bluuebunny/crossref_metadata_2025 huggingface dataset:
The metabolism of high intakes of tryptophan, nicotinamide and nicotinic acid in the rat
Authors: McCreanor Gwyn M. , Bender David A.
Published: June 2005

1. The metabolic fate of high dietary intakes of nicotinamide, nicotinic acid and tryptophan, and of acute doses of nicotinamide and nicotinic acid, has been studied in the rat. A new high-pressure liquid chromatography method for measurement of the principal urinary metabolites of niacin is described.

2. Administration to rats of a single oral dose of nicotinamide or nicotinic acid (up to 100 mg/kg body-weight), or maintenance for 3 weeks on diets providing 150 mg nicotinamide or nicotinic acid/kg diet, resulted in only a small increase in the liver content of nicotinamide nucleotide coenzymes (NAD and NADP). The quantitative metabolism of nicotinamide and nicotinic acid differed, suggesting that intestinal bacterial deamidation is not the major fate of nicotinamide.

3. A high dietary intake of tryptophan (5.9 g/kg diet) led to a considerable increase in liver NAD(P) and also in urinary excretion of niacin metabolites. The results suggest that, as indicated by enzyme kinetic studies (Benderet al.1982), the utilization of nicotinamide and nicotinic acid for nucleotide synthesis is limited, while there is little or no limitation of NAD(P) synthesis from the tryptophan metabolite quinolinic acid.
The effect of dietary polyunsaturated fat on cation transport and hypertension in the rat
Authors: Murray Gordon E. , Nair Raman , Patrick John
Published: June 2005

1. Essential hypertension is associated with increased intracellular sodium in both erythrocytes and leucocytes. Reports in the literature indicate that increasing the level of polyunsaturated fat in the diet reduces hypertension. In the present study, spontaneously hypertensive rats (Wistar-Kyoto, which develop systolic blood pressures in excess of 140 mmHg by 8 weeks of age) were fed on high-fat diets (40% energy derived from fat), the fat being maize oil (high in polyunsaturated fatty acids, PUFA) and coconut oil (low in PUFA).

2. Significantly higher blood pressures developed by 110 d of age in the rats fed on a high-PUFA diet, compared with those fed on the low-PUFA diet.

3. In thymocytes, ouabain-sensitive efflux rate constants were significantly lower in the group fed on the high-PUFA diet. Ouabain-insensitive efflux rate constants were unaffected by diet.
Effect of previous nutrition on body composition and maintenance energy costs of growing lambs
Authors: Ferrell C. L. , Koong L. J. , Nienaber J. A.
Published: June 2005

1. Forty-eight intact male lambs (30 kg) were fed to gain 16 (H), 5 (M) or –6 (L) kg during a 42 d interval (period 1). Lambs from each of the H and M groups were fed to gain either 16 (HH, MH), 5 (HM, MM) or –6 (HL, ML) kg and lambs from the L group were fed to gain 27 (LS), 16 (LH) or 5 (LM) kg during the ensuing 42 d (period 2).

2. Fasting heat production (FHP) of four lambs from each treatment was determined at the end of period 2.

3. Weights and compositions of the carcass, offal and digesta-free body as well as weights of major internal organs were determined for four lambs of each treatment at the end of periods 1 and 2.

4. Within groups of lambs of similar weight at the end of period 2, body composition was, in general, similar, but FHP was greater in lambs that had been on higher planes of nutrition during period 2.

5. Within groups of lambs of similar weight, lambs that were fed at higher planes of nutrition during period 2 had greater weights or proportions of liver, small intestine, large intestine and stomach.

6. Neither weight of the liver, kidney, stomach, small intestine, large intestine nor daily fasting heat production were constant functions of body-weight. Relations of these traits to body-weight changed with rate of gain.

7. Regression analysis indicated that the feeding of lambs at higher planes of nutrition during period 1 resulted in higher maintenance requirements of those lambs during period 2.
The role of condensed tannins in the nutritional value ofLotus pedunculatusfor sheep
Authors: Barry T. N. , Allsop T. F. , Redekopp Carolyn
Published: June 2005

1. Three experiments were conducted using Lotus pedunculatus containing high concentrations of condensed tannins (CT), and utilizing the principle that polyethylene glycol (PEG) application (molecular weight 3350) will irreversibly bind a portion of the CT and thus reduce the dietary reactive (i.e. non-PEG bound) CT concentration. Lotus diets containing 95, 45 and 14 g total reactive CT/kg dry matter (DM), induced by spraying with three PEG rates, were given to sheep at hourly intervals (600 g DM/d) for 21 d (Expt 1). In Expts 2 and 3, lambs grazed areas oversown with either lotus (89 g CT/kg DM) or clovers (Trifolium repens and Trifolium pratense; < 1 g CT/kg DM) for 42 and 92 d respectively. In Expt 2 half the animals grazing each forage received oral PEG (75 g/d), whilst in Expt 3 half the lambs were sired by rams selected respectively for low or high levels of sub- cutaneous fat deposition.

2. Hormone concentrations in plasma (Expt 1 only) were determined by radioimmunoassay. Rates of [U-14C]-acetate and D-[U-14C]glucose incorporation and oxidation by subcutaneous and abdominal adipose tissue removed at slaughter, together with rate of glycerol release, were determined during in vitro incubation in all three experiments.

3. Plasma concentration of growth hormone was positively and linearly related to dietary reactive CT concentration, whilst 3, 5, 3'-triiodothyronine (T3) concentration tended to be negatively and linearly related to dietary reactive CT concentration. Diet CT concentration had no effect on plasma concentrations of the other hormones measured.

4. Feeding of lotus high in CT was associated with a consistent but non-significant increase in the rate of glycerol release from adipose tissue, which was reduced as dietary reactive CT concentration was lowered through PEG application, and a reduction in the lipogenesis: lipolysis value. Selection for leanness decreased acetate incorporation and increased glycerol release from adipose tissue, with the effect not interacting with the diet.
Effects of preweaning nutritional deprivation on basal metabolism and thermoregulatory thermogenesis in the rat
Authors: Muralidhara D. V. , Shetty P. S.
Published: June 2005

1. Nutritional deprivation was induced preweaning in Wistar rats by increasing the litter size to sixteen, while paired litters with only five pups served as controls. The nutritionally deprived pups were rehabilitated after weaning by ad lib. access to an adequate diet.

2. The body-weights and body lengths were significantly lower in the nutritionally deprived group and significant differences persisted even after 9 weeks of rehabilitation.

3. The body temperature of the nutritionally deprived animals was significantly lower than that of their paired controls, both before and following nutritional rehabilitation, except for a short period after weaning when the nutritionally deprived animals were initially given the diet ad lib.

4. The resting oxygen consumption of the nutritionally deprived animals was comparable to that of the controls when corrected for metabolic body size, both before and after weaning. Noradrenaline-stimulated increase in 02 consumption (non-shivering thermogenesis; NST) was reduced by 50% at weaning in the nutritionally deprived animals and returned to levels comparable to those of controls within a short period of rehabilitation.

5. The decrease in NST capacity seen in the nutritionally deprived animals was associated with an inability to thermoregulate when exposed to cold (5°), resulting in death. Cold-induced thermogenesis (CIT) also reappeared soon after nutritional rehabilitation.

6. Reduction in metabolic rate, NST and CIT seen in the animals nutritionally deprived preweaning was short-lived and disappeared soon after nutritional rehabilitation. Rapid reversal of these physiological changes indicates that they do not confer any long-term benefit or change in metabolic efficiency and are unlike the changes in body size and growth which do not completely recover following nutritional rehabilitation.
The effect of shearing on the energy metabolism of the pregnant ewe
Authors: Symonds M. E. , Bryant M. J. , Lomax M. A.
Published: June 2005

1. Metabolizable energy (ME) intakes, heat production, non-protein respiratory quotient (NPRQ) and the plasma concentrations of glucose, non-esterified fatty acids (NEFA), 3-hydroxybutyrate, insulin, growth hormone (SH) and cortisol were measured in shorn and unshorn pregnant ewes.

2. Lamb birth-weight was 17% higher from shorn ewes despite similar ME intakes in the two groups. Shearing resulted in a significant decrease in the digestibility of dry matter and energy.

3. Both shorn and unshorn ewes were found to be in positive nitrogen balance and negative energy balance. Heat production was 28% higher in shorn ewes. This increase in heat production in the shorn group could be completely accounted for by an increase in the oxidation of fatty acids as measured using the NPRQ values.

4. Despite an apparent increase in the use of fat as an energy source there were no effects of shearing on the mean plasma concentrations of NEFA, 3-hydroxybutyrate, GH and cortisol.

5. Measurements made at 1 h intervals for 24 h indicated a tendency for the concentrations of glucose to be increased and insulin decreased in shorn ewes, particularly, between 6 and 11 h after feeding.

6. It is concluded that shearing pregnant ewes at 8 weeks before lambing results in a chronic increase in energy requirements which are met by oxidizing body fat depots. The cold stress induced by shearing may also inhibit insulin secretion resulting in increased plasma glucose concentrations. The effects of shearing on energy metabolism in the ewe are discussed in relation to the nutrient supply for the developing fetus.
Nutritional value of lupin (Lupinus albus)-seed meal for growing pigs: availability of lysine, effect of autoclaving and net energy content
Authors: Batterham E. S. , Andersen L. M. , Lowe R. F. , Darnell R. E.
Published: June 2005

1.Two experiments were conducted to assess the nutritional value of lupin (Lupinus albus)-seed meal for growing pigs. In the first, the availability of lysine was assessed using slope-ratio analysis. In the second, the effects of autoclaving lupin seeds and formulating the diets on the basis of estimated digestible or net energy were assessed.

2. In the first experiment, the availability of lysine in three samples of lupin-seed meal was compared with that in meat-and-bone meal and soya-bean meal. Availability of lysine in the five protein concentrates, using food conversion efficiency on a carcass basis as the criterion of response, was (proportion of total): lupin-seed meal no. 1 0.44, no. 2 0.57, no. 3 0.53, meat-and-bone meal 0.42, soya-bean meal 0.80.

3. Availability estimates, based on protein deposited:food intake, were: lupin-seed meal no. 1 0.82, no. 2 0.73, no. 3 0.70, meat-and-bone meal 0.27, soya-bean meal 0.77. These estimates had higher standard deviations than those based on carcass response.

4. Regressing the measures of response v. lysine intake resulted in estimates of availability similar to, or higher than, the slope-ratio analysis but was associated with greater statistical invalidity and higher standard deviations.

5. The proportion of energy retained in the carcasses was unaffected by the inclusion levels of lysine or soya-bean meal. Energy retention was depressed (P < 0.05) with the three lupin-seed meals and the meat-and-bone meal.

6. In the second experiment, the response of pigs given a diet containing lupin-seed meal was inferior, on a carcass basis (P < 0.05), to that of pigs given a diet containing soya-bean meal formulated to similar total lysine and digestible energy contents.

7. The addition of soya-bean oil to the diet containing lupin-seed meal, to equalize the estimated net energy of the diet to that of the diet containing soya-bean meal, depressed protein deposition (P < 0.05) and increased fat deposition (P < 0.05), indicating that energy was not limiting the growth of pigs given the lupin-seed-meal diet.

8. Autoclaving the lupin-seed at 121°for 5 min had no effect on the growth of pigs, indicating that the low availability of lysine was not due to the presence of heat-labile anti-nutritional factors.
The effect of a dietary supplement ofn-3 polyunsaturated fat on platelet lipid composition, platelet function and platelet plasma membrane fluidity in healthy volunteers
Authors: Gibney M. J. , Bolton-Smith Caroline
Published: June 2005

1. Eight healthy male volunteers (aged 22–39 years) supplemented their normal daily diet with 15 g encapsulated fish oil (MaxEPA) for a 6 week period. Fasting blood samples were taken before, at the completion of and 3 months after the period of supplementation.

2. Evaluation of nutrient intakes showed that the intake ofn-3 polyunsaturated fatty acids rose significantly (P< 0·01) during supplementation. This was reflected in changes in the fatty acid composition of platelet phosphatidyl choline (PC) and phosphatidyl ethanolamine (PE) without any changes in phosphatidyl serine, phosphatidyl inositol or sphingomyelin.

3. In both PC and PE there were significant (P< 0·05) increases in the levels of 18:1n-9 and 20:5n-3 fatty acids and a significant (P< 0·05) decrease in 20:4n-6 during supplementation. 16:0 rose significantly in PC (P< 0·05) while in PE, 18:0 fell and both 22:5n-3 and 22:6n-3 rose significantly (P< 0·05).

4. There were no significant effects of fish-oil supplementation on serum lipids, platelet cholesterol: phospholipid, collagen-induced platelet aggregation or collagen-induced platelet thromboxane B2production. However, there was a significant correlation (P< 0·001; r+0·63) between total phospholipid arachidonic acid and platelet thromboxane production.

5. The fluorescent probe 1,6-diphenyl-1,3,5-hexatriene was used to determine whether fish-oil supplementation altered fluorescence polarization of isolated platelet plasma membrane and, by inference, platelet plasma membrane fluidity. No significant effect of fish-oil supplementation on fluorescence polarization was seen.
Uptake of exogenous and endogenous eicosapentaenoic acid by cultured human mononuclear cells
Authors: Gibney M. J. , Connolly Aedeen
Published: June 2005

1. Peripheral blood mononuclear cells from eight healthy volunteers were cultured, with or without concanavalin A (Con A), in a medium containing (ml/1) 100 normal autologous serum, 100 experimental autologous serum or 100 heterologous (fetal calf) serum.

2. The control and experimental autologous sera were obtained from the volunteers, before and after 15 d supplementation with 15 g fish oil (MaxEPA)/d to provide 1.5 g eicosapentaenoic acid (EPA; 20:5n-3)/d. The sera were frozen at -20°. The level of EPA increased from trace quantities in the control autologous serum to 14.3% w/w free fatty acids and between 6.9 and 8.1% w/w lipoprotein phospholipids in the experimental autologous serum. The heterologous fetal calf serum was enriched with EPA, complexed with bovine serum albumin, to provide a final concentration of 15μg/ml. All culture medium contained 10 ml fresh autologous serum/l and cells were obtained from the volunteers for the culture studies about 60 d after the end of EPA supplementation.

3. Portions of cells were removed from culture at 36, 48 and 72 h for phospholipid fatty acid analysis.

4. The level of EPA in phospholipids of cells cultured with exogenous EPA in fetal calf serum was increased significantly (P< 0.05) at all sampling times, both with and without Con A. By 48 h the levels had peaked at 15.8 (se2.7) and 18.4 (se4.5) % w/w respectively.

5. Resting cells, i.e. with no Con A present, failed to accumulate EPA when cultured in the experimental autologous serum containing 8.6% w/w total lipids as endogenous EPA. When cells were stimulated to divide by the mitogen Con A, there was a gradual increase in phospholipid EPA levels of mononuclear cells cultured with experimental autologous serum containing endogenous EPA. The maximum level obtained was at 72 h (7.2 (se2.7)).

6. In a separate experiment, the effect of Con A at increasing doses (0, 1,5, 10 and 20 μg, final concentration) on lymphocyte blastogenesis was determined by estimating the incorporation of3[H]thymidine. No significant effects due to serum in the culture medium were observed.
Nutritional status of healthy, active, Chinese elderly
Authors: Woo Jean , Ho S. C. , Donnan S. P. B. , Swaminathan R.
Published: June 2005

1. Anthropometric indices are presented for 402 healthy Chinese elderly subjects leading an active life in the community in Hong Kong.

2. Women had higher body-mass index (weight/height2) and body fat, while fat-free mass, arm-muscle circumference and corrected arm-muscle area were higher in men. Body-mass index, fat-free mass, arm-muscle circumference and corrected arm-muscle area did not decline with age. Total body fat was lower in women aged 75 years and above compared with those aged 60–64 years.

3. All values were lower than those for elderly Caucasians. A different criteria for severe wasting malnutrition among elderly Chinese should be established.
The effect of dietary modification and hyperglycaemia on gastric emptying and gastric inhibitory polypeptide (GIP) secretion
Authors: Morgan L. M. , Tredger J. A. T. , Hampton S. M. , French A. P. , Peake J. C. F. , Marks V.
Published: June 2005

1. Five healthy volunteers whose usual fat and energy intakes were moderately high (fat intake 155 (SE 11) g/d; energy intake 13683 (SE 909) kJ/d) were given on two separate occasions (a) 96 g fat and (b) 96 g fat and intravenous (IV) glucose (250 g glucose/1; 100 ml followed by a 2 ml/min infusion for 180 min).

2. Subjects continued on a low-fat diet for 35 d (fat intake 25 (SE 4) g/d; energy intake 6976 (SE 539) kJ/d) and the tests repeated.

3. The gastric inhibitory polypeptide (GIP) response to oral fat was significantly attenuated by IV glucose whilst subjects were consuming their normal diets and the GIP response to fat alone was significantly diminished during the low-fat diet. Post-prandial plasma triglycerides, light scattering indices (LSI; an index of post-prandial chylomicronaemia) and paracetamol levels paralleled the integrated GIP responses on both normal and low-fat diets.

4. The study of oral fat with or without glucose was repeated on seven further volunteers consuming their usual diet, substituting 10 MBq 99Tcm-labelled tin colloid for the paracetamol to investigate the rate of gastric emptying by radionuclide imaging.

5. Plasma GIP, insulin, triglyceride and LSI levels were similar to those found in the first study. IV glucose almost doubled the gastric emptying time of the oral fat load (half emptying time (t½) 148 (SE 11) min after fat alone and 224 (SE 18) min after fat and IV glucose). Post-prandial plasma motilin levels were significantly depressed by IV glucose.

6. We conclude that (a) the GIP response to oral fat is attenuated both by IV glucose and by a low-fat diet, (b) the delay in gastric emptying induced by IV glucose may be partly responsible for the diminished GIP response to oral fat when IV glucose is infused, (c) it is possible that some of the changes observed with IV glucose are mediated via changes in motilin.
The effect of underfeeding on the physiological response to food ingestion in normal weight women
Authors: Mansell P. I. , Macdonald I. A.
Published: June 2005

1. The thermogenic, cardiovascular and metabolic responses to the ingestion of a 30 kJ/kg body-weight test meal were studied in six normal weight, female subjects before and after a 7 d period of underfeeding at 60 kJ/ kg ideal body-weight per d.

2. With underfeeding there were decreases in body-weight, plasma insulin and 3,5,3'-triiodothyronine concentrations, resting metabolic rate and respiratory exchange ratio, with increased blood ketone levels. Baseline ‘arterialized’ venous plasma noradrenaline and adrenaline concentrations were not affected by underfeeding.

3. Ingestion of the test meal caused similar increases in heart rate and calf blood flow and changes in blood pressure in the fed and underfed states. There was a greater glycaemic response to the test meal in the underfed state compared with the fed state although the rise in plasma insulin concentration was similar and ketogenesis was suppressed. The increases in metabolic rate and plasma noradrenaline concentrations following the test meal were similar in the fed and underfed states.

4. Although the period of underfeeding in the present study led to considerable metabolic adaptation, and some alteration in physiological responses to ingestion of a test meal, there was no evidence that there were associated changes in sympathetic nervous system activation.
Effect of dietary methionine on tissue selenium and glutathione peroxidase (EC1.11.1.9) activity in rats given selenomethionine
Authors: Waschulewski Ingo H. , Sunde Roger A.
Published: June 2005

1. The effect of dietary methionine on the utilization of selenium from dietary selenomethionine ([Se]Met) for tissue Se deposition and for glutathione peroxidase (EC1.11.1.9; GSH-Px) synthesis was studied in male weanling rats.

2. When rats were given 0.5 mg Se as [Se]Met/kg diet supplemented with 0, 4 or 9 g methionine/kg, Se in plasma, erythrocytes, liver and muscle increased significantly over the 20 d period for all methionine-treatment groups. The increases in erythrocyte and muscle Se, however, were significantly higher in rats fed on the methionine-deficient diet compared with the methionine-supplemented diets.

3. In contrast to the increases in tissue Se, GSH-Px activity in liver, plasma and muscle decreased in methionine-deficient rats given 0.5 mg Se as [Se]Met/kg whereas GSH-Px activity was maintained or increased in rats supplemented with methionine.

4. The percentage of tissue Se associated with GSH-Px was calculated from the measured Se concentration and GSH-Px activity. A significantly lower percentage of Se was associated with GSH-Px in methionine-deficient rats compared with methionine-supplemented rats.

5. These results show that Se from dietary [Se]Met is preferentially incorporated into body proteins rather than used for GSH-Px synthesis when methionine is limiting in the diet.

6. These results further suggest that [Se]Met might not be the optimum Se compound to use for Se supplementation because metabolism of dietary [Se]Met to a biochemically active form, such as GSH-Px, was impaired when [Se]Met was provided in diets low in methionine.
Effect of the duration of malnutrition and of nutritional rehabilitation on blood glucose homeostasis and pancreatic hormones in rats
Authors: Dollet Jean-Marc , Beck Bernard , Max Jean-Pierre
Published: June 2005

1. To study the efficiency of rehabilitation after different periods of protein–energy malnutrition, we used as a model preweaning malnourished rats. After weaning, male Wistar rats were fed on a protein-deficient diet (50 g casein/kg) ad lib. for the whole study (DR group) or rehabilitated with normal diet (180 g casein/kg; RR group) from weaning, week 0, or weeks 1, 3, 5, 8 and 16 thereafter.

2. Twelve animals from the DR group were killed at the beginning of each rehabilitation period. The twelve rehabilitated rats were killed after 2 weeks. Body-weight and epididymal adipose tissue weight, blood glucose, plasma immunoreactive insulin (IRI) and immunoreactive glucagon (IRG), and pancreatic contents of IRI and IRG were determined.

3. Food intake of RR rats rose significantly except during the last period where body-weight increased less than that during the previous periods. Fat-pad weights increased in the same manner in DR and RR groups.

4. Blood glucose fell and plasma IRG rose significantly without any change in plasma IRI after each rehabilitation period, except during the last period where blood glucose concentrations became stable. Pancreatic IRG and IRI showed the same type of response to those of the plasma.

5. All short-term rehabilitation periods were similarly efficient at producing catch-up growth. High insulin sensitivity of target cells was responsible for good recovery except after long-term malnutrition.
Absorption kinetics of dietary hydrolysis products in conscious pigs given diets with different amounts of fish protein
Authors: Rérat A. , Vaissade P. , Vaugelade P.
Published: June 2005

1. Concentrations of amino-nitrogen, glucose, reducing sugars and lactic acid in blood obtained from arterial and portal permanent catheters were measured together with the portal hepatic blood flow-rate during a post-prandial period of 8 h in twenty unanaesthetized pigs (initial mean body-weight 52·3 (SEM 0·9) kg) receiving experimental meals (200–1000 g) at 3–4 d intervals from 6–8 to 20 d after surgical implantation of the catheters and electromagnetic flow probe. The semi-synthetic starch-based diets contained variable amounts of fish meal giving crude protein (nitrogen x 6·25; CP) concentrations (g CP/kg) of 80 (seven meals), 120 (twenty-two meals), 160 (six meals) and 240 (nine meals).

2. After the meal the concentration of amino-N increased with increasing levels of protein intake and increased more in the portal than in the arterial blood. There were significant relations between amounts of amino-N appearing in the portal blood at various time-intervals after the meal and the level of protein intake. Values for the ratio, amount absorbed within 8 h: amount ingested (absorption coefficient: 0·633 for a mean intake of 13·4 g N) decreased with increasing level of protein intake.

3. There was a rise in glycaemia after the meal, increasing with the amount of carbohydrate eaten, and this was more marked in the portal than in the arterial blood. There were also significant relations between amounts of glucose absorbed and amounts of starch ingested. However, the appearance of glucose in the portal blood was less marked than that of amino-N since the absorption coefficient within 8 h was lower (0·504 for a mean intake of 291 g reducing sugars). This was most probably due to a larger uptake of glucose by the intestinal cell wall.

4. Amounts of lactic acid appearing in the portal vein during the post-prandial period did not depend on amounts ingested; they ranged from 3 to 1·6 g/h from the 1st to the 8th hour after the meal.
Absorption kinetics of dietary hydrolysis products in conscious pigs given diets with different amounts of fish protein
Authors: Rérat A. , Jung J. , Kandé J.
Published: June 2005

1. Concentrations of amino acids (AA) in blood obtained from arterial and portal permanent catheters were measured together with the portal hepatic blood flow-rate during a post-prandial period of 8 h, in nine conscious pigs (initial mean body-weight 49.3 (SEM 1.8) kg) receiving experimental meals (500, 600 or 1000 g) at 3–4 d intervals from 6–8 to 20 d after the surgical implantation of the catheters and electromagnetic flow probe. The semi-synthetic starch-based diets contained variable amounts of fish meal giving crude protein (nitrogen x 6.25; CP) concentrations (g/kg) of 80 (seven meals), 120 (seven meals), 160 (five meals) and 240 (three meals).

2. During the post-prandial period, variations in the individual blood AA concentrations were parallel to those of total amino-N (Rératet al.1988) to a greater or lesser extent according to the AA considered. Portal concentrations, which always exceeded arterial ones (except for glutamic acid and glutamine), increased quickly and, after a peak, returned slowly to reach initial values (small intake) or above (large intake) after 8 h.

3. Relations between amounts of each AA appearing during 8 h after the meal and amounts ingested were characterized by a highly significant linear regression (with the exceptions of glutamic acid and cystine). There were also close and significant relations between amounts of AA absorbed during the first 2 and 4 h after the meal and the amounts ingested.

4. For a mean intake of 90 g CP, aromatic AA showed the highest hourly absorption coefficients (about 010 /h), and sulphur-AA (0.07/h), lysine (007/h) and arginine (0.056/h) the lowest ones. Alanine was synthesized (amounts absorbed within 8 h exceeding those ingested) at the expense of glutamic acid (absorption coefficient 001/h).

5. For a given period of time, the AA abscrption coefficients decreased with increasing intake, but not in the same proportions for all AA, resulting in an enrichment (lysine, arginine, serine, proline) or depletion (branched- chain AA, histidine) of the absorbed mixture.

6. Some substances of the urea cycle were synthesized in rather large amounts in the gut wall (for a mean level of intake of 90 g CP: citrulline 2.41 g/8 h, ornithine 1.09 g/8 h). Blood glutamine was taken up by the gut wall in larger amounts (4.28 g/8 h).
Initial studies on leucine metabolism in the rumen of sheep
Authors: Marsden M. , Bruce C. I. , Bartram C. G. , Buttery P. J.
Published: June 2005

1. [3H]leucine infused directly into the rumen of sheep labelled microbial protein and, when compared with the specific activity of the rumen free-leucine pool, indicated that 50% of the bacterial protein leucine originated from the rumen free-leucine pool.

2. The lower limit for bacterial protein turnover in the rumen was 0.37/d when calculated as the difference between the specific rate of disappearances of labelled bacteria from the rumen and the liquid-phase dilution rate.

3. Intravenously infused leucine also labelled the rumen bacteria. The build-up of specific activity in the rumen bacteria was sigmoidal and did not resemble that of the salivary protein which suggested that the rumen epithelium was a major endogenous protein input to the rumen. Additionally, bacteria isolated from the rumen epithelium had high radioactivity indicating that they were ingesting the rumen epithelial cells.
Quality improvement of sweet-potato (Ipomoea batatasL. Lam.) roots as feed by ensilage
Authors: Lin Yaw-Huei , Huang Tzou-Chi , Huang Chia
Published: June 2005

1. Sweet-potato (Ipomoea batatasL. Lam.) strips (SPS) mixed with maize powder (CP) in proportions 10:0, 9:1, 8:2, and 7:3 were ensiled for 1, 2 or 3 months.

2. Trypsin inhibitor activity (TIA) decreased during ensilage in samples of all treatments while the SPS–CP mixture (7:3, w/w) ensiled for 3 months contained the lowest TIA.

3. SPS–CP (8:2, w/w) dried or ensiled for 2 months, or ensiled for 2 months and dried, were each mixed with twice the amount of control diet (1:2, w/w) to make three diets. These three diets together with the control diet were used for a feeding experiment with rats to evaluate the nutritive value.

4. General composition analysis (including metabolizable energy), fatty acid composition and amino acid analysis (including percentage of essential amino acids) of the samples did not change during ensilage to an extent which could explain the improved performance of rats fed on ensiled diets.

5. Rats fed on diets containing dried SPS–CP (8:2, w/w) showed significantly lower (P< 0.05) body-weight gain than rats fed on the control diet or ensiled SPS diets, at the end of the 8th week. They also showed enlargement of the pancreas. The adverse effect of SPS was associated with TIA which seemed to be prevented to some extent by ensilage.

6. The possibility that the starch of SPS may also contribute to the adverse effect cannot be excluded at present.
Intestinal microflora and gastrointestinal adaptation in the rat in response to non-digestible dietary polysaccharides
Authors: Wyatt G. M. , Horn N. , Gee J. M. , Johnson I. T.
Published: June 2005

1. A comparison was made of the effect of a fibre-free diet and diets containing non-digestible polysaccharides on rat caecal and colonic physiology and microflora.

2. All polysaccharide-containing diets led to enlargement of the caecum and colon, associated with increased weight of contents, and of tissue. Carboxymethylcellulose (CMC) had the most marked effect and animals given this also had watery faeces.

3. The density of bacteria in the caecum and colon varied significantly with diet and the proportion of aerobic bacteria in the flora was increased by the CMC diet.

4. In vitro, CMC and hydroxypropylmethylcellulose were poorly fermented.

5. There was a high correlation (caecum r 0.93; colon r 0.94) between tissue weight and wet weight of organ contents but no correlation with bacterial density, number of bacteria per organ, moisture content or short-chain fatty acid content.

6. It is concluded that caecal and colonic enlargement is due to tissue hypertrophy in response to increased bulk of contents, irrespective of the nature of that bulk which varies with diet; it is unlikely that short-chain fatty acids or other microbial metabolites are the stimulus for the trophic response seen when non-digestible dietary polysaccharides are fed to rats.
The effect of alcoholic beverages on iron and zinc metabolism in the rat
Authors: Fairweather-Tait Susan J. , Southon Susan , Piper Zoe
Published: June 2005

1. Male Wistar rats (approximately 200 g) were given distilled water and a semi-synthetic control diet for 6 d. On day 7, 37 kBq65Zn were administered intramuscularly and the rats were given distilled water, beer, cider, red wine, whisky or ethanol as their only source of fluid. The wine, whisky and ethanol were diluted so that each of the beverages contained a similar ethanol concentration (approximately 30 g/1). Food and fluid intake, growth rate and whole-body65Zn were measured regularly over 11 d, after which animals were killed and blood haemoglobin (Hb) concentration, liver iron stores and the Zn concentration in testes determined.

2. There were no differences in body-weight gain or food intake between groups but fluid intake for the beer group was considerably higher than that for the other groups.

3. There was a significant effect of the type of alcoholic beverage consumed on whole-body65Zn retention. Rats given whisky had a smaller daily loss of65Zn than those given water, beer or cider. The ethanol group also showed a lower rate of65Zn loss compared with the water group. The observed changes in whole-body65Zn retention could be explained by an adverse influence of ethanol on Zn absorption from the diet.

4. Blood Hb and testes Zn concentration were similar in all groups but the type of liquid consumed influenced liver Fe levels. The cider group had the lowest liver Fe values and the ethanol group the highest values.

5. It is apparent from the present study that ethanol and alcoholic beverages affect Zn and Fe metabolism, but that the effects of ethanol are moderated by other components of the alcoholic beverages.
Effects of dietary-fish-oil feeding on muscle growth and damage in the rat
Authors: Jackson M. J. , Roberts J. , Edwards R. H. T.
Published: June 2005

1. Giving diets containing 100 g fully-refined, non-hydrogenated fish oil/kg to rats caused substantial modification of skeletal-muscle-membrane fatty acid composition compared with control animals fed on an equivalent diet containing 100 g maize oil/kg.

2. Total muscle arachidonic acid (20:4ω6) was reduced from 138 (sd25) mg/g total fatty acids to 15 (sd2) mg/ g and phospholipid arachidonic acid content showed equivalent changes.

3. Reduction in muscle arachidonic acid content had no influence on the growth of individual muscles.

4. Variation in muscle fatty acid composition exacerbated the response of muscle to calcium-induced damage assessed by efflux of intracellular creatine kinase (EC2.7.3.2).

5. It is concluded that metabolites of arachidonic acid are unlikely to be primary controlling factors of muscle growth or specific mediators of muscle sarcolemmal damage leading to enzyme efflux.
Fermentation of wheat bran and gum arabic in rats fed on an elemental diet
Authors: Walter D. J. , Eastwood M. A. , Brydon W. G. , Elton R. A.
Published: June 2005

1. Gum arabic and wheat bran were added to an elemental diet (100 g/kg) in order to study their metabolism in the caeca of adult male albino Wistar rats.

2. Dry stool weight (g/d) over 12 weeks was 0.70 (SE 0.05) on the elemental control diet. Wheat bran increased mean dry stool weight to 1.09 (SE 0.08), an increase of 56 %. There was no significant difference between faecal weights (0.65 (SE 0.08)) of the gum-arabic-supplemented group and the unsupplemented group.

3. Wet caecal-sac weight, dry caecal-contents weight, and faecal and caecal bacterial mass (measured by 2,6-diaminopimelic acid) all increased significantly with the gum-arabic-supplemented diet but not with the wheatbran-supplemented diet.

4. Total short-chain fatty acids (mostly acetate) increased in the caecum and faeces with the gum-arabic-supplemented diet but not with the wheat-bran-supplemented diet.

5. Breath hydrogen and methane production decreased to negligible amounts over the 12 weeks of the experiment.
Monitoring the fate of dietary proteins in rumen fluid using gel electrophoresis
Authors: Spencer D. , Higgins T. J. V. , Freer M. , Dove H. , Coombe J. B.
Published: June 2005

1. When fractionated by sodium dodecylsulphate-polyacrylamide gel electrophoresis (SDS-PAGE), strained rumen fluid from sheep fed on pelleted lucerne (Medicago sativa) hay showed no major protein components that stain with Coomassie Blue. This feature made it possible to monitor the fate of individual polypeptides within a protein mixture incubated in rumen fluid in vitro.

2. Extracts from a number of seed meals (sunflower (Helianthus annuus), lupin (Lupinus angustifolius), rape (Brassica napus) and pea (Pisum sativumL.)), as well as casein and bovine serum albumin, were examined in this system. The protein components of each seed type showed a wide range of resistances to degradation. One protein in pea seeds (pea albumin 1), which is particularly rich in cysteine, was almost as resistant to rumen degradation as bovine serum albumin.

3. Analysis of synthetic-fibre-bag experiments by SDS-PAGE showed that the rate of loss of total protein from solid meal residues does not provide an index of the resistance of individual protein components of the meal to rumen degradation. While there was no qualitative change in the protein profile of residual pea-seed meal inside a synthetic-fibre bag, there was considerable variation in the rate at which individual, solubilized protein components were degraded in the surrounding rumen fluid.
Feeding frequency for lactating cows: diurnal patterns of hormones and metabolites in peripheral blood in relation to milk-fat concentration
Authors: Sutton J. D. , Hart I. C. , Morant S. V. , Schuller E. , Simmonds A. D.
Published: June 2005

1. The present paper reports the effects of dietary modifications on the diurnal pattern of concentrations of certain metabolites and hormones in the peripheral blood of lactating dairy cows. The cows were given fixed rations of hay and high-cereal concentrates in the proportions of 30:70 or 10:90 (w/w). The concentrates were given in either two or six equal meals daily; the hay was given twice daily.

2. Previous reports of the same experiment had shown that milk-fat yield and concentration were reduced by increasing the proportion of concentrates in the diet and increased by more frequent feeding of the concentrates. These changes could be explained in part by changes in rumen volatile fatty acid (VFA) proportions and mean daily concentrations of VFA, particularly propionic acid, and insulin in the peripheral blood, but these factors failed to explain all the increase in milk-fat concentration caused by more frequent feeding.

3. Analysis of blood samples taken at hourly intervals for 24 h at two stages of lactation showed that, in the cows fed six times daily, the concentrations of metabolites and hormones remained relatively constant over the day. In the cows fed twice daily, the concentrations of VFA, 3-hydroxybutyric acid and insulin all increased after both meals whereas the concentrations of glucose and growth hormone tended to fall. The concentration of non-esterified fatty acids tended to increase overnight and fall rapidly after the morning feed. The concentrations of glucagon, thyroxine and prolactin showed no clear pattern in relation to meals. The postprandial responses of propionate, insulin and growth hormone were greater with the higher concentrate diet.

4. The maximum concentration and the diurnal range of concentrations were reduced by more frequent feeding of both diets in the case of propionic acid and of the higher concentrate diet in the case of insulin, but the effects on insulin concentrations of more frequent feeding of the lower concentrate diet were smaller and not significant. The maximum concentration and the diurnal range of concentrations of growth hormone were unaffected by meal frequency.

5. It is concluded that the severity of milk-fat depression in cows fed twice daily is increased by the rapid rise in propionic acid concentration in the peripheral blood after a meal, which in turn increases insulin secretion and may be accompanied by a suppression of growth hormone release. This causes lipogenesis to be diverted towards adipose tissue at the expense of the mammary gland. In cows fed more frequently, VFA absorption is more evenly spread over the day and is not closely associated with changes in insulin or growth hormone concentrations.
Effects of condensed tannins prepared from leaves of fodder plants on digestive enzymes in vitro and in the intestine of rats
Authors: Horigome T. , Kumar R. , Okamoto K.
Published: June 2005

1. Of the nineteen plants screened, six were found to contain large quantities of condensed tannins. Black locust (Robinia pseudo-Acacia), bush clover (Lespedeza bicolor), wistaria (Wistaria floribunda) and Japanese knotgrass (Reynoutria japonica) were used for the present experiment. Tannins of the investigated plants were fractionated into three or four molecular forms, according to the degree of polymerization, by chromatography on a column of Sephadex LH-20.

2. The protein-precipitating capacity of the fractionated tannins increased with the increase in degree of polymerization. The inhibitory effect of tannins on trypsin (EC3.4.21.4), a-amylase (EC3.2.1.1) and lipase (EC3.1.1.3) activities in vitro also increased with the increase in degree of polymerization. The digestion of tannin-bovine serum albumin complex by trypsin was related to the degree of polymerization of tannins complexed.

3. Inclusion of black locust tannins in the diet (10 g/kg) depressed the activities of trypsin and α-amylase in the upper, middle and lower parts of the intestine of the rats, but the lipase activity was increased in the middle part and remained unaffected in the upper and lower parts. It is presumed that the tannins have little affinity for lipase.

4. Digestion trials, when the microflora level of the alimentary canal of rats was reduced by dietary antibiotic treatment, revealed that the inclusion of tannins in the diet (20 g/kg) depressed the digestibilities of proximate constituents, except crude fat, and increased faecal bile acid excretion.
The effect of date of cut and barley substitution on gain and on the efficiency of utilization of grass silage by growing cattle
Authors: Thomas C. , Gibbs B. G. , Beever D. E. , Thurnham B. R.
Published: June 2005

1. A primary growth of perennial ryegrass (Lolium perenne) was cut early or late to produce silages of high and low digestibility. The crops were wilted for 2–4 h and preserved with formic acid at 2.4 litres/t fresh weight. The resulting silages were well preserved with a pH of 3.9 and 3.8, lactic acid content of 108 and 73 g/kg dry matter (DM) and total nitrogen content of 24.6 and 18.4 g/kg DM for early- and late-cut silage respectively.

2. Forty-two British Friesian male castrates (steers) initially 12 months of age and 305 kg live weight (LW) were used, of which ten were slaughtered at the start of the experiment. The remaining steers were divided into four groups of eight animals and were given the early-cut silage alone (H) or the late-cut silage alone (L) or with barley at either 280 (LCI) or 560 (LC2) g DM/kg total DM. The intake of total DM was restricted to a daily allowance of 18 g DM/kg LW and the steers were slaughtered in two groups after 119 and 140 d on experiment.

3. Both earlier cutting of herbage and substitution of late-cut silage with barley significantly (P <0.001) increased the apparent digestibility of gross energy (H0.748, L0.619, LC10.668, LC20.705), whereas earlier cutting increased the digestibility of acid-detergent fibre from 0.638 (L) to 0.777 (H) and substitution with barley resulted in a significant (P <0.001) depression to 0.595 (LCI) and 0.519 (LC2). Substitution of late-cut silage with barley significantly (P <0.001) increased metabolizable energy (ME) intake from 58.9 (L) to 69.5 MJ/d (LC2) and crude protein (N × 6.25; CP) intake from 688 (L) to 779 g/d (LC2), but the highest intakes of ME and CP (73.5 MJ/d and 952 g/d respectively) were achieved with the early-cut silage.

4. Earlier cutting resulted in significant (P <0.001) increases in body-weight gain from 292 to 696 g/d, fat gain from 121 to 260 g/d, protein gain from 31.1 to 86.9 g/d and energy retention from 5.5 to 12.2 MJ/d for silages L and H respectively. However, substitution of the late-cut silage with barley increased gains to a greater extent. Thus, empty-body gain was increased to 552 and 800 g/d, fat gain to 189 and 302 g/d, protein gain to 76 and 116 g/d and energy retention to 9.2 and 14.6 MJ/d for diets LCI and LC2 respectively. The difference in gains between diets H and LC2 achieved significance (P <0.05) for all components except fat.

5. It is concluded that although earlier cutting of herbage for silage results in increased gains of protein and energy, the amounts retained are less than those from a similar increment of ME and CP achieved by substituting a late-cut silage with barley.