1. Skinfold thickness and body density were measured on 105 young adult men and women and 86 adolescent boys and girls.

2. The correlation coefficients between the skinfold thicknesses, either single or multiple, and density were in the region of −0.80.

3. Regression equations were calculated to predict body fat from skinfolds with an error of about ±3.5%.

4. A table gives the percentage of the body-weight as fat from the measurement of skin-fold thickness.

1. The efficiency of absorption of and liver storage from a single oral dose of 10000 i.u. vitamin A palmitate decreased in chicks reared on a diet containing 10% protein as compared to the efficiency in chicks reared on a diet in which the protein level was adequate. When the chicks were given orally an equivalent dose of vitamin A alcohol, the absorption was equally efficient at both dietary protein levels.

2. The vitamin A alcohol content of this intestine, plasma and liver of chicks dosed with vitamin A palmitate was decreased by protein restriction. The physiological change responsible for this decrease seems to be the lowering of the hydrolysing activity for vitamin A palmitate in pancreas and in the duodenal mucosa.

3. The importance of the enzymic step in the absorption of an oral dose of vitamin A palmitate is shown by the finding that protein malnutrition reduced only slightly the final liver stores when vitamin A in its different forms (palmitate, acetate or alcohol) was injected directly into the blood stream.

4. The uptake of injected vitamin A from the blood was much delayed when the vitamin was injected as palmitate, i.e. the ester of a long-chain fatty acid, instead of the acetate ester of the free alcohol.

5. When vitamin A was injected, the liver content did not rise continuously with time, but showed a temporary decrease after a certain period. The phenomenon was apparently due to changes in the rate of the two inverse processes of uptake of the vitamin by the liver and liberation from it.

1. The whole of the lower half of the small intestine, with the exception of the last few cm of the ileum, has been removed from sixteen suckling pigs, 3–4 kg in weight.

2. The operation is technically easy, but the exposure and handling of the intestines may produce crippling adhesions.

3. The postoperative management presents no serious nutritional difficulties.

4. If the operation is successful the animals become functionally normal, if slightly small, adults.

1. Vitamin E-deficient rats were found to be more susceptible than vitamin E-supplemented controls to the toxic effects of hyperbaric oxygen (60 lb/in.2 for 20 min). This agrees with the findings of other workers.

2. Hyperbaric O2 treatment did not increase the metabolic destruction of a small amount (46.65 μg) of [14C-5-Me]D-α-tocopherol given to adult vitamin E-deficient rats 24 h previously. The O2 treatment also did not affect the soluble sulphydryl compounds and ascorbic acid of rat liver, nor the percentag haemolysis in vivo of rat blood.

3. Hyperbaric O2 treatment did not increase the true lipid peroxide content of rat brain, compared to control rats treated with hyperbaric air, which has no toxic effects. Increases in ‘lipid peroxidation’ reported by previous workers are considered to have been due to the use of inadequate controls (untreated rats) and of in vitro techniques that are open to criticism.

4. The toxic effects of hyperbaric O2 in the vitamin E-deficient rat cannot be attributed to peroxidation in vivo.

5. Vitamin E was not found to protect rats against the effects of reduced O2 tension (anoxic anoxia). This finding contrasts with some reports by earlier workers. Reduced O2 tension had no effect on the metabolism of radioactive tocopherol, on blood haemolysis in vivo, or on the soluble sulphydryl compounds and ascorbic acid of liver.

1. The effects of iron overloading and unsaturation of dietary lipid on the metabolism of α-tocopherol in the rat were studies.

2. Young adult male vitamin E-deficient rats were given 1000 i.u. of vitamin A and 100 μg of [14C-5-Me]D-α-tocopherol and then given diets containing 5% methyl oleate or 5% cod-liver oil fatty-acid methyl esters. Rats from each group were given intramuscular injections of iron-dextran (50 mg Fe/kg rat) at 48 h intervals for 15 days, and compared with controls given dextran. After this time, liver, kidney and the remainder of the carcass were analysed for [14C]α-tocopherol, and liver and kidney were also analysed for vitamin A.

3. There was no evidence that Fe overloading caused any increase in the destruction of either tocopherol or vitamin A in vivo, whether or not the diet contained polyunsaturated fatty acids. Indeed, treatment with Fe significantly decreased the metabolism of the radioactive tocopherol dose in all three tissues studied.

4. These experiments show that the stress effect of Fe in the vitamin E-deficient animal is unrelated to an increase in oxidative reactions. They provide further evidence that ‘lipid peroxidation’ is not causally concerned in ‘anti-vitamin E’ stress conditions and that α-tocopherol does not function, in vivo, as an antioxidant.

1. The nutritive values of nine varieties of groundnut were determined by the nitrogen balance method in diets containing 10% protein. The results indicated that the varietal differences did not affect the biological values significantly.

2. Three varieties showing small but significant differences of approximately 5% in methionine content were further assayed for protein efficiency ration at the 10% level of protein for a period of 4 weeks. No significant differences in per were obtained, but the least significant difference that could have been detected under these conditions was approximately 8%.

1. Experiments were conducted with wether sheep in 1964 and 1965 fed pelleted or chopped mature Digitaria decubemes Stent (pangola grass) bay containing different crude protein contents. The voluntary intake of food, digestibility of dry matter and nitrogen, nitrogen retention and apparent time of retention of feed organic matter in the reticulo-rumen were measured. The different crude protein contents of the grass were obtained by applications of urea to the sward 14 and 28 days before cutting for hay in 1964 and 1965 respectively. This treatment increased the crude protein content of the dry matter from 4.9% to 8.7% in 1964 and from 3.7% to 7.2% in 1965. The size of the particles of the ground hay before pelleting is given.

2. The mean voluntary intake of chopped fertilized grass was 10% and 54% greater than that of the unfertilized; the voluntary intake of pellets made from fertilized grass was 35% and 75% greater than of those made from the unfertilized grass in 1964 and 1965 respectively.

3. The voluntary intake of pellets of unfertilized grass was 7% and 14% greater than that 30% greater than that of chopped fertilized grass in 1964 and 1965 respectively.

4. The digestibility of the pellets was less than that of the chopped grass.

5. The apparent digestibility of the feed nitrogen was increased by the fertilizer nitrogen, but grinding and pelleting had no consistent effect. Sheep eating chopped or pelleted fertilized hay were in positive nitrogen balance.

6. The apparent retention time of organic matter in the reticulo-rumen was longer when the sheep were eating chopped hay than when they were eating pellets. In 1964 the apparent retention time of organic matter in the reticulo-rumen was shorter for chopped and pelleted unfertilized grass than for chopped and pelleted fertilized grass, but in 1965 the order was reversed.

7. The relationship between voluntary intake, apparent retention time of organic matter in the rumen and the protein content of the food is discussed.

1. In two experiments with chicks given diets of different manganese content, the effects of vitamin D on the Mn contents of bone and liver and on the retention of 54Mn in bone, liver and the whole body were determined.

2. Vitamin D slightly increased the Mn content of dry fat-free bone but the proportion of Mn to ash remained unchanged and the Mn content of bone was influenced much more by the level of dietary Mn than by the presence of vitamin D.

3. Vitamin D, when given over a 3-week period, increased slightly the Mn content of the liver, but again the level of dietary Mn had a greater effect than the presence of vitamin D.

4. The retention of an oral dose of 54Mn was not uniformly influenced by vitamin D, but in birds given the hign-Mn diet retention was reduced by vitamin D, indicating a decrease in the turnover of Mn.

1. Analytical values are presented for body nitrogen, both on a fresh and dry carcass basis, body water and N to body water ratios for rats, of various ages, of the Sprague–Dawley Strain.

2. For 33- and 40-day-old animals, there were significant differences in body composition, including N:H2O ratio, between animals given a protein-free diet and those given protein at the 10% dietary level. For all age groups the N and water percentages were higher in the carcasses of animals given the non-protein diet.

3. For all age groups there were significant negative correlations between the percentage of N in the dry carcass and the net dietary protein value (NDpv) of the diet. For 33-, 37- and 40-day old animals there were significant negative correlations between the N content of the fresh carcass and the NDpv of the diet. For 33-day-old animals only, the correlation between N:H2O ratio and NDpv was also highly significant.

4. Body N values calculated from N:H2O ratio and from N:body-weight ratio were compared. At all ages, an equally good prediction was obtained from the N:body-weight ration as from the N:H2O ratio provided that the correct factors were used for animals given the non-protein and test diets.

1. A survey in Eastern Nigeria revealed an area of endemic goitre with a marked variation in incidence form village to village not accounted for by iodine deficiency alone.

2. As dried unfermented cassava was consumed in large quantities in the highly goitrous areas, experiments with rats were undertaken to assess the significance of this factor.

3. Groups of rats were fed (a) cassava, (b) equal parts cassava and standard diet, (c) cassava with added iodine and (d) standard diet, and each rat received and intraperitioneal injection of 20 μc iodine 24 h before being killed.

4. The iodine content and hardness of the water in the various areas were estimated and the chemical and bacteriological indices of pollution determined.

5. The following effects were observed: thyroid weight, iodine uptake and plasma-protein-bound iodine were all increased in the cassava-fed animals, the last markedly so. the thyroid's precursor and hormone iodine stores were severely depleted in these animals, which also showed an impaired transfer of iodine from monoiodotyrosine to diiodotyrosine and a high proportion the iodine present as iodothyronine. The giving of iodine with the cassava did not prevent these changes from taking place.

6. Many of the observed effects suggest that cassava was acting like the thionamide group of an antithyroid drug.

7. These findings are discussed.

1. Feeding rats with a 15% ethanol solution for several weeks caused structural and functional changes in their liver mitochondria, although their intake of solid food was about the same as that of the controls.

2. Attempts were made to counteract these effects of ethanol by increasing the intake of amino acids, vitamins, lipotropic compounds and electrolytes beyond that which is adequate when water is the drinking fluid.

3. An increased intake of nicotinic acid, together with aqueous ethanol, caused a further enlargement of the mitochondria above that obtained with ethanol solution alone. the diluted matrix observed with the ethanol and nicotinic acid treatment suggested that water imbibition by the mitochondria caused this further enlargement.

4. In rats receiving ethanol fortified with magnesium sulphate and lipotropic compounds (choline, methionine) there was a further increase in mitochondrial size, as compared with those receiving ethanol alone. The matrix was, however, of the same density as in the mitochondria from the rats receiving ethanol alone. the oxidation rate of pyruvate and succinate was unchanged, but α-glycerophosphate and β-hydroxybutyrate were oxidized at a higher rate than in mitochondria from rats drinking ethanol or water.

5. When the ethanol solution was supplemented with amino acids (casein hydrolysate), vitamins and electrolytes, the mitochondrial enlargement after 120 days of treatment was less than with ethanol alone and was completely absent after 300 days. the oxidation rate of pyruvate and succinate was, however, not fully restored to normal.

1. The excretions of magnesium, calcium, potassium and faecal dry matter (DM) by sheep grazing the same pasture have been determined at intervals throughout two grazing seasons. Two groups of four wethers, 2 and 7 years old, were used. Collections of faeces were total and of urine only partial; creatinine was used as an indicator of urine volume.

2.The overall mean outputs of DM in the faeces of the young and old sheep were 509 and 387 g/day respectively.

3. The values for the percentage digestibility of herbage DM ranges from 81.1 in spring to 63.2 in winter. The overall means for the estimated intake of DM by the young and old sheep were 1859 and 1405 g/day respectively and the difference was highly significant (P < 0.001).

4. The mean values for overall excretion of Mg by the young and old sheep were respectively 0.452 and 0.292 g/day in the urine and 2.70 and 2.21 g/day in the faeces. For all sheep there was a highly significant rectilinear relationship between the amount in urine and in faeces, but there were significant differences between the regression coefficients for the individual sheep.

5. The values for the excretion of Ca in urine and faeces were significantly higher for the young than for the old sheep; the respective means were 0.385 and 0.306 g/day for urinary Ca and 13.02 and 10.8 g/day for faecal Ca.

6.The mean values for the excretion of K by the young and old sheep were respectively 28.2 and 29.1 g/day in the urine and 7.1 and 3.9 g/day in the faeces, the latter differences being highly significant.

7.High values for the total excretion of Mg, Ca and K occurred in June and low values in winter.

8. Intakes of Mg, Ca and K by the sheep have been calculated from the information on intake of DM and chemical composition of the cut herbage and compared with total excretion in urine and faeces. Good agreement between the two sets of values was obtained for Mg, but not for either Ca or K. The possible causes of these findings have been discussed and it was concluded that the sheep selected herbage with concentrations of Ca and K different from those in the samples of cut herbage.

1. The compositions of the lipids in the atheromatous lesions of rabbits have been studied in an experiment in which two groups of rabbits (twelve/group) were given different atherogenic diets for a period of 38 weeks. One group of rabbits was given a diet in which 35% of the total calories was derived from butterfat and the other group was given a diet in which 48% of the total calories was derived from starch.

2. At the end of the feeding period the rabbits were killed and the atheromatous plaques were dissected out from the aortic intima of each rabbit. The lipid compositions of the aortic lesions were determined and the results compared with the compositions of the plasma lipids.

3. In the lipids of the aortic lesions in the rabbits given the high-butterfat diet, the proportions of cholesterol and cholesterol esters were higher and the proportion of triglycerides was lower than in the lipids of the aortic lesions in the rabbits given the high-starch diet. Irrespective of dietary treatment, free cholesterol constituted a higher proportion of the lesion lipids than it did of the plasma lipids.

4. In the rabbits on either dietary treatment, the lesion cholesterol esters contained higher concentrations of oleic acid and lower concentrations of linoleic acid than did the plasma cholesterol esters. In the lesion phospholipids there were higher concentrations of palmitic, palmitoleic, stearic and oleic acids and lower concentrations of linoleic and arachidonic acids than in the plasma phospholipids.

5. In both groups of rabbits the phospholipids of the aortic lesions contained higher proportions of cephalin and sphingomyelin and lower proportions of lecithin than did the plasma phospholipids.

6. The results of this investigation are discussed in relation to the possible origins of the lipids in the aortic lesions of the experimental rabbits.

1. The compositions of the fatty acids in ryegrass were determined in fresh samples, and in samples dried at room temperature for 26 h, at 50° and for 18 h or at 100° for 12 h. The drying of grass resulted in a small increase in palmitic acid and a decrease in linolenic acid in the total fatty acids.

2. Samples of grass dried at 50° and 100° were stored at three relative humidities (rh < 3%, 47% and 80%) for 13 months.

3. There were marked changes in the samples stored at 80% rh, with an onset of mould growth and a loss of dry matter. The samples stored at lower humidities had no mould.

4. There were two types of change in the fatty acids during storage. The deterioration brought about and mould was accompanied by a decrease in the concentration of linolenic acid and an increase in the concentrations of oleic and linoleic acids. The other type of change observed at the lower humidities resulted in a decrease in the content of linolenic and an increase in the content of palmitic, and did not affect the amounts of oleic and linoleic cells.

5. There was little difference between the changes that occurred in the composition of the total fatty acids of the grass dried at 50° and of that dried at 100°. The changes that were at all significant appeared to occur less rapidly, particularly in the early months of storage, in the grass dried at the higher temperature for the shorter time.

1. The relationship between the heart rate and the energy expenditure of four sheep, S6, S7, S8 and S1, was studies under conditions known to increase energy metabolism.

2. A close relationship between heart rate and energy expenditure was shown to exist in three of the four sheep tested when energy expenditure was increased by cold exposure and by increased levels of food intake.

3. The source and magnitude of the errors associated with this relationship were studied by analysis of the variation occurring in the O2 pulse (ml O2/heart beat) of the sheep in response to factors other than those directly related to changes in heart rate. In two sheep, S8 and S6, variations in O2 pulse were random. The errors associated with the estimation, from heart rate measurements, of the energy expenditure of these sheep were ±6.8% and ±8.1% respectively. In the other two sheep, S7 and S1, O2 pulse tended to vary significantly during the experiments, in a way that was not directly related to changes in heart rate. The errors of the relationship in these sheep were ±8.6% and ±13.8% respectively.

4. Indirect evidence was obtained to suggest that continuous measurements of heart rate continued to reflect with reasonable accuracy the energy expenditure of the three sheep, S6, S7 and S8 when they were standing and lying and when they were eating.

5. Direct measurements were made of the O2 consumption and heart rate of sheep S7 and S1 during the act of eating. The energy expenditure of sheep S7 estimated from its O2 consumption was close to that estimated from measurements of its heart rate. Large errors were noted between these two estimates in sheep S1.

6. It was concluded that sheep S8 and S6 would be suitable for long-term experiments designed to predict energy expenditure from heart rate measurements made in the field. Sheep S7 was considered to be of limited value for short-term experiments. Sheep S1 was considered to be unsuitable.

1. The effects of changes in zinc intake on weight gain, plasma Zn concentration and the development of clinical lesions of Zn deficiency have been studies in Zn depletion and repletion studies with calves and lambs.

2. A basal diet, the principal components of which are urea, dried egg white, starch, glucose, cellulose and arachis oil has been developed for trace element deficiency studies with ruminants.

3. Weight gain ceased abruptly in both calves and lambs when either the unsupplemented basal diet was given or when Zn supplements provided only 0.05 mg Zn/kg live weight per day. Mean plasma Zn concentrations in these animals fell from pre-experiment values of between 0.8 and 1.2 μg Zn/ml to below 0.4 μg Zn/ml after 1 week on these treatments.

4. Supplements providing 0.2 mg Zn/kg live weight per day were sufficient to maintain a good rate of growth but insufficient to prevent a fall in plasma Zn.

5. Growth arrest occurring within 2 weeks and a rapid fall in plasma Zn occurring within 1 week after Zn supplements were withheld from calves and lambs that had previously received 0.7 mg Zn/kg live weight per day for 6 and 14 weeks respectively indicated that these species have only a limited capacity to store Zn in a form that can be utilized during periods of inadequate Zn intake.

6. Tentative estimates are presented of the Zn requirements of calves maintained on this type of basal diet and the influence of ration composition of Zn availability is discussed.

7. The possible value and the limitations of plasma Zn determination as an aid to the field diagnosis of Zn deficiency are considered.

1. Nine important varieties of groundnut (Arachis hypogaea Linn.) were analysed for amino acid composition by an ion-exchange chromatographic procedure. Cystine, as cysteic acid, and methionine and tryptophan were determined by colorimetric methods.

2. Small, but statistically significant, differences in the contents of nitrogen, serine, glutamic acid, proline, alanine, leucine, phenylalanine, tyrosine, lysine, methionine and cystine were found in the varieties.

3. A positive correlation (P < 0.05) between methionine any cystine was observed.

4. There was, however, no indication that selection from the varieties studied would permit development of a variety of superior protein quality.

1. Body-weight changes and nitrogen balance were studied, together with the concentration of various nitrogenous muscle components, in adult cocks before and after a 6-day period on a N-free diet and again after a 16-day repletion period on diets supplying various amounts and types of dietary N.

2. In the first experiment a comparison was made during the repletion period between a fish-protein supplement and a supplement of glycine + glutamic acid added to an essential amino acid mixture.

3. During the depletion period the muscle concentration of RNA, DNA and of two transaminase enzymes decreased significantly; during the repletion period these components increased again significantly, and usually to levels greater than the pre-depletion concentration. There were no differences in these responses obtained during repletion with the two N supplements, although the cocks given the glycine–glutamic acid supplement differed from those receiving fish protein in being in Negative N balance and in losing body-weight during the repletion period.

4. In the second experiment one group of depleted cocks was given an essential amino acid mixture alone as the dietary N source and a second group this mixture supplemented by aspartic acid.

5. A decrease in RNA and in the transaminase enzymes during depletion was followed by a significant increase during repletion, but the increase was greater for the group receiving the aspartic acid than for that receiving only the essential amino acid mixture.

6. It was concluded that adding non-essential amino acids to a maintenance mixture of essential amino acids will permit greater repletion in mature cocks.

7. The fluctuations in concentration of RNA and of certain enzymes with dietary protein supply may well be controlling factor in the regulation of N losses and accretions during protein deficiency and sufficiency.

5. The relative constancy of muscle DNA in contrast to the fluctuations in other nitrogenous muscle constituents provides additional support for the concept of protein reserves.