Four sheep sustained by intragastric nutrition were used to study saliva secretion and the relationship between osmotic pressure in the rumen and net water transport across the rumen wall. Different concentrations of buffer were infused into the rumen to change the rumen osmotic pressure. Salivary secretion was estimated from entrance of P into the rumen. Net water transport across the rumen wall was calculated as the difference between water inflow and water outflow from the rumen. A negative linear relationship between the rumen osmotic pressure (X, mOsm/kg) and the water absorption across the rumen wall (Y, ml/h) was found: Y = (394 SE 8·3)–(l·22 SE 0·03) X, r20·83, (P < 0·001), and a positive linear relationship was found between the rumen osmotic pressure (X, mOsm /kg) and the outflow rate of rumen fluid (Y, ml/h): Y = (34·0 SE 8·0) + (0·97 SE 0·03), X, r2 0·56, (P < 0·001). The implication is that rumen osmotic pressure can be a key factor in the control of the net water transport across the rumen wall, the outflow of rumen fluid to omasum and the rumen liquid dilution rate. A method is suggested by which salivary secretion in sheep may be calculated from the water balance in the rumen.

To assess the effect of an antenatal nutrition programme designed specifically for the local population, questionnaires on nutrition knowledge, attitudes to healthier eating and 4 d diet diaries were completed by women attending routine antenatal clinics. Women who received the nutrition education programme were allocated into an Intervention Education Group whilst those women who did not were allocated into a Routine Education Group. The results showed that knowledge about nutrition was significantly higher in the intervention group. However, no significant differences were detected between the two groups for attitude variables or nutrient intake. It is concluded, therefore, that the most-widely-read form of nutrition advice for pregnant women may have some impact on nutrition knowledge but has little effect on nutrient intake during pregnancy.

Twelve male subjects took part in a study to investigate the effects of overfeeding a high-fat diet (19·17 MJ/d; 58% energy from fat) for 2 weeks on plasma cholecystokinin (CCK) levels, food intake, and subjective feelings of hunger and fullness. Before and after the diet, subjects completed a 2-week weighed dietary inventory, formal measurements of food intake from a pre-selected appetizing evening meal were carried out, and blood samples were taken after a standard breakfast for measurement of CCK. Hunger and fullness were rated on visual analogue scales before and after each of these meals and at evening meals during the diet period. Following the high-fat diet there was a small non-significant increase in food intake from the pre-selected meal (6919 (SE 615) kJ ν 6405 (SE 540) kJ; P = 0·1) and a significant increase in the average daily food consumption measured from the diaries (10·25 (SE 0·49) MJ/d ν. 9·59 (SE 0·62) MJ/d; P = 0·05). Corresponding trends of increasing feelings of hunger and declining fullness also occurred over the study period. Plasma CCK responses to the standard breakfast were raised following the diet (1285 (SE 153) ν. 897 (SE 78) pM min; 3h integrated CCK production post ν. pre diet; P < ·01) with the major differences observed at 90 and 120 min following the meal. These results suggest that the increase in food intake may be related to a down-regulation in putative CCK receptors responsible for food intake. Elevated CCK levels might suggest a corresponding down-regulation in CCK receptors responsible for feedback inhibition of CCK release.

Two experiments were carried out to investigate the capacities of pigs for bulky feeds. In Expt 1 fifteen pigs were offered, from 12 to 25 kg live weight, ad lib. access to one of five feeds which were made by progressively diluting a high-quality feed with wheat bran. Intake initially increased, and then declined, as the proportion of wheat bran was increased. The pigs became better able to accommodate to the more bulky feeds over time. In Expt 2 thirty-six pigs, initially of 12 kg live weight, were used. The feeds were the same high-quality basal feed as in Expt 1 and three others made almost entirely of either wheat bran, dried grass or dried citrus pulp, respectively. The equal-parts mixtures of each of these three bulky feeds with the basal feed were also made to give three series of feeds each comprising the basal, the mixture and the bulky feed. The three feeds in each series were given ad lib. to twelve pigs in a design of two replicated Latin squares with three time-periods. Within each series, and across periods, the intakes of the feeds that were limiting intake were directly proportional to live weight and so a scaled intake, expressed as g/kg live weight per d, was calculated. Across the six limiting feeds, scaled intakes in the final 5 d of each period, when the pigs were in equilibrium with their feeds, were directly proportional to the reciprocal of the water-holding capacities (WHC) of the feeds, as measured by a centrifugation method. There were large effects of feed changes on intake, in the short term, with previous experience of a bulky feed leading to higher intakes of another bulky feed. The intake of the basal feed was not affected by the feed given previously. It was concluded that: (a) the time of adaptation to bulky feeds needs to be considered when attempting to measure, or predict, the rates of intake on different bulky feeds and, (b) the WHC of the feeds could be an appropriate measurement of‘bulk’responsible for limiting their intake, and could be used to predict the maximum feed intake capacity of pigs on different bulky feeds.

Adaptation of energy metabolism to undernutrition and to the duration of undernutrition was studied in adult, non-pregnant, non-lactating ewes at the whole-animal, portal-drained viscera, liver and hindquarters levels. Arterio-venous and indirect calorimetry techniques were used. Animals were successively fed at 1 times (3 weeks) and at 0.5 times (7 weeks) their metabolizable energy requirements for maintenance (MEm). Portal, hepatic and hindquarters blood flows in quietly standing ewes decreased by 22, 19 and 11% respectively within the first week of undernutrition and remained at that level thereafter. Standardizing hindquarters blood flow to that in a given posture (quietly standing) reduced blood flow by 9.8%. In the portal-drained viscera and liver, O2 extraction rates decreased, leading to 34 and 38% drops in O2 consumption with underfeeding respectively. In the hindquarters, O2 extraction rate increased, partly counterbalancing the drop in blood flow. Thus O2 consumption of hindquarters tended to decrease but the effect was not significant. All changes appeared to be completed from day 5 of underfeeding. Consequently, the portal-drained viscera, liver and carcass were responsible for 39, 32 and 5% respectively of the drop in whole-animal O2 consumption with underfeeding. At the end of the 0.5 X MEm period, in vivo metabolic rates averaged 1.65, 4.89 and 0.38 mmol O2 consumed/d per g fresh weight of adipose-tissue-free portal-drained viscera, liver and boneless hindquarters respectively. Undernutrition imposed a much greater nutritional challenge to splanchnic tissues than to hindquarters. The former reduced theirenergy expnditure whereas hindquarters metabolism adapted by counteracting the slight drop in nutrient supply.

Ornithine (Orn; α-ketoglutarate (αKG) salt) and arginine (Arg) supplementation of enteral diets has been advocated in the treatment of hypercatabolism of trauma patients, but both compounds are subject to extensive hepatic metabolism. To compare the metabolism of these two compounds and to evaluate the possible influence of the αKG moiety, livers were perfused with αKG, Orn, ornithine α-ketoglutarate (OKG) or Arg (n 6 in each group) for 1 h. Arg uptake was nearly fourfold higher than Orn uptake (690 (SD 162) ν. 178 (SD 30) nmol/min per g liver), and Orn uptake was not modified by αKG. Orn was totally metabolized by the liver, whereas Arg led to Orn release (408 (SD 159) nmol/min per g liver) and a threefold stimulation of urea production (Arg 1·44 (SD 0·22) ν. Orn 0·45 (SD 0.09) μol/min per g liver). αKG alone only increased hepatic aspartate uptake but, when associated with Orn as OKG, it led to an increase in giutamate release and in proiine content in the liver and to a decrease in proiine uptake. From these findings we conclude that (1) Arg load is extensively metabolized by the liver, inducing urea production, (2) in enteral use, Orn supplementation appears preferable to Arg as it is less ureogenic (as also recently demonstrated in vivo in stressed rats receiving isomolar amounts of Arg and Orn), (3) the liver participates in the Orn-αKG metabolic interaction, mostly in proiine metabolism, which occurs in the splanchnic area.

Increased intake of dietary fibres is associated with several beneficial effects on carbohydrate and lipid metabolism. The colonic fermentation of dietary fibres produces short-chain fatty acids (SCFA; acetate, propionate and butyrate). Some authors have suggested that SCFA could be partly responsible for the effects of dietary fibres. The purpose of the present study was to test the effects of one of the SCFA, propionate. The effects of moderate amounts of dietary propionate on insulin sensitivity and hepatic glucose production were studied in male Sprague-Dawley rats. Two groups of twenty-one adult rats were fed for 3 weeks on a diet containing 78 g propionate/kg (P) or 78 g/kg of a poorly fermentable cellulose (control group; C). Feed intake, body weight, fasting plasma glucose, insulin, free fatty acids, alanine, lactate, glycerol and β-hydroxybutyrate levels were measured weekly in anaesthetized rats. At the end of the feeding period basal hepatic glucose production (BHGP) was measured with a primed continuous infusion of [3−3H]glucose and the in vivo insulin sensitivity in rats was quantified by the euglycaemic-hyperinsulinaemic clamp technique (0.6 and 2 U/kg per h). At that time fasting plasma glucose measured in anaesthetized rats was significantly lower in group P than in group C: 7·7 (SE 0·2) v. 8.5 (SE 0·2) mmol/l respectively (P < 0·002); plasma insulin levels were not significantly different. Neither the BHGP (mg/min per kg; C 14·8 (SE 1·3), P 15·1 (SE 1·3); n 7, not significant) nor the basal metabolic clearance (ml/min per kg; 8·9 (SE 08) v. 9·9 (SE 1·1); not significant) were different between treatments. Hepatic glucose production and glucose utilization at the two insulin concentrations (approximately 500 and 1500 mU/l respectively, n 7) did not differ significantly between the two groups. These results show that dietary propionate chronically ingested by normal rats could decrease fasting glycaemia, but from our findings, no effect on hepatic glucose production and whole-body glucose utilization could be clearly demonstrated.

During pregnancy a higher amino acid requirement may be expected, but the increase in food intake does not match the increased growth rate during pregnancy. It is hypothesized that amino acid utilization can be increased during both fasting and feeding in order to account for the increased requirement. Therefore mature female rats (20 weeks old) were investigated before and at day 18 of pregnancy. Rats were fed on a high-protein (HP) diet (210 g casein/kg diet) for 3 weeks and fasted overnight Rats were then subjected to an 8 h constant infusion of L-[1-14C]leucine with continuous measurement of expired 14CO2 (as a percentage of the infused dose). After 3 h infusion a 5 g HP or low-protein (LP;75 g casein/kg diet) meal was offered for 30 min. Pregnant rats had a significantly lower percentage leucine oxidation in the fasted state (12·5 (SE 0·7) ν. 15·9 (SE 1·1); P < 0·05), which suggests improved reutilization of leucine. Meal ingestion resulted in a fast increase in 14CO2 expiration. After the LP meal the level of 14CO2 expiration decreased again after the acute response (0–1·5 h), but this was not the case after the HP meal. After the HP meal (average 1·5–5 h), no difference was observed between pregnant and non-pregnant status (36·8 (SE 1·6) ν. 35·0 (SE 2·5)). After the LP meal (average 1·5–5 h), however, the percentage leucine oxidation tended to be lower in pregnant rats but this difference did not reach statistical significance (19·7 (SE 1·1) ν. 25·8 (SE 2·8)). In conclusion, pregnancy improved leucine utilization in the fasted state, and tended to improve it after marginal protein feeding.

Experiments were conducted to determine the effect of heating field peas (Pisum sativum) on the N balance and urine, serum and plasma composition of growing pigs. In the first experiment, four diets containing raw field peas (cv. Wirrega) or field peas heated to 150° (cv. Wirrega), 165° (cv. Wirrega) or 150° (cv. Dundale) for 15 min respectively were formulated to contain 1·15 g ileal digestible N/MJ digestible energy (DE) and 036 g ileal digestible lysine/MJ DE in a sugar-based diet. Digestibility estimates were based on those for the Dundale cultivar of field peas used in previous experiments. Total urine and faeces collection from eight pigs was conducted over two 7 d collection periods with a 7 d diet change-over period. Serial blood sampling from the external jugular vein was conducted on the final day of each collection period. There was no significant difference (P > 0·05) in the N balance or apparent biological value of the field-pea treatments. Pigs fed on diets containing peas heated to 150° (cv. Wirrega) or 165° (cv. Wirrega) had a significantly lower (P < 0·01) daily output of urea and uric acid in the urine, and depressed serum protein and serum urea concentrations. Plasma lysine concentration and daily urine lysine output were not significantly different (P > 0·05) in pigs fed on heated peas. Protein excretion in the urine of pigs fed on diets containing peas heated to 165° increased 3–7 times (depending on estimation technique) the level observed in pigs fed on diets containing raw peas. A second experiment was conducted to determine the apparent ileal digestibility of N and amino acids in cv. Wirrega field peas. This study revealed that N digestibility (0·44) and lysine digestibility (0·35) in peas heated to 165° were significantly lower than the cv. Dundale estimates (0·57 and 0·62 respectively) used in diet formulations. The depressed serum and urine variables in pigs fed on heated peas were attributed to overestimation of digestibility. The results exemplify the fact that it is not possible to draw general conclusions as to the effects of heat on any particular protein concentrate. Variability in N balance experiments and problems associated with urine analysis are suggested as likely reasons for the current study not reflecting poor utilization of ileal digestible lysine from heat-treated field peas. Despite considerable variation in the results, it is possible that a large proportion of non-utilizable amino acids in heated field peas may be excreted from the pig via the urine in the form of a protein.

The effects of oat saponins (a mixture of avenacosides A and B) on plasma and liver lipids in gerbils (Meriones unguiculatus) and rats were investigated. Cholesterol-containing diets high in total and saturated fat and with different avenacoside contents (zero (ethanol-extracted oats), normal (oats) and twice normal (ethanol-extracted oats plus added avenacosides)) were used. Compared with a cellulose control group the oat diets in both species gave a significantly higher cholesterol content in the HDL fraction and a significantly lower liver cholesterol content. No significant differences in total plasma cholesterol, HDL-cholesterol and plasma triacylglycerols were found, however, between the groups fed on oats with different avenacoside content. The liver weight, total liver cholesterol and free liver cholesterol were also similar, whereas the liver lipid content was significantly lower in rats given the highest amount of avenacosides compared with zero or normal amounts. The tendency was the same in gerbils. Thus, the oat saponins had only minor effects on lipid metabolism in gerbils and rats.

Male Wistar rats were meal-fed on diets containing various amounts of resistant starch in the form of raw starch (either amylomaize starch, potato starch or modified high-amylose starch) or retrograded starch (prepared from each of the starches) for 6 weeks. Two diets containing normal maize starch were fed as diets poor in resistant starch. Energy absorption (energy consumption minus faecal energy loss), growth, weight of the epididymal fat pads, serum total cholesterol and triacylglycerol concentrations and a number of intestinal and faecal variables were determined. The resistant starches affected all the variables determined except the serum total cholesterol concentration. Relationships were found between energy absorption and both growth and the weight of the fat pads, and between the weight of the fat pads and both the serum triacylglycerol concentration and the serum total cholesterol concentration. No clear differences between the effects of ihe two types of resistant starch (raw starch ν. retrograded starch) were found except that raw potato starch hardly stimulated H2 excretion and led to lower amounts of propionic and butyric acids in the caecal contents than the other starches. The results suggest that dietary resistant starch reduces energy absorption leading to less abdominal depot fat and lower serum triacylglycerol concentrations.

The effects of the trace lipids (Ll and L2) extracted from two kinds of whey-mineral complex on bone metabolism were studied in young ovariectomized (OW) rats. The concentrations of oestradiol in the L1 and L2 oils were 305 and 1313 pg/ml respectively, wbile the concentrations of progesterone were 34.3 and 36.9 ng/ml respectively. Trace amounts of lα, 25dibydroxycbolecalciferol (lα29(0H)2D) were detected: 56 pg/ml in the L1 oil and 132 pg/ml in the L2 oil. The OVX rats were orally given 0.4 ml each test oil twice weekly. Other animals were given with only a vehicle (control) or an oil mixture with similar levels of oestradiol and progesterone to those in L2 oil (PE oil) for comparison. The Ca absorption rate, bone density of the humerus and femoral Ca content in the rats given L2 were significantly higher than those in the control rats (P < 0.05). Serum calcitonin and lα,25-(OH)2D from rats given L2 were both sigdicantly higher than those from the control rats, while serum progesterone in the L2 group was slightly lower. It is suggested that the bone metabolism of rats given L2 reflected the compound effect of 1,2yOH), D and oestradiol in the L2 oil. In contrast, the relatively low level of these hormones might have been associated with the mediacre bone cbarocteriStcs of the L1 group. It is suggested from these results that the trace level of hormones could be one of the reasons why wbey-mineral complex showed good Ca availability.

A double-blind controlled Ca supplementation trial was conducted for 6 months in thirty-four 7-year-old Chinese children from Hongkong and Jiangmen, China. The children were randomly allocated to the study group (n 17) or control group (n 17), and a CaCO3 tablet (300 mg Ca) or a placebo tablet was taken daily. True fractional Ca absorption (TFCA) was evaluated before and after the trial using stable isotopes: 8 mg44Ca mixed in 100 g chocolate milk was given after an intravenous injection of 0·75 mg 42Ca. There was no significant difference in baseline TFCA between the study group (60·6 (SD 11·4)%) and the controls (58·2 (SD 9.0)% P = 0·55). Serum 25-hydroxycholecalciferol levels were comparable between the two groups (P = 0·71). After 6 months, TFCA of the study group (55·6 (SD 12·7)%) was significantly lower than that of the controls (64·3 (SD 10·7)% P = 0·015). By comparing the individual changes in TFCA after the trial between the two groups there was a non-significant reduction in TFCA (5·03 (SD 12·4)% P = 0·11, Wilcoxon signed-rank test) in the study group (60·6–55·6%), whereas a significant increase in TFCA (6·17(SD 7·7)% P = 0·004, Wilcoxon signed-rank test) was observed in the controls (58·2–64·3%). The differential in TFCA between the two groups after 6 months was significantly different (P = 0·001), and remained significant after adjustment for baseline dietary intakes, weight and height by multiple-regression analysis (P = 0·003). If the mechanism of TFCA from chocolate milk in response to the treatment effects is similar to that from the total diet, then our results suggest that children with adequate vitamin D status can adapt to a change in Ca intake by adjusting the efficiency of TFCA. In corollary, children on habitually-low Ca diets have a higher TFCA than the counterparts with higher Ca diets.

Studies on hospitalized elderly subjects have demonstrated that negative energy balance is common during hospitalization, but have concentrated primarily on long-stay and psychogeriatric patients. There is little information on energy balance in elderly patients admitted with acute illness from the community, despite the importance of this patient group and the presence of a number of factors likely to predispose such patients to negative energy balance. In the present study energy balance was quantified in twenty patients (eight males, mean age 82 (SD 05) years; twelve females, mean age 84 (SD 6) years) admitted from the community with acute illness, and predicted basal metabolic rate (BMR) was compared with measured resting metabolic rate (RMR). Most patients were in negative energy balance during hospitalization, and median measured energy intake (El):measured RMR ratio was 1·0 (range 0·7–1·8). The mean difference between measured El and estimated total energy expenditure was −1·3 MJ/d (range -3·4 to +2·5 MJ/d). Estimated total energy expenditure exceeded measured El in fifteen of the patients and there was a significant decline in mid-arm muscle circumference (paired t, P < 0·05) during hospitalization. We conclude that moderate negative energy balance is common in this patient group, and that these patients are at risk of undernutrition during their hospital stay.