1. Eighteen males (31–62 years) who habitually consumed significant amounts of table sucrose (approximately 25% of total carbohydrate intake) were supplied with their usual intake of sucrose for consumption in conjunction with their normal diet for 1 year, and a record kept of the amount consumed. The sucrose was then replaced isoenergetically by dried glucose syrup (55 D. E.) which contained saccharin to equate the sweetness to that of sucrose.

2. Fasting blood samples were taken every 4 weeks during the 2 years, and the plasma analysed for glucose, cholesterol, triglycerides and phospholipid-P by automated colorimetric methods. Dietary questionnaries were issued every 3 months to confirm that subjects were not substantially altering their diets.

3. In subjects whose weight remained unchanged and in those who lost weight there was a significant fall in cholesterol (P < 0.025) and phospholipid (P < 0.025) in the glucose-syrup period compared with the sucrose period; triglycerides did not change. In subjects who gained weight there was a significant increase in triglycerides (P < 0.05), but no change in cholesterol; phospholipid-P fell significantly (P < 0.0005).

4. The dietary modification in this experiment was sufficiently long to ensure that subjects had adapted, and the results obtained show stable changes in blood lipids which may be attributed to the isoenergetic replacement of table sucrose by glucose syrup.

1. The metabolic effects of increasing or decreasing the usual energy intake for only 1 d were assessed in eight adult volunteers. Each subject lived for 28 h in a whole-body calorimeter at 26° on three separate occasions of high, medium or low energy intake. Intakes (mean±SEM) of 13830 ± 475 (high), 8400 ± 510 (medium) and 3700 ± 359 (low) kJ/24 h were eaten in three meals of identical nutrient composition.

2. Energy expenditure was measured continuously by two methods: direct calorimetry, as total heat loss partitioned into its evaporative and sensible components; and indirect calorimetry, as heat production calculated from oxygen consumption and carbon dioxide production. For the twenty-four sessions there was a mean difference of only 1.2 ± 0.14 (SEM)% between the two estimates of 24 h energy expenditure, with heat loss being less than heat production. Since experimental error was involved in both estimates it would be wrong to ascribe greater accuracy to either one of the measures of energy expenditure.

3. Despite the wide variation in the metabolic responses of the subjects to over-eating and under-eating, in comparison with the medium intake the 24 h heat production increased significantly by 10% on the high intake and decreased by 6% on the low intake. Mean (± SEM) values for 24 h heat production were 8770 ± 288, 7896 ± 297 and 7495 ± 253 kJ on the high, medium and low intakes respectively. The effects of over-eating were greatest at night and the resting metabolic rate remained elevated by 12% 14 h after the last meal. By contrast, during under-eating the metabolic rate at night decreased by only 1%.

4. Evaporative heat loss accounted for an average of 25% of the total heat loss at each level of intake. Changes in evaporative heat loss were +14% on the high intake and −10% on the low intake. Sensible heat loss altered by +9% and −5% on the high and low intakes respectively.

5. It is concluded that (a) the effects on 24 h energy expenditure of over-feeding for only 1 d do not differ markedly from those estimated by some other workers after several weeks of increasing the energy intake; (b) the resting metabolic rate, measured at least 14 h after the last meal, can be affected by the previous day's energy intake; (c) the zone of ambient temperature within which metabolism is minimal is probably altered by the level of energy intake.

1. Iron absorption from maize (Zea mays) and sorghum (Sorghum vulgore) beer was more than twelvefold greater than from a gruel made from the constituents used to prepare the beer.

2. The effect of changes occurring during brewing were investigated. These changes include a decrease in the solid content, and the formation of 30 ml ethanol/l and 5 ml lactic acid/].

3. The presence of solid material was found to inhibit Fe absorption markedly, especially when the solid content was 100 g/l or more.

4. The presence of ethanol potentiated Fe absorption but the effect was only modest in gruels with a high solid content.

5 Fe absorption from a 2 ml lactic acid/] solution was four-fold greater than from a hydrochloric acid solution of the same pH. When lactic acid was added to a gruel containing 200 8 solids/l the mean absorbtion rose from 0.4 to 1.2%.

6. In a direct comparison, Fe absorption from beer was significantly better than from a gruel of similar pH containing lactic acid.

7. The results suggest that at least three factors are responsible for the enhanced Fe absorption from maize and sorghum beer. These include the removal of solids during fermentation and the presence of ethanol and of lactic acid in the final brew.

8. In order to reproduce the way in which beer is brewed domestically in Fe containers, a study was done in which beer was prepared in the presence of Fe wire. Under such circumstances Fe was rapidly dissolved and the final Fe concentration of the brew was 89 mg/l. However, the nature of the Fecontaining compound or compounds was not elucidated.

1. Total carbohydrate (CHO) and ingested glucose oxidation was measured in five obese subjects with normal glucose tolerance after an oral load of 100g naturally-labelled [13C]glucose using indirect calorimetry and mass spectrometry respectively.

2. CHO utilization rate (107 ± 14 mg/min in the post-absorptive state) increased 30 min after the glucose load to reach a plateau (245±25 mg/min) between 90 and 120 min. It then decreased to basal values at 330 min. Cumulative CHO oxidation over 480 min was 66±7 g and the CHO oxidized above basal levels was 26 ± 7g.

3. Enrichment of expired carbon dioxide with 13c began at 45 min and maximum values were observed between 210 and 300 min. At 480 min, cumulative oxidation of the ingested glucose was 24± 2 g.

4. Compared with controls, the obese subjects exhibit an impairment of CHO utilization which precedes glucose intolerance. This impairment can be explained by an increased availability of free fatty acids which favours lipid oxidation at the expense of ingested [13C]glucose oxidation.

1. The effect of energy and protein intake on the growth, food efficiency and nitrogen retention of artificially-reared pigs was studied over three 8 d periods between 8–32 d of age in an experiment employing a 5×3×2 factorial design. The factors were initial energy: N value (I; 250, 355, 460, 565 or 670 kJ/g N), rate of increase of 1 at 8 d intervals (0, 12.5 or 25%) and plane of nutrition (three times daily to appetite or 75% of this intake).

2. The range of energy: N values was obtained by formulating five diets based on dried skim milk, lactose and casein and feeding appropriate combinations of two diets. The diets, which were pelleted, contained 100 g maize oil/kg and the gross energy content was approximately 20 MJ/kg.

3. N digestibility was high at all three age intervals, reaching 0.99 on the diet containing the highest dietary crude protein (N × 6.25) level. Metabolic faecal N excretion was found to be 1.1 g/kg dry matter (DM) intake.

4. Growth rate, feed conversion ratio (kg food intake/kg wt gain; FCR), N retention (NR) and the proportion of digested N retained (NR:apparent digested N (ADN)) were significantly (P < 0.001) affected by I values at all age intervals and the responses were quadratic. Response curves were calculated by the least squares method and optimum values of I determined for each of the criteria.

A constant energy:N value of approximately 400 kJ/g N was indicated by growth, FCR and NR optima but the NR:ADN value fell from 0.77 for the 8–16 d period to 0.60 for the 24–32 d period at this I value. It is concluded that a suitable compromise would be an I value of 470 kJ/g N increasing by 10%/week.

5. There was a significant interaction between plane of nutrition and I values on FCR between 16–24 d (P < 0.001) and 8–32 d (P < 0.01) indicating that FCR was better at high protein levels and worse at low protein levels when the diets were fed on the lower plane of nutrition.

1. The effect of energy and protein intake on the nitrogen and energy utilization and carcass composition of artificially-reared pigs was studied between 8 and 32 d of age in an experiment employing a 5 × 3 × 2 factorial design. The factors were initially energy:N value (I) (250, 355, 460, 565 or 670 kJ/g N), rate of increase of I (R) at 8 d intervals (0, 12.5 or 25%) and plane of nutrition (three times daily to appetite or 75% of this intake).

2. The range of energy:N values was obtained by formulating five diets based on dried skim milk, lactose and casein and feeding appropriate combinations of two diets.

3. The metabolizable energy (ME) intake, carcass dry matter (DM) content, carcass protein gain and carcass fat gain exhibited significant (P < 0.001) quadratic responses to I.

4. The carcass fat content in the DM increased from 200 to 342 g/kg (P < 0.001) and the carcass crude protein (N × 6.25) content decreased from 657 to 519 g/kg with increasing level of I (P < 0.001). The fat and protein contents were 309 and 556 g/kg and 242 and 610 g/kg respectively on the high and low plane of nutrition (PN) and were significantly different (P < 0.001).

5. There was a significant I × R interaction in relation to carcass protein gain with the maximum gain occurring at 460 kJ/g N when I was constant and at 355 kJ/g N when R was 25% per 8 d.

6. The proportion of apparent digested N intake retained (N retention (NR): apparent digested N (ADN)) was significantly (P < 0.001) affected by all three factors and there were significant I × R (P < 0.001), I × PN (P < 0.01) and R × R × PN (P < 0.01) interactions. The maximum value of NR:ADN was 0.80.

7. Carcass fat gain and carcass energy gain exhibited quadratic responses to I reaching maximum values at 460 kJ/g N. The energy content of the live-weight gain increased linearly (P < 0.001) from 5.79 to 7.90 MJ/kg with increasing level of I. PN and R also produced significant (P < 0.001) responses the means being respectively 7.52 and 6.39 MJ/kg on the high and low PN and 6.55, 6.94 and 7.38 kJ/kg with increasing value of R.

8. Multiple regression analysis of ME intake on live-weight (W), protein gain (PG) and fat gain (FG) yielded the equation: <m:math><m:mrow><m:mtext>ME</m:mtext><m:mo stretchy="false">(</m:mo><m:mtext>MJ</m:mtext><m:mo stretchy="false">)</m:mo><m:mo>=</m:mo><m:mn>0</m:mn><m:mo>.</m:mo><m:mn>644</m:mn><m:msup><m:mtext>W</m:mtext><m:mrow><m:mn>0</m:mn><m:mo>.</m:mo><m:mn>75</m:mn></m:mrow></m:msup></m:mrow><m:mo>+</m:mo><m:mn>32</m:mn><m:mo>.</m:mo><m:mn>6</m:mn><m:mtext>PG</m:mtext><m:mo>+</m:mo><m:mn>48</m:mn><m:mo>.</m:mo><m:mn>2</m:mn><m:mtext>FG</m:mtext><m:mo>.</m:mo></m:math>

This result is discussed in relation to published values for the energy requirements of the young pig.

1. The heat production of groups of pigs, weaned at 10 d of age, was determined in an open-circuit respiration chamber at various ages between 10 and 33 d at temperatures above and below the lower critical temperature (Tcl).

2. The heat production was lowest on the second or third day post weaning when pigs were given feed increasing by 25 g/pig per d from day 2. There was a marked diurnal pattern in heat production, the lowest values being recorded between 24.00 and 08.00 h.

3. The mean thermal conductance (H/ΔT, kJ/h per m2 per °ΔT, where His total heat production, m2 is the surface area calculated as 0.097 W kg0.633 (Brody, 1945) and °ΔTis the difference between rectal temperature, taken as 39°, and air temperature) below Tcl was calculated as 18.0, 16.9, 18.5 and 21.2 respectively at 10, 17, 24 and 31 d of age. Maximum values of H/ΔT obtained during feeding periods were. on average, 4.5 kJ/h per me per °ΔT higher than the mean values.

4. The maximum value for Tcl during the immediate post-weaning period was 25.9°. The mean Tcl at 17, 24 and 31 d were respectively 21.7, 18.4 and 18.6° for pigs fed almost to appetite.

1. Male WAG/Cpb inbred rats fed on rations with approximately 1–5rng copper/kg (deficient), 6.0 mg Cu/kg (adequate) and 25.0 mg Cu/kg (excess) were supplemented with varying amounts of molybdenum (0, 50, 150 and 500 mg/kg diet) and the effect on the Cu concentration of blood, plasma, liver and kidney, the caeruloplasmin activity of plasma and the Mo concentration of liver and kidney were studied.

2. Mo increased the Cu concentration of blood, plasma, liver and kidney and the Mo concentration of liver and kidney.

3. In the plasma of Mo-supplemented rats the presence of a Cu-containing fraction was demonstrated, the Cu of which did not react with dithiocarbamate and was not related to caeruloplasmin. The Cu in this fraction was not able to increase the caeruloplasmin activity in the plasma of Cu-deficient Mo-supplemented rats. The Cu concentration of the erythrocytes did not seem to have been increased by the Mo treatment.

4. When compared to Cu-adequate rats the effect of Mo on the Cu distribution was reduced both by Cu deficiency and Cu excess. This decreased effect of Mo was explained by reduced uptake or retention of MO in the body as observed in the liver and kidney.

1. An automated colorimetric method for determination of methionine using an iodoplatinate reagent is described. Methionine sulphoxide does not react under the chosen conditions.

2. The method may be used to distinguish between unoxidized and total methionine by doing one deter- mination without and one determination with previous reduction of a portion of the sample with titanium trichloride. Methionine sulphoxide is then obtained by difference.

3. The method has been used with protein concentrates, mainly fish meals, after hydrolysis with barium hydroxide. Interference from cysteine-cystine is eliminated by adding a small amount of cadmium acetate to the sample before hydrolysis.

4. Results obtained for total methionine and for methionine sulphoxide by independent methods show good agreement with results obtained with the iodoplatinate method.

1. Hepatic fatty acid synthesis, measured in vivo using 8H2O, was increased by a single dose of L-tryptophan (50 mg/kg body-weight) to both fed and fasted rats and by a supplement of tryptophan to the diet (2.5 g/kg diet for 7 d) when the rats were killed midway through the feeding period.

2. Additional dietary tryptophan was hypotriglyceridaemic in normal rats but exacerbated the hyper- triglyceridaemia in rats when lipoprotein clearance was impaired 24 h after an injection of Triton WR 1339 (Chromatography Services Co., Birkenhead, Cheshire).

3. The effects of tryptophan on hepatic fatty acid synthesis and the concentration of serum triglyceride were not directly related to the action of the amino acid on gluconeogenesis. A lack of correlation between inhibition of gluconeogenesis and enhancement of lipogenesis was confirmed using mercaptopicolinic acid, a specific inhibitor of phosphoenolpyruvate carboxykinase (EC 4.1.1.32).

4. DL-Tryptophan itself did not provide a significant contribution of substrate to the total rate of lipogenesis. Other possible explanations for the activity of tryptophan noted in the present experiments are discussed.

5. In conclusion, moderate intakes of tryptophan affect fatty acid and triglyceride metabolism under physiological conditions and it is proposed that the amino acid may be involved in the control of lipid metabolism in a variety of metabolic states.

1. Seasonal changes in retinol-binding holoprotein (holoRBP) concentration in plasma of group of male and female Japanese quail (Coturnix coturnix japonica) were examined over 18 months.

2. In Expts 1 and 2 the birds were maintained under natural lighting conditions and in Expt 3 under artificial-light photoperiods corresponding to the changing daylength at 56° N latitude. All groups were at 18–20° and received Superlayers' (Rank Hovis McDougall) pellet diet.

3. The mean plasma holoRBP concentration in all groups changed in an annual cycle with minimal values in September–October and maximal values in February–April, when daylength or light photoperiod increased to more than 10 h.

4. The group mean values in the female cycle change 2- to 3-fold from 50–100 μg/ml in late summer to 220–280 μg/ml in the spring, whereas in the male the range is only 1.3–1.5 times, from 140–170 to 180–250 μg/ml.

5. In the female the rate of egg laying was maximal in April–May and lowest in November–December.

6. The spring increase in plasma holoRBP reflects the increased vitamin A requirement of birds for reproduction and it is presumably under hormonal control. The wider amplitude in the female cycle compared with the male probably arises from the additional demand for the transfer of vitamin A into the eggs and hence the need for a higher initial secretion rate from the female liver to meet it.

1. When weanling rats were fed on a diet containing 0.1 g/kg of the diet as polyunsaturated fatty acid, it was found that after 2 weeks the level of linoleate in the lymphocyte total lipids was 56 mg/ g total fatty acids, as compared with a level of 138 mg/ g in rats on a normal diet (P < 0.005). Similar levels were obtained from rats which had been fed for up to 16 weeks on the deficient diet, but in a group killed after 28 weeks on the diet the level was found to be only 20 mg/ g total fatty acids. The arachidonate level was found to be approximately 220 mg/ g total fatty acids, regardless of whether the rats were fed on a diet deficient in linoleate for up to 16 weeks or on a normal diet. In the group of rats killed after 28 weeks on the linoleate deficient diet, however, the arachidonate level was only 60 mg/ g total fatty acids.

2. Percentage values for total fatty acids are given for plasma, adipose tissue, and lymphocytes for rats on normal and experimental diets.

3. Scatter diagrams of the levels of linoleate v. arachidonate in the lymphocyte total fatty acids showed no correlation between the levels of the two acids (r 0.05), but similar plots of linoleate and oleate levels showed an inverse correlation (r – 0.68).

1. Serum prealbumin, transferrin and iron concentrations were measured in ninety-two north Cameroonian children under 5 years of age. The results were grouped according to the blood haemoglobin concentration range in order to show the interactions of anaemia with prealbumin and transferrin concentrations.

2. Transferrin concentration showed a significant negative correlation with serum Fe and percentage saturation of transferrin values. Prealbumin concentration showed a significant direct correlation with haemoglobin but did not correlate with either serum Fe or percentage saturation of transferrin.

3. It is concluded that in regions where Fe-deficiency anaemia is endemic transferrin concentration may be of little value in determining nutritional status. On the contrary, prealbumin seems to be more useful.

1. α2HS-glycoprotein accumulates in bone and dentine and its plasma levels could vary in conditions in which the rate of bone formation is altered.

2. The plasma concentration of this protein was found to be lower in thirteen children suffering from protein–energy malnutrition compared with age-matched healthy preschool children.

3. This finding might be associated with the phenomenon of stunting in protein–energy malnutrition.

Tissue ascorbic acid (AA) contents of approximately 12 and 100% saturation respectively were produced in two groups of guinea-pigs. The ‘low-AA’ group had significantly lower muscle carnitine concentrations than the ‘high-AA’group. There was no concomitant emergence of the symptoms customarily regarded as characteristic of hypovitaminosis C. It is concluded that muscle carnitine (β-OH-γ-(trimethylamino) butyric acid) is a highly-sensitive indicator of tissue AA contents; this could account for the lassitude and fatigue reported to precede the emergence of frank scurvy in man.

1. Dry matter and crude protein (nitrogen × 6.25) digestibility of four poultry diets determined by an in vitro method using the intestinal fluid of pigs was significantly correlated with corresponding in vivo digestibility values obtained with hens.

2. The intestinal fluid could be lyophilized and stored for at least 35 d without losing its activity on digestion.