental conditions, average daily weight gain indicated no effect of environmental temperature on thiamin requirement. By using erythrocyte transketolase (EC 2.2.1.1) activity and its percentage stimulation by thiamin pyrophosphate (TPP stimulation per cent) as criteria, there was a significant effect of environmental temperature on the thiamin requirement of growing-finishing pigs. At 20°, the thiamin requirement for maintaining maximum transketolase activity or minimum TPP stimulation per cent was found to be approximately 3·3 mg/kg diet; at 30°, the requirement was between 3·7 and 4·0 mg/kg diet. As estimated from erythrocyte transketolase activity, and the rate of TPP stimulation per cent increase, the thiamin requirement might be higher than 4·0 mg/kg diet at 35°.

3. There was a significant effect of environmental temperature on daily weight gain and food intake. The rate of weight gain and food intake decreased with increasing temperature. The efficiency of food utilization generally showed no significant differences among temperatures.

1. Leucine, lysine, valine and phenylalanine uniformly labelled with 14C were given by intragastric or intravenous infusion for 4 h, after an overnight fast, to rats which had been fed on normal or protein-free diets for 20 d. Expired CO2 was collected during the infusion. At the end of the infusion the rats were killed and radioactivity was measured in liver, muscle, skin, gastrointestinal tract and the remaining carcass.

2. There were no significant differences between the results obtained with different amino acids.

3. When the two routes of infusion were compared, there was no difference in the output of 14CO2, expressed as a proportion of the administered radioactivity. With intragastric infusion a slightly larger proportion of radioactivity was recovered from liver and gastrointestinal tract and significantly less from the skin.

4. When the rats adapted to a protein-free diet were compared with those on the control diet, there was again no difference in the proportion of dose oxidized to CO2. In the rats on the protein-free diet significantly more of the dose was recovered in the liver and gastrointestinal tract, and less in the skin.

5. The rats on the protein-free diet excreted more CO2 per kg body-weight, with a lower specific radioactivity.

6. The results show no indication of adaptive changes in the oxidation of essential amino acids, but the evidence is not conclusive. Under these experimental conditions the output of 14CO2 is not a valid measure of the extent of amino acid oxidation. The difficulties of interpretation are discussed.

1. The proximate composition, amino acid composition and the quality of the protein of the African locust-bean (Parkia filicoidea Welw.) seed, seed with pulp, and various processed forms, with or without amino acid supplementation, were assessed.

2. The crude protein content of the locust-bean seed was 303 g/kg and the crude fibre content was 121 g/kg.

3. The seeds contained (mg/g protein): 67 lysine, 6.1 methionine and 8.9 tryptophan.

4. Diets containing 100 g protein/kg supplied by the seed did not support growth in rats, demonstrating that the protein was of poor quality.

5. Utilization of the protein of locust-bean seeds was improved by cooking, and by removal of the tough leathery outer testa of the seeds.

6. Supplementation with methionine alone resulted in positive growth and a very substantial increase in protein values.

7. Supplements of methionine and tryptophan caused further improvement in protein quality and increased the growth of rats to almost that obtained with whole egg.

1. Apparent digestibility, apparent absorption and nutrient-balance studies were made with two Ayrshire and three Friesian calves given milk-substitute diets. Cannulas were inserted into the duodenum of the calves at about 21 d old, so that the quantity of pancreatic secretion entering the duodenum could be varied.

2. After cannulation, there was a significant reduction in the apparent digestibility of the dry matter, organic matter, crude protein and fat, and in the apparent absorption of calcium and phosphorus from a milk-substitute diet containing ‘mildly’ pre-heated, spray-dried skim-milk powder. The amounts of nitrogen and P retained by the calves were also significantly reduced.

3. Collection and removal of the pancreatic secretion for a period of 12 h/d resulted in a further significant reduction in the apparent digestibility of the dry matter, organic matter and crude protein of the milk-substitute diet.

4. At 77 d of age, there was no significant effect on the nutrient balance or on the digestibility of a diet containing a ‘severely’ pre-heated, spray-dried skim-milk powder when the normal secretion of the pancreas was supplemented for 12 h/d with additional pancreatic secretion collected from the same calf.

5. Friesian calves, in comparison with Ayrshires, tended to have a higher digestibility of dry matter, organic matter and fat, apparent absorption of Ca and P and retention of N, Ca and P. These differences were apparent both before and after the calves were cannulated.

1. The long-term fate of an oral dose of [75Se]selenite was studied in three young women.

2. Urinary and faecal excretion, respiratory and dermal losses and whole-body retention of 75Se were measured, and also 75Se turnover in whole body, blood and tissues during a period of 16–20 weeks.

3. Intestinal absorption of [75Se]selenite by the three subjects was 70, 64 and 44% of the dose.

4. Urinary excretion accounted for 14–20% of absorbed 75Se in the 1st week. There were only trace amounts of radioactivity in expired air and no dermal loss was detected.

5. After an initial phase in which radioactivity decreased rapidly, whole-body retention of 75Se diminished exponentially with a half-time of 96–144 d. Radioactivity in the liver, heart and plasma decreased more rapidly than that in the whole body, but radioactivity in skeletal muscle and bone decreased more slowly.

1. The effects of processing cereals on aspects of rumen metabolism, physiology and pathology were investigated in five experiments with lambs. Three experiments studied the effects of diets containing loose whole, pelleted whole or pelleted rolled barley on rumen volatile fatty acid ratios, rumen pH and digestibility. In a 4th experiment the effects, on the same measurements, of pelleting whole barley, maize, oats or wheat compared to feeding the whole grains in the loose form were studied. The firmness of subcutaneous fat was measured in two of these experiments when injections of cyanocobalamin or hydroxycobalamin were given and in one experiment when the diets were supplemented with two levels of cobalt. In a 5th experiment, the effect on rumination time of pelleting whole barley compared to feeding loose whole grain was assessed.

2. When the diet contained whole barley in a loose mix and also when it contained whole maize, oats or wheat, the proportion of acetic acid in the rumen fluid was significantly increased and that of propionic acid decreased in comparison with the proportions observed when the pelleted diets were offered.

3. The pH of the rumen liquor was not significantly changed by feeding pellets based on rolled or whole barley, but when barley, maize, oats or wheat was given in loose form, there was an increase in the pH by about 1 unit in comparison with the pelleted diets. This increase in pH was, for all cereals, associated with complete elimination of ruminitis which, except for the oat diet, was always apparent with the pelleted feeds.

4. In general the digestibilities were not affected greatly by processing and in two experiments there were no significant differences. In one experiment pelleted whole barley was better digested than pelleted rolled barley. In another experiment the digestibility of barley was slightly greater when it was fed whole and loose compared to pelleted, while the digestibility of whole wheat was less than that of pelleted wheat. The mean digestibilities of organic matter for barley, maize, oats and wheat were 0.791, 0.832, 0.687 and 0.846 respectively.

5. Neither injections of vitamin B12 nor cobalt supplementation of the diet had any effect on the firmness of subcutaneous fat. Feeding diets containing loose whole barley increased the firmness of the subcutaneous fat, and this was associated with a decrease in the proportion of propionic acid in the rumen fluid.

6. The feeding of loose whole barley instead of pelleted whole barley caused an increase in time of rumination from 3.6 to 6.6 h/24 h.

1. The possibility that, when lambs are fed on barley-rich diets, vitamin B12 might limit hepatic utilization of propionate and result in the formation of branched-chain fatty acids was investigated with thirty-six animals allocated to twelve treatments according to a 3 × 2 × 2 factorial design.

2. From 13 kg live weight to slaughter at 35 kg the lambs were given diets containing barley in one of three physical forms, and one of two levels of cobalt (0.1 and 0.9 mg/kg diet). In addition, half the lambs received twice-weekly injections of cyanocobalamin (40 μg/kg body-weight).

3. The fatty acid composition of triglycerides from subcutaneous and perinephric adipose tissue was determined at slaughter.

4. Neither additional dietary Co nor the administration of cyanocobalamin (alone or in combination with additional Co) influenced the proportions of branched-chain acids in the triglycerides. The possibility is discussed that the ability of the lamb to respond to the increased supply of propionate which is provided by a high-barley diet is not restricted by the availability of cyanocobalamin, but by hepatic capacity to utilize it for the production of methylmalonyl-CoA mutase (EC 5.4.99.2).

5. Regardless of diet, subcutaneous triglycerides contained greater proportions of propionate-derived fatty acids than did perinephric triglycerides which contained greater proportions of exogenously-derived C18 unsaturated acids. Lambs given whole barley in loose mix produced triglycerides containing relatively less odd-numbered n-acids and branched-chain acids than did lambs fed on either of two pelleted diets containing rolled or whole barley.

1. Skinfold thicknesses at four sites – biceps, triceps, subscapular and supra-iliac – and total body density (by underwater weighing) were measured on 209 males and 272 females aged from 16 to 72 years. The fat content varied from 5 to 50% of body-weight in the men and from 10 to 61% in the women.

2. When the results were plotted it was found necessary to use the logarithm of skinfold measurements in order to achieve a linear relationship with body density.

3. Linear regression equations were calculated for the estimation of body density, and hence body fat, using single skinfolds and all possible sums of two or more skinfolds. Separate equations for the different age-groupings are given. A table is derived where percentage body fat can be read off corresponding to differing values for the total of the four standard skinfolds. This table is subdivided for sex and for age.

4. The possible reasons for the altered position of the regression lines with sex and age, and the validation of the use of body density measurements, are discussed.

1. A method is described for the estimation of the microbial and dietary protein entering the small intestine of sheep, based on an intraruminal infusion of [35S]sulphate, and isolation of the labelled microbial protein.

2. Samples of the microbial fraction contained in duodenal digesta were isolated by highspeed centrifugation and a scheme of analysis was devised for the determination of the specific activity of the methionine in the microbial fraction and the duodenal digesta.

3. In the absence of dietary methionine in duodenal digesta, it was postulated that the ratio of the specific activities of microbial methionine (M) and digesta methionine (D) should equal 1. Using two purified diets containing urea as the sole source of nitrogen, the M:D ratio was found to vary from 0·94 to 1·08 (mean 1·01 ± 0·01).

4. Addition of known quantities of dietary protein to labelled duodenal digesta obtained from one sheep fed on a non-protein diet increased the M:D ratio. Prediction of the dietary protein present from changes in the M:D ratio gave satisfactory agreement with the amounts of dietary protein known to be present (96–101% of known value, mean 98·4 ± 1·24%).

5. When animals were fed hourly the M:D ratio remained reasonably constant throughout 24 h. In contrast, with twice-daily feeding the M:D ratio varied markedly throughout the 24 h. However, summation of the estimates made of the flow of microbial and dietary protein into the duodenum in each 2 h period throughout 24 h agreed closely with the estimates made from samples withdrawn from the accumulated flow of digesta over the whole 24 h period.

6. The method was finally adapted to situations with either frequent or infrequent feeding patterns, and the need for a priming infusion period of 16 h before the collection and sampling of duodenal digesta was established.

1. A comparison was made of the efficiency of food conversion and body composition of the preruminant lamb and young pig when offered cow's milk supplemented with minerals and vitamins from 2 to 10 weeks of age.

2. The daily voluntary intake of gross energy/kg live weight0·75 of the pigs was significantly greater than that of the lambs. The daily voluntary intake of the lambs decreased from 1895 to 1573 kJ/kg live weight0·75 (453 to 376 kcal/kg0·75) over the experimental period and that for the pigs increased from 2063 to 2519 kJ/kg live weight0·75 (493 to 602 kcal/kg0·75).

3. Of the organic matter of the milk, 0·97–0·98 was digested by both species. Food conversion ratio (kg dry matter milk/kg live-weight gain) did not differ between the species when food was given ad lib. but pigs restricted to 80% of voluntary food intake or to 1255 kJ/kg live weight0·75 (300 kcal/kg0·75) had a lower food conversion ratio than lambs similarly restricted in intake.

4. A 20% reduction in the voluntary intake of gross energy decreased daily protein deposition in the lambs only but decreased daily fat deposition in both species.

1. This study set out to measure the sensitivity of muscle RNA content to food intake and food restriction, and to relate this to plasma insulin and intracellular amino acid concentrations.

2. Young rats were trained for 2 weeks to consume their daily food ration in a single 4 h period. After this time they had resumed normal growth. The rats were killed at intervals over 24 h and subsequently at daily intervals. One group was given a protein-free meal in place of the stock diet and a similar procedure was followed. Measurements were made of plasma insulin, concentration of nucleic acids and protein in liver, heart and skeletal muscle, and free amino acids in the gastrocnemius muscle.

3. Following the meal there was a fivefold increase in plasma insulin, which was accompanied by small increases in the concentrations of the intracellular amino acids in muscle. In all the tissues, after feeding, the RNA:DNA ratio increased by (%) 20, 19 and 12 in liver, skeletal and heart muscle respectively.

4. During the fasting period the plasma insulin decreased, and this decrease was accompanied by rapid losses of RNA from liver, muscle and heart at similar rates. There were increases in the concentrations of the essential amino acids, especially methionine and the branched-chain amino acids, but decreases, in general, in those of the non-essential amino acids. When the protein-free meal was given, there was a small increase in the plasma insulin, but the RNA was lost from the three tissues at the same rate as in the starved rats. There was, however, a transient fall in the concentrations of the essential amino acids.

5. The rapid changes in muscle RNA concentrations following food intake demonstrate that the minimum turnover rate of RNA in this tissue must be considerably faster than has been previously reported, and must be similar to that in liver. There is a direct correlation between tissue RNA concentration and that of plasma insulin, but little correlation between tissue RNA concentration and that of the intracellular essential amino acids.

1. A solution of gelled maize starch and Cr-EDTA was continuously infused for 4 weeks via the abomasum into sheep of different ages. The proportions of infused α-glucoside passing the terminal ileum as glucan (ethanol-precipitable α-glucoside), dextrins (ethanol-soluble glucose polymers) and glucose, and the glucan and over-all α-glucoside disappearances in the small intestine were determined. Ethanol-soluble α-glucoside compounds in ileal digesta were further separated by paper chromatography.

2. Glucan was efficiently degraded, since little reached the terminal ileum. Most of the α-glucoside in ileal digesta consisted of glucose and dextrins (mainly short chain length oligosaccharides), suggesting that α-amylase activity was not limiting over-all starch utilization.

3. No adaptation of intestinal starch utilization was evident except that the proportion of infused α-glucoside passing the terminal ileum as glucose decreased with time.

4. A negative correlation existed between the pH and the total α-glucoside content of the ileal digesta, possibly relating to changes in the microbial activity.

5. The advantages and disadvantages of feeding with starch so as to by-pass rumen fermentation are discussed.

1. Twelve sheep were offered a diet of hay and molassed sugar-beet pulp for 18 weeks, and from the 3rd to the 16th week the sheep were divided into four groups of three; one of each of the groups received daily 170 mg trichloroacetamide, 140 mg chloroform, 30 g linseed oil or no additive.

2. The additives had no significant effect on the apparent digestibility of the dry matter, organic matter, nitrogen or energy of the diet.

3. When either trichloroacetamide or chloroform was added to the diet, methane production was almost totally suppressed and some hydrogen was produced but, although these changes persisted with chloroform, they were much reduced after 28 d of trichloroacetamide administration. When linseed oil was added to the diet the methane production was reduced by almost 15%.

4. Each additive caused a significant reduction in the concentration of total volatile fatty acids in the rumen liquor and in the molar proportion of acetic acid in the total volatile fatty acids, with a corresponding increase in the molar proportion of propionic acid. The effect was greatest immediately after the introduction of the compound into the diet but it diminished and appeared to attain a stable value within the experimental period of 98 d.

5. All the effects disappeared within 14 d of the withdrawal of the compounds from the diet.

6. It is suggested that these effects may be the result of selective effects on the rumen microflora and that further work is needed to find an additive whose effects are persistent.

1. Using a double-lumen tube jejunal perfusion system, the rate of glycine absorption from a glycylglycine solution (50 mmol/l) was measured in three groups of Zambian African subjects: in fifteen subjects there was no evidence of an infection (normal group); in eleven there was acute bacterial pneumonia and five had a chronic systemic infection.

2. Differences between the mean absorption rates for the three groups were not significant.

3. Glycine absorption rate has been shown previously to be increased in subjects with acute bacterial pneumonia. The present result provides further evidence that glycine and glycylglycine use separate transfer mechanisms in man, and suggests that dipeptide absorption rate is influenced to a lesser extent than that for free amino acids by systemic stimuli.

1. A study of the food intake, during a period of 7 consecutive days, was made on 192 boys and girls, aged 14 years, attending Glasgow schools in 1964. A similar study was done in 1971 on 419 boys and girls of the same age. The children came from all the various socio-economic backgrounds and were subdivided into four social groups.

2. The heights and body-weights of the groups studied in 1964 and 1971 were similar but the percentage contribution of fat to the body-weight had increased in the boys.

3. Between 1964 and 1971 there had been a decrease in the mean energy intake of both boys and girls of between 0.8 and 1.0 MJ (200–250 kcal)/d. A similar proportionate decrease had also occurred in the protein, fat, carbohydrate, calcium and iron contents of the diet. However, no individual had a very low intake of protein.

4. Only the boys of the poorest social group (4) showed a lower intake of nutrients than the other groups. There were almost no differences between the girls from the different socio-economic groups.

5. Eating school meals did not affect levels of total energy and nutrient intake.

6. The proportion of energy and nutrients derived from different food groups did not appear to have appreciably altered in the two surveys, although the amount of milk drunk had become less. Fish, eggs and cheese contributed surprisingly little to the diet.

7. The combination, in both sexes, of a reduction in energy intake in 1971 compared to 1964, together with, for the boys, an increased body fat content, could be accounted for by a marked reduction in physical activity.

8. Although a comparison of the energy intake of the fattest and of the thinnest boys showed no clear differentiation, there was a consistently lower energy intake, in all social groups, by the fattest girls (‘fattest’ 7.07 MJ (1690 kcal)/d; ‘thinnest’ 9.23 MJ (2207 kcal)/d).

9. These and other recent results suggest that the national (UK) recommended energy requirements, at least for this group, are too high.

1. Simple extracts of raw navy (haricot) beans (Phaseolus vulgaris L.) known to be toxic to conventional Japanese quail (Coturnix coturnix japonica) have been fractionated and tested for toxicity by feeding to this species.

2. Of the various fractions obtained during the biochemical purification of the phytohaemagglutinin, only those possessing agglutinating activity were found to be toxic.

3. The final purification stage yielded an homogeneous protein with both agglutinating and toxic properties.