1. Guinea-pigs on a low, controlled intake of ascorbic acid (0.3 mg/100 g body-weight) were given daily an oral supplement of L-ascorbic acid (AA) or of D-isoascorbic acid (isoAA) (both 1.5 mg/100 g body-weight). The AA was deposited in the tissues, the isoAA was not.

2. Intramuscularly administered isoAA was deposited in the tissues but not to the same extent as equivalent amounts of intramuscularly administered AA.

3. Paper chromatography confirmed that intramuscularly administered isoAA was deposited in the tissues as isoAA, i.e. there was no conversion into AA.

4. It is concluded that in guinea-pigs (a)AA is absorbed from the gastro-intestinal tract much more readily than isoAA and (b)AA is either more readily abstracted from the blood or is more readily retained by the tissues or both, than is isoAA.

1. Lambs fitted with cannulas in the abomasum, terminal ileum and caecum were used to study the digestion of starch and dry matter when rations with high starch content were given. Polyethylene glycol was used as an indigestible reference substance.

2. In Expt I reduction in level of feeding from an estimated ad lib. intake to 70% of this level reduced the amount of dietary starch escaping fermentation in the rumen from 6.8 to 4.4% of intake on a barley diet and from 12.8 to 7.7% on a diet consisting of 40% dried grass and 60 yo barley. Inclusion of 40% chopped dried grass in the diet increased the amount of dietary starch escaping fermentation in the rumen. There appeared to be a linear relationship between the concentrations of starch in abornasal and ilcal dry matter, indicating a limited capacity for starch digestion in the small intestine.

3. In Expt 2 a barley diet was compared with diets based on flaked maize, ground maize or cracked maize. With these diets the percentage of dietary starch escaping fermentation in the rumen was respectively 6.2, 5.4, 12.1 and 142, showing that more starch escapes fermentation with uncooked maize diets than with barley diets.

4. The molar proportions of volatile fatty acids produced by fermentation in the caecum were apparently influenced by the amount of starch passing to the intestines. The highest proportion of acetic acid (78%) was associated with 4.5% of starch in abomasal dry matter, and the lowest proportion (57%)was associated with 20.1% of starch in abomasal dry matter.

5. The possible relationships between the extent of fermentation in the rumen and energy and nitrogen metabolism are discussed.

1. A description of the population resident on Tristan da Cunha during the winter of 1966 is given.

2. Sources of food supplies are discussed.

3. A brief description of island meal patterns is given and methods of food preparation are discussed.

4. Samples of unusual foods and unique dishes consumed on Tristan da Cunha were collected and analysed for moisture, total nitrogen, fat, calcium, iron and ascorbic acid.

5. The dietary patterns and way of life of the Islanders resident on Tristan da Cunha have changed owing to contact with the outside world and to the development of a monetary economy. These changes were accelerated by the enforced period of 2 years spent in England. The Islanders are now very dependent upon a cash economy and subsistence agriculture provides only a relatively small part of the present diet.

1. Individual energy intakes and expenditures of seven Tristan men aged between 16 and 57 years, and ten Tristan women aged between 15 and 61 years, were measured daily for 7 consecutive days between May and October 1966.

2. Details of the subjects' main activities together with the energy cost of these activities are given.

3. The mean daily calorie intakes were 2650 kcal for men and 1830 kcal for women; the mean expenditures were 2860 and 2060 kcal per day respectively. Separate values are given for two individuals, a brother and sister, who gave results bearing no resemblance to those of the rest of the subjects.

4. Protein, fat, carbohydrate and alcohol accounted for 12.7, 29.6, 53.7 and 40 % respectively of the men's total calorie intake and 11.9, 27.2, 61.0% and 0% of the women's total calorie intake. The fat content of the diet was low when compared with that of the Islanders' diet while in England, though total calorie intake was greater (Taylor, Hollingsworth & Chambers, 1966). More than half the total calorie intake was provided by processed foodstuffs, but island produce provided a large proportion of the protein in the diet.

5. It is deduced that mean energy requirements of about 2750 kcal per day for men and 1950 kcal per day for women are adequate for the Tristan population and that there are sufficient food supplies available to meet this requirement.

1. The behaviour of fatty acids in dilute bile salt solution and in dispersions of triglyceride in bile salt solution was examined. The properties of fatty acids in bile salt solution were defined in terms of their saturation ratio, and of the critical micellar concentration of bile salt for each fatty acid as solute. The partition of fatty acids between the oil phase and the micellar phase of the dispersions was defined as the distribution coefficient K M/O. The phases were separated by ultracentrifugation.

2. Of the fatty acids examined, palmitic and stearic acids behaved in bile salt solution as typical non-polar solutes. Lauric, oleic and linoleic acids had properties similar to typical amphiphiles. The effectiveness of these and other amphiphiles was expressed in terms of an amphiphilic index.

3. The trans-fatty acids, vaccenic acid and linolelaidic acid possessed solubility properties similar to their cis-isomers. The properties of elaidic acid were intermediate between those of the non-polar and the amphiphilic solutes.

4. The distribution coefficients of fatty acids differed less significantly than their solubilities in bile salt solution, but were influenced to some extent by the composition of the oil phase.

5. The effect of pH on the partition of fatty acids was similar for all fatty acids examined. There was a marked increase in the partition of fatty acids in the micellar phase as pH increased above 6.2.

6. In the presence of Ca2+ ions above a threshold concentration of I m-equiv./l. and at a pH higher than 6.4, the partition of stearic acid in the micellar phase of the bi-phasic system was restricted. No interaction of Ca2+ ion and pH was observed with oleic acid.

7. The effect of some amphiphiles on the distribution coefficient of stearic acid was examined. The capacity of lysolecithin to solubilize stearic acid in the micellar phase of dispersions was about twice that of I-mono-olein. The significance of the results in relation to fat absorption in the pig and the sheep is discussed.

1. The body temperatures and resting oxygen consumptions of calorie-deficient and protein-deficient pigs have been measured at 12, 21, 26, 30, 36 and 40°.

2. A fall in the environmental temperature was followed by a rise of the same order in the oxygen consumptions of the two groups of animals, and past and present evidence indicates that the rise in normal animals of the same size is similar.

3. The rectal temperatures and oxygen consumptions of the protein-deficient pigs were higher at all the above temperatures than those of the calorie-deficient animals but not as high as those of normal animals.

4. The differences in rectal temperatures and oxygen consumptions were highly significant at 30°, which is probably within or near the zone of thermal neutrality of all the animals.

1. After 14 days on a diet containing 5 or 25% casein male rats received a fracture of the left femur. Four hours before they were killed the injured and control rats were injected with [1-14C]leucine; the incorporation of radioactivity into an isolated fraction of skeletal muscle ribosomes was studied 6, 12, 24, 48, 72, 96 and 228 h after injury.

2. The incorporation of [14C]leucine into the ribosome fraction in right thigh muscles dropped to 40% of control values 72 h after fracture in well-nourished rats and after 96 h with diets containing 5 or 25%, casein.

3. The specific activity of the trichloroacetic acid-soluble fraction of muscle from injured rats was equal to or higher than that of the controls during the first 72 h but lower at 96 h.

4. These results suggest that a reduced incorporation of amino acids by ribosomes from the right thigh muscle occurred on day 3 after fracture in the group receiving 25% casein but not in the group receiving 5% casein.

5. Muscle RNA and DNA concentrations were not affected by the injury.

6. The relationship between these findings and the loss of muscle N after injury is discussed.

1. Control groups of pigs were given a basal diet alone and treated groups received the same diet supplemented with 250 ppm of copper. The animals were about 10 weeks of age at the start of the experiments and were killed when they weighed 90 kg live weight.

2. The ratio of oleic acid to stearic acid in the whole back fat (inner plus outer layers) was somewhat higher in the pigs given the copper supplement than in the control animals. The melting point of the back fat was about 10° lower in the pigs given the copper supplement than in the control groups.

3. Separate analyses of the inner and outer layers of the back fat showed that the ratio of oleic acid to stearic acid in the outer fat layer of the control pigs, and in both the inner and the outer fat layers of the pigs given the copper supplement, was somewhat higher than that in the inner fat layer of the control animals. The melting point of the outer fat layer of the control pigs and of both back fat layers in the pigs given the copper supplement was 10–15° lower than that of the inner fat layer of the control groups.

4. Evidence is presented that changes in the positional distribution of the fatty acids within the triglycerides of the back fats rather than differences in gross fatty acid composition are mainly responsible for the observed differences in physical properties.

1. A vitamin E-low diet containing 7% stripped lard was given to hooded rats for periods up to 14 months. Control rats were given the same diet with a vitamin E supplement (I i.u./rat per day).

2. No consistent pattern of changes was found in the total fatty acids of testis, lung, spleen, pancreas, heart, kidney, liver, brain, skeletal muscle and small intestine from rats given the deficient diet for 5, 6 or 7 months when compared with control rats.

3. The fatty acids of the total phospholipid from the same tissues were examined after 4, 5, 8 or 14 months. In the rats deficient in vitamin E the polyunsaturated fatty acids of the linoleic series (ω6) decreased, except for 20:4ω6, which in some tissues tended to increase. After 14 months there were considerable decreases in the percentages of all the ω6 series including 20:4ω6 with increases in the percentages of 18:1ω9 and 20:3ω9 the pattern was similar to that found in essential fatty acid deficiency.

1. It has been suggested that carbon tetrachloride damages rat liver by accelerating processes of lipid peroxidation at subcellular sites and that the protective action of vitamin E is due to its functioning as an antioxidant in vivo. Direct evidence for these mechanisms in vivo has been sought and is critically examined.

2. The increased production of malondialdehyde by rat liver microsomal fractions during incubation with CCl4 was shown to be a function of the vitamin E status of the rat and of an in vitro reaction, which could not be correlated with the hepatotoxic action of CCI4.

3. Evidence for the production of lipid peroxides by CCl4 in the livers of vitamin E-deficient and vitamin E-supplemented rats was sought (I) by measurement of ultraviolet spectral changes ('diene' formation) and (2) by direct micro-iodimetric determination of the peroxide. No differences in peroxide content were found between CC14-treated and control rats, nor were the spectrophotometric changes in the ultraviolet region related to the presence of vitamin E.

4. The effect of CCI4 (2.0 ml/kg orally) on ATP levels in rat liver was studied at intervals from 3 to 68 h. The primary lesion leading to necrosis and fat accumulation after CCl4 treatment occurred many hours before the eventual slight decline in ATP. Although the levels of ATP were somewhat higher in vitamin E-deficient rats, vitamin E did not prevent the slight decline in ATP that took place. Since ATP is known to be highly sensitive to peroxidation, the results suggest that lipid peroxidation is not the primary event in CCl4 poisoning.

5. The effect of CC14on the metabolism of [14C]D-α-tocopherol in the rat was studied. A single intraperitoneal dose of CCl4 (2.0 m/kg) did not increase the destruction of α-tocopherol in the liver or carcass after 24 h. Three smaller daily doses of CC14 (0.25 ml/kg) also did not increase α-tocopherol catabolism; on the contrary, significantly more α-tocopherol was found in the livers of rats treated with CCI4. These results suggest that CCl4 does not increase lipid peroxidation in vivo.

1. Fatty liver was induced in 4-month-old male rats by oral dosing with ethanol. The marked increase in liver fat was not accompanied by a rise in lipid peroxides.

2. Homogenates were prepared from the livers of vitamin E-deficient rats and incubated with ethanol. In the concentration range of 10–50 μl/3 ml, ethanol increased the production of malondialdehyde. Methanol, which is not a hepatotoxin, showed a similar effect at 10–35 μl/3 ml homogenate. These findings indicate that the pro-oxidative effect of alcohols in vitro is unrelated to their hepatotoxic action in vivo.

3. Fatty liver was induced in 3.g-month-old, vitamin E-deficient male rats by oral dosingwith ethanol. The effect of pretreatment with vitamin E and N,N'-diphenyl-p-phenylenediamine (DPPD) was studied. D-α-Tocopheryl acetate, given as three doses of 350 mg/kg at 48, 24 and 2 h before the ethanol, failed to decrease the fat accumulation and seemed rather to increase the fat content of the liver. DPPD, given as three doses of 600 mg'kg at similar intervals before the ethanol dose, reduced the fat content of the liver almost to normal.

4. Weanling rats of both sexes were given a vitamin E-deficient diet containing 1% orotic acid for 15 days to induce fatty liver. Dietary supplements of D-a-tocopheryl acetate (500 ppm), selenium (I ppm) or DPPD (100 ppm) did not reduce the lipid accumulation. Lipid peroxides and malondialdehyde levels were lower in the livers of animals treated with orotic acid than in controls, regardless of the presence of vitamin E.

j. Liver necrosis was produced in 9-week-old female vitamin E-deficient rats by the intra-peritoneal injection of zoo mg thioacetamide. Promethazine hydrochloride (Phenergan), given intraperitoneally as two doses (25 mg/kg at the same time as the thioacetamide and 12.5 mg/kg 6 h later), markedly reduced the necrosis. D-α-Tocopheryl acetate, given as two oral doses of 1000mg/kg 48 h and 24 h before the thioacetamide, tended to exacerbate the necrosis.

6. The results are discussed in relation to the question of lipid peroxidation as a cause of hepatotoxicity.

1. The following techniques, which have been applied successfully to goats, were used to study mammary metabolism in lactating sows:(I) measurements of mammary arteriovenous (A-V) differences in milk precursors in the conscious undisturbed animal (five sows); (2) continuous intravenous infusion of [U-14C]glucose with concomitant arterial and mammary venous blood sampling for measurement of mammary blood flow and specific radioactivity of glucose and CO, (one sow); (3) perfusion of the isolated gland in vitro (eight glands from four sows), with the inclusion of [U-14C]glucose (two glands) and [U-14C]acetate(two glands) in the substrate mixture.

2. Sow mammary tissue was similar to that goats in its milk yield, blood flow, and glucose uptake per unit weight of tissue. As in goats, mammary uptake of glucose was many times that of the rest of the body and the total mammary tissue was utilizing about half of the total glucose entering the circulation. Glucose was a major source of milk lactose and glycerol and of mammary CO2.

3. Of the plasma lipid components, only the triglyceride fraction was consistently and significantly removed by the gland. In contrast to the results obtained for the goat, both [U-14C[acetate and [U-14C]glucose carbon were used for milk fatty acid synthesis, and although the pattern of labelling of fatty acid from each precursor was similar, the formation of fatty acids from glucose was at least five times greater than that from acetate. Quantitative evaluation of the contribution of these precursors was not possible, but the RQ (1.09–1.63) suggest that in some instances it may have been considerable.

4. The substantial A-V differences of most plasma essential amino acids suggest that these are the sole precursors of the corresponding residues in the mammary synthesized protein. The low A-V differences for several non-essential amino acids suggest that these are synthe- sized in the gland; this suggestion is supported by the incorporation of glucose carbon into non-essential amino acid residues of casein observed in one experiment. However, in contrast to results with the goat, mammary absorption of serine was consistently large.

1. Changes in blood sugar levels after giving carbohydrates have been used to assess carbohydrate utilization in pre-ruminant calves aged between 10 and 50 days.

2. Glucose, galactose and lactose were readily utilized by all calves; the utilization of glucose and galactose increased with age, whereas that of lactose remained constant.

3. Maltose and fructose utilization was low in young calves and increased slightly with age.

4. Sucrose and starch were not utilized.

5. Studies with three older pre-ruminant calves (aged 53, 88 and 106 days) in which the carbohydrates were infused into the proximal duodenum showed that glucose, galactose, lactose and xylose all caused marked increases in the level of blood reducing sugar, whereas fructose and sucrose caused no increase, and maltose was intermediate. Xylose and galactose caused very little change in the blood glucose concentration.

6. It appeared that preferential uptake occurred of glucose from a glucose-galactose mixture.

7. A non-linear relationship was found between the concentration of glucose or galactose infused and the increase in the level of blood reducing sugar.

1. A semi-synthetic vitamin B12-deficient diet, based on soya flour, is described. When supplemented with cydnocobalamin the diet appeared to be adequate for growth and reproduction in the rat.

2. Compared with their litter-mates on the supplemented diet, rats fed on the deficient diet from weaning showed reduced levels of vitamin B12 activity in the plasma and tissues, but their growth rates were unaffected unless they were bred from mothers that had been given the deficient diet since mating.

3. When they were reared on the deficient diet, rats bred from mothers on the deficient diet since mating excreted much more methylmalonic acid in the urine than their litter-mates on the supplemented diet. There was wide variation in the level of excretion, both between different animals and from day to day in the same animal.

4. Starvation for more than 16 h caused a marked depression in the amount of methylmalonic acid excreted by rats on the deficient diet.

5. Intraperitoneal injection of sodium propionate into deficient animals after starvation for 24 h caused increased excretion of methylmalonic acid during the following 16 h of continued starvation. Isoleucine had a similar but smaller effect.

6. Tested in the starved animal, sodium propionate and valine given either by intra- peritoneal injection or by mouth, and isoleucine given intraperitoneally, caused increases in the excretion of methylmalonic acid. In contrast, methionine had no effect and threonine only a slight effect.

1. Individual body fat and body measurements such as lengths, girths and selected skinfold thicknesses were determined in our laboratory strain (BHE), a highly inbred strain (IN) of BHE rats and in a strain of Wistar rats. Measurements were made on unconscious rats in less than 5 min per rat just before autopsy; body fat content was determined in individual rats of both sexes at 50, 100 and 300 days of age.

2. Among the strains, mean total body fat was highest in BHE rats at each age; IN rats of similar average body size were leanest. Statistically significant differences in body fat among the strains were due primarily to differences among the male rats at 300 days. Total protein and skeletal mass increased with increases in age and body size, as did body fat in rats after maturity. IN rats had the largest fat-free weights. Although significant age differences in body fat and body measurements occurred, they were in part dependent upon changes in body- weight, sex and strain of the animals. Female rats had more fat per unit body-weight than males at each age studied. Females, though fatter than males, had smaller skinfold thicknesses, indi- cating that female fat increases are primarily in visceral fat.

3. Large variation in fat among individuals within strains of the same body-weight and age suggests a genetic influence in fat potential in rats not associated with age or body-weight.

4. Results from multiple regression analyses showed differences among adjusted means and partial regression coefficients due to strain and sex of the animals. Although final body-weight was the predictor common to all equations, body length, abdominal girth and subscapular skinfold were common to all but one set of equations. Chest girth, tibia length, triceps and abdominal skinfolds decreased in frequency of appearance in that order. Some of the measurements were more effective predictors at one age than at another. It was clearly necessary to take into account body dimensions other than weight to obtain an optimal prediction of body fat.

5. Differences in characteristics of the rats support the concept of genetic influences in fat deposition in individuals and indicate the complex nature of these influences.

1. Rats were given a rachitogenic diet for 28 days; some were dosed with vitamin D 2 or 3 days before they were killed and some received vitamin D throughout the experiment.

2. Parathyroid leucine aminopeptidase was measured histochemically as an index of parathyroid activity and silver impregnation as a criterion of bone calcification.

3. Calcium and phosphorus were estimated in bone ash and in serum. In rats killed 2 days after a single dose of vitamin D, increases were found in the Ca and P content of serum and bones and in epiphyseal Ca deposition. Parathyroid activity was decreased. In rats killed 3 days after a dose of vitamin D there was a marked increase in serum Ca and P but a less clear change in bone Ca and P although epiphyseal calcification was evident. The parathyroid activity was less than in rats dosed throughout the experiment.

1. In seven experiments sheep were given diets ranging from all-hay to all-barley, and also a diet comprising one part hay to two parts flaked maize. Each sheep was equipped with a cannula into the rumen and a re-entrant cannula in the proximal duodenum; six of the ten also had a re-entrant cannula in the terminal ileum. Paper impregnated with chromic oxide (Cr2O3) was given twice daily by rumen fistula.

2. Amounts of α-linked glucose polymer entering and leaving the small intestine and excreted in the faeces were measured. Some values for a fraction designated non-glucose reducing polymer for cellulose and for gross energy were also obtained. The amounts passing the proximal duodenum and the terminal ileum were adjusted to give 100% recovery of Cr2O3 and the values were used to measure the extent of digestion in various parts of the alimentary tract.

3. When rolled or whole barley was given alone or was the major feed constituent the amount of α-linked glucose polymer entering the small intestine was 6.0±0.76% of that ingested (range 2.6–8.1%). The value was significantly lower than that found for the diet of hay and flaked maize (10.4±1.3%, range 8.0–13.6 %).The α-linked glucose polymer which entered the small intestine was almost completely digested there.

4. The digestibility of the non-glucose reducing polymer, which included much of the hemicelluloses present, ranged from 51 to 73% and almost all the digestible fraction (93–97%) was digested before the small intestine when hay or predominantly hay diets were given. On high-cereal diets only 71–85% of the digested fraction disappeared before the small intestine and appreciable amounts were digested in the large intestine.

5. On the all-hay diet 91% of the digestible cellulose and 67% of the digestible energy were lost before the small intestine, 0 and 21% in the small intestine and 9 and 12% in the large intestine.

6. Mean digestibility coefficients determined in sheep fed solely on either whole or rolled barley were: for dry matter 88.1 and 87.9%, for nitrogen 83.5 and 82.1%, for crude fibre 53.7 and 56.6% and for gross energy 87.7 and 88.0%.

1. The urinary excretions of total diethyl ether-soluble acids and total aromatic acids of three sheep given maintenance diets containing different proportions of hay, rolled oats and decorticated groundnut meal were determined.

2. When the sheep were given the diet containing 70% rolled oats the excretion of aromatic acids in the urine was less than that observed when the sheep were given diets high in roughage or protein concentrates.

3. The amounts of aromatic acids excreted in the urine were not related to the dietary intakes of crude protein, apparently digestible crude protein, crude fibre, lignin or cellulose.

4. The excretion of comparatively large amounts of aromatic acids in the urine of ruminants is discussed in relation to the smaller amounts normally excreted by non-ruminants. Possible reasons for the failure to observe any relationship between the amounts of aromatic acids excreted in the urine of the sheep and those constituents of the diets that were investigated are discussed and the nature of other precursors is suggested.

1. Healthy young men ate diets high in carbohydrate with a fixed protein content: (a) 18% protein with maize starch, (b) 18% protein with sucrose, (c) 9% protein with sucrose. Sucrose or starch was given at a level of 7 g/kg body-weight per day.

2. The serum albumin concentration fell by 7–10% after 16 days with all three diets; the falls were statistically significant. No change in γ-globulin concentration was seen with the 18% protein diets. With the 9% protein diet there was a significant increase in this fraction. The β-globulin concentration rose significantly with the diet containing 18% protein with sucrose but there was no change in this fraction with the other diets. α1- and α2-globulins rose significantly with the diet containing 18% protein with sucrose but no increase in these fractions was seen on the other diets.

3. Possible mechanisms concerned in the production of these changes are discussed.

1. Rates of oxygen consumption and carbon dioxide production were measured in pigs from birth to 3 days of age in an open-circuit system.

2. The mean respiratory quotient (RQ) during the first 6 h following birth was 0.95 in fasted pigs and 0.91 in pigs which were allowed to feed.

3. The RQ fell during the remainder of the first postnatal day to mean values close to 0.85, whether the pigs were allowed to feed from birth or were fasted.

4. From 1 to 3 days of age the RQ had a mean value of 0.79.

5. There was little difference in the RQ of pigs exposed to environmental temperatures of either 32 or 16°.

6. It is concluded that the baby pig is not exclusively dependent on carbohydrate for its energy metabolism.