1. The role of the starch component of cereals and legumes on the utilization of casein-protein was studied.

2. In comparison with maize starch the legume and potato starches caused a significant lowering of net protein utilization (npu). And this reduction in npu could be partially restored by cooking the diets before they were fed to the rats.

3. It is suggested that in npu studies involving rats the experimental diet should always be cooked so that the conclusions drawn may be applicable to human diets.

1. The concentrations of vitamin B12 and folate in the serum and folate in the erythrocytes were determined and full blood counts made on a series of caucasian vegans and omnivore controls.

2. The blood counts and films were normal in all the vegans and no subject had a haemoglobin concentration below the lower limit of normality.

3. Although within the normal range, male but not female vegans had lower values for erythrocyte counts and higher values for mean corpuscular volume and mean corpuscular haemoglobin than their controls regardless of whether they were taking vitamin B12 supplements or not.

4. The mean serum vitamin B12 concentration was lower in the vegans not taking vitamin B12 supplements and in those using foods supplemented with the vitamin than in the controls, but in no subject was it below 80 ng/l.

5. The serum folate concentrations were higher in the vegans than in their controls. The mean value for erythrocyte folate tended to be greater in the vegans not taking vitamin B12 supplements. No subject had an erythrocyte folate concentration of less than 100μg/l.

6. It is concluded that megaloblastic anaemia is very rare in caucasian vegans and that a diet consisting entirely of plant foods is generally adequate to promote normal blood formation providing it is composed of a mixture of unrefined cereals, pulses, nuts, fruit and vegetables and is supplemented with vitamin B12.

1. The effect on calcium and phosphorus metabolism of a high rate of Ca infused directly into the blood of Ca-deficient wethers, already receiving an adequate Ca intake, has been studied by a combination of balance and radioisotope techniques.

2. The rate of Ca retention, which was already high, increased only slightly during the infusion before it reached a maximum. The surplus Ca was compensated for by a decrease in the rate of absorption and an increase in the rate of urinary Ca excretion.

3. These findings support the theory that at maximum retention the rate of Ca absorption becomes regulated according to the rate at which Ca can be stored in bone.

4. Results suggest that the decreased absorption was due to a decrease in the rate of active absorption and that the low rate remaining was due to diffusion.

5. The rate of P retention was increased by the Ca infusion, possibly as a result of the increased Ca retention.

1. Eight protein concentrates were compared on a total lysine basis in lysine-deficient diets for pigs during the 20–45 kg growth phase. Each diet was also supplemented with free lysine to verify that lysine was the first limiting amino acid.

2. With fish meal, skim-milk powder, rapeseed meal and soya-bean meal growth rates and feed conversion efficiencies were similar and superior (P < 0.05) to those produced with cottonseed meal, two meat meals and sunflower meal.

3. The response to added free lysine confirmed that lysine was the first limiting amino acid in all diets except skim milk, where the growth response was not significant (P < 0.05).

4. The growth response of the pigs indicated that the availability of lysine in cottonseed meal, the two meat meals and sunflower meal was reduced by approximately 60% compared to that in the other protein concentrates.

5. Rat bio-assay estimates of the availability of lysine in the protein concentrates were in general agreement with those calculated from the response of pigs. There was little relationship between the Silcock estimates for lysine availability for the cottonseed, meat meals or sunflower meal relative to either the rat bio-assay estimates or the response of pigs.

1. The fatty acids of the triacylglycerols of subcutaneous adipose tissue of cattle, sheep, goats and red deer (Cervus elaphus) which consumed either herbage or a barley-rich diet were analysed for their content of branched-chain components.

2. Whereas the consumption of the barley-rich diet by sheep and goats was associated with the occurrence of relatively high proportions of branched-chain fatty acids, it was not in cattle and red deer.

1. Seven isonitrogenous diets were prepared containing soya-bean meal and dried grass either unsupplemented, or supplemented with wheat starch or paper or equal mixtures of both.

2. The diets were allocated according to a balanced incomplete block design to seven Clun Forest wether sheep, each fitted with a re-entrant duodenal cannula.

3. After each sheep had received a diet for 6 d, daily samples of digesta were collected automatically for the next 3 d.

4. The amounts of dry matter, gross energy and major nitrogenous components consumed in the diet, passing into the duodenum and excreted in the urine and faeces were determined.

5. A novel method was applied to estimate the proportion of the total amino acids passing into the duodenum which was of microbial origin.

6. The amounts of microbial total amino acids synthesized were compared with the amounts of energy disappearing in the rumen for each of the seven diets tested. For the starch- and paper-containing diets an average of 14.7 g microbial total amino acid passed into the duodenum per MJ energy disappearing in the rumen, whilst for the diets containing either paper or starch alone the mean value, 6.1 g/MJ, was significantly lower (P < 0.05).

7. The results of the experiment suggested that the energy released from a mixture of starch and paper was utilized more efficiently for microbial protein synthesis than when the energy was provided by supplements of either paper or starch alone.

1. Quantitative selenium metabolism has been studied in normal young New Zealand women by measuring total Se intake and urinary and faecal Se output, and by using values for absorption, excretion and turnover of 75Se determined after administration of [75Se]selenomethionine or [75Se]selenite.

2. In a period of 14 d when a normal ad lib. diet was being consumed, mean dietary Se for four women was 24.2 μg/d, mean urinary Se was 13.1 μg/d and mean faecal Se was 10.8 μg/d; mean Se balance during this time was +0.3 μg/d.

3. Intestinal absorption of food Se was 0.76−0.83 of intake (mean 0.79).

4. Whole-body Se was calculated in three different ways; (a) using the specific activity of urinary Se and retained whole-body 75Se; (b) using plasma Se and the occupancy of 75Se in whole-body and plasma; (c) using absorbed food Se and the occupancy of absorbed 75Se in whole-body.

5. Whole-body Se calculated from measurements obtained following the administration of [75Se]seleno-methionine was 4.7−10.0 mg (mean 6.9) using method (a), 4.1−7.2 mg (mean 5.2) using method (b) and 4.3−8.9 mg (mean 6.2) using method (c).

6. Whole-body Se calculated from results obtained after giving [75Se]selenite was 2.7−3.4 mg (mean 2.9) using method (a), 2.3−5.0 mg (mean 3.5) using method (b) and 2.1−3.0 mg (mean 2.6) using method (c).

7. The results of this study indicate that the minimum dietary requirement of Se for the maintenance of normal human health is probably not more than 20 μg/d.

1. Food intake studies were carried out on three groups of captive primates (anthropoid apes (Pongidae), lemurs (Lemuridae) and marmosets (Callitrichidae).

2. Determination and analysis of the nutrient intakes were carried out by calculations based on food tables. The results from all groups were compared.

3. Marmosets were found to have higher intakes of energy and many other nutrients than the apes and lemurs.

4. The results suggest that there is a tendency towards over use of dietary supplements and foods of higher nutrient density for captive primates.

1. Groups of chicks were given a low-residue diet with or without supplements of dietary fibre in the form of wheat bran, wheat straw or bagasse. Growth and food conversion efficiency (g weight gained/g food eaten; FCE) during the first 4 weeks of life were measured.

2. In every one of seven experiments supplementation of the diet with 100 g wheat bran/kg resulted in improved growth, and in three experiments FCE was also increased.

3. Supplementation with coarsely-milled wheat straw to provide an amount of unavailable carbohydrate equivalent to that in the bran diet resulted in poorer growth; finely-milled wheat straw had little effect on growth.

4. The growth-promoting effect of bran was destroyed by sterilization with heat or gamma-radiation.

5. In some experiments weights, lengths and volumes of small intestines were measured. Differences in intestinal dimensions between birds given the diet with and without fibre were not consistent, nor were they correlated with growth rate or FCE.

6. Histometric observations on small intestines from a few birds indicated that those given coarse wheat straw had longer villi and thicker muscularis layers, and the caecal tonsils had a greater area of lymphoid tissue and more follicles.

1. Fistulated sheep given a concentrate diet were used to study the behaviour of solute ([51Cr]EDTA) and particle ([103Ru]phenanthroline) markers in the stomach under conditions of continuous feeding.

2. An injection of a mixed dose of [51Cr]EDTA and [103Ru]phenanthroline was given into the rumen and the time course of marker concentrations in the rumen and the abomasum was recorded. The curves were analysed on the assumption that the stomach of the sheep could be represented as two mixing compartments (reticulo-rumen and abomasum) and a time delay (omasum). This model provided a very good description of the data.

3. [103Ru]phenanthroline associated with small particles was retained in the rumen much longer than [51Cr]EDTA. Although exchange of [103Ru]phenanthroline occurred between large and small particle fractions, the results suggested that small particles may have been retained somewhat longer in the rumen than solutes. However, it was clear from the results that the mean retention times for particulate matter in the rumen could not be simply obtained using adsorbable markers.

4. Cyclical fluctuations in the concentration of [51Cr]EDTA in the rumen indicated that there were daily variations in net water flux in the rumen.

5. The presence of protozoa was associated with much shorter retention times of both solutes and particles in the rumen. Protozoa were also associated with reduced rumen volumes.

1. The concentration of 2-aminoethylphosphonic acid (AEP) in 96 h cultures of Tetrahymena pyriformis W was studied in order to apply it as an indicator in the assay of the relative nutritive value (RNV; protozoa population with test protein: protozoa population with whole-egg powder) of protein. Foodstuffs and food mixtures of different protein contents and qualities were used as test samples.

2. RNV values based on AEP determination (RNVAEP) were compared with corresponding values calculated from protozoa counts (RNVpc), as well as with biological value (bv) and net protein utilization (npu) of the same proteins assayed on rats.

3. Both for foodstuffs and food mixtures highly significant correlations were found between RNVAEP and RNVpc, RNVAEP and both bv and npu, and RNVpc, and both bv and npu.

4. AEP content in the protozoal suspension was preferred to cell count as a measure of growth response, since it took into account large differences in cell dimensions that were observed between cultures grown with different test proteins.

1. Twelve gastric-cannulated litter-mate pigs were used to study secretion and proteolytic activity in the stomach of suckling and early-weaned pigs in relation to age and food intake.

2. Results demonstrate that from the first observation at day 8, piglets were able to secrete acid. pH and acid concentration did not change during the first 4 weeks of life.

3. Proteolytic activity was low during the first 2–3 weeks of life and rapidly increased thereafter.

4. Two phenomena differentiated suckling pigs from pigs given dry cow's milk: (1) a low buffering capacity the gastric contents, beginning 1 h after feeding the dry cow's-milk formula, results in a low total acid concentration in the weaned pigs and (2) the increase in proteolytic activity in relation to the age is much more pronounced in the artificially-reared pigs.

5. These two phenomena are discussed and related to the formation of a hard casein clot in the stomach of the cow's-milk-fed pigs, which has a long retention time and stimulates gastrin release.

1. The voluntary ethanol consumption, ethanol elimination rate and blood acetaldehyde level after intraperitoneal injection of ethanol were studied in rats receiving diets with highly imbalanced proportions of dietary protein, carbohydrate and fat.

2. The rats, which received the low-protein diet containing 0.05 of the total energy as protein, 0.80 as carbohydrate and 0.15 as fat, drank only approximately half as much ethanol as did the control group, which received 0.30 of its total food energy from protein, 0.55 from carbohydrate and 0.15 from fat. Ethanol elimination rate in the low-protein group was decreased and the blood acetaldehyde level after ethanol injection was markedly increased.

3. On the high-fat diet, which contained 0.30 of the total energy from protein, 0.05 from carbohydrate and 0.65 from fat, the rats drank significantly more ethanol than did the rats on the control diet; their ethanol elimination rate was decreased but their blood acetaldehyde level was not affected.

4. In conclusion, the strong decrease in voluntary ethanol drinking by the low-protein group may have been caused by the increased acetaldehyde accumulation in the blood, but a particularly low blood acetaldehyde level was not one of the factors inducing excessive ethanol drinking in the high-fat group.

1. A method of estimating whole-body zinc, and Zn balances using a two-compartment model in combination with whole-body counting of 65Zn, is described. The method is applied to patients with rheumatoid and osteoarthritis.

2. The results suggested that there was not a wide variation in whole-body Zn and Zn turnover in individuals with these two diseases and no clearcut difference between patients with one or the other.

1. The lipolysis of cow's milk fat by salivary lipase (EC 3.1.1.3) in the preruminant calf has been studied in vitro by a simulated abomasal digestion, and also in vivo by examining the abomasal effluent collected over 12 h after giving whole milk to a calf.

2. In the in vitro experiment the liquid drained from the clot contained a higher proportion of short-chain fatty acids than the abomasal effluent in the in vivo experiment. This was considered to indicate the absorption of short-chain free fatty acids from within the abomasum.

3. Preferential release of short-chain fatty acids both in vitro and in vivo was observed.

4. The outflow of butyric acid from the abomasum of the calf was initially rapid, but had levelled off at approximately 6 h, whereas the outflow of a typical long-chain fatty acid (palmitic) was fairly constant over the 12 h.

Butyric acid predominated in the free fatty acids of abomasal effluent 0.5 h after feeding (668 mmol/mol total free fatty acids) but had become a minor component by 12 h (15 mmol/mol total free fatty acids).

5. The mean amounts of free and esterified fatty acids (mmol/mol fatty acid ingested) present in the abomasal effluent from the 12 h collection period were: triglyceride 465, diglyceride 215, monoglyceride 68, free fatty acid 252. These values showed that only one-third of esterified fatty acids ingested are lipolysed to absorbable products by salivary lipase.

1. Lysosomal stability was slightly increased in regenerating livers from rats receiving a zinc-deficient (< 0.5 mg/kg) diet for 10 d before surgery.

2. The activity of superoxide dismutase (EC 1.15.1.1) was significantly reduced in the same tissues.

3. The results do not support the view that increased lysosomal fragility represents a major biochemical consequence of nutritional Zn deficiency in animals.

1. Using male rats, the availability of fluoride from five by products of the aluminium smelting industry was tested. This was done by considering the balance between fluoride administered in controlled diets and the total fluoride content of waste products eliminated over an experimental period of 1 week.

2. Results indicated that yields of available fluoride expressed as percentage weight of original material were cryolite (Na3ALF8), 45.9%; sodium fluoride (NaF), 41.7%; aluminium fluoride (ALF3.H2O), 9.1%; mist eliminator grid solids (with CaF2), 9.4%; reclaimed alumina with adsorbed F, 0.27%.

3. Of the various tissues analysed for fluoride content, only the kidney and femur showed any significant correlation with the amounts of fluoride absorbed or retained.

1. The rate of transfer of plasma urea-nitrogen to rumen ammonia was measured by infusion of 15NH4Cl and [15N]urea into sheep given brome grass (Bromus inermis) or lucerne (Medicago sativa) pellets. Urea was infused into the rumen or abomasum of two sheep given brome grass in order to increase the concentration of rumen ammonia.

2. From 6.2 to 9.8 g/d of plasma urea-N were transferred to the rumen of sheep given brome grass pellets and a measurement of 1.3 g nitrogen/d was obtained for a sheep given lucerne pellets. When urea was infused into the rumen of sheep given brome grass pellets the transfer was only 2.8–3.7 g N/d.

3. There was a significant negative correlation between the rate of transfer of plasma urea-N to the rumen and the concentration of rumen ammonia.

1. Rats were fed on either a diet deficient in essential fatty acid (EFA) or one supplemented with dihomo-γ-linolenic acid (20:3,n-6) at levels that represented 0.25, 0.5, 1.0 and 2.0% of the dietary energy.

2. Supplementation of the diet of EFA-deficient animals with 20:3,n-6 reversed most of the fatty acid changes induced in the liver phospholipid fraction.

3. The EFA potency of 20:3,n-6 was found to be similar to that of γ-linolenic acid (18:3,n-6) which has been shown to be higher than that of linoleic acid (18:2,n-6).