1. Japanese sumo wrestlers have a diet rich in energy, which results in marked obesity. Their plasma urate and triglyceride levels were significantly elevated.

2. Erythrocyte phosphoribosylpyrophosphate (PRPP) and ATP concentrations in sumo wrestlers were significantly elevated when compared to the levels in control subjects.

3. There were no significant differences in erythrocyte PRPP synthetase (EC 2.7.6.1), purine nucleoside phosphorylase (EC 2.4.2.1) and hypoxanthine guanine phosphoribosyl transferase (EC 2.4.2.8) activities between sumo wrestlers and control subjects.

4. Erythrocyte adenosine kinase (EC 2.7.1.20), adenosine deaminase (EC 3.5.4.4) and adenine phosphoribosyl transferase (EC 2.4.2.7) activities in sumo wrestlers were significantly elevated.

5. It seems that sumo wrestlers have an increased turnover of adenine nucleotides which may contribute to hyperuricaemia.

1. A group of rats were given ad lib. a diet with a protein-energy: total energy (P:E) value of 0·03. Other animals received the same protein intake (g/kg body-weight per d) as this group, but had their energy consumption reduced to either 90, 80. 70, 60 or 50% of the ad lib. value.

2. The restricted growth rate of rats fed on the P:E – 0·03 diet ad lib. has been shown to be due entirely to their insufficient protein consumption. In contrast, energy intake was far in excess of that required for maintenance and the limited amount of growth.

3. Carcass analysis demonstrated that some of the excess energy intake was stored as fat, but a greater part had been dissipated, presumably by diet-induced thermogenesis.

4. The plasma concentration of triiodothyronine (T3) was elevated in all animals consuming excess energy and was significantly related to both the total surplus and the amount of energy dissipated.

5. In the group of animals restricted to 50% of the ad lib. intake, energy rather than protein appeared to be the factor limiting growth. Energy intake was below estimated requirements for maintenance and was associated with values for plasma T3 that were lower than those found in well-fed control rats.

6. Although all the animals had similar protein intakes, plasma albumin concentration differed between the groups and was found to be inversely proportional to the energy intake. Thus it was lowest in animals receiving food ad lib. and rose to near normal values in the most-severely-restricted rats.

7. It is suggested that hypoalbuminaemia, and perhaps other features of protein deficiency, seen in animals fed on low-P:E diets may occur as an undesirable consequence of the metabolic response required to deal with excess energy consumption.

1. Male and female mice, 4 weeks old, were fed ad lib. diets containing various amounts of lard (0–300 g/kg) or various kinds of dietary fats (300 g/kg) for 13 weeks. Fat cell number and size were determined by a histological method in three different adipose sites.

2. Lard at 200 g/kg diet (43% energy from lipids) was sufficient to promote fat cell hyperplasia in the parametrial fat. Hyperplasia was also observed in the subcutaneous fat in males. The relationship between fat cell hypertrophy and the level of lard in the diet was dependent on site and sex.

3. Obesity was produced whatever the kind of dietary fat eaten: lard, beef tallow, sunflower oil or soya-bean oil. In the subcutaneous depot of males given lard, fat cell size and number were increased, but only cell hypertrophy was observed in those given soya-bean oil. In the female groups of mice fat cell hyperplasia or hypertrophy or both were related to the adipose site but not the kind of dietary fat.

4. It is concluded that dietary fats of different origin can induce obesity in mice. The effects on adipose tissue cellularity depend on the levels and kind of fat eaten, the adipose site and sex.

1. Ascorbic acid deficiency results in a reduction in the activity of the hepatic mixed function oxidase systems in the guinea-pig. In this study, male Dunkin-Hartley guinea-pigs were given 0, 50, 100, 200 or 300 mg ascorbic acid/d in two equal doses in buffered sucrose solution (200 g/l) for 4 d. Controls received an equal volume of sucrose solution.

2. A dose of 50 mg ascorbic acid/d resulted in a significant rise in the specific activities of both cytochromes P-450 and b5. At doses of 200 and 300 mg ascorbic acid/d the concentration of both haemoproteins was significantly lower than the control values. These effects were mirrored by total microsomal haem concentration.

3. These results suggest that when given in large doses, ascorbic acid ceases to act simply as a vitamin and should be considered a drug competing for substrates and cofactors with co-administered drugs and endogenous substrates such as cholesterol.

1. Transport of L-homocitrulline, an amino acid which occurs in milk products, was studied with rat small intestine in vitro and from the human mouth in vivo. Absorption was partially dependent, in both systems, on the presence of sodium ions.

2. Metabolic inhibitors decreased L-homocitrulline uptake across the small intestine. Transport across the intestine did not occur against the concentration gradient but did show saturation kinetics.

3. The barbiturate, amytal, did not inhibit buccal absorption. Saturation kinetics were demonstrated.

4. Experiments were conducted with L-citrulline, or other amino acids, as possible inhibitors of L-homocitrulline transport. Results were compatible with Na+-dependent carrier-mediated uptake across the buccal mucosa. Active transport could be involved with the small intestine assuming that L-homocitrulline has a low affinity for the carrier system.

1. Pigs weaned at 2 d of age were given diets in which a functional fish-protein concentrate (FFPC) supplied 0 (diet U), 350 (diet H), 525 (diet I) or 700 (diet G) g crude protein (nitrogen × 6·25, CP)/kg total CP. The remainder of the CP was supplied by dried skim-milk and whey. The diets were reconstituted (200 g dry matter (DM)/l), from two spray-dried powders (diets U and G) and these were mixed in the proportions 1:1 and 1:3 (v/v) to give diets H and I respectively. All four diets were given at hourly intervals on a scale based on live weight, and supplemented with vitamins and minerals. All diets contained the same amounts of calcium, phosphorus, sodium and potassium.

2. In an experiment to 28 d of age with ten pigs/diet, performance was inversely related to the amount of FFPC in the diet. One pig (diet I) and four pigs (diet G) died after scouring. In healthy pigs, N retention (g/d per kg live weight) was not affected by partial replacement of dried skim-milk (diet H).

3. Digestion of protein was studied in a further experiment with eight pigs/diet, killed at 7 d of age and at 1 h after a feed. The amount, pH, DM and total N contents of the digesta in the stomach were also inversely related to the amount of FFPC in the diet.

4. FFPC had no consistent effect on proteolytic enzymes. Greater amounts of trypsin and chymotrypsin were present in the distal compared with the proximal region of the small intestine, but source of dietary protein had no effect.

5. The proportion of non-protein-N in the total N in digesta from the small intestine was lower in pigs receiving FFPC suggesting that this protein may be more resistant to proteolysis than milk proteins. The apparent absence of an increase in enzyme secretion when FFPC was given could, therefore, explain the decrease in performance.

6. Some general effects of non-milk proteins from this series of experiments in the baby pig are discussed. It is suggested that performance may be inversely related to the rate of gastric emptying, as indicated by the amount of DM in the stomach. Unlike milk, other sources of protein did not coagulate in the stomach, and reduced the pH, DM and total N contents of the digesta. Giving diets containing a single-cell protein did appear to stimulate proteolytic enzyme secretion, unlike fish or soya-bean proteins.

1. Two experiments are reported. In Expt 1, pregnant Sprague–Dawley rats (200–220 g) were given purified diets containing 35, 75, 150 or 300 mg Fe/kg throughout gestation and lactation. In Expt 2, the levels of Fe given were 250 and 300 mg/kg diet.

2. Litters were standardized at birth to contain seven pups. On day 20 of lactation blood, milk, spleen and liver were collected for Fe analysis.

3. A dietary Fe concentration of 35 mg/kg maintained maximum weight gain, food intake, liver and spleen weight, haemoglobin concentration and packed cell volume in the growing maternal rat through 20 d of lactation. Dam liver and spleen Fe concentrations were maximized between 75 and 250 mg Fe/kg diet.

4. Pups (20-d-old) nursed by dams given 35 mg Fe/kg tended to have lower body and organ weights compared to other groups. Liver and spleen Fe concentrations increased with increasing maternal dietary Fe and were significantly increased between 150 and 250 mg Fe/kg.

1. Weanling rats fed on a relatively low protein diet were infected with several intestinal tapeworms. The weight gain and daily food intake of the rats were measured for 3 weeks before the animals were killed and the adult tapeworms recovered. The tissues of the rats and worms were then analysed for protein. Controls were provided by uninfected rats either pair fed or fed ad lib. For comparison, a similar experiment was conducted on rats fed on a relatively high protein diet.

2. The effect of the infection on the protein-malnourished rats and of the low level of protein on the worms were apparently not significant. The amount of protein contained in the worm burdens was less than 1·5% of the average total intake of the protein-malnourished rats.

1. In an attempt to investigate calcium absorption in the rat during the postprandial period, with the least alteration of the physical environment, the undisturbed small intestine was ligated in situ 2·5 or 3·0 h after ingestion of a diet containing 200 g casein/kg or an equivalent amino acid mixture, or 925 g casein/kg. Estimation of Ca absorption was made by comparing the amount of soluble 40Ca or 45Ca in the contents of segments from the rats receiving 45Ca by intubation 30 min after withdrawal of food, ligated after a further 30 min, then killed after 0 or 30 min.

2. Under conditions such that the estimated amount of a marker, polyethylene glycol, in segments ligated in a defined position was little changed in rats killed 30 min apart, the difference in the amount of soluble 40Ca was much higher in the rats fed on the basal diet containing 200 g casein/kg than in other groups.

3. This specific effect on Ca absorption, particularly in the distal portion of the small intestine, could be seen also after 45Ca was directly injected into ligated segments in situ. The amount of 45Ca in the portal blood 15 min after injection of the label was also highest in the rats given the basal diet.

4. The results were in agreement with our previous findings that the formation and accumulation of casein phosphopeptides causes an increase in the amount of soluble Ca in the distal small intestine.

1. Twenty heifer calves were allocated to four groups and maintained for 32 weeks on a diet based mainly on barley and straw and containing 4 mg copper/kg. The diet was supplemented with 0 or 800 mg iron/kg and 0 or 5 mg molybdenum/kg.

2. Liver and plasma Cu concentrations, erythrocyte superoxide dismutase (EC 1.15.1.1) and plasma caeruloplasmin (EC 1.16.3.1) activities decreased greatly and rapidly in all calves given the Fe or Mo supplements or both. Levels indicative of severe Cu deficiency were attained within 16 weeks. There were no significant differences in values in animals given Fe, Mo or Fe plus Mo.

3. Clinical signs of Cu deficiency developed after 20 weeks in the calves given the Mo supplement. Growth rates were reduced, skeletal lesions developed and hair texture and colour were affected. No such effects were observed in the calves given only the Fe supplement.

4. Plasma and liver Fe concentrations increased in calves given the Fe supplement but were not greatly affected by Mo, even when the calves were severely Cu-deficient.

5. The significance of the effects of Fe and Mo on Cu metabolism are discussed with special regard to the influence of soil ingestion on Cu availability and to the frequent lack of correlation between the Cu status of animals and their clinical condition.

1. Studies were made of the extent to which p-cresol, catechol, quinol and orcinol infused through rumen or abomasal cannulas to sheep were recovered in their urine.

2. Rumen fermentation of dietary phenolic compounds caused the excretion of simple phenols in the urine. In decreasing order of magnitude these were: p-cresol, catechol, phenol and 4-methylcatechol with only traces of quinol and orcinol.

3. The percentages of rumen-infused p-cresol or orcinol recovered as increments in the urinary phenol outputs of sheep (94 and 99% respectively) following infusion showed that rumen degradation of these phenols was negligible.

4. After rumen infusion of catechol and quinol, mean recoveries of these phenols in urine were only 55 and 77% respectively. Possible reasons for these incomplete recoveries are discussed.

5. Studies were also made of the use of the urinary phenol output of phenols characteristic of particular forages as indices of their voluntary intake by sheep. Calluna vulgaris L. (Hull) (heather) may contain 1300–3600 mg/kg dry matter (DM) of orcinol and 200–800 mg/kg DM of quinol as β-glycosides. When heather was offered ad lib. to sheep given one of five levels of grass, linear relationships were found between heather intake and urinary quinol and orcinol outputs.

6. The urinary output of aromatic acids was also determined when sheep ate grass and heather. Urinary phenylacetic acid output was linearly related to grass but not to heather intake. The relationship between urinary phenylacetic acid output and grass intake could vary with different forages but that between orcinol output and heather intake was considered a useful index of heather intake.

7. Methods for the assay of urine phenols are discussed.

1. A pepsin + pancreatin method was used to assess the digestibility of pure cultures of rumen bacteria and mixed bacteria prepared from rumen fluid.

2. Individual species of Gram-negative rumen bacteria were highly digestible, whereas Gram-positive species, especially cocci, were more resistant to digestion.

3. A similar difference was observed microscopically with mixed rumen bacteria, but the influence of the relative proportions of Gram-positive and Gram-negative bacteria on the digestibility of bacterial protein in rumen fluid was small.

1. The effects of level of feeding and level of protein in the early postnatal period on the cellularity of subcutaneous adipose tissue and body fat content of pigs were investigated in two experiments.

2. In Expt 1, piglets were given a common liquid diet at energy intakes equivalent to 2·8 or 5·2 times energy for maintenance (M) between 1·8 and 6·5 kg live weight (LW), and a common dry diet at 2·8 or 4·5 M between 6·5 and 20 kg LW. Between 20 and 75 kg LW all pigs were given a second dry diet at 4·0 M.

3. In both experiments the effects of nutritional treatments on fat cell number at 20 and 75 kg LW (Expt 1) and at 45 kg LW (Expt 2) were assessed by measuring the DNA content of the subcutaneous adipose tissue contained in the left shoulder joint. Fat cell size was assessed in the same tissue by measuring the diameter of collagenase-released adipocytes.

4. In Expt 1, raising the level of feeding between 1·8 and 6·5 kg LW increased body fat content and average fat cell diameter at both 6·5 (P < 0·01) and 20 kg LW (P < 0·05) but had no effect on either measurement at 75 kg LW. Similarly, raising the level of feeding between 6·5 and 20 kg LW increased body fat content and fat cell size at both 20 (P < 0·01) and 75 kg LW (P < 0·05). There was an almost twofold increase in the DNA content of subcutaneous adipose tisuue between 20 and 75 kg LW. However, it was not significantly affected at either weight by level of feeding before or subsequent to 6·5 kg LW.

5. In Expt 2, reducing the level of dietary protein between 1·8 and 6·5 kg LW increased body fat content (P < 0·01) and fat cell size (P < 0·01) at the latter weight. Although level of dietary protein to 6·5 kg LW had no effect on body fat content or the weight of subcutaneous adipose tissue in the shoulder joint at 45 kg LW, pigs given the lowest-protein diet contained less DNA (P < 0·05) in the subcutaneous adipose tissue and had larger (P < 0·05) fat cells than those given the highest-protein diet to 6·5 kg LW. Reducing the protein content of the diet fed subsequent to 6·5 kg LW increased the body fat content (P < 0·01) and fat cell size (P < 0·01) at 45 kg LW.

1. Steers fitted with simple rumen, abomasal and sometimes duodenal cannulas were given isonitrogenous and isoenergetic diets consisting of pellets containing equal amounts of rolled barley and chopped straw together with tapioca alone (B), or with some tapioca replaced by coarse soya-bean meal (M) or finely ground soya-bean flour (F). Diet B had an estimated rumen degradable nitrogen (RDN): metabolizable energy (ME) value of approximately 0·8 g/MJ. The corresponding value for each of the supplemented diets was 1·3–1·4. Diets were given at two levels of intake designed respectively to provide ME intakes to support weight gains of 0·5 kg/d (L) and 1·0 kg/d (H). Chromic oxide and polyethylene glycol were given as indigestible markers. Values were calculated for flows (g/24 h) at the abomasum of organic matter (OM), non-ammonia-N (NAN) and microbial (bacterial)-N (MN). Estimates of MN were based on RNA and α-ε;-diaminopimelic acid (DAP) measurements. The steers had low rumen protozoal counts throughout the whole experiment with fewer than 8000 ciliate protozoa/ml of rumen fluid.

2. Proportions of OM apparently digested between the mouth and abomasum were significantly lower for H than for L intakes but showed no other significant differences. Mean estimated efficiency of microbial protein synthesis was approximately 17 g N/kg OM apparently digested in the rumen for the LB diet, but was significantly greater at approximately 26 g N/kg OM apparently digested for the HB diet. The protein-supplemented diets gave values of 31–32 which were significantly greater than the value for the LB but not the HB diet.

3. Amounts of feed nitrogenous constituents surviving between the mouth and the abomasum were estimated from NAN minus MN corrected for endogenous N. Values for the proportions of feed N degraded, derived from these estimates, were 0·71, 0·66, 0·72, 0·69, 0·67 and 0·70 for diets LB, HB, LM, HM, LF and HF respectively. There were no significant differences due to level of feeding, supplementary protein or the physical form of that protein.

4. Estimates of MN flows at the abomasum based on RNA determinations in fresh samples did not differ significantly from estimates based on DAP determinations. However, storage of aqueous suspensions of mixed rumen bacteria by deep-freezing or freeze-drying resulted in significant losses of RNA. No such losses were observed for abomasal digesta. This meant that if samples were stored by these means before analysis, the use of RNA as a microbial marker was vitiated.

5. In some experiments digesta samples were taken from the duodenum as well as the abomasum. Estimates of total N flows did not differ significantly between these sites.

1. The over-all and regional metabolism of non-esterified fatty acids (NEFA) was studied using a combination of isotopic and arteriovenous-difference techniques.

2. There was a common linear relationship, whether stearic, palmitic or oleic acids were used as tracer, between the arterial NEFA concentration and the rates of entry and oxidation.

3. Assuming that the tracer used reflected the metabolism of all the NEFA, the total entry rate in fed and fasted pregnant ewes was (mean±SE) 0·44±0·02 and 0·55±0·07 mmol/h per kg body-weight respectively. Oxidation of NEFA contributed (mean±SE) 34±5 and 58±7% to the respiratory carbon dioxide in fed and fasted animals, this accounting for (mean±SE) 46±6 and 59±3% of the respective entry rates.

4. Hind-limb muscle both utilized and produced NEFA. The mean gross fractional extraction (calculated from isotopic uptake) was (mean±SE) 9±1%. Gross utilization of any NEFA and appearance of 14CO2 across the muscle were linearly related to the arterial concentration of tracer fatty acid, irrespective of whether this was oleate or stearate. The amount of 14CO2 appearing was consistent with (mean±SE) 54±8% of the CO2 produced by the hind-limb being derived from NEFA oxidation.

5. Infused NEFA were partly converted to ketone bodies. Uptake and oxidation in the hind-limb of ketones formed in the liver could account for approximately 20% of the 14CO2 apparently produced in muscle from NEFA. Correction for this reduces the proportion of CO2 derived from NEFA to 43%. There was some indication that ketones were also produced from NEFA in the hind-limb.

6. NEFA were not a significant energy source for the gravid uterus.

7. An over-all view of energy sources for the whole animal and for hind-limb muscle in normal and fasted pregnant sheep was presented.

1. The effects of phosphorus deprivation on phytate digestibility, phosphorus utilization and intestinal phytase (EC 3.1.3.8) and alkaline phosphatase (EC 3.1.3.1) in rats were investigated.

2. P deprivation was achieved by giving rats a diet containing 3 g P/kg and resulted in hypophosphataemia, hypercalcaemia, hypercalciuria, and lower levels of P absorbed and retained, and calcium retained.

3. Rats adapted to P deprivation by increasing the digestion of total dietary-P and phytate-P.

4. Levels of intestinal alkaline phosphatase and alkaline phytase were not different between the two treatment groups.

5. P deprivation in the rats given the marginal-P diet may be a result of a lower absorption of total dietary-P or increased absorption of inositol phosphates formed during the enzymic hydrolysis of phytate which are not readily utilized by the rat.

6. These results suggest that intestinal phytase and alkaline phosphatase do not play a role in the adaptive increase in phytate digestibility by rats given marginal-P diets. The adaptation may result from enhanced phytase or alkaline phosphatase synthesis by the gastrointestinal microflora stimulated by a lower level of P in the digesta.

1. Absorption of magnesium from the temporarily-isolated, emptied and washed rumen of four 10–12-month-old heifers was measured at five different Mg concentrations (2·5, 5·0, 7·5, 12·5 and 20 mmol/l).

2. Net absorption of Mg was observed at all concentrations. Saturation occurred at a concentration of 12·5 mmol Mg/l.

3. Using an Eadie–Hofstee plot, the Michaelis–Menten constant (Km; 11·43 mmol/l) and maximal efflux (Vmax; 120·3 μmol/min) were estimated.

4. The phenomenon of saturation supports the assumption that Mg transport across the rumen wall of heifers is an active process.

1. Glucose turnover in fed and 48 h-starved lactating goats was determined during a glucose load of 500 μmol/min using a continuous infusion of [U-14C]- and [3-3H]glucose.

2. Endogenous rates of irreversible glucose turnover (i.e. total rates of irreversible glucose turnover minus the rate of exogenous glucose supply) were depressed during glucose loading by 14 and 62% in the fed and starved animals respectively.

3. Plasma glucose concentrations increased significantly by 57 and 88% in the fed and starved goats respectively. Plasma insulin concentrations increased by 108 and 128% in the fed and starved animals respectively.

4. Milk yields increased significantly (41%) in the starved animals during glucose loading, but were unaffected in fed animals.

5. In both the fed and 48 h-starved goats, mammary glucose metabolism via glycolysis and the pentose phosphate pathway appeared to be stimulated by glucose loading.