1. Thirteen adult females and two males were overfed a total of 79–159 MJ (1900–38 000 kcal) during a 3-week period at the Clinical Research Center, Rochester. The average energy cost of the weight gain was 28 kJ (6.7 kcal)/g, and about half the gain consisted of lean body mass (LBM) as estimated by 40Kcounting.

2. A survey of the literature disclosed twenty-eight normal males and five females who had been overfed a total of 104–362 MJ (2500–87000 kcal) under controlled conditions: twenty-five of these had assays of body composition, and three had complete nitrogen balances.

3. When these values were combined with those from our subjects (total forty-eight), there was a significant correlation between weight gain and total excess energy consumed (r 0.77, P < 0.01) and between LBM gain and excess energy (r 0.49, P < 0.01). Based on means the energy cost was 33.7 kJ (8.05 kcal)/g gain and 43.6% of the gain was LBM; from regression analysis these values were 33.7 kJ (8.05 kcal)/g gain and 38.4% of gain as LBM.

4. Individual variations in the response could not be explained on the basis of sex, initial body-weight or fat content, duration of overfeeding, type of food eaten, amount of daily food consumption or, in a subset of subjects, on smoking behaviour.

5. The average energy cost of the weight gain was close to the theoretical value of 33.8 kJ (8.08 kcal)/g derived from the composition of the tissue gained.

1. Results from two independent metabolic balance studies in patients with ileal resection with or without a remaining colon were examined to assess the precision of the mineral, protein and fat balances obtained.

2. Low day-to-day variation in balances was found in patients with ileostomy/jejunostomy, irrespective of formula diet composition. In contrast, patients with a remaining colon showed considerable variation, with reliable cumulative balances often not reached for many weeks.

3. In conclusion, short-term cumulative balances can be performed with good precision in patients with ileostomy or jejunostomy.

1. The concentration of taurine in the diets, plasma, urine and breast milk were measured in vegans and age- and sex-matched omnivore controls. Plasma and urinary amino acid concentrations were also determined

2. Taurine was absent from the vegan diet and occurred in variable amounts in the diets of the omnivores. Urinary taurine levels were less than half those of the omnivores but plasma and breast-milk levels were only slightly lower.

3. Dietary energy intakes were similar in the vegans and omnivores, but protein intakes tended to be lower in the vegans.

1. The mean adipocyte volume and cellularity of adipose tissue in twelve anatomically defined depots were measured in 190 virgin and reproductive guinea-pigs aged 6 months to 2 years, maintained on five different regimens of diet and exercise.

2. The total adipocyte complement was constant up to the age of about 10 months and increased by 65–70% during the 2nd year of life. At constant percentage body-weight as fat, age-related accumulation of adipocytes was accompanied by reduction in average adipocyte volume. A period of high percentage body-weight as fat was not a necessary antecedent to age-related accumulation of adipocytes, and the effect was not observed in specimens that exercised regularly.

3. In guinea-pigs over 13 months old, changes in adipose tissue cellularity made a major contribution to total fatness. The mean volume of samples of adipocytes was a satisfactory indicator of fatness only in younger specimens in which adipose tissue cellularity was not changing.

4. The lean body mass and the total adipocyte complement were lower in guinea-pigs on the sedentary, restricted-diet regimen, whether the regimen began at the age of 19 weeks or 31 weeks, but the depots studied were not equally affected. Both moderate and strenuous exercise on an ad lib. diet caused a reduction in the percentage body-weight as fat in males but not in females. The total adipocyte complement and lean body mass were unchanged, although the males became almost as thin following exercise as those on the restricted-diet regimen.

5. Among guinea-pigs under 400 d old, there were no significant differences between males and virgin females in the site-specific volume of adipocytes relative to the size of those in other depots of the same specimen; there was only one significant difference in this index between the older and the younger specimens. The diet and exercise regimens modified the site-specific adipocyte volume relative to those in other depots; adipocytes under the trapezius muscle of the neck (UMN), at the interscapular depot (HUMP) and those in the depots anterior to the forelimb became relatively smaller following exercise, while those in the popliteal fat mass were relatively larger. Adipocytes in the UMN and HUMP also became more numerous relative to those in the other depots following both moderate and strenuous exercise. Those in the groin site, the intra-abdominal depots and the intermuscular depots became relatively smaller following dietary restriction without exercise.

6. The retroperitoneal depot was the most consistently and extensively depleted following dietary restriction without exercise, and the mesenteric and omental, ventral groin and anterior forelimb depots were not significantly depleted in any of the virgin guinea-pigs on this regmen. Thus those on the restricted diet had more adipocytes at these depots, in proportion to lean body mass, than the ad lib.-fed controls. Following age-related adipocyte proliferation, there were relatively more adipocytes in the abdominal depots, and relatively fewer in depots around the forelimbs in guinea-pigs that were first exercised strenuously and then placed on a sedentary at lib.-feeding regimen, compared with never-exercised controls.

7. Some of the correlation coefficients between the volumes of adipocytes in all depots studied were significantly higher in the ad lib.-fed, sedentary mothers than in ad lib.-fed sedentary males of the same age. No other effects of maternity on site-specific differences in the relative volume or relative abundance of adipocytes were identified.

8. Site-specific differences in adipocyte accumulation contributed more to age and regimen-related changes in body conformation than changes in the relative volume of adipocytes.

1. The milk yield of eight mothers each breast-feeding twins was determined by test weighing the mothers. Milk yield was determined at 2, 3, 6, 9, and 12 months post partum; however, only one mother was studied at all these times.

2. At 6 months post partum the milk yield for individual breasts of three mothers fully breast-feeding and four mothers partially breast-feeding their infants ranged from 0.84 to 2.16 kg/24 h and 0.42 to 1.39 kg/24 h respectively. The average frequency of breast-feeding for the mothers studied at 6 months post partum was 15.4 feeds124 h.

3. The milk yield of one mother fully breast-feeding 2.5-month-old triplets was 3.08 kg/24 h and the infants were fed twenty-seven times in 24 h.

4. The concentration of lactose, protein and mixed fat in the milk from individual breasts of mothers fully breast-feeding their infants ranged from 65.6 to 82.2, 7.8 to 15.7 and 16.7 to 46.2 g/1 respectively. For the three mothers partially breast-feeding 12-month-old infants the values ranged from 54.8 to 71.8, 14.2 to 19.9 and 4.7 to 40.5 g/l respectively.

5. At 6 and 12 months of age, the proportion of the total energy intake of the infants which was derived from breast milk ranged from 64 to 100% and 6 to 13% respectively.

6. It is concluded that the maximum potential milk yield for women may be higher than the often quoted value of 70–800 m1/24 h.

1. Forty-two mothers from social classes I, I1 and IIInon-manual and twenty-one from social classes IIImanual (M), IV and V were studied longitudinally. The mean daily nutrient intakes in months 4–9 of pregnancy, months 2– 4 of lactation and 3 and 6 months post-lactation are presented and are compared with the UK and the US recommended daily allowances (RDA).

2. The quality of the diets (nutrients per 4184 kJ (1000 kcal)) was found to be better than that of other adult female populations studied in the UK, except for a group of dietitians.

3. The mean daily intakes of nutrients for which there are UK RDA were almost all greater than 100% of the RDA. The exceptions were iron, which in the manual group (social classes IIIM, IV and V) was 85% of the RDA in pregnancy and 75% post-lactation, and vitamin D.

4. Among the nutrients for which there are US, but not UK RDA, only phosphorus and vitamin B,, intakes were greater than 100% of the RDA in both groups at all stages of the study. Intakes of other nutrients were below the RDA: pantothenate 7G91, vitamin B, zinc, vitamin E and copper 40–72, folate 21–44, and biotin < 20% of the RDA.

5. The bases of the RDA for adult women were examined; for most nutrients the information is limited. It was concluded that the RDA for magnesium, vitamin E and pantothenate are probably higher than necessary and that deficiency is unlikely; that zinc, copper, vitamin B, and folate are probably ‘marginal’ nutrients for ‘at risk’ groups; and that information on biotin is insufficient even roughly to assess the dietary requirement.

1. Energy intakes, body-weights, body fat index, total body fat and interscapular brown adipose tissue (IBAT) were examined in adult male, spontaneously hypertensive, stroke-prone (SHR-SP) rats and normotensive Wistar/Kyoto (WKY) controls given one of four diets for 33 d: (a) a starch diet, (b) a starch diet and a sucrose solution drinking option, (c) an 80xenergy from fat (F80) diet, (d) the F80 diet and a sucrose drinking option.

2. The SHR-SP rats showed a complete resistance to obesity on all four diets. For the high-fat diet the WKY animals became markedly obese with approximately two-fold increases in body-weight gain and body fat index when compared with the SHR-SP rats. The gain in total body fat was also significantly greater. IBAT as a percentage of total body-weight did not differ between the WKY and SHR-SP groups.

3. Compared with the WKY animals, the SHR-SP rats showed a reduced food intake but had the same potential to gain weight from the high-fat diet.

4. It is concluded that the resistance to obesity by the hypertensive animals is the result of a diminished energy intake.

1. A randomized controlled trial of cross-over design was set up to examine the effect of alcohol on blood lipids and certain haematological variates relevant to ischaemic heart disease.

2. One hundred subjects drank some alcohol for 4 weeks (mean intake 18.4 g/d) and abstained totally for 4 weeks, the order of these periods being randomized.

3. Alcohol appeared to produce a rise of 7% in serum high-density-lipoprotein(HDL) cholesterol, probably due to a rise in the HDL2 subfraction.

4. No significant change was detected in plasma fibrinogen or the other haematoiogical indices.

5. These results are consistent with the hypothesis that a moderate intake of alcohol confers some protection against heart disease.

1. Body-weight, body height and skinfold measurements were taken in 419 adult males working in the UK offshsore oil industry. Percentage body fat was estimated from skinfold thicknesses and the Quetelet index (weight: height2) determined.

2. The prevalence of overweightness, assessed from the Quetelet index, in the age groups 20–29, 30–39 and 40–49 years was 31.6, 50.0 and 66.2% respectively. The Office of Population Census and Surveys (1981) showed that for age-matched groups, the incidence of overweightness in an onshore population was 26, 40 and 50% respectively.

3. The percentage body fat for each respective age group was greater than that reported for an age-matched onshore population.

4. The Quetelet index was significantly related to body fat (r 0.765, P < 0.0001) and poorly correlated with height, thus this weight: height relation may be utilized in the assessment of overweightness in offshore personnel.

5. In conclusion it appears that the offshore population had a higher percentage body fat than their onshore peers and that the prevalence of overweightness was also greater.

1. The efficacy of oral vitamin E supplementation in preventing the early anaemia of the premature infant was assessed in a 10-week double-blind trial. Forty-two babies received either a placebo or 5 or 15 mg supplementary vitamin E/d with oral feeding. No infant received less than the recommended vitamin E:polyunsaturated fatty acid (E:PUFA) value of 0.6. No iron supplement was given.

2. Weekly full blood counts were taken, and plasma vitamin E assay and in vitro haemolysis tests performed on blood sampled on day 1, and also at 6 and 10 weeks of age. All blood withdrawn and transfused and all feeds were documented.

3. Thirty-six (86%) of the babies had a plasma vitamin E level at birth below the accepted adult norm, i.e. < 5200 μg/l. At 6 weeks of age thirty-three (79%) and at 10 weeks thirty-five (83%) of the babies had levels within the normal adult range. No baby showed either clinical or haematological evidence of a vitamin E deficiency state during the trial.

4. It is concluded that in the absence of Fe supplementation and observing the minimum recommended E:PUFA value, contemporary feeding practices allow for the absorption of sufficient vitamin E by the premature baby to prevent the development of an early haemolytic anaemia.

5. No significant relation was found between plasma vitamin E levels and the degree of peroxide haemolysis.

1. Female weanling rats were fed on a purified diet containing either no vitamin A, apart from traces present in casein (deficient groups), or the same diet containing 1.55 mg retinol as retinyl acetate/kg (control groups). In one experiment the deficient groups were given 1 μg retinol/d after 10 weeks, to permit successful reproduction under conditions of marginal vitamin A status. A proportion were mated at 11 weeks after weaning, and fetal development was permitted for 7 d or for 20 d before killing.

2. Carotene dioxygenase (EC 1. 13.11.21) activity was measured in a supernatant fraction from intestinal mucosal scrapings. For each group, activity was 20–30% greater in the vitamin-A-deficient animals than in the controls, and the difference reached statistical significance for the virgin and 7 d pregnant animals in the first experiment (severe deficiency) and for the 20 d pregnant animals in the second experiment (less-severe deficiency).

3. It is suggested that low tissue vitamin A levels may feedback to increase carotene dioxygenase activity, by mechanisms at present unknown, presumably to ensure a more efficient use of precursor dietary carotenoids.

1. Young male rats were fed on a pelleted stock diet or a variety of palatable food items (‘cafeteria’ diet) and housed at 24° or 29°.

2. ‘Cafeteria’ feeding at the lower temperature stimulated energy intake, gain and expenditure, but reduced energetic efficiency such that over 70% of the excess intake was expended.

3. Housing at 29° suppressed intake and expenditure in animals on both diets, but to a greater extent in ‘cafeteria’-fed rats and energetic efficiency was greater than control values at this higher temperature.

4. The thermogenic capacity of brown fat (mitochondrial purine nucleotide binding) was increased by ‘cafeteria’ feeding, but was suppressed in animals kept at 29°.

5. The results demonstrate that diet-induced thermogenesis is inhibited by high environmental temperatures.

1. In the previous work (Varvikko & Lindberg, 1985), 15N-labelled rapeseed (Brassica napus), barley, ryegrass (Lolium perenne) and barley straw were incubated in the rumen in nylon bags for 5, 12 and 24 h and microbial nitrogen in the residues was quantified using the feed 15N-dilution method. In the present study, residual amino acids (AA) of these feeds were analysed, and microbially corrected AA of feed origin (feed AA) were estimated as the difference between total residual AA and respective microbial AA, assuming a constant AA composition for the microbial protein.

2. In barley and barley-straw residues, and also in ryegrass incubated in the rumen for 24 h, very large enrich- ment by microbial N and AA-N was found. The microbial enrichment was rather small in rapeseed residues and ryegrass incubated for 5 or 12 h. During the rumen incubation, feed N and AA-N (g/kg feed dry matter (DM)) decreased very clearly in all the feeds, and feed and incubation time effects were always statistically significant (P < 0.001).

3. The slow degradation of essential (E) feed AA compared with the respective non-essential (NE) AA degradation increased the proportion of feed EAA (g/kg determined feed AA) in barley and barley-straw residues. In rapeseed and ryegrass, residual feed EAA: NEAA remained very similar to the original. Branched-chain (Br) AA tended to increase proportionally in all the feed residues, suggesting these AA to be, on average, more resistant against microbial degradation in the rumen than other AA. Similarly, lysine was clearly increased in barley residues. A rumen degradation faster than the average rate caused decreased residual feed glutamic acid in rapeseed; methionine, alanine and glycine in barley; arginine and alanine in ryegrass; and methionine, asparagine and tyrosine in barley straw. Feed and incubation time effects were significant (P < 0.054–001) for feed AA (g/kg determined feed AA) grouped as EAA, BrAA or NEAA, and for most individual AA, as well as for feed AA disappearance (%) and relative amounts (%) of feed AA in the respective residual AA.

4. According to present findings, AA composition of the rumen-undegraded vegetable feed residues may markedly differ, either quantitatively or qualitatively (or both), from their original AA composition. When determining the feed AA composition of nylon-bag residues, the microbial error may be very large with starchy or fibrous feeds of low protein content. The microbial AA do not, however, considerably confuse the AA determination of protein-rich feeds.

1. Lean (Fa/?) and obese (fa/fa) Zucker rats were adrenalectomized or sham-operated at 19 d of age (3 d before weaning). Injection of corticosterone for 3 d after weaning (1.0 mg/d) was necessary to ensure survival of adrenalectomized fa/fa but not Fa/? rats. Intact and adrenalectomized fa/fa rats had a lower rectal temperature than Fa/? animals before and 3 d after adrenalectomy. The post-weaning survival of adrenalectomized fa/fa rats was enhanced by maintenance at an ambient temperature of 30° rather than 22°.

2. Adrenalectomized and sham-operated rats were therefore kept at 30°, fed ad-lib. and killed at 34 d. Adrenalectomy had only small effects on the growth, body composition and appetite of Fa/? rats. The hyperphagia, greater lipid content, reduced protein content and hyperinsulinaemia of fa/fa rats were completely abolished by adrenalectomy.

3. Intact fu/fa rats had higher liver glycogen contents and higher activities of the hepatic enzymes tyrosine aminotransferase (EC 2. 6. 1. 5) and acetyl CoA carboxylase (EC 6. 4. 1. 2) than intact Fa/? animals. Adrenalectomy abolished these phenotypic differences.

4. Injection of adrenalectomized rats with 1.0 mg corticosterone-21-acetate daily from weaning to 34 d restored the abnormal body composition, hyperphagia, hyperinsulinaemia, higher hepatic glycogen and enzyme activities of fa/fa rats.

5. In a second experiment adrenalectomized rats were injected with 1.0 mg corticosterone-21-acetate daily from weaning to 34 d and kept at 22°, fa/fu rats adrenalectomized and injected with corticosterone had a reduced body lipid content compared with intact fa/fa rats but still contained more lipid than intact or similarly treated Fa/? animals.

6. In both experiments adrenalectomized Fa/? and fa/fa rats injected daily with corticosterone had the same plasma concentrations of this hormone when killed 3 h after the last injection at 34 d. It is concluded that corticosterone is required for expression of the abnormal appetite, hyperinsulinaemia and body composition of the fa/fa rat.

1. Rumen microorganisms convert trans-aconitate to tricarballylate. The following experiments describe factors affecting the yield of tricarballylate, its absorption from the rumen into blood and its effect on mammalian citric acid cycle activity in vitro.

2. When mixed rumen microorganisms were incubated in vitro with Timothy hay (Phleum praiense L.) and 6.7 mM-trans-aconitate, 64 % of the trans-aconitate was converted to tricarballylate. Chloroform and nirate treatments inhibited methane production and increased the yield of tricarballylate to 82 and 75% respectively.

3. Sheep given gelatin capsules filled with 20 g trans-aconitate absorbed tricarballylate and the plasma concentration ranged from 0.3 to 0.5 mM 9 h after administration. Feeding an additional 40 g potassium chloride had little effect on plasma tricarballylate concentrations. Between 9 and 36 h there was a nearly linear decline in plasma tricarballylate.

4. Tricarballylate was a competitive inhibitor of the enzyme, aconitate hydratase (aconitase; EC 4.2.1.3), and the inhibitor constant, KI, was 0.52 mM. This KI value was similar to the Michaelis-Menten constant (Km) of the enzyme for citrate.

5. When liver slices from sheep were incubated with increasing concentrations of tricarballylate, [I4C]acetate oxidation decreased. However, even at relatively high concentrations (8 mM), oxidation was still greater than 80% of the maximum. Oxidation of [I4C]acetate by isolated rat liver cells was inhibited to a greater extent by tricarballylate. Concentrations as low as 0.5 mM caused a 30% inhibition of citric acid cycle activity.

1. The objective of the present experiment was to study the level of plasma somatomedin-C (SM-C) and the status of zinc in rats as affected by three levels of Zn given in combinations with two levels of protein.

2. Six groups of rats were fed, for 21 d, on six different diets based on combinations of two levels of dietary protein (low protein, 75 g/kg; high protein, 200 g/kg) and three levels of zinc (low Zn, 0.9 pglkg; moderate Zn, 55 pg/kg; high Zn, 110 pglkg). All groups were pair-fed with the group receiving the low-Zn-low-protein diet. An additional group of six rats served as an ad lib.-fed control group and was fed on a diet that contained 55 pg Zn/kg and 200 g protein/kg ad lib.

3. Body-weight gain and food intake were recorded daily. Rats were killed at the end of the experimental period (21 d). Zn was assayed in plasma, tibia and liver by atomic absorption technique. Plasma SM-C was assayed by radioimmunoassay.

4. In rats given the low-Zn-low-protein diet, the level of plasma SM-C increased in response to the increase in the amount of Zn or Zn and protein in the diet. However, no change was observed when the level of protein alone was increased.

5. Among all groups tested, adlib.-fed rats showed the highest level of plasma SM-C. Thus it may be concluded that a balanced diet combined with adequate food intake is necessary to maintain an optimal level of plasma SM-C.

1. Iron absorption was measured in weanling riboflavin-deficient (RD) rats or weight-matched (WM) controls fed on appropriate diets for 7 weeks. Concentrations of radio-Fe (68Fe) in plasma were monitored every 30 min for 4 h following intragastric administration.

2. Total Fe absorption in RD rats was significantly lower than that in WM controls, and the tissues of the stomach and small intestine of RD rats retained significantly (P < 0.001) more 68Fe by comparison with WM groups.

3. In a separate experiment, ferritin-Fe concentrations were measured in the livers of four groups of rats (adlib. (C), pair-fed (PF) and WM controls and RD) at day 0, and subsequently at days 14, 21, 28, 35 and 49.

4. Liver ferritin-Fe concentration was significantly lower (P < 0.05) in RD rats than in all other controls after 3 weeks on the respective diets and remained lower for the remainder of the experiment.

1. The present paper reports the effects on rumen fermentation and plasma metabolites and hormones of giving fixed rations of hay and high-cereal concentrates at different meal frequencies to lactating cows. In Expt 1 the total ration was given in two and twenty-four meals daily and in Expts 2–4 the concentrates were given in two and five or six meals and the hay in two meals daily. The diets contained 600–920 g concentrates/kg.

2. In Expt I, minimum rumen pH was higher but mean pH was lower when cows were given their ration in twenty-four meals/d rather than two meals/d.

3. In all the experiments, the effects of increased meal frequency on the molar proportions of rumen volatile fatty acids (VFA) were small and not significant, although there was a general tendency for the proportion of acetic acid to increase and that of propionic acid to fall. Increasing the proportion of concentrates in the diet reduced the proportion of acetic acid and increased the proportions of propionic and n-valeric acids.

4. In Expt 3, more frequent feeding was found to reduce the concentration of non-esterified fatty acids in the blood, but changes in other metabolites were small and not significant. Increasing the proportion of concentrates in the diet reduced the concentrations of acetic acid and 3-hydroxybutyric acid and increased the concentrations of propionic acid and glucose.

5. The mean daily concentration of insulin in the blood was reduced by more frequent feeding of the higher-concentrate diet but not of the lower-concentrate diet. The concentration of glucagon also tended to fall with more frequent feeding. Increasing the proportion of concentrates in the diet increased the concentration of insulin.

6. More frequent feeding reduced the depression in milk-fat concentration caused by feeding the low-roughage diets. About three-quarters of the variation in milk-fat concentration could be related to changes in rumen VFA proportions, but the relations for the two meal frequencies had different intercepts although similar curves. The results suggest that milk-fat depression on low-roughage diets with twice-daily feeding was due to a change in rumen VFA proportions accompanied by elevated plasma insulin concentrations. The improvement in milk-fat concentration due to more frequent feeding could be explained partly by the small change in rumen VFA proportions and partly by a reduction in mean plasma insulin concentrations, but these mechanisms did not fully account for the milk-fat responses observed.