Abnormal haemostasis, and specifically a pre-thrombotic state characterized by hypercoagulability, increased platelet aggregation and impaired fibrinolysis, is associated with increased atheroma and thrombosis. The recent literature clearlyindicates that diet may prevent or be used to treat some abnormal haemostatic stats. There are reports on effects of energy intake and expenditure, alcohol consumption, intakes of total fat, different fatty acids, fish oil, NSP and vitamins on markers of coagulation, platelet function and fibrinolysis. Some of the confusion and controversy in this field has arisen because the wrong markers of haemostasis have been measured in dietary trials. Moreover, many of the studies have lacked good dietary control. It is suggested that more sensitive, functional markers of the balance between the different facets of the haemostatic system should be measured. It is also important to test hypotheses developed from known observations and to propose mechanisms of action of the various dietary factors, based on our improved understanding of the haemostatic system.

The protein requirements of the elderly were investigated with [13C]leucine balance studies of metabolic demand, the efficiency of postprandial protein utilization (PPU) and the consequent apparent protein requirement. Ten elderly subjects aged 68–91 years (five men and five women) and ten young adult subjects aged 21–31 years (five men and five women) were infused with L-[1-13C]leucine for 9h commencing in the postabsorptive state (0–3h), continuing during the half-hourly feeding of low-protein meals (LP; protein 3% energy, 3–6 h), and during similar feeding of isoenergetic higher protein meals (HP; protein 15% energy, 6–9h). Leucine oxidation and balance were determined from plasma [l-13C]-α-ketoisocaproate enrichment and expired 13CO2 excretion measured during the 3rd hour of each 3h period. The protein intake during the HP phase was similar to the habitual intake estimated in the subjects from 24h urinary N excretion. Metabolic demand was defined as equal to twice the body-protein equivalent of measured postabsorptive leucine oxidation. The efficiency of PPU was calculated from the increased leucine oxidation observed during feeding, and the apparent protein requirement was defined as metabolic demand/PPU and calculated in relation to both body weight (BW) and fat-free mass (FFM) determined by densitometry or bioimpedance. Metabolic demand in the young adults was 0·83g protein/kg per d; in both elderly groups it was 36% lower when expressed per kg BW and 30% lower when expressed per kg FFM. The apparent protein requirement calculated from metabolic demand and PPU was 0·99g protein/kg per d in the young adults and this was also lower in the elderly, although this was only significant in the men (0·66g per kg BW, P=0·013; 0·79g per kg FFM, P=0·02). The results show that in this group of healthy elderly adults protein requirements as assessed from leucine balance studies were either similar to or less than those of younger adults.

In ninety-four Dutch nulliparous women the effects of a low-Na diet in pregnancy on blood pressure, energy and nutrient intake, Ca metabolism, Zn and Mg status and body composition were studied longitudinally. The women were randomly divided into an intervention group (n 41), which used a low-Na diet (mean urinary Na excretion 61 mmol/24 h) from week 14 of pregnancy until delivery and a control group (n 53; mean urinary Na excretion 142 mmol/24 h). No effect of the diet on blood pressure was observed. The use of a low-Na diet resulted in significantly reduced intakes of energy, protein, carbohydrates, fat, Ca, Zn, Mg, Fe and cholesterol. However, the women on the low-Na diet appeared to be able to adapt quite well to the reduced intake since Ca, Zn and Mg homeostasis was maintained. In the case of Ca and Mg this was probably due to the observed reduced urinary excretions of these nutrients. Non-significant reductions in weight gain (1·5 kg) and fat-mass gain (0·9 kg) over pregnancy were found in the women on the low-Na diet. No significant effects of the diet on birth weight or placental weight were observed.

The present study was conducted to investigate the effect of dietary protein on urinary Ca excretion, apparent Ca absorption and Ca balance in young and elderly subjects. Young adults (n 29) and elderly persons (n 26) consumed diets containing 12% (diet A) and 21% (diet B) of total energy as protein for 3 weeks according to a randomized crossover design. Results showed no differences between the two age groups with respect to the interaction between protein intake and Ca excretion (both in urine and in faeces), apparent Ca absorption and Ca balance. Therefore analyses were done for both age groups separately and also for the whole group. In elderly persons and in the whole group the Ca excretion in faeces (as a percentage of Ca intake) was lower during the higher protein intake (elderly: diet A, 106 (SEM 7)% diet B, 86 (SEM 7) % P = 0·018; whole group: diet A, 99 (SEM 4) % diet B, 84 (SEM 4) % P = 0·003). In young adults faecal Ca excretion tended to be lower when they consumed diet B (diet A: 94 (SEM 5)% diet B: 83 (SEM 6)% P = 0·093). Relative urinary Ca excretion was greater during the higher protein intake in young adults and in the whole group while relative urinary Ca excretion was not different in the elderly (diet A: 15 (SEM 1) %, 14 (SEM 1) %, 15 (SEM 1) % diet B: 16 (SEM 1) %, 16 (SEM 1) % 17 (SEM 2) % for the whole group, the young and elderly subjects respectively, P = 0·019; P = 0·016; P = 0·243).The resulting Ca balance was not influenced by the amount of protein in the diet in young adults. Values for the elderly and for the whole group showed that the Ca balance during diet A was significantly more negative compared with Ca balance during diet B, despite the higher urinary Ca excretion during diet B. It can be concluded that increasing the protein intake from 12 to 21% of total energy ntake had no negative effect on Ca balance.

In two experiments the potential value of diets based on casein or free amino acids (FAA) for amino acid utilization experiments were examined. In Expt 1 the optimum dietary electrolyte balance (dEB) for a casein-based diet was estimated by supplemention with 10 or 20 g NaHCO3/kg, to produce diets containing 64, 183 or 302 mmol/kg. In addition, piglet growth performance and efficiency of nutrient deposition of piglets given the casein diets were compared with two multiple protein source diets; Supercreep, a commercial multiple protein source diet or CFS (casein-fish-soyabean-sugar) or a FAA-based diet. Expt 2 was designed to compare piglet response to FAA diet stored at - 15° with twice daily feeding, with FAA diet stored at ambient temperature (13–30°) and offered ad libitum. A CFS diet was used as a positive control and the experiment was conducted over the 10–20 kg growth phase. Expt 1 used forty-eight piglets weaned at 20–22 d of age and allocated to one of six treatments formulated to contain at least 0·84 g lysine/MJ digestible energy in a randomized block design. Piglets given the CFS and Supercreep diets produced superior growth rates (518, 491 g/d) to those given a FAA diet (353 g/d) or casein diet containing 0, 10 or 20 g NaHCO3/kg respectively (365,417,390 g/d) between 5 and 20 kg live weight. Piglets given the casein and FAA diets had higher amino acid digestibilities than those given the Supercreep and CFS diets.The increase in the dEB of the casein diet from 64 to 183 mmol/kg improved piglet growth performance between 5 and 20 kg by 14%. All piglets given casein diets had similar ileal and faecal digestibilities, empty-body compositions, nutrient deposition rates and retention ratios. The results of Expt 2 showed that there was no beneficial effect on piglet performance of storing the FAA diet at -15° and feeding twice daily. Based on the results of these two experiments, neither the casein (0, 10, 20 g NaHCO3/kg) nor FAA diets were suitable for estimating amino acid utilization by the piglet. There remain unidentified factors which limit the growth performance of piglets given the casein and FAA diets.

The present work was undertaken to study the energy value of a mixture of acetic, propionic and butyric acids (0·682: 0·226: 0·092) infused intracaecally in growing pigs. A basal diet low in fibre (42 g NSP/kg DM) was given at below the requirement for maximum weight gain. In six 2-week periods, N and energy balance measurements in eight growing pigs were carried out with and without infusion of short-chain fatty acids (SCFA). Heat production was measured using open-circuit chambers and the concentration of SCFA in faeces was determined. Less than 1% of the infused SCFA was excreted in faeces illustrating the capacity of the hind-gut to absorb and metabolize SCFA. Infusion of SCFA did not affect the digestibility of nutrients and energy. However, N retention increased demonstrating that SCFA are an energy source for protein gain when pigs are fed at below the requirement of energy. Increased CH4 production together with an increased excretion of branched-chain fatty acids in faeces suggested that there was a higher microbial activity in the hind-gut during infusion. The partial utilization of the infused energyin SCFA was 0·821. A small proportion of the infused energy in SCFA was retained in protein (0·099) and a considerable amount was retained as fat (0·722).

Fifty-four roughages of known voluntary dry-matter intakes (DMI; range 7·8−35·2 g/kg live weight per d) were examined in vitro in a gas production test. Samples (200 mg) of roughage and roughage neutral-detergent fibre (NDF) respectively were incubated in a mixed suspension of rumen contents for 96 h and the gas volumes recorded after 4,6,8,12,24,30,36,48,54,60 and 96 h. The kinetics of gas production were derived from the volume recordings described by the exponential equation Y=A+B(l—e-ct) where A is the intercept and ideally reflects the fermentation of the soluble and readily available fraction of the feed, B describes the fermentation of the insoluble (but with time fermentable) fraction and c the fractional rate at which B is fermented per h; A+B describes total fermentation. In vitro true dry matter (TD) and NDF degradabilities (NDF-D) after 24 h incubation were also determined. Of the variation in DMI, 75% was accounted for by the in vitro gas production parameters A, B and c in stepwise multiple regressions; 82% of the variation in DMI was explained by the parameters (ANDF+BNDF) and cNDF as obtained from the incubation of roughage NDF. The rate constants (c) were less important than parameters related to the extent of gas production, accounting for only 6·5 (whole roughage) and 4·1% (NDF) of the variation in DMI. There was no statistical advantage in the use of the exponential model describing extent and rate of fermentation over some of the simple gas volume measurements: 75% of the variation in DMI was accounted for by in vitro gas production of whole roughage after 8 h of incubation. On average gas production from NDF measured from 24–96 h accounted for 81% of the variation in DMI. A combination of gas volume measurements after a short period of incubation (4–8 h) with a concomitant determination of NDF-D after many hours (≥24 h) can render NDF preparations and long incubation times redundant. A method is suggested to obtain two results for DMI prediction in one single incubation. Of the variation in DMI 80% was accounted for by the incubation of 500 mg whole roughage when incubation was terminated after 24 h and the residual undegraded substrate quantified.

Crossbred sheep (n 16,8·5 months of age and 33 (SE 0·9) kg) were used in a 21 d experiment (2x2 factorial) to determine effects on net flux of nutrients across the portal-drained viscera (PDV) and liver of ad libitum consumption of bermudagrass (Cynodon dactylon; B) v. ryegrass (Lolium multiflorum)-wheat (Triticum aestivum; RW) hay, coarsely chopped (CC) or finely ground and pelleted (GP). Crude protein concentrations were 86, 81, 113 and 119g/kg and neutral-detergent fibre concentrations were 710, 688, 654 and 672 g/kg (dry matter basis) for B-CC, B-GP, RW-CC and RW-GP respectively. Digestible energy intake (6.0,9.6·, 10·2 and 13·8 W/d) Mered (P < 0·01) with grass source and form, and digestible N intake values were 4·4, 7·0, 8·4 and 14.1 (SEM 0·82) g/d for B-CC, B-GP, RW-CC and RW-GP diets respectively. Consumption of O2 by the PDV (118,165,144 and 155mmol/h) and splanchnic bed (196,273,247 and 266 mmollh for B-CC, B-GP, RW-CC and RW-GP respectively) was greater (P=O·O7) for GP than for CC. The ratio splanchnic heat energy production: digestible energy intake was greater (P=0·06) for B than for RW (0·374,0·300,0·278 and 0·219 for B.CC, B-GP, RW-CC and RW-GP respectively). α-Amino-N release by the PDV (P< 0·01; 11·6, 12·8, 23·0 and 18·7 mmoyh) and uptake by the liver (P=0·07; 15·2, 6·1, 17·0 and 19·3 mmol/h for B-CC, B-GP, RW-CC and RW-GP respectively) were greater for RW than for B. Release of NH3-N by the PDV was greater (P=O·02) for CC than for GP (12·5, 6·2, 15·7 and 8·9 mmol/h), and hepatic urea-N release differed between grass sources (P=O·O3) and physical forms (P=0·07; 22·6, 12·7, 31·4 and mmol/h for B-CC, B-GP, RW-CC and RW-GP respectively). In conclusion, decreases in forage particle size elicited by grinding and pelleting did not affect the difference between grass sources in splanchnic tissue heat energy production relative to digestible energy intake.

The uptake and metabolism of propionate in the isolated perfused caudal lobe of the liver and in isolated hepatocytes were examined following treatment of sheep with glucagon or saline. Glucagon or sterile saline was infused at 9·8 µg/min for 3 h into the jugular vein and then the caudal lobe of the liver was removed surgically under anaesthesia. The caudal lobe was used either to prepare hepatocytes or in a non-recirculating perfusion experiment. Uptake and metabolism of propionate were studied using [2-14C]propionate. In studies using the non-recirculation perfusion of the caudal lobe of the sheep liver it was shown that the treatment of sheep with glucagon resulted in an increased rate of gluconeogenesis from propionate and in an increased net uptake of propionate by the caudal lobe. The uptake of propionate into the hepatocytes was saturable, concentrative and exhibited a Km for propionate of 0·24 (SE 0·07) mM and a maximal rate of uptake (Vmax) of 6·7 (SE 0·6) nmol/mg dry cells per min and was unaffected by glucagon treatment of sheep. After incubation of cells in medium containing 0·5 mM-[2-14C]propionate for 10 min, the rate of gluconeogenesis from propionate was 22 % higher in the hepatocytes isolated from glucagon-treated sheep. Concentrations in the medium of 1·35 mM butyrate and 1 mM-caproate inhibited propionate uptake by about 50 % and abolished the glucagon-induced stimulation of gluconeogenesis from propionate. The results are consistent with a regulatory role for glucagon in the gluconeogenesis from propionate in the sheep liver.

In the present study we examined the immune-enhancing effect of a nucleoside-nucleotide mixture on the non-specific T-cell immune functions of senescence-accelerated mice (SAM) fed on a low-protein diet. The immune functions studied were in vitro thymic and splenic cell lymphoproliferative responses to phytohaemagglutinin, lipopolysaccharide and concanavalin A and their production of interleukin-2 (IL-2) and interferon-γ (INF-γ) in response to mitogen stimulation. SAMP8 mice aged 3 and 6 months were used. In each age group, mice were fed on diets containing either 50g casein/kg, 50 g casein/kg supplemented with 5 g nucleoside-nucleotide mixture/kg or 200 g casein/kg for 3 weeks. The supplemented 3- and 6-month-old mice had higher (P<O·O5) thymic and splenic cell counts compared with the low-protein group. In both age groups of mice, concanavalin A induced higher (P<0·05) total thymic and splenic lymphoproliferative responses for the nucleoside-nucleotide mixture-supplemented group compared with the 50 g casein/kg dietary groups. Thymic and splenic production of IL-2 was higher for the 3-month-old mice in both the supplemented and the 200 g casein/kg dietary groups. INF-γ production in the supplemented 3-month-old group and the 6-month-old 200 g casein/kg dietary group was higher (P<0·05) compared with the other groups. Overall the supplemented 3-month-old mice exhibited both higher lymphoproliferative responses and production of cytokines compared with the supplemented 6-month-old mice. The results indicate that early nucleoside-nucleotide mixture supplementation may enhance the immune response in protein-deprived SAMP8 mice

To obtain further information about the immunomodulatory effects of specific dietary fatty acids, weanling male rats were fed for 6 weeks on high-fat (178 g/kg) diets which differed according to the principal fatty acids present. The nine diets used differed in their contents of palmitic, oleic, linoleic and α-linolenic acids; as a result the total polyunsaturated fatty acid (PUFA) content and the PUFA: saturated fatty acid ratio varied (from 17·8 to 58·5 g/lW g fatty acids and from 0·28 to 5·56 respectively). The n−6 PUFA: n−3 PUFA ratio was kept constant in all diets at approximately 7·0.The fatty acid compositions of the serum and of spleen lymphocytes were significantly influenced by that of the diet fed. The ex vivo proliferation of spleen lymphocytes decreased as the levelof oleic acid in the diet increased. Spleen natural killer cell activity decreased as the oleic acid content of the diet increased and increased as the palmitic acid content of the diet increased. The extent of the effects of these fatty acids on lymphocyte functions was modified by the nature of the background fatty acid composition of the diet.