The objective of the present study was to validate energy intake data, obtained by dietary history, in twelve elderly women aged 69–82 years. Energy and protein intakes were obtained using the dietary history method with a reference period of 30 d. Reported energy intake was compared with total energy expenditure (TEE) measured on two consecutive days in a respiration chamber. Reported protein intake was compared with mean N excretion from four 24 h urine collections. Mean reported energy intake was 7.2 (SD 1.5) MJ/d which was lower than TEE (P=0.059). Reported protein intake was 64 (SD 13) g/d and lower than estimated protein intake (P=0.053). The percentage underestimation was not related to body weight or percentage body fat. Subjects with a relatively high TEE or a relatively high estimated protein intake underestimated their energy intake to a greater extent. The discrepancy between reported energy intake and TEE was positively associated with the discrepancy between reported and estimated protein intakes. The results of this present study show an underestimation of energy intake of about 12% when using the dietary history method. Physical activity diaries completed in the chamber and during 4 d at home, as well as pedometer counts, indicated a higher level of physical activity in the free-living situation compared with the chamber situation. This suggests that the actual underestimation of energy intake may be even higher in this group of elderly women. These results have implications for the use of the dietary history method in, for example, epidemiological studies carried out in elderly subjects.

In order to study the localization and mechanisms of intestinal phosphate transport in sheep and goats, unidirectional inorganic phosphate (Pi) flux rates across isolated stripped epithelial tissues were measured in vitro by applying the Ussing-chamber technique. In the first experiment the tissues were obtained from animals which had been kept on an adequate dietary P supply. In the second experiment the animals had either been kept on an adequate Ca and P supply or were Ca- and/or P-depleted. Significant net Pi absorption was measured in all segments of the small intestine and in the proximal colon of sheep and in the duodenum and jejunum of goats. Since the experiments were carried out in the absence of any electrochemical gradient, this clearly indicates the presence of active mechanisms for Pi transport in the intestinal tract of small ruminants. In sheep jejunum, reduction of mucosal Na concentration to 1·8 mM or serosal application of ouabain (0·1 mM) resulted in significant decreases of net F; absorption of the same order of magnitude, indicating that about 65% of active Pi transport in sheep jejunum is mediated by a Na-dependent active transport mechanism. The mechanism for the remaining Na+-independent active Pi transport has not yet been identified. Dietary P depletion caused hypophosphataemia and induced a significant stimulation of net Pi absorption in goat duodenum and jejunum. This increase was independent of dietary Ca supply and was not associated with increased plasma calcitriol concentrations. This suggests substantial differences in hormonal regulation of Pi transport in small ruminants in comparison with single-stomached species.

The effects of fasting on the thermogenic, lipolytic and cardiovascular responses to adrenaline were examined in nine normal, young, non-obese subjects. Each subject attended for study after 12, 36 and 72 h fasting. After basal measurements adrenaline was infused at 25 ng/min per kg ideal body weight for 90 min. Fasting increased the thermogenic effect of the adrenaline (mean 14·6 (SE 1·7), 16·6 (SE 1·8), 22·6 (SE 1·6) J/:min per kg fat-free mass after 12, 36 and 72 h fasting respectively; P < 0·001, ANOVA). Basal plasma palmitate turnover increased with duration of fasting (1·48 (SE 0·22), 1·95 (SE 0·34) and 2·26 (SE 0·33) μmol/min per kg body weight: P < 0·001, ANOVA), but the response to adrenaline was unaffected by fasting. The percentage values for basal plasma palmitate turnover oxidized were 44 (SE 2; 12 h), 46 (SE 5; 36 h) and 42 (SE 4)% (72 h). In response to adrenaline this percentage fell, suggesting that adrenaline infusion may favour intra-tissue lipid oxidation.

Postprandial kinetics of porto-arterial concentration differences of glucose (G), galactose (Gal), L-lactic acid (LA) and amino-N (AN) were studied in the piglet after the ingestion of 107 colony-forming units (cfu) Sporolactobacillus P44 (SP), or 106 cfu Bacillus cereus IP5832 (AC), or 106 cfu of a combination of Lactobacillus acidophilus, L. fermentum and L. brevis (AB)/g feed. Sixteen fistulated piglets (portal vein and brachiocephalic trunk; mean body weight 22 (SD 2) kg) were used. The diet was based on skimmed milk (320 g/kg), barley (300 g/kg), wheat bran (110 g/kg), maize (100 g/kg) and lactose (70 g/kg). The postprandial blood kinetics, four measurements per animal at 1-week intervals, were studied for 6 h after the ingestion of test meals of 400 g basal diet (BD) or this diet supplemented with the bacteria (SP, AC and AB respectively). Areas of porto-arterial concentration differences (APACD) of G, Gal and LA were not influenced by the bacteria supplements. APACD of AN was significantly higher after the ingestion of the SP diet than that estimated for BD.

The ‘single-dose end-product’ approach for the measurement of protein turnover is the only method suited for application to free-living individuals and for field studies. However, the method has never been widely accepted because the results obtained appear to vary from one situation to another. There is the need for a formal comparison of the different approaches that have been used and the assumptions on which they are based in order to be able to understand the extent to which the variation in the results obtained is real or might be attributed to methodological differences. The present study used the ‘prime/intermittent-dose end-product’ approach over 18 h as a reference with which to compare the ‘single-dose end-product’ approach, with urine being collected for periods of 9 to 48 h. N flux was derived in a total of thirteen normal men using oral [15N]glycine and measurement of I5N enrichment in urinary NH3 or urea, with isotope being given either as prime/intermittent doses or a single dose in separate studies. The pattern of results was similar to those reported in the literature. In all studies the rates of N flux derived from urea were higher than those derived from NH3, under equivalent conditions, by about 25–30%. The single-dose approach, with urine collection over 9 h, gave results which were consistently higher than the prime/intermittent-dose approach. The extent of the difference was influenced by the duration of time over which the cumulative excretion of isotope in urine was determined, and with NH3 as the end-product the most consistent estimates of N flux could be obtained with a urine collection of at least 12 h and no greater than 24 h. With urea as the end-product, correction for the label retained in the body pool at 9 h gave similar results for N flux to those derived from the total excretion of label in urea over 24 h. The derivation of values for protein synthesis and protein degradation from measures of flux requires care to ensure that the time periods over which N intake and excretion are measured accord with those for which the measurement of flux apply. It is concluded that measurements of protein turnover similar to those obtained with the prime/intermittent-dose approach can be obtained with the single-dose approach in the fed state during the daytime, either from the excretion of label in urinary NH3 over a period of 12 h or with the excretion of label in urinary urea over a period of 24 h. The suitability of the method for use in the fasted state or at night time remains to be determined.

A population sample of 375 men and women cigarette smokers were recruited to take part in a prospective study of smoking cessation to test the hypothesis that stopping smoking is associated with an increased consumption of the essential fatty acid linoleic acid, which explains the concomitant reduction in risk of coronary heart disease. Diet was assessed using a 10 d weighed record in 301 smokers at baseline, 153 at 4-month follow-up, of whom twenty-six had quit smoking, and 122 at 1-year follow-up, of whom twenty had quit. Compared with continuing smokers, those who had quit at the 4-month follow-up (mean 10 and 13 weeks for men and women respectively) had statistically significant increases in body weight (5%), energy intake (13%), total dietary fat (24 %), all specific types of dietary fat (26% polyunsaturated fat, 26% linoleic acid, 30% eicosapentaenoic acid, 23% monounsaturated fat and 22% saturated fat) and vitamin E intake (19%). The foods which appeared to contribute to increases in energy and fat intakes at the 4-month follow-up were vegetable oils and polyunsaturated margarines, processed meats and meat pies. By follow-up at 1 year (mean time since quitting 31 and 41 weeks for men and women respectively) there were no detectable differences in energy and total fat intakes. However, intakes of eicosapentaenoic acid and pteroylglutamate (folate) were statistically significantly higher in the quitters compared with the continuing smokers (37% for eicosapentaenoic acid and 16% for folate). We conclude that the short-term increase in dietary intake of linoleic acid, which is not sustained by 1 year, cannot explain the reduction in risk of coronary disease following smoking cessation.

There is considerable evidence for the beneficial effects of dietary arginine, a conditionally essential amino acid that enhances anabolism and T-cell function. However, the safety and efficacy of higher doses of arginine supplementation following infection have not been investigated completely. These issues were explored therefore, in a murine model of malnutrition and infection. Severe protein malnutrition was induced by feeding mice for 6 weeks on an isoenergetic diet containing only 10 g protein/kg. Mice were then allowed to consume diets with normal amounts of protein (200 g/kg) with 50 g/kg provided as amino acid mixtures of glycine and arginine in which the arginine content ranged from 0 to 50 g/kg. During the repletion period a significant weight gain was noted in the groups fed on diets with either 10 or 20 g arginine/kg, but not in the group fed on the diet with 50 g arginine/kg, compared with the diet with 0 g arginine/kg. Mortality rates after infection with Salmonella typhimurium were not decreased by the addition of 10 or 20 g arginine/kg to the diet, and were in fact worsened by supplementation with 50 g arginine/kg. The results of the present study showed that not only are the beneficial effects of arginine supplementation after infection lost when high doses are administered, but also that these high doses become toxic. Mice fed on higher doses showed significant impairment of weight gain and an increase in mortality rates.

A diet low in fat and rich in fibre has been recommended to optimize general health and in particular cardiovascular health. Health attitudes to fat and fibre were studied in relation to food and nutrient intake and sociocultural and lifestyle factors amongst the general population of Northern Ireland. The study population comprised 592 adults aged 16–64 years; health attitudes to fat and fibre were assessed by questionnaire (based on a social psychological model, which adjusted for taste and convenience factors). Dietary intake was estimated using the weighed inventory technique. Fat-phobic and fibre-philic attitudes were more prevalent in women than men. Fat-phobic attitudes in women were inversely related to intake of fat through a reduced intake of chips, butter and sausages. In contrast, men's fat-phobic attitudes were not strongly correlated with fat intake; consumption of chips and sausages was negatively associated with fat-phobic attitudes, but cake/biscuit, buns/pastries and milk consumption was positively associated with fat-phobic attitudes. Fibre-philic attitudes were positively associated with dietary fibre intake; intakes of potatoes, vegetables, wholemeal bread and breakfast cereal were positively associated with fibre-philic attitudes. There were clear sociocultural and lifestyle differences in relation to dietary attitude. These findings have implications for campaigns designed to effect population dietary change.

An experiment was carried out with kid goats of the Granadina breed to identify the dietary factors affecting voluntary feed intake of the kid goat and those that additively could determine its body composition. The animals used were from birth to 61 d of age, fed ad lib. on different milk replacers containing 200, 240 and 280 g crude protein/kg DM and 200, 240 and 280 g fat/kg DM, thus giving nine dietary treatments. The utilization of the milk replacers and the animals' body composition were determined by balance and slaughter trials. There were significant positive effects of protein concentration of the milk replacers on component digestibilities, energy metabolizability, feed intake, empty-body weights, empty-body composition and protein and fat retention. The concentration of fat in the milk replacers also had a significant positive effect on the digestible and metabolizable energy concentration of the diets and on fat retention. The relationships existing between feed intake and diet composition (concentration of digestible protein, metabolizable energy and digestible protein:metabolizable energy ratio) as well as between empty-body composition or protein and fat retention and diet composition, were examined. From these it was deduced that feed intake was significantly influenced by the digestible protein concentration of the diets. The higher the digestible protein concentration the higher the feed intake up to a maximum digestible protein concentration value. As the digestible protein concentration of the diets was the dietary factor which significantly influenced feed intake, this also significantly influenced the body composition and the protein and fat retention. The protein concentration of the feed at which metabolizable energy intake in these animals would be greatest was estimated to be 347 g/kg DM.

An experiment was designed to test the prediction that two genetically-very-different kinds of pigs would retain the same amounts of protein in their bodies when given the same allowances of the same feed for the same period of time, when these allowances were limiting for both. An allowance of 33·957 kg of a feed with 12·76 MJ metabolizable energy (ME) and 189 g crude protein (N × 6·25)/kg feed was given to Large White × Landrace (LW ×) and Chinese Meishan (CM) female pigs over three different periods of time: (1) ad lib. (AL) with the time taken by individual pigs to consume the allowance being a variable, (2) over a period of 7 weeks (H) and (3) over a period of 9 weeks (L). In addition, in a fourth treatment, pigs of both breeds received the same allowance but supplemented with starch also over a period of 7 weeks (HS). The performance of the pigs on treatment AL was affected by pig breed, with CM pigs gaining protein at a slower, and lipid at a faster, rate than LW × pigs. On treatments L, H and HS the average amounts of protein retained were 2·693 and 2·655 kg for the LW × (n 15) and CM (n 15) pigs respectively (SED 0·106 kg). There was a statistical indication that the LW × pigs may have been more efficient on L, and less efficient on HS, than the CM pigs but we have been unable to propose any biological reason for such an effect, if it was in fact a real one. Thus, the efficiency with which ideal protein was utilized was close to being constant, and apparently at its maximum, for the two breeds. However, although CM pigs had the same protein gain, and the same live weights, on the same feed allowances as the LW × pigs, they gained significantly more lipid. This was attributed in part to their digesting their feed better and in part to their having a lower energy requirement for maintenance through a lower level of physical activity. Given that these two very different kinds of pigs use limiting protein with the same efficiency, it is suggested that it is safe to make the assumption in models of pig growth that the material efficiency of using limiting protein is constant across genotypes of pig.

The aim was to compare the effect on atherogenesis of dietary monounsaturated and saturated fatty acids in cholesterol-clamped rabbits. To obtain an average plasma cholesterol concentration of 20 mmol/l in each rabbit during the 13-week cholesterol-feeding period, dietary cholesterol was adjusted weekly. The amount of fat fed daily was 10 g per rabbit in Expts A (n 23), C (n 36), and D (n 58) and 5 g per rabbit in Expt B (n 24). The source of monounsaturated fatty acids was olive oil in all four experiments. The source of saturated fatty acids was butter in Expt A, lard in Expt B, coconut oil in Expt C, and butter or lard in Expt D. Generally, olive oil-fed groups received more cholesterol and tended to have more cholesterol in VLDL and less in LDL compared with groups receiving saturated fat. Analysis of variance of the combined results of all four experiments showed that, in comparison with saturated fat, olive oil lowered aortic cholesterol by 13 (−9–30, 95% confidence interval) % in the aortic arch, and by 10 (−10–26) % in the thoracic aorta, which was not significant. In the comparison with olive oil, no differences in effects on aortic cholesterol content were detected between butter, lard and coconut oil. These findings do not support the view that replacement of dietary saturated fat with olive oil has a major impact on the development of atherosclerosis in addition to that accounted for by changes in plasma cholesterol levels.

Trans fatty acids produced during hardening of oils have been associated with higher cholesterol levels and increased risk of heart disease. The potential risk from trans fatty acids may be greater in populations with relatively low intakes of essential fatty acids such as the Scots, who also have a high prevalence of heart disease. Means and ranges of trans fatty acid intakes are reported here for a Scottish population. A semi-quantitative food-frequency questionnaire was used to survey the diet of 10359 Scottish men and women aged 40–59 years in 1984–6 as part of the baseline Scottish Heart Health Study. Trans fatty acid levels were calculated for each food item on the questionnaire and the total subdivided into that which is derived naturally (primarily by bacterial fermentation in ruminants) and that which is produced during industrial hydrogenation (hardening) of vegetable and fish oils. Means and ranges of intakes of each trans fatty acid variable were calculated by sex, age, smoking and social class groups. Mean total trans fatty acid intakes for men were 7.1 (SD 3·1) g/d, 2·7 (SD 2·9)% energy and for women were 6.4 (SD 2·9) g/d, 3·3 (SD 3·0)% energy. Industrially hydrogenated trans fatty acids made up nearly 58% of the total intake for men and 61% for women, with about 60% coming from cakes, biscuits and sweets, and 20% coming from the cheaper hard margarines. The main sources of the naturally derived trans fatty acids were red meat (27%), milk (20%), butter (18–19%) and cheese (13–16%). Differences between age, smoking and social class groups were apparent. However, apart from the social class differences of up to 1 g/d, these were so small that they are unlikely to be of any biological significance unless compounded by other factors such as marginal essential fatty acid adequacy. The possibility of trans fatty acid intakes up to 48 g/d and 12% total energy (compared with the Department of Health (1991) recommendations of 5 g/d or 2% energy) highlights the need for careful monitoring of the health risks at these high levels of intake.

The effects of ammoniation of wheat straw with or without supplementation of protein sources of either high (casein) or relatively low (potato protein) rumen degradability on intake and digestion were studied with four sheep in a 4 × 4 Latin square design. Rations offered were: (1) untreated wheat straw (UWS), (2) ammoniated wheat straw (AWS), (3) AWS supplemented with 3·2 g casein/kg live weight (W)0·75 per d (AWSC) and (4) AWS supplemented with 3·9 g potato protein/kg W0·75per d (AWSP). Straw was offered ad lib. and all rations were supplemented with sugarbeet pulp and a mineral mixture. NH3 treatment increased intake and digestion. Supplementation of AWS with potato protein increased total digestible organic matter intake (DOMI) compared with AWS whereas supplementation with casein did not affect total DOMI. Protein supplementation of AWS significantly reduced rumen digestion of cellulose, and when the supplementation was with casein it reduced rumen digestion of neutral-detergent fibre and hemicellulose also. This lower rumen digestion was compensated by a higher proportion of digestion occurring in the hindgut for hemicellulose (P<0·05 for AWSC, P>0·05 for AWSP), but not for cellulose. Across all rations, rumen fluid volume increased with increasing cell-wall intake. The efficiencies of microbial protein synthesis were (average of three different methods of estimation) 23·3, 26·2, 34·8 and 31·7gN/kg apparently-rumen-degraded organic matter for UWS, AWS, AWSC and AWSP respectively. The difference between UWS and AWS was not significant, but values for AWSC and AWSP were significantly higher than that for AWS. The rumen digestion of feed aimno acid-N (AA-N) was significantly higher for AWSC than for the other rations. The apparent small-intestinal digestion of AA-N and N was significantly higher for AWSP than for the other rations. The true small-intestinal digestion values were 0·86, 0·84 and 0·68 for AA-N, N and non-protein-N respectively. Heal endogenous losses of AA-N were approximately 6 mg/g duodenal non-protein dry-matter flow. Linear relationships were observed between DOMI and N balance and truly absorbed AA-N, indicating that DOMI could have been limited by small-intestinal amino acid availability. Regression of N balance v. truly absorbed AA-N resulted in an estimate of net efficiency of utilization of truly absorbed AA-N of 0·54.

Propionate is a short-chain fatty acid formed in the colon and supposedly involved in the cholesterol-lowering effect of soluble fibre. To explore the underlying mechanism(s) of this fibre action, we have used human hepatocytes in primary culture to study the effects of propionate on hepatic lipid synthesis. Initial experiments with mevalonate and mevinolin, a competitive inhibitor of hydroxymethylglutaryl (HMG)-CoA reductase (EC 1·1·1·88) were performed to evaluate basic regulatory mechanisms in these cells; results were compared with those obtained with rat hepatocytes. Incubation for 24 h with mevalonate caused a similar, concentration-dependent inhibition of [14C]acetate incorporation. into cholesterol in human and rat hepatocytes. Likewise, mevinolin (100 μmol/l) inhibited the formation of cholesterol from radiolabelled acetate by about 80% in cells from both species. Propionate inhibited cholesterol as well as triacylglycerol synthesis from [14C]acetate with a similar concentration-dependency in rat hepatocytes. Fifty percent inhibition was obtained at a propionate concentration of only 0·1 mmol/l· This propionate-induced inhibition was not affected by a 100-fold excess of unlabelled acetate. Human hepatocytes were much less susceptible in this respect: propionate concentrations of 10–20 mmol/l were required to obtain similar inhibitory effects in these cells, i.e. values greatly exceeding reported portal propionate concentrations in humans. The results suggest the existence of differences in the regulation of hepatic cholesterol (and triacylglycerol) synthesis between human and rat liver cells. These results do not support the hypothesis that the fibre-induced decrease in plasma cholesterol concentration in man is mediated by a direct effect of propionate on hepatic cholesterol synthesis.

The effect of the energy density (ED) of feeds offered as a choice on the diet selection of sheep, and the relationship between the rumen environment and the diet selected from feeds of different ED were investigated in two experiments. In the first experiment two feeds, L and H, and their mixture M (3:1 w/w) were formulated. All feeds had similar calculated metabolizable protein: metabolizable energy (ME) ratios, but differed in ED (7·4, 8·1 and 10·1 MJ ME$sol;kg fresh feed for L, M and H respectively). The feeds were offered ad lib. either singly or in paired choices (L/M, L/H and M/H; n6 per treatment) to growing sheep. Although the rate of live-weight (Lwt) gain on feed H was higher than on feeds L or M, and the daily rate of feed intake lower, the sheep on feed choices did not consume only feed H. Instead they selected a mixture of both feeds offered, such that the total amount of H consumed per kg fresh feed was similar on choices L/H and M/H. The rate of Lwt gain of sheep on choices L/H and M/H was not different from that achieved on feed H alone. In the second experiment the choice L/H was offered to fistulated sheep (10 months of age, mean Lwt 57·5 kg) in an 8×8 Latin square, with 7 d periods. Treatments were infusions into the rumen (total volume 1 litre) over 4 h on days 1–4 of each period of acid (HC1; Acid 1, 400; Acid 2, 300 and Acid 3, 200 mmol/l), alkali (NaOH; Alk 1, 316; Alk 2, 212 and Alk 3, 109 mmol/l) and control (NaCl; Con 1, 315 and Con 2, 209 mmol/l). Infusate osmolalities (mOs/kg) were 795 (Acid 1), 585 (Acid 2, Alk 1 and Con 1), 390 (Acid 3, Alk 2 and Con 2) and 200 (Alk 3). Infusion treatment significantly affected the diet selection of the sheep (P < 0·05) according to the osmolality of infusate, but not according to rumen pH. During infusions intake of feed H tended to decline with increasing treatment osmolality, whereas intake of L remained constant. The effects on diet selection and feed intake were of a short duration with no carry-over effects. These results show that sheep given a choice between two feeds of different ED select a substantial quantity of the low-ED feed; this diet selection is affected by short-term manipulations of their rumen environment, in a manner that is consistent with the maintenance of effective rumen conditions.

Chickens fed on semi-purified low (7%) or high (61%) protein-energy diets for 14 or 17 d were used for determinations of oxidative phosphorylation and specific amounts of mitochondrial protein in liver. The ADP: oxygen (ADP:O) values obtained when pyruvate + malate were used as substrates were significantly reduced in the high-protein-fed group after the 4th day compared with those for the group fed the low-protein diet, while the differences in ADP:O values between the two treatments when L-glutamate was used as substrate were found to be significant on the 14th day. At any feeding period no significant differences in ADP:O values were observed between the two groups when α-ketoglutarate, malate, or octanoate + malate were used as substrates, nor in specific amounts of mitochondrial protein in liver. The dependency of the pyruvate + malate-supported respiration rate on the temperature in the reaction medium was also determined. The results of an Arrhenius plot showed that transition temperatures, and the lower and upper energies of activation, were similar for the groups fed on low- and high-protein diets. Furthermore, no morphological changes in mitochondria were observed among chickens fed on diets with various protein levels for 14 d. From these results we concluded that the reduction of ADP: O value with pyruvate + malate or L-glutamate substrates in chickens fed on a high-protein diet was substrate-specific, and was not due to functional damage to the respiratory chain for electron flow from NAD-linked substrates to the ubiquinone pool, nor to modulation of properties of the inner mitochondrial membrane.

To investigate the effect of dried Bacillus subtilis culture on growth, body composition and hepatic lipogenic enzyme activity, female broiler chicks were fed on either no additive (control) or dried B. subtills-culture-supplemented commercial diets (215 g crude protein/kg, 12.85 MJ metabolizable energy/kg) at 10 or 20 g/kg diet for 28 d from 14 to 42 d of age. Body weight, and moisture, fat, protein and ash contents of the body were not influenced by the B. subtilis culture. Feed efficiency. N utilization, the ratio of abdominal fat or liver to body weight, acetyl-coenzyme A carboxylase (EC 6·4·1·2) activity, liver and serum cholesterol contents were significantly lower in treatment groups, while fatty acid synthetase activity and serum cholesterol concentration were not significantly different, compared with the control group. Liver triacylglycerol concentration was decreased in chicks given 20 g culture·kg diet, while serum and carcass triacylglycerol concentrations were significantly lower in treatment groups than in the control group. Serum phospholipid concentration was increased but carcass phospholipid concentration was decreased in chicks given 20 g B. subtilis/kg diet, while liver phospholipid concentration was not significantly influenced. The advantages of inclusion of B. subtilis to the broiler diet included improved feed efficiency, less abdominal fat, reduced triacylglycerol concentrations in the liver, serum and carcass and reduced cholesterol concentrations in the liver and carcass.

Three screening tests for protein quality, modified limiting amino acid score (MLAAS), net weight gain (NWG) and net protein ratio (NPR), were compared. Two experiments using young broiler chickens were conducted in a temperature-controlled room at 28·5 ± 0·5° with no adaptation to cages and diets, or at 31 ± 0·5° with 2 d adaptation to cages and diets. Nine isoenergetic diets containing nominally 100 g crude protein/kg supplied by legume meals and one isoenergetic N-free diet were randomly allocated to chicks in single cages in each side of a four-tier battery brooder. Each dietary treatment had eight replicates. The chickens had access ad lib. to diet and drinking water throughout a 14 d observation period. Body weight and feed were measured at the start on day 7 and at the end on day 21. The results indicated that keeping the chickens at 31 ± 0·5° and giving them a 2 d adaptation period decreased the variability of chickens' responses to each treatment. MLAAS, NWG and NPR methods could distinguish legume proteins of high, medium and low feed values. MLAAS correlated well with NWG (r 0·90; P < 0·001) and NPR (r 0·78; P < 0·01) in evaluating the protein quality of grain legumes used as sole sources of protein for meat chickens. However, MLAAS did not predict the exact order of NWG and NPR. Growth was limited because dietary methionine, the first limiting amino acid, provided only 27·6–55·2% of the recommended proportion in the protein. Although the results should be interpreted cautiously since a small sample size was used, it was concluded that the MLAAS calculation could be used as a reasonable estimate of the relative protein quality of most grain legumes, but that NWG and NPR were better methods as they detected limiting factors other than limiting amino acids in raw and processed legumes.

In the present study the actual role of propionic acid in the control of fatty acid and cholesterol synthesis was investigated in isolated liver cells from fed rats maintained in the presence of near-physiological concentrations of glucose, glutamine and acetate. Using 3H2O for lipid labelling, propionate appears as an effective inhibitor of fatty acid synthesis and to a lesser extent of cholesterol synthesis, even at the lowest concentration used (0·6 mmol/l). Butyrate is a potent activator of both synthetic pathways, and the activating effect was not counteracted by propionate. Using 1-[14C]acetate, it was observed that propionate at a moderate concentration, or 1 mmol oleate/l, are both very effective inhibitors of 14C incorporation into fatty acid and cholesterol. This incorporation was drastically inhibited when propionate and oleate were present together in the incubation medium. The net utilization of acetate by rat hepatocytes was impaired by propionate, in contrast to oleate. 1-[14C]butyrate was utilized at a high rate for fatty acid synthesis, but to a lesser extent for cholesterol synthesis; both processes were unaffected by propionate. Intracellular citrate concentration was not markedly depressed by propionate, whereas it was strongly elevated by butyrate. In conclusion, propionate may represent an effective inhibitor of lipid synthesis when acetate is a major source of acetyl-CoA, a situation which is encountered with diets rich in readily-fermentable fibres. The present findings also suggest that propionate may be effective at concentrations close to values measured in vivo in the portal vein.

In a 2×2 balanced factorial experiment the biochemical effects on pigs of two dietary factors were investigated. The first factor was α-tocopherol and Se supplementation and the second factor was supplementation with α-tocopherol-stripped linseed oil. In pigs fed on diets depleted of α-tocopherol and Se, increases in concentrations of markers of lipid peroxidation (4-hydroxynonenal and hexanal) were observed. However, skeletal myopathy was only observed in those pigs fed on diets depleted of α-tocopherol and Se and supplemented with oil. In those pigs, increased lipid peroxidation was observed in heart and supraspinatus muscle. The plasma concentration of thromboxane B2 was increased in pigs fed on diets depleted of α-tocopherol and Se, suggesting an increased tendency towards platelet aggregation. However, this change was reversed in pigs depleted of α-tocopherol and Se, but supplemented with oil. This may have been a consequence of loss of arachidonic acid, the substrate for thromboxane formation, as a result of lipid peroxidation.