The effect of long-term supplementation with CaCO3 on indices of Fe, Zn and Mg status was investigated in a randomized, double-blind intervention study of sixty lactating Gambian women. The supplement contained 1000 mg Ca and was consumed between meals 5 d/week, for 1 year starting 1.5 weeks postpartum. Compliance was 100%. Plasma ferritin concentration, plasma Zn concentration and urinary Mg output were measured before, during and after supplementation at 1.5, 13, 52 and 78 weeks postpartum. No significant differences in mineral status were observed at any time between women in the supplement and placebo group. Analysis of the longitudinal data series showed that plasma ferritin and Mg excretion were characteristic of the indivdiual (P < 0·001). Within individuals, ferritin concentration was higher at 1.5 weeks postpartum than later in lactation (P = 0.002). Plasma Zn concentration was lower at 1.5 weeks postpartum than at other tima (P < 0·001), an effect which disappeared after albumin correction. Low plasma concentrations of ferritin and Zn indicated that the Gambian women were at high risk of Fe and Zn deficiency. Measurements of α1-antichymotrypsin suggested that the results were not confounded by acute-phase responses. The results of the present study indicate that 1000 mg Ca as CaCO3 given between meals does not deleteriously affect plasma ferritin and Zn concentrations or urinary Mg excretion in women who are at risk of Fe and Zn deficiency

The effect of condensed tannins (CT) from heated and unheated cottonseed on the apparent ileal digestibility of amino acids for the growing rat and pig was determined. In Expt 1, twenty-four rats were allocated to four semi-purified diets which contained cottonseed kernel and hulls as the only protein source. Two of the diets contained unheated solvent-extracted cottonseed kernel and hulls, while the remaining two diets contained similar material but which had been heat-treated by autoclaving at 110° for 120 min. In Expt 2, twelve rats and twelve pigs were fed on four semi-purified diets containing commercial cottonseed meal (CSM) as the only protein source. Cr2O3, was added to all diets as an indigestible marker. For each pair of diets in both experiments, PEG was either included or excluded. The effect of CT was assessed by comparing control animals (-PEG; CT acting) with PEG supplemented animals (+ PEG; CT inactivated). Ileal contents from the terminal 150 and 450 mm of ileum were collected at slaughter, 7 h from the start of feeding, for the rats and pigs respectively. Apparent ileal amino acid digestibility for rats fed on the diet containing cottonseed kernel and hulls was significantly depressed by the heat treatment, particularly for lysine and threonine. On average, apparent ileal amino acid digestibility in the diets without PEG was decreased from 0·80 to 0·70 by heat treatment. Dietary cottonseed CT depressed apparent ileal protein digestibility in the pig and in the rat. The addition of PEG to the diets significantly increased the apparent ileal digestibility of N and some amino acids for the pigs and the rats. The mean increase in apparent ileal digestibility due to PEG addition for the fourteen amino acids was 2 percentage units in both species fed on the commercial CSM diets, and 2 or 4 percentage units in rats fed on the unheated or the heated cottonseed kernel and hull diets respectively. The effect of PEG was similar in the heated and unheated cottonseed kernel and hulls for most amino acids, but apparent ileal digestibilities of threonine, tyrosine and lysine were increased more by PEG in heated than in unheated CSM. Apparent ileal N digestibility was lower in the pig than in the rat. For several of the amino acids there were significant animal species differences in apparent ileal digestibility. Studies into the effects of cottonseed CT should be carried out in the target animal species. The commercial CSM had a low apparent ileal amino acid digestibility overall, particularly for the essential amino acids lysine and threonine. It was concluded that effects of heating did not eliminate the reversible reactivity of cottonseed CT on amino acid digestion in rats and pigs but rather appeared to increase it for threoniw, tyrosine and lysine in Expt 1, causing large reductions in apparent ileal digestibility of these amino acids.

Maximal voluntary contraction (MVC) using a handgrip dynamometer was assessed in seventy-two young adult males. The subjects were divided into two groups on the basis of a BMI of 18·5 kg/m2. The subjects with a BMI < 18·5 kg/m2 (n 38) were further divided into an underweight (UW;n 20) group and a chronically energy-deficient (CED; n 18) group. The CED subjects had significantly lower MVC (30·1, SD 5·9 kg) than either the well-nourished controls (BMI > 18·5 kg/m2: 39·8, SD 5·8 kg) or the underweight group (37·6, SD 4·9 kg). The differences between the CED and UW groups persisted even after the MVC were corrected for forearm muscle area and stature. The results suggest that MVC may be a useful functional indicator of nutritional status particularly in differentiating subjects with chronic undernutrition from individuals who are underweight and not undernourished but have similar BMI.

The absorption of Zn or Fe from breakfast meals containing oat porridge prepared from malted and soaked oats and a control porridge made from untreated oats was measured in human subjects. The effect on Zn and Fe absorption of reducing the phytate content of oat-porridge meals was examined in each subject by extrinsic labelling of porridge with 65Zn and of bread rolls with 55Fe and 59Fe, and measuring whole-body retention and the erythrocyte uptake of isotopes. Each experiment comprised nine to ten subjects. The absorption of Zn from malted-oat porridge with a phytate (inositol hexaphosphate) content of 107 μmol was 18·3%, and significantly higher (P < 0·05) than from the control porridge containing 432 μmol phytate (11·8%). Fe absorption from the meal containing malted-oat porridge with 107 μmol phytate (Expt 2) was also significantly improved (P < 0·05) compared with that from the meal containing control porridge with 437 μmol phytate. The average increase in Fe absorption was 47%, or from 4·4 to 6·0%. In the breakfast meal containing malted porridge with 198 μmol phytate (Expt 3) the increase in Fe absorption was not significantly improved. Even though the phytate content was reduced to a greater extent in Expt 3 than Expt 2, the average increase in Fe absorption in Expt 3 was only 25% more than that from the meal containing control porridge (with 599 μmol phytate), depending on the higher absolute amount of phytate. In conclusion, an improvement in Zn and Fe absorption from oat products can be achieved by practising malting and soaking in the processing of oats. This may be of importance in the prevention of mineral deficiency in vulnerable groups.

The dynamics of N metabolism in mature horses were investigated when they were fed on a low-N diet or the same diet supplemented with sufficient urea or soyabean meal to meet their theoretical N requirements. There were no differences in DM, organic matter or neutral-detergent-fibre digestibilities for the three diets. N digestibilities and digestible-N intakes were similar for the urea- and soyabean-supplemented diets and very low for the low-N diet. For all three diets plasma urea was degraded in the digestive tract to NH3 which was utilized by the bacterial population as a N source. NH3 was absorbed from the large intestine into the blood and converted to urea. NH3 was also incorporated into plasma proteins. The horses fed on the low-N diet degraded a greater proportion of endogenous urea in the digestive tract than did horses fed on the urea- or soyabean-supplemented diets. However, the horses fed on the urea diet had the highest degradation rate of urea. The quantity of urea degraded in the digestive tract of horses fed on the urea-supplemented and the low-N diets could not compensate for a lack of dietary crude protein in these diets. The horses were in a negative N balance when fed on the low-N and urea-supplemented diets and a positive N balance when fed on the soyabean-supplemented diet. Dietary urea supplementation did not benefit the horses.

A factorial experiment was conducted to study the effects of condensed tannins (CT) from the tropical legumes Desmodium intorturn and Calliandra calothyrsus on the digestion and utilization of protein and carbohydrate in sheep and goats. CT-free Centrusema pubescens was also fed for comparison with the CT legumes, and each legume was included (300 g/kg DM) in a basal diet of pangola grass (Digitmia decumbens). Pangola grass alone was used as a control diet. There were no significant (P>0.05) differences between sheep and goats for the efficiency of digestion of N (0.574, SE 0.013), organic matter (OM; 0.519, SE 0.010), neutral-detergent fibre (NDF; 0.524, SE 0.011) and acid-detergent fibre (ADF; 0.407, SE 0.016). Diets containing desmodium and calliandra were digested less well in the rumen (64 and 62% of total OM digested) when compared with the pangola and centrosema diets (74 and 73% of total OM digested in rumen). There was an apparent net gain of 30% in ADF across the digestive tract of sheep and goats given calliandra, and this gain was ascribed to the formation of ‘artifact’ fibre as a result of fibre-tannin interaction. Overall, inclusion of legume at 300 g/kg in the diet significantly increased (P>0.05) the concentration of acetic acid and decreased butyric acid concentration in the rumen fluid of sheep and goats. Significantly higher proportions of dietary N apparently reached the abomasum of animals given the diets containing desmodium (50%) and calliandra (56%) when compared with animals given the centrosema and pangola diets (35%). Sheep and goats given the CT diets also had higher excretions of faecal N. This increment of faecal N (14%) did not affect post-rumen N digestion (P>0.05) since animals given CT diets absorbed more N (19%) per kg total OM digested than those given the control diets. It was concluded that whilst the low levels of CT provided in desmodium (1.0%) and calliandra (2.3%) diets protected dietary protein from degradation in the rumen, there were no overall beneficial or detrimental effects of CT in these diets for sheep or goats. A method was developed to categorize CT into fractions representative of their forms (free, protein-bound, and fibre-bound) during the digestion process. A quantitative model of CT metabolism during passage through the digestive tract was developed from the measured exchanges of CT between free, protein-bound and fibre-bound pools in the rumen and lower digestive tract. CT interchange mainly occurred in the reticulo-rumen of both animal species. Desmodium and calliandra free CT showed net losses of 68 and 78% in the rumen respectively and 57 and 68% of the fibre-bound CT was lost in the same site for sheep and goats respectively. However, protein-bound CT increased across the rumen by 73 and 56% for both animal species. Post-rumen losses of the total CT abomasal flow were 86 and 83% (free CT) for sheep and goats respectively, 70 and 66% (protein-bound CT), whilst 28% loss of fibre-bound CT occurred in sheep and goats respectively.

In the present study we have developed the agar-fill method for the measurement of gastrointestinal-tract capacity (GTC) to replace the in vitro water-fill method. This would estimate GTC without using complex equipment and techniques, and can be applied to the measurement of GTC for small laboratory animals. We attempted to confirm the efficiency of the agar-fill method by investigating the relationship between dietary neutral-detergent fibre (NDF) content and GTC. The digestion trials were carried out using the Syrian hamster (Mesocricefus auretus). The trials were conducted using both sexes, two age-groups and three levels of dietary NDF with a cross-classified design. The size of each gastrointestinal organ was determined as tissue weight(TW)and GTC. The DM intake, digestible DM intake, DM digestibility, NDF digestibfity, aciddetergent fibre(ADF) digestibfity and digesta transit time were also measured. GTC increased with increasing NDF content of the diets. TW responded similarly to increasing NDF content, but the response was smaller than that of GTC. DM digestibility decreased with increasing NDF content of the diet. The digestible DM intake did not decrease with increasing NDF because DM intake increased with NDF content. Digesta transit time was not shorter of the high-NDF-diet group but DM intake increased with increasing NDF content. NDF digestibility did not differ significantly between low- and medium-NDF diets. ADF digestibility was low in the low-NDF-diet group.The digestion characteristics were highly correlated with TW and GTC, except for TW of small intestine. These correlations were higher with GTC than with TW. The results of the present study confirm previous findings suggesting that the agar-fill method is a useful means of estimating GTC for small laboratory animals.

The absorption of lysine synthesised by the gastrointestinal microflora was estimated by comparing the15N incorporated into body lysine in four germ-free (15N-GF) and four conventional (15N-CV) rats. They were fed for 10d on a protein-free diet containing fermentable carbohydrates and 15NHM4Cl; another four conventional rats (control), fed on the same diet but with unlabelled NH4Cl, were used to estimate the natural abundance of 15N. The eviscerated carcass of each rat was homogenized and a sample hydrolysed. Lysine was isolated by ion-exchange chromatography and its 15N enrichment was measured by isotope-ratio mass spectrometry. The 15N-CV rats significantly incorporated 15N into their body lysine. The 15N-GF rats had a statistically significant, although small, incorporation of 15body lysine, probably arising from a measurement artifact. It was concluded, therefore, that all [15N]lysine was of microbial origin. The total lysine content in the body and the 15N enrichment of lysine in the microbial fraction of the faeces of the 15N-CV rats were also determined. The amount of microbial lysine absorbed by the 15N-CV rats was estimated by dividing the total amount of [15N]lysine in the body by the enrichment of microbial lysine. It was estimated that the daily absorption of microbial lysine by the conventional rats was 21·3 (SE 2·04) mg/kg body weight0·75

Detailed anthropometric measurements were made on 169 healthy children aged between 4 and 40 months during a comprehensive study of the diet and nutritional status of Asian children (of Pakistani and Bangladeshi origin) living in Sheffield. These measurements were used to describe the growth profile of these apparently healthy children and to compare this with both international and UK reference data. The distribution of values for most anthropometric measurements was close to the UK reference data although both boys and girls tended to be slight of build, and girls tended to have relatively smaller head circumferences. Nevertheless, it was concluded that their growth and nutritional status over this age range can be evaluated using standard (UK) growth charts

The present study aimed to identify dietary patterns, from the frequency of consumption of food items and some semiquantitative data, in a random sample of 9003 British adults, and to examine the associations of the main dietary patterns with demographic factors, lifestyle habits, measures of self- reported health and mortality. Principal component analysis was used to identify four main dietary patterns, and analysis of variance employed to examine the characteristics associated with them. The four components explained, respectively, 10·2, 7·3, 5·1 and 4·9% of the total dietary variation. Component 1, frequent fruit, salad and vegetable consumption with infrequent consumption of high-fat foods, was associated with middle age, non-manual socio-economic groups, non- and ex-smokers, ‘sensible’ drinkers, small households, the south of the country, and self-assessed ‘excellent’ or ‘good’ health. Component 2, frequent consumption of high-starch foods, most vegetables and meat, was popular with young men, older men and women, large households, non-smokers, non-drinkers and those who viewed themselves as healthy. Component 3, frequent consumption of high-fat foods, was predominantly consumed by young people, smoking women, ‘high-risk’ drinkers, and men reporting many illness and/or malaise symptoms. Component 4, high positive loadings for sweets, biscuits and cakes, with negative weightings for vegetables, was most favoured by students, the elderly, those living alone, residents in Scotland, but not those in central England, and those who did not smoke. For women only the first component was associated with low all-cause mortality, and the third component with excess mortality

Energy intake profoundly influences many endocrine axes which in turn play a central role in development. The specific influence of a short period of mild hypothyroidism, similar to that induced by undernutrition, in regulating muscle development has been assessed in a large mammal during early postnatal life. Hypothyroidism was induced by providing methimazole and iopanoic acid in the feed of piglets between 4 and 14 d of age, and controls were pair-fed to the energy intake of their hypothyroid littermates. Thyroid status was evaluated, and myofibre differentiation and cation pump concentrations were then assessed in the following functionally distinct muscles: longissimus dorsi (l. dorsi), soleus and rhomboideus. Reductions in plasma concentrations of thyroxine (T4; 32%, P < O·Ol), triiodothyronine (T3;48%, P < 0·001), free T3, (58%, P < 0·001)and hepatic 5'-monodeiodinase (EC 1.11.1.8) activity (74%, P < 0·001) occurred with treatment. Small, although significant, increases in the proportion of type I slow-twitch oxidative fibres occurred with mild hypothyroidism, in l. dorsi (2%, P < 0·01) and soleus(7%, P < 0·01). Nuclear T3-receptor concentration in l. dorsi of hypothyroid animals compared with controls increased by 46% (P < 0·001), a response that may represent a homeostatic mechanism making muscle more sensitive to low levels of circulating thyroid hormones. Nevertheless, Na+, K+-ATPase (EC 3.6.1.37) concentration was reduced by 15–16% in all muscles (l.dorsi P< 0·05,soleusP < 0·001, rhomboideusP < 0·05), and Ca2+-ATPase (EC 3.6.1.38) concentration was significantly reduced in the two slow-twitch muscles: by 22% in rhomboideus (P < 0·001) and 23% in soleus (P < 0·05). It is concluded that during early postnatal development of large mammals a period of mild hypothyroidism, comparable with that found during undernutrition, induces changes in myofibre differentiation and a down-regulation of cation pumps in skeletal muscle. Such changes would result in slowness of movement and muscle weakness, and also reduce ATP hydrolysis with a concomitant improvement in energetic efficiency.

Three experiments were undertaken to determine the effect of condensed tannin (CT) in Lotuspedunculutus (45–55 g extractable CT/kg DM) on the digestion of the principal leaf protein, ribulose-1,5-bis phosphate carboxylase EC 4.1.1.39; Rubisco; fraction 1 leaf protein). In two of the experiments Lotus pedunculutus was fed to sheep, with one group receiving a continuous intraruminal infusion (per fistulum) of PEG (molecular weight 3500) to bind and inactivate the CT (PEG group). The other group, which did not receive PEG, was termed the control sheep (CT acting). Expt 3 involved in vitvo incubations of Lotus pedunculutus in buffered rumen fluid, with and without PEG added. In all experiments the results have been interpreted in terms of the effects of CT on Rubisco solubilization and degradation. Disappearance of N and Rubisco from Lotus pedunculutus suspended in polyester bags in the rumen was used as a measure of solubilization. Degradation was defined as the disappearance of Rubisco from in vitro incubations of Lotus pedunculatusinrumen fluid. In Expt 1, CT reduced the digestion of Rubisco in the rumen from 0.96 to 0.72 of intake (P < 0.01). Rubisco digestion in the small intestine was 0.27 of intake in control sheep and 0.04 of intake in PEG sheep. In Expt 2, PEG had no effect on the loss of Rubisco from Lotus pehneulatus contained in polyester bags which were incubated in the rumen, hence CT did not affect the solubilization of Rubisco. Observations in Expt 1 were confirmed by in vitro incubations in Expt 3, where PEG addition substantially increased the rate of degradation of plant protein to NH2. Addition of PEG decreased the period of time taken to degrade 50% of the Rubisco from about 13.8 h to about 3.0 h. It was concluded that the action of CT reduced the digestion of Rubisco in the rumen of sheep fed on fresh Lotus pedunculutus, and that this was primarily due to the ability of CT to slow its degradation by rumen micro-organisms, without affecting its solubilization. Both fresh-minced, and freeze-dried and ground lotus were used for in saccoand in vitro incubations; however, fresh-minced lotus was more suitable for the evaluation of protein solubilization and degradation in fresh forages.

Broiler chickens (1-d-old) were fed ad libitum on a control diet based on maize and maize starch or diets containing low-, medium- or high-viscosity chitosans at an inclusion level of 15 g/kg. Body weights and feed intakes of chickens given chitosan-containing diets were generally depressed in comparison with those of control-fed animals on days 11 and 18 of the experiment. On days 12 and 19, feeding the low-viscosity-chitosan diet reduced plasma triacylglycerol and total plasma cholesterol concentrations in relation to chickens receiving the control diet, while the medium- and high-viscosity-chitosan-containing diets reduced total plasma cholesterol and elevated, although not significantly, plasma HDL-cholesterol concentrations compared with those of control-fed animals. Chitosan feeding generally improved plasma HDL-cholesterol: total cholesterol ratio in comparison with control feeding, which was attributed to the general reductions in plasma cholesterol concentrations rather than increases in plasma HDL-cholesterol concentrations. Feeding the high-viscosity-chitosan-containing diet significantly reduced the ileal digestibility of crude protein (N x 6·25) and crude fat compared with chickens given the control diet. The reduction in ileal crude fat digestibility was greatest among chickens receiving the high-viscosity-chitosan-containing diet and chitosan-containing diets reduced ileal fat digestibility by 8% on average compared with that of control-fed birds. However, increasing the viscosity of the chitosan fraction could not be correlated with increases in terminal ileal digesta viscosity and, therefore, it could not be established that increased ileal lumen viscosity alone contributed to reductions in body weight, feed intake and plasma cholesterol concentrations. However, the fact that ileal digestibility of fat was reduced by feeding chitosan to chickens suggests the action of other hypolipidaemic mechanisms

Urea kinetics were measured using prime/lintermittent oral doses of [15N15N]urea, on five separate protocols in thirteen normal young women. Each woman underwent either two or three study protocols.Measurements were made at day 12 and day 22 of the menstrual cycle, whilst consuming their habitual protein intake in seven women not taking the contraceptive pill and in six women taking the contraceptive pill. In three woman taking the pill, and three not taking the pill, urea kinetics were measured whilst taking a diet in which the intakewas restricted to 55 g protein/d. There was no difference in the rate of urea production, urea excretion or urea hydrolysis between the women taking the pill and those not taking the pill at day 22. In the women not taking the pill there was no difference in any measure between day 12 and day 22. In the women taking the pill there was a significant difference in the disposal of urea N to excretion or hydrolysis on day 12 compared with day 22, with a relative decrease in excretion and enhancement of hydrolysis at day 12 compared with day 22. On the restricted diet, an intake of 55 g protein/d represented 77% of the habitual intake and urea production, excretion and hydrolysis were reduced to about 84% of the rate found on the habitual intake. In paired studies the reduction in urea production was statistically significant, and there was a statistically significant linear relationship between urea production and either intake or the sum of intake plus hydrolysis. The within-individual variability for urea production was about 10% for excretion 15% and for hydrolysis 44% The between-individual variability for intake was about 17% on the habitual intake. The variability for production, excretion and hydrolysis (14, 13, 36%) was less in the women not taking the contraceptive pill than in those taking the pill (23,32,42% respectively). The variability was reduced on the controlled low intake of 55 g protein compared with the habitual intake.These results confirm the wide variability in aspects of urea kinetics between individuals. In women this variability is not, to any large extent, accounted for by changes associated with themenstrual cycle

The aim of the present study was to determine the errors in the conceptualization of portion size using photographs. Male and female volunteers aged 18–90 years (n 136) from a wide variety of social and occupational backgrounds completed 602 assessments of portion size in relation to food photographs. Subjects served themselves between four and six foods at one meal (breakfast, lunch or dinner). Portion sizes were weighed by the investigators at the time of serving, and any waste was weighed at the end of the meal. Within 5 min of the end of the meal, subjects were shown photographs depicting each of the foods just consumed. For each food there were eight photographs showing portion sizes in equal increments from the 5th to the 95th centile of the distribution of portion weights observed in The Dietary and Nutritional Survey of British Adults (Gregory et al. 1990). Subjects were asked to indicate on a visual analogue scale the size of the portion consumed in relation to the eight photographs. The nutrient contents of meals were estimated from food composition tables. There were large variations in the estimation of portion sizes from photographs. Butter and margarine portion sizes tended to be substantially overestimated. In general, small portion sizes tended to be overestimated, and large portion sizes underestimated. Older subjects overestimated portion size more often than younger subjects. Excluding butter and margarine, the nutrient content of meals based on estimated portion sizes was on average within± 7% of the nutrient content based on the amounts consumed, except for vitamin C (21% overestimate), and for subjects over 65 years (15–20% overestimate for energy and fat). In subjects whose BMI was less than 25 kg/m2, the energy and fat contents of meals calculated from food composition tables and based on estimated portion size (excluding butter and margarine) were 5–10% greater than the nutrient content calculated using actual portion size, but for those with BMI 30 kg/m2or over, the calculated energy and fat contents were underestimated by 2–5% The correlation of the nutrient content of meals based on actual or estimated portion sizes ranged from 0·84 to 0·96. For energy and eight nutrients, between 69 and 89% subjects were correctly classified into thirds of the distribution of intake using estimated portion size compared with intakes based on actual portion sizes. When ‘average’ portion sizes (the average weight of each of the foods which the subjects had served themselves)were used in place of the estimates based on photographs, the number of subjects correctly classified fell to between 60 and 79%. We report for the first time the error associated with conceptualization and the nutrient content of meals when using photographs to estimate food portion size. We conclude that photographs depicting a range of portion sizes are a useful aid to the estimation of portion size. Misclassification of subjects according to their nutrient intake from one meal is reduced when photographs are used to estimate portion size, compared with the use of average portions. Age, sex, BMI and portion size are all potentially important confounders when estimating food consumptionor nutrient intake using photographs

Four rats were housed in cages with mesh floors; another four rats were housed in tubular anti-coprophagy cages, in which they could not turn round to reach their own faeces. Both groups were fed for 6 d on a low-protein diet containing fermentable carbohydrates and 15NH4Cl. At the end of the experiment the rats were killed and their carcasses were homogenized, lysine was isolated by ion-exchange chromatography and its 15N enrichment measured by isotope-ratio mass spectrometry. The 15N enrichment in the lysine of the microbial fraction of faeces and the total amount of lysine in the body were also determined in order to estimate the amount of microbial lysine absorbed. The 15N enrichment in body lysine of non-coprophagic rats was not different from that previously measured in rats given unlabelled NH4Cl, but in coprophagic rats it was significantly higher. The daily absorption of microbial lysine by the coprophagic rats accounted for 20·7 (SE 2·55) mg/kg body weight0·75 but was only 0·5 (SE 1·04) mg/kg body weight0·75 for the non-coprophagic rats. This value was not significantly different from zero. The utilization of microbial amino acids via coprophagy resulted in a higher weight gain (adjusted for intake) in the coprophagic group (15·5 g/6 d) than in the non-coprophagic rats (3·1 g/6 d). It was concluded that, in rats, the utilization of microbial lysine occurred exclusively via coprophagy.

The aim of the present study was to assess, in healthy volunteers and under physiological conditions, the acceptability, clinical tolerance and effects on colonic motility of chronic supplementation of the usual diet with new dietary fibre sources. Three studies were carried out, one after a period of habitual diet, and two after randomized 3-week periods of supplementation with fibre extracted either from pea hulls or carrots, added to the meals as a fine powder. The 24 h motility was recorded on an unprepared colon at five levels to determine the initiation site and the number of high amplitude propagated contractions (HAPC) and to quantify motor activity every 30 min, particularly in the two periods following lunch and breakfast. With the habitual diet the motility pattern was an irregular alternation of quiescence and sporadic non-propagated contractions. HAPC always started from the ascending colon and occurred mainly after breakfast. With either type of fibre the 24 h motor profiles, the 24 h variations and the number of HAPC were not significantly modified but a more distal initiation of HAPC was found. The colonic postprandial motor response was more diffuse after dietary enrichment with carrot fibre than after enrichment with pea-hull fibre. In healthy volunteers the long-term addition of fibre extracted from pea hulls and carrots to the usual diet was easy and well-tolerated without clinical side-effects, but with limited colonic motor effects. However, the more distal initiation of HAPC observed could be deleterious.

We investigated the hydrolysis of sucrose in the small intestine and the subsequent absorption and metabolism of fructose in sucking piglets by measuring temporal changes in the concentration of fructose in the plasma following the administration of physiological amounts of these carbohydrates. Calculations of the area under the curve for fructose in the plasma showed that there was no age limit to the piglets'ability to absorb fructose. However, there was a limit to the amount of fructose that the younger piglets could get from a dose of sucrose. Indeed, we demonstrated that there was a positive linear correlation between a piglet's capacity to hydrolyse sucrose and the age of the piglet up to 15 d of age (r 0·98).The half-life for fructose was 495, 103, 38, 49 and 28 min in 2-, 5-, 7-, 10- and 15-d-old piglets respectively and, thus, there was only limited utilization of fructose in the younger piglets. However, there were 13·0- and 1·4-fold increases in the elimination rate of fructose from the plasma of piglets from 2 to 7 d and from 7 to 15 d respectively, consistent with the reported increase in the deposition of fat in piglets of a similar age range. Hence, the effective metabolism of fructose may bepartially dependent on the amount of adipose tissue present and the phosphorylation of this monosaccharide by hexokinase (EC 2·7·1·1) in this tissue.

Daily (24 h) rates of water and electrolyte turnover were measured in a conventional balance study in ten adult female pastel mink (Mustela vison) given free access to a standard mink feed for a 1-week conditioning period, followed by a 4 d experimental period and a 2 d fasting period. Drinking water was available throughout. In addition, the completeness of urine collection and the fraction of urine collected with the faeces were determined using a new experimental technique based on 24 h recoveries of specific urinary markers such as tritiated p-aminohippuric acid ([3H]PAH) or 14C-1abelled inulin ([14C]IN) continuously delivered by small Alzet® osmotic pumps implanted intraperitoneally. During feeding the mean individual percentage recovery in urine of [3H]PAH released from tbe osmotic pumps ranged from 68 to 88% (median 78%). Tbe mean percentage of urinary [3H]PAH recovered from faecal collections was 6% (range 3–12%). In response to fasting the mean individual percentage recovery of [3H]PAH in urine ranged from 62 to 78% (median 68%). For urinary [14C]IN the mean percentage recoveries in fed and fasted animals were 79 and 63% respectively. Furthermore, during fasting, withdrawal of the supplies of dietary water caused a slight but insignificant (P = 0·17) increase in the daily intake of drinking water and, hence, the animals maintained their normal water balance by a dramatic reduction in urine excretion (P < 0·001). At the same time urinary solute excretion declined significantly (P < 0·001), due in part to the cessation of dietary electrolyte intake and in part to reduced formation of urea, whereas urinary osmolality decreased only moderately. The mean 24 h balances of Na, K, Ca, Mg, Cl and P were close to zero and only minor differences between the feeding and fasting periods were observed. When corrected for the measured inaccuracies in urine collection the balance data obtained in the present study represent useful reference standards for normally fed and fasted non-growing mink and, to some extent, useful guidelines for future studies in experimental animals.

Two experiments were conducted to determine apparent ileal DM and crude-protein (CP) digesibilities in rations fed to pigs. An evaluation was made of Cr2O3 and HCl-insoluble ash as digestive markers. In addition, the effects of body weight (BW) on apparent ileal DM and CP (N x 6.25) digestibilities were studied. In Expt 1, thirteen barrows averaging 35 kg BW were fitted with post-valve T-caecum (PVTC) cannulas to determine the apparent ileal DM and CP digestibilities of a wheat gluten-bran ration (B2) and a soyabean-meal ration (E1). Immediately after morning feeding ileal digesta samples were collected on an hourly basis for a total of 12 h. Subsequently, N and marker contents were determined in the samples. The postprandial patterns of N and Cr passage were more similar than those of N and HCl-insoluble ash. Therefore Cr2O3 is more suitable as a marker than HCl-insolube ash. The apparent ileal CP digestibility coefficient of ration B2 derived using Cr2O3 as a marker was significantly (P > 0.05) higher by 0.018 compared with the value obtained using HCl-insoluble ash. The corresponding values for ration E2 obtained using Cr2O3 and HCl-insoluble ash were both 0.825. In Expt 2, apparent ileal DM and CP digestibilities were determined in eighteen rations using twelve barrows also fitted with PVTC cannulas (BW from 40 to 100 kg). The protein sources for these rations were from different groups of feedstuffs. In four and three of the rations apparent ileal DM and CP digestibilities respectively were significantly different (P < 0.05) when assessed using the two markers. The digestibility coefficients were not systematically higher or lower for either marker. Absolute differences were < 0.049 on average. Significant effects of live weight on apparent ileal CP digestibilities were found.