1. The effects of dietary supplementation on milk output and maternal body composition were investigated in the lactating rat. The supplement was a cooked homogeneous mixture of eggs and maize oil, and had the same protein-energy: total energy value as the control diet.

2. During 2–12 d post partum rats were fed ad lib., either on the control diet alone or on the control diet plus the supplement. Measurements were made of milk output using an isotope-dilution technique, milk composition, and dam and litter body-composition changes.

3. Compared with the dams receiving only the control diet, dams provided with the supplement consumed 19.7% more energy and protein and produced 31.2% more milk and mobilized less body fat.

4. By 12 d of age, pups in litters of dams receiving the supplement were significantly heavier than those in litters of dams receiving the control diet only, and they contained more protein and more fat.

5. It is concluded that dietary supplementation of lactating rats can enhance lactational performance.

1. In rat studies, circulating concentrations of N-acetylneuraminic acid (NANA) have been shown to be an indicator of NANA concentrations in the brain and functional brain activity, in relation to nutritional state and stimulation. Abnormal behaviour can be improved with exogenous NANA. In the present study, the plasma NANA concentration has been measured in children with severe malnutrition and compared with that in controls.

2. NANA was measured colorimetrically in the plasma of twenty-three severely malnourished children (mean age 11.43 (SD 6.05) months) before and after recovery, and in thirty-four controls (mean age 14.28 (SD 7.32) months). In thirteen of the malnourished children, NANA was measured after infections had been treated with a course of antibiotics.

3. Mean plasma NANA concentration was significantly higher in protein-energy malnutrition (PEM)(2.89 (SD 0,58)μmol/ml; n 23) compared with controls (2.13(SD 0.37)μmol/ml; n 34, P < 0.001). The levels remained high in PEM after infections had been treated (2.87(SD 0.43) μmol/ml, n 13) but returned to control levels at recovery from PEM (2.14(SD 0.24)μmol/ml).

4. In contrast to the findings in rats, in malnourished children plasma NANA concentrations were not reduced and did not relate directly to nutritional state or, by inference, brain function. These findings do not provide any support for the use of exogenous NANA supplements to improve brain function in humans.

1. The water-holding capacities (WHC) of four sources of fibre were measured using dialysis membranes and osmotic-suction pressures of 45, 89 and 178 mosmol/l (1, 2 and 4 atm). At all pressures, pectin had the highest WHC, followed by cabbage (Brussicu oleruceu) and lucerne (Medicago sativu) and then cellulose. A suction pressure of 89 mosmol/l (2 atm) was used in the subsequent fermentation study since it had the lowest standard error of the mean and most closely approximated physiological conditions.

2. The four fibres were anaerobically fermented in vitro with human faecal inoculum for 24 h. The WHC of the fermentation residues were measured. The potential water-holding capacity (PWHC), a function of the extent of fermentability and the WHC of the fermentation residues, was highest for lucerne, followed by cellulose, then cabbage and, finally, pectin. Only the PWHC values ranked the four fibres in the same order as in vivo values.

3. It was concluded that the ethanol-insoluble residues containing unfermented fibre organic matter and microbial organic matter, both of which hold water, should be used to calculate PWHC and to predict the effect of fibre on rate of passage and faecal mass in humans.

1. The effect of lysine- and threonine-supplemented wheat gluten on cholesterol metabolism was studied using male weanling rats. Animals were fed on cholesterol-free diets containing 100 or 200 g gluten/kg with or without amino acid supplementation, and compared with animals given 50, 100 and 200 g casein/kg diets, for 3 weeks.

2. A hypocholesterolaemic effect observed with the wheat gluten-fed rats, compared with the animals given 100 and 200 g casein/kg diets, was accompanied by increased turnover of cholesterol as expressed by enhanced cholesterol biosynthesis and increased faecal excretion of cholesterol and bile acids. This effect was not abolished by lysine and threonine supplementation.

3. Low levels of blood cholesterol were also observed in the rats fed on the 50 g casein/kg diet. However, a different mechanism, related to impairment of cholesterol transport from the liver, was most likely responsible for the hypocholesterolaemia found in these protein-malnourished animals.

4. The effect on cholesterol metabolism produced by dietary wheat gluten was independent of the low quality of the protein and of its specific deficiency in lysine and threonine.

1. The effects of meal consumption on plasma leucine and alanine kinetics were studied using a simultaneous, primed, continuous infusion of L-[I-13C]leucine and L-[3,3,3-2H3]alanine in four healthy, young, adult male subjects. The study included an evaluation of the effect of sampling site on plasma amino acid kinetics, with blood being drawn simultaneously from an antecubital and dorsal heated hand vein.

2. In comparison with the postabsorptive state, the ingestion of small hourly meals resulted in a 35% increase in plasma leucine flux and a 77% increase in leucine oxidation. Calculated entry of leucine into the plasma compartment from endogenous sources decreased by 65%. Plasma alanine flux more than doubled, indicating a significant enhancement in de now alanine synthesis. 13C enrichment of leucine in venous and arterialized plasma did not differ significantly, but alanine flux calculated from isotopic measurement in venous plasma was substantially greater than that based on analysis of arterialized blood plasma.

1. Unfractionated gliadin and its α-, β-, γ- and ω-gliadin subfractions were used as rabbit immunogens. The antisera were characterized by (1) Ouchterlony double diffusion, (2) binding of 125I-labelled gliadin subfractions, (3) inhibition by several gliadin subfractions of binding between γgliadin antiserum and 125I-labeIled γgliadin.

2. Double diffusion showed identical cross-reactivity between the antisera and the gliadin subfractions with the exception of ω-gliadin. Precipitin lines of partial identity with gliadin were observed against rye secalins and barley hordeins but not oat avenins or maize zeins.

3. Binding was observed between unfractionated 125I-labelledα-, β-, γ- and ω-gliadins and all the antisera. There was binding of 125I-labelled ω-gliadin to the ω-gliadin antiserum but poor binding of 125I-labelled ω-gliadin to unfractionated α-, β- and γ-gliadin antisera. Competitive inhibition of binding between 125I-labelled γ-gliadin and γ-gliadin antiserum diluted 1:250 (v/v) demonstrated similar competition between α-, β- and γ-gliadins and this antiserum but poor competition between ω-gliadin, wheat glutenins, albumins and globulins, rye secalins, barley hordeins and oat avenins.

4. These findings suggest that there is a good correlation between the antigenic structure of gliadin proteins and their toxicity to patients with coeliac disease.

1. The effect of leavening of bread containing bran on the phytic acid content and on zinc absorption in man was studied.

2. Twenty breads with leavening times varying from 0 to 120 h were prepared. The breads contained 250 g wheat bran/kg flour. The phytic acid content was determined after baking.

3. The phytic acid content of bread containing bran was reduced to about 40% after 2 h of leavening and to 15 % after 2 d. No further decrease was observed.

4. Zn absorption from single meals was determined using a radioisotope technique. Forty-two students volunteered for these studies. They were served a breakfast of milk, butter, bread and 10, 16 or 30 g bran served either raw or baked into the bread with fermentation times of 15 min, 45 min, 3 h or 16 h. One meal contained no bran, but phytate and Zn were added in amounts equivalent to the content of 10 g bran.

5. The amount and percentage of Zn absorbed increased at each bran level as fermentation was prolonged. The percentage of Zn absorbed was reduced by increased bran content in the meal.

6. It is concluded that the fermentation of bread containing bran reduces the phytic acid content and increases Zn absorption from such bread. This may be of importance to people subjected to diets with a high cereal content, especially in combination with a low animal-protein intake.

1. The production of propionate in the caecum of the horse has been measured in two Shetland-type ponies fitted with caecal and colonic cannulas and fed on hay or on hay and wheat bran. A continuous intracaecal infusion of 14C-labelled sodium propionate was used and samples were obtained from a cannula at the origin of the right ventral colon. A simultaneous intravenous infusion of [2-3H]glucose was used to measure total glucose entry.

2. On a hay diet which provided 177 kJ/kg body-weight per d, mean caecal propionate production was 19.6 (range 17.2–21.2) mg/h per kg body-weight and on a hay and wheat bran diet, which provided 187 KJ/kg body-weight per d, mean caecal propionate production was 34.0 (range 28.9–38.3) mg/h per kg body-weight.

3. Mean total glucose production (mg/h per kg body-weight) in one pony was 104 (range 100–110) and in the other 135 (range 123–153). Rates were not influenced by diet.

4. About 7% of total glucose production was derived from propionate produced in the caecum and this percentage was unaffected by diet or by individual animals.

1. The reactions between protein-bound amino acids and oxidizing lipid were investigated in a whey protein-methyl linolenate (C18.3)–water model system. The extent of fat oxidation was followed by measuring oxygen uptake, hydroperoxide formation and hydrocarbon (ethane and pentane) formation.

2. Significant losses occurred with lysine (up to 71 %), tryptophan (up to 31 %) and histidine (up to 57%). Methionine was extensively oxidized to its sulphoxide but less than 2% was further oxidized to the sulphone. No other amino acids were affected.

3. Increasing storage temperature (20°, 37°, 55°) resulted in an enhancement of fat oxidation reactions and amino acid degradation.

4. Increasing water activity (0.28, 0.65, 0.90) increased losses of lysine and tryptophan but had no influence on the oxidation of methionine, the level of remaining hydroperoxides or 02 uptake. Hydrocarbons were decreased.

5. Limitation of 02 uptake to 1 mol/mol lipid instead of excess 02 (02 uptake about 2.5 mol/mol lipid in 4 weeks) significantly reduced the degradation of lysine and tryptophan but had less influence on the oxidation of methionine. The level of remaining hydroperoxides was increased but hydrocarbons were unaffected.

1. The consequences of reactions between protein and oxidizing lipids on the nutritional quality of food proteins have been investigated using a whey protein–methyl linolenate-water model system.

2. In rat assays, significant reductions were observed in protein efficiency ratio, net protein ratio, net protein utilization, biological value and true nitrogen digestibility, especially when the reaction had taken place at high moisture content, high temperature and in the presence of excess oxygen.

3. The losses of bioavailable lysine and tryptophan as measured by rat assays followed a similar pattern. The chemical value of each amino acid multiplied by the true N digestibility closely resembled the rat assay value. In general, the reaction products of lysine and tryptophan formed during lipid oxidation were biologically unavailable.

4. The bioavailabilities of methionine and of ‘methionine plus cyst(e)ine’ were determined in separate assays. Cyst(e)ine was calculated as ‘methionine plus cyst(e)ine’ minus methionine. In whey protein which had reacted with oxidizing methyl linolenate, the bioavailable methionine content was not significantly reduced even though 82% of the methionine residues were present as methionine sulphoxide. In hydrogen peroxide-treated casein in which all methionine residues were oxidized to the sulphoxide, methionine sulphoxide was found to be 96% as utilizable as a methionine source to the rat. Free methionine sulphoxide was 87% utilizable.

5. Cyst(e)ine appeared to be as sensitive as lysine to reactions with lipid oxidation products. In whey protein which had reacted with oxidizing methyl linolenate, the bioavailabilities of cyst(e)ine, lysine, tryptophan and methionine were reduced by 28, 24, 11 and 8% respectively and true N digestibility by 9%. These results are discussed in relation to food products.

1. Male Wistar rats (100 g) were given a commercial pellet feed or a semi-synthetic diet ad lib. Although the pellet-fed group grew slightly faster than the other group during the early part of the feeding period, there was no significant difference between the final weights of the groups.

2. The fractional rates of protein synthesis in jejunum, proximal ileum and liver were measured by a technique based on the determination of L-[4−3H]phenylalanine incorporation over a short time period. Protein synthesis was higher in both jejunum and ileum of the pellet-fed rats compared with those eating the semi-synthetic diet, but there was no difference between the rates of protein synthesis measured in the livers of the groups.

3. The rate of mucosal cell division was significantly faster in the ileal mucosa of the pellet-fed group compared with the other group, and there were significant differences in some aspects of mucosal morphology.

4. The maintenance of higher rates of cell turnover and protein synthesis in animals given commercial pellet feed is unexplained, but it may be related to the presence of non-absorbable polysaccharides or other complex plant materials in the pellet feed.

1. Young female rats were made riboflavin-deficient by feeding a purified diet containing casein (210 g/kg). This basal diet provided 0.40 mg riboflavin/kg diet, to which was added additional riboflavin at 0, 0.12 or 0.25 mg/kg diet. Control animals received the same diet with 15 mg added riboflavin/kg. The diets were given for 4 weeks before mating, then throughout pregnancy and for 15 d of lactation.

2. With no added riboflavin in the diet, reproduction was severely impaired and fetal resorption was usually observed. With 0.12 mg added riboflavin/kg diet, however, reproduction was usually successful, and the growth of dams and pups was only marginally depressed in comparison with pair-fed controls optimally supplied with riboflavin.

3. The activation coefficient (stimulated: basal activity) of erythrocyte glutathione reductase (NAD(P)H) (EC 1.6.4.2)was high, and the concentration of riboflavin in the liver was correspondingly low in the dams receiving diets containing 0.12 or 0.25 mg added riboflavin/kg and in their sucking pups at 15 d post partum. Riboflavin levels in the milk from both groups of dams were about eightfold lower than in controls. There was little evidence that the sucking pups could maintain their riboflavin level at the expense of that in the maternal tissues.

1. An increase in 1iver:body-weight and in hepatic triacylglycerol content, together with changes in the fatty acid profiles of hepatic phospholipids, were observed as a result of moderate riboflavin deficiency in sucking rat pups. Oxygen consumption by hepatic mitochondria, with palmitoyl L-carnitine as substrate, was not significantly impaired.

2. Mitochondria from interscapular brown adipose tissue, however, showed a marked impairment of O2 Consumption, with palmitoyl L-carnitine as substrate, in the riboflavin-deficient pups. This impairment was also apparent after uncoupling with carbonyl cyanide p-trifluoromethoxyphenylhydrazone, but was not consistently observed after the addition of GDP to suppress uncoupled oxidation. It was much less evident, and did not reach statistical significance, for the mitochondria of brown adipose tissue of the corresponding deficient dams.

3. Binding of 3H-labe11ed GDP by brown adipose tissue mitochondria was unaffected by riboflavin deficiency in the pups, suggesting that the effect on O2 consumption is more likely to be due to impaired integrity of the mitochondrial respiratory chain, than to impairment of the specific capacity for uncoupling of respiration which is characteristic of brown adipose tissue mitochondria. Total cytochrome c oxidase (EC 1.9.3.1) activity of the brown adipose tissue of riboflavin-deficient pups was not significantly reduced.

4. A small but significant impairment was observed in the stimulation ofwhole-body O2consumption by injected noradrenaline in the riboflavin-deficient pups, suggesting that the impairment of brown adipose tissue mitochondrial function may be accompanied by impaired physiological capacity in vivo.

1. The results are reported of four feeding experiments in which lactating cows were given fixed rations of hay and high-cereal concentrates at different meal frequencies. In Expt 1 the total ration was given in two and twenty-four meals daily and in Expts 2–4, the concentrates were given in two and five or six meals and the hay was given twice daily. The diets contained 600–900 g concentrate /kg.

2. In all the experiments, more frequent feeding of these low-roughage diets reduced milk fat depression and increased milk fat yield. In each experiment the increase was greater with the diet containing the lower proportion of hay. There was no significant effect on milk yield, the protein or lactose contents of the milk or live-weight gain. Digestibility of dry matter, organic matter and energy was increased in one of the experiments but not in two others in which it was measured.

3. More frequent feeding was calculated to increase the net energy secreted in milk and there was a tendency for it to increase the net energy in live-weight gain with diets containing 600 or 700 g concentrate/kg but to decrease it with diets containing 800 or 900 g concentrate/kg. These results are discussed in relation to theories of energy partition in lactating cows.

4. It is concluded that at fixed feed intakes, the main response to increased meal frequency is likely to be a reduction in milk fat depression and that this will be confined to diets containing not more than about 200 g modified acid-detergent fibre/kg dry matter.

1. Studies of iron utilization and haem synthesis were carried out with hepatic mitochondria obtained from copper-deficient and pair-fed control rats.

2. Ferric chloride can be used as Fe substrate for mitochondrial haem synthesis in the presence of succinate. Utilization is further enhanced by the addition of FMN.

3. Ferritin does not support haem synthesis in the presence of succinate alone, but does support haem synthesis when FMN is added.

4. Mitochondria1 haem synthesis is impaired in Cu deficiency when either FeCl3 or homologous ferritin is used as Fe substrate.

5. The results of the present study suggest that impaired haem synthesis in Cu deficiency occurs at a step following the chemical reduction of Fe substrate.

1.Forty pigs between 23 and 51 d of age were given ad lib. diets containing wheat and one of five protein concentrates: meat meal A, meat meal B, soya-bean meal, milk and lupins (Lupinus augustifolius). Twenty of these pigs were given indigestible markers from 51 to 56 d of age and were killed at 56 d of age.

2.The diets containing meat meals A and B, soya-bean meal and milk contained 2.3 g total methionine/kg and the diet containing lupins contained 2.1 g/kg.

3.A further forty pigs of the same age were given the same diets supplemented with 1 g synthetic methionine/kg.

4.The weight gains and feed conversion ratios of the pigs given the diets containing 2.1–2.3 g methionine and 3.1–3.3 g methionine/kg were not significantly different.

5. The weight gains of the pigs given lupins (2.1 g methionine/kg) were less than those of the pigs given the diets containing 2.3 g methionine/kg.

6. The apparent digestibility of dry matter (DM) and nitrogen was less for the diets containing the meat meals (0.75 and 0.78 respectively) than for those containing the other protein concentrates (0.80 and 0.84).

7.The retention times in the large intestine of the diets containing soya-bean meal and lupins were 965 and 1083 min which were greater than those of the diets containing the other protein concentrates, mean 732 min.

8. The major site of N digestion and absorption for the diet containing milk was the area of the small intestine 25–50% of total length from the pylorus, while for the other protein concentrates the major site was 50–75% of its total length from the pylorus.

9. The digestion and absorption of N in the large intestine was less (3.4%) for the diet containing milk than for those containing the other protein concentrates (7.5–11.3%).

10. The apparent digestibility of the methionine to the ileum for the five diets ranged from 0.74 to 0.86 while the calculated retention of the apparently-absorbed methionine was 1.00. It was suggested that methionine digestibility could be used as an indicator of availability.

11. The calculated retention of apparently absorbed N in the carcass was 0.71 for the pigs given the diet containing milk and 0.51–0.58 for the pigs given the other diets.

1. Duplicate groups of rainbow trout (Salrno gairdnert) (mean weight 11 g) were given for 40 weeks one of four partially purified diets that were either adequate or low in selenium or vitamin E or both.

2. Weight gains of trout given the dually deficient diet were significantly lower than those of trout given a complete diet or a diet deficient in Se. No mortalities occurred and the only pathology seen was exudative diathesis in the dually deficient trout.

3. There was significant interaction between the two nutrients both with respect to packed cell volume and to malondialdehyde formation in the in vitro NADPH-dependent microsomal lipid peroxidation system.

4. Tissue levels of vitamin E and Se decreased to very low levels in trout given diets lacking these nutrients. For plasma there was a significant effect of dietary vitamin E on Se concentration.

5. Glutathione (GSH) peroxidase (EC 1. 1 1. 1.9) activity in liver and plasma was significantly lower in trout receiving low dietary Se but was independent of vitamin E intake. The ratios of hepatic GSH peroxidase activity measured with cumene hydroperoxide and hydrogen peroxide were the same for all treatments. This confirms the absence of a Se-independent GSH peroxidase activity in trout liver.

6. Se deficiency did not lead to any compensatory increase in hepatic GSH transferase (EC 2. 5. 1. 18) activity; values were essentially the same in all treatments.

7. Plasma pyruvate kinase (EC 2. 7. 1.40) activity increased significantly in the trout deficient in both nutrients. This was thought to be due to leakage of the enzyme from the muscle and may be indicative of incipient (subclinical) muscle damage.

1. Sixteen sheep, each fitted with cannulas in the rumen and proximal duodenum, were given four diets in the chopped or ground and pelleted form, at fixed intakes at intervals of 2 h. The sheep were closely shorn and exposed to temperatures of 22–25° or 1–4° for four periods of 45 d. Flow of duodenal digesta by reference to the markers CoEDTA and 103Ru-phenanthroline, chewing behaviour and particle size of rumen and duodenal digesta were measured.

2. Apparent digestibility of organic matter (OM) in the gastrointestinal tract was depressed (P < 0.05) by grinding and pelleting the diet, and by exposure of sheep to cold ambient temperatures. This was attributable to depression (P < 0.01) by 0.1 of OM digestion in the reticulo-rumen. No effects on intestinal digestion of OM were observed.

3. Cold ambient temperatures did not affect the content, but increased the rate of digestion for pelleted diets but not for chopped diets, of potentially-degradable cell-wall constituents of ground dietary material incubated in nylon-bags in the rumen.

4. Retention times of markers of the particulate and liquid phases of rumen digesta were not significantly (P < 0.05) affected by ambient temperature, despite significant (P < 0.001) increases in the rate of contraction of the reticulum. Retention time of 103Ru-phenanthroline in the intestines was not affected by cold exposure.

5. Cold exposure was associated with depression (P < 0.05) of volatile fatty acids concentration in the rumen and elevated (P < 0.05) pH. Molar proportions of acetic and isovaleric acid were reduced (P < 0.01), accompanied by increased (P < 0.001) proportions of propionic acid during cold exposure.

6. Cold exposure and pelleting of the diets were both associated with reduction in digesta particle size in the rumen. Duodenal particle size was not affected by cold exposure. Pelleting of the diet markedly reduced (P < 0.001) duration of chewing and number of chews/d during eating and rumination. Cold exposure of sheep resulted in a faster (P < 0.01) rate of eating of the diets.

7. When allowed to express their voluntary feed consumption during a 10 d period, intakes of chopped diets were increased by 0.13 (P < 0.01) by cold exposure, in contrast to lack of significant change in sheep given pellets.

8. The results did not support the hypothesis that the effect of cold exposure on digestion was dependent on the physical form of the diet given at fixed intake, but did indicate that increased voluntary feed consumption was a result of increased clearance of digesta from the rumen throdgh decreased rumen particle size and increased reticulum motility.

1. Some metabolic indicators of thyroid hormone activity have been investigated in rats fed on either protein-deficient or energy-restricted diets.

2. Rats were divided into three groups. Control animals were maintained on a diet of protein energy: total energy (P:E) value of 0.20, while the low-protein group (LP) were allowed ad lib. access to food of P:E 0.03. Energy-restricted (ER) rats were given limited amounts of a control diet (P:E 0.20) such that their rate of growth matched that of LP animals.

3. Animals fed on the LP diet had elevated plasma concentrations of both total and free triiodothyronine (T3)concentrations whereas those on the ER regimen showed values below those of controls.

4. The activities of mitochondria1 α-glycerol-3-phosphate dehydrogenase (EC 1. 1.99.5) and of the αglycerol-3-phosphate shuttle system were elevated in the liver of LP rats, but malate-aspartate shuttle operation was reduced. All three activities were reduced in ER animals.

5. Cytochrome c oxidase (EC 1.9.3.1) activity of brown adipose tissue indicated a high rate of thermogenic activity in this tissue in LP rats, but ER animals showed some evidence of below normal function.

6. The results indicate that both the raised plasma T3 of LP rats and the reduced levels observed in ER animals are physiologically significant.