bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on the energy metabolism of the pregnant sow
Authors: Close W. H. , Noblet J. , Heavens R. P.
Published: May 2005

1. The heat losses and energy and nitrogen balances of pregnant gilts, and of their non-pregnant litter sisters (controls), were measured for periods of 7 d at feed intakes of 1.8 or 2 3 kg/d (20 or 30 MJ metabolizable energy (ME) respectively) at an environmental temperature of 20°. The measurements were made within three separate periods of gestation; 40–60 d (early), 60–80 d (mid) and 90–110 d (late). Values for ME intake, heat loss, energy retention (ER), protein deposition and fat deposition were determined for both the pregnant and control animals on each treatment.

2. When expressed per kg body-Weight 0.75 per d, there was little difference in heat loss between pregnant and non-pregnant animals and between pregnant animals at the different stages of gestation at any given ME intake. However, heat loss was higher at the higher ME intake.

3. ER vaned inversely with heat loss. The decrease in ME intake (kJ/kg body-Weight 0.75 per d) during pregnancy resulted in a decrease in ER so that the pregnant animals were in negative energy balance at the low feed intake during late gestation. From the relation between ER and ME intake, estimates of the maintenance energy requirement (MEm) of 411 and 401 kJ/kg body-weight0.75 per d were calculated, with corresponding partial efficiencies of energy utilization (k) of 0.74 and 0.68 for the pregnant and non-pregnant animals respectively.

4. For the pregnant animals, protein deposition was highest during mid-pregnancy and was relatively independent of level of feeding during mid- and late pregnancy. There was little difference in protein deposition between pregnant and non-pregnant animals at the high feed intake. At the low feed intake, the pregnant animals generally had a higher protein deposition than their non-pregnant litter sisters and this was entirely associated with the accretion in reproductive tissue.

5. Fat deposition depended on the level of feeding, and at any given ME intake was similar for pregnant and control animals. In late gestation the low level of feeding was insufficient to prevent the pregnant animals losing fat. It was calculated that at term these animals lost 140 g fat/d from maternal stores.

6. From the relation between ME intake and protein and fat deposition, estimates of ME, and the energetic efficiencies of protein (k,) and fat (k,) deposition were determined. There was little difference in ME, (422 and 420 kJ/kg body-weight 0.5 per d) and k, (0.88 and 0.90) between pregnant and non-pregnant animals respectively. However, the pregnant animals had a higher k, (0.69 compared with 0.49 for controls) and this reflected the higher rates of protein deposition associated with pregnancy.

7. The efficiency of energy deposition in the reproductive tissue was calculated to be 0.72.
Stability of tryptophan during food processing and storage
Authors: Nielsen Henrik K. , De Weck D. , Finot P. A. , Liardon R. , Hurrell R. F.
Published: May 2005

1. The stability of tryptophan was evaluated in several different food model systems using a chemical method (high pressure liquid chromatography after alkaline-hydrolysis) and rat assays. Losses of tryptophan were compared with the losses of lysine and methionine.

2. Whey proteins stored in the presence of oxidizing lipids showed large losses of lysine and extensive methionine oxidation but only minor losses of tryptophan as measured chemically. The observed decrease in bioavailable tryptophan was explained by a lower protein digestibility.

3. Casein treated with hydrogen peroxide to oxidize all methionine to methionine sulphoxide showed a 9% loss in bioavailable tryptophan.

4. When casein was reacted with caffeic acid at pH 7 in the presence of monophenol monooxygenase (tyrosinase; EC 1.14.18.l), no chemical loss of tryptophan occurred, although fluorodinitrobenzene-reactive lysine fell by 23%. Tryptophan bioavailability fell IS%, partly due to an 8% reduction in protein digestibility.

5. Alkali-treated casein (0.15 M-sodium hydroxide, 80°,4 h) did not support rat growth. Chemically-determined tryptophan, available tryptophan and true nitrogen digestibility fell 10, 46 and 23% respectively. Racemization of tryptophan was found to be 10% (D/(D+L)).

6. In whole-milk powder, which had undergone ‘early’ or ‘advanced’ Maillard reactions, tryptophan, determined chemically or in rat assays, was virtually unchanged. Extensive lysine losses occurred.

7. It was concluded that losses of tryptophan during food processing and storage are small and of only minor nutritional importance, especially when compared with much larger losses of lysine and the more extensive oxidation of methionine.
Resting heat production in Bos indicus and their F1 crosses with exotic breeds at a thermoneutral environment
Authors: Singh Khub , Bhattacharyya N. K.
Published: May 2005

1. Resting heat production, 18 h post-feeding, was studied in Hariana cattle (Bos indicus; Zebu) and in their F1 crosses with Jersey, Brown Swiss and Holstein Friesian, at 18.5° ambient temperature in a psychrometric chamber at different ages.

2. There was no significant change in the resting heat production on a per kg body-weight (W)0.75 per 24 h basis from 16–19 to 37–40 months of age in any of the genetic groups. The daily resting heat production, however, increased with increases in body-weight and age.

3. The resting heat production in all three F1 crosses was higher than that in Hariana cattle. Among the crosses, the resting heat production was highest in the Holstein Friesian x Hariana and lowest in the Jersey x Hariana.

4. Metabolizable energy (ME) intake per 24 h was significantly different between genetic groups and in different age groups. However, ME intake per kg W0.75 was not significantly different between genetic groups.
A new bioassay for assessment of copper availability and its application in a study of the effect of molybdenum on the distribution of available Cu in ruminant digesta
Authors: Price J. , Chesters J. K.
Published: May 2005

1. Investigations were carried out on the feasibility of using an oral repletion technique in the rat to assess the bioavailability of copper in experimental sources providing no more than 250 μg Cu from any one source.

2. Preliminary studies on the response in plasma Cu ofpartially Cu-depleted rats given repletion doses of 20–50 μg Cu as CuSO4/d on four consecutive days indicated that this index of Cu status was insufficiently sensitive to Cu dose.

3. Incontrast, theactivityofcytochromecoxidase(EC1. 9.3.1)in theduodenalmucosa ofpartiallycu-depleted rats showed a measurable and uniform response to 10 μg Cu as CuSO4/d given on three consecutive days. Furthermore, when the rats were given 0, 2.5, 5.0 or 10.0 μg Cu/d, the increase in cytochromecoxidase activity above that of the unsupplemented control group was linearly related to Cu dose. The mean response in cytochromecoxidase activity in groups of eight rats was therefore used to assess the availability of Cu from experimental sources relative to that of Cu as CuSO4, only 240 μg Cu being required from each experimental material.

4. The assay was used to study the effect of the Cu-antagonist molybdenum on the distribution of available Cu in digesta from sheep given dried grass either untreated (1.6 mg Mo/kg dry matter (DM)) or treated with ammonium molybdate (11.6 mg Mo/kg DM).

5. The relative availability of Cu in untreated dried grass (75%) was substantially higher than in rumen (12%), duodenal (43%) or ileal (28%) digesta. In all cases, addition of Mo to the diet resulted in a substantial reduction in Cu availability.

6. The effects of Mo on availabilitv of Cu are discussed with suecial reference to the Dossible involvement of thiomolybdates in the Cu-Mo antagonism.
Removal of digesta components from the rumen of steers determined by sieving techniques and fluid, particulate and microbial markers
Authors: Dixon R. M. , Milligan L. P.
Published: May 2005

1. When 103Ru-labelled Tris (1, 10-phenanthroline) ruthenium II chloride (103Ru-P) particulate marker in aqueous solution was added to the rumen of four steers given 5.5 kg grass hay/d at two-hourly intervals, the distribution of 103Ru-P marker among rumen particles of various sizes was the same at 4 h, 3 d and 7 d after administration, the concentration of 103Ru-P/g dry matter (DM) was inversely related to particle size and 0.30 of the 103Ru-P was associated with the DM of particles too large to be moved from the rumen at a meaningful rate. Thus, fractional outflow rate (FOR) of 103Ru-P would reflect, but was not a direct measure of, the FOR of the small particle pool in the rumen.

2. When rumen digesta were labelled with 103Ru-P, placed in nylon cloth bags and incubated in vitro with unlabelled digesta, 59% of the 103Ru-P disappeared from the nylon bag in 24 h, and 74% in 48 h. Similar results were obtained when large particles (retained by a 3.2 mm mesh screen during wet sieving) from rumen digesta were subjected to this procedure.

3. In a further experiment, the steers were given the hay in either the long or ground form and drinking water to which 10 g sodium chloride/l were, or were not, added.

4. The FOR of 51CrEDTA in centrifuged rumen fluid was increased (P < 0.05) from 1.78 to 2.10/d by grinding of the hay diet, but was not influenced by the intake of an additional 257 g NaCl/d. The FOR values of 103Ru-P in mixed rumen digesta and organic 35S in micro-organisms were linearly correlated (P < 0.05) and were not affected (P < 0.05) by grinding and salt treatments. On average, the FOR of organic 35S in micro-organisms was 0.41 of that of 51CrEDTA in centrifuged rumen fluid and 0.85 of that of 103Ru-P in rumen digesta respectively.

5. Grinding of the hay did not (P > 0.05) change the proportion of rumen DM (0.476–0.515) or faecal DM (0.107–0.153) retained by the 3.2 mm mesh and larger screens.

6. FOR from the rumen of a given size group of particles was calculated as the ratio, estimated daily flow from the rumen of the size group: rumen pool of the group. With increasing particle size there was a progressive decline in FOR; values of FOR for groups of particles greater than 4.0 mm were negligible. If the rumen DM was considered to behave as two pools, the 3.2 mm mesh screen appeared to be an appropriate division between the large-particle and the small-particle DM pools.

7. FOR of lignin present in mixed rumen digesta was 0.48 of the mean of the FOR values of the particle groups of the small-particle pool, while the FOR of lignin present in the small-particle pool was 0.92 of the mean small-particle FOR.
Mitochondria1 uncoupling and the isodynamic equivalents of protein, fat and carbohydrate at the level of biochemical energy provision
Authors: Livesey Geoffrey
Published: May 2005

1. The effects of uncoupling of mitochondria1 oxidative phosphorylation on the efficiency of energy conservation during oxidation of amino acids, fatty acids, glycerol, glucose and 101 food proteins have been examined in order to compare how uncoupling at coupling site 1 affects energy yields compared with uncoupling at sites 2 + 3 and uncoupling by proton leakage. The effects of uncoupling by each mechanism on the isodynamic equivalents of carbohydrate, fat and protein at the level of cytoplasmic ATP yield have been estimated.

2. Energy conservation during amino acid oxidation decreases relative to that for glucose as uncoupling by all three mechanisms increases. This effect is least when uncoupling is at site 1 and is associated with a fall in the isodynamicequivalent for protein: glucose of 4%maximally, and a fall in the cytoplasmic ATP yield for glucose of 25% (15–30% when accounting for uncertainty in the choice of proton stoichiometries).

3. Variation in the efficiency of energy conservation for the different amino acids is large for both highly coupled and uncoupled mitochondria but the range of efficiencies for the oxidation of 101 food proteins is relatively small (less than 6% of the mean) for a tightly coupled system. This range increases absolutely (minimally fourfold) and relatively (minimally 44% of the mean value) with severely uncoupled mitochondria but is nearly constant (changes by less than 1% relative to the mean) within the probable physiologically relevant range of uncoupling in the whole body and in the full range of uncoupling at site 1. The rank order position of particular proteins within the range of values is found to change most for gelatin which is oxidized with least energy conservation in a severely (unphysiologically) uncoupled system and most efficiently in a fully coupled system when oxidation of protein is considered to be direct, i.e. not via gluconeogenesis.

4. For medium- and long-chain fatty acids, uncoupling at site 1 elevates the efficiency of energy conservation relative to that for glucose (maximally 4%) whereas uncoupling by other mechanisms decreases this relative efficiency. The pattern of effects for short-chain fatty acids resembles that for the amino acids.

5. The changes in the isodynamic equivalents of protein:glucose and of fat:glucose are small when uncoupling occurs at site I and tend to cancel for a mixed diet but are additive in the effect on food energy values when uncoupling is by the other mechanisms. Hence changes in the efficiency of oxidative energy coupling at site 1 in association with Luft's disease or dietary changes would result in effects which are of little true dietetic significance on the isodynamic equivalents of nutrients at the level of cytoplasmic ATP yield in vivo.
The hypocholesterolaemic effects of pectins in rats
Authors: Judd Patricia A. , Truswell A. S.
Published: May 2005

1. The hypocholesterolaemic effects of pectins were studied in a series of five experiments in weanling Sprague-Dawley rats.

2. Expt A examined the effects of differing levels of dietary fat on plasma and liver lipids. Rats were given diets containing 100 g pectin, National Formulary (NF)/kg, and either 50,100, 150 or 200 g oil/kg. All diets contained 10 g cholesterol/kg. Plasma cholesterol levels were lower in all pectin-fed groups compared with rats given the control diet containing 100 g Solkafloc and 100 g oil/kg. Liver lipid and cholesterol levels increased with increasing fat content of the diet, reaching a plateau at 150 g fat/kg diet, but were still significantly lower in all pectin-fed groups compared with the control group.

3. Expt B. The effects of molecular weight and degree of methoxylation of pectins were studied in five groups of rats given either a control diet containing 100 g Solkafloc/kg or high molecular weight, high methoxyl pectin (HMW HMP); high molecular weight, low methoxyl pectin (HMW LMP); low molecular weight, high methoxyl pectin (LMW HMP); low molecular weight, low methoxyl pectin (LMW LMP). All diets in this and subsequent experiments contained 100 g fat and 10 g cholesterol/kg. Plasma cholesterol levels were significantly lower than control values only in the HMW HMP group. Compared with controls, animals given HMW pectins had lower levels of liver lipid and liver cholesterol; on the LMW HMP diet the liver cholesterol, but not the liver lipid, was lower.

4. Expt C. An attempt was made to clarify the possible effect of degree of methoxylation by feeding diets containing either 100 g Solkafloc/kg,100 g pectin NF/kg or 100 g very high methoxyl pectin/kg.Plasma cholesterol levels were significantly reduced by both pectins but there was no difference in effect between the two. Both had similar viscosities suggesting that this is a more important factor than methoxyl content.

5. Expts D and E. Effects of dose on hypocholesterolaemic effects of HMP and LMP were studied. Diets containing 50 or 100 g Solkafloc, HMP or LMP/kg were given in Expt D, and 25 g Solkafloc or HMP/kg, 50 g Solkafloc, HMP or LMP/kg and 100 g Solkafloc or LMP/kg in Expt E. Plasma cholesterol levels were significantly reduced in groups given 50 or 100 g HMP/kg and in groups given 100 g LMP/kg.

6.HMP were found to be more effective at lowering plasma cholesterol levels than LMP. LMW pectins were not effective. This suggests that the hypocholesterolaemic effects are at least partly due to viscosity.

7. Gut length and weight was increased in pectin-fed animals compared with controls despite their lower body-weight. The weight of small intestinal contents at death was also greater in pectin-fed rats (Expts A and B), particularly in the distal small intestine.
Zinc, copper and iron concentrations in the plasma and diets of lactating Nigerian women
Authors: Mbofung Carl M. F. , Atinmo Tola
Published: May 2005

1. Zinc, copper, iron, protein and energy intakes of 232 lactating women (consuming self-selected diets during the first 3 months post-partum) were computed from food intake values obtained using a 3 d dietary-recall method. Non-pregnant, non-lactating women (100) served as controls. Blood samples of subjects were also analysed for packed cell volume and haemoglobin concentrations as well as for plasma Zn, Cu and Fe levels by atomic absorption spectrophotometry.

2. Except for Fe, intakes of all nutrients measured were significantly lower than recommended dietary allowances for lactation. Daily mean (and SD) Zn, Cu, Fe (mg), protein (g) and energy (MJ) intakes for lactating women were 8.2 (1.6), 1.6 (0.5),29.0 (5.8), 52.4 (9.2) and 10.21 respectively. There was a significant intercorrelation between the different nutrients in the diet.

3. Mean (and SD) plasma Zn, Cu and Fe concentrations (μg/l) during the first 3 months of lactation were 666.0 (76.0), 1290.0 (150.0) and 730.0 (185) respectively. These values were significantly (P < 0.05) lower in the case of Zn and Fe and higher in the case of Cu than those of non-pregnant, non-lactating women. Maternal plasma levels of the trace elements also vaned significantly with nutritional status as indexed by haemoglobin status.

4. Correlation analysis between dietary and plasma trace element concentrations was significant for Zn (r 0.26, P < 0.00Ol) and Fe (r 0.17, P <0.05). Dietary protein intake was significantly correlated with plasma Zn (r 0.18, P < 0.005) and Fe (r 0.12, P < 0.05).

5. While maternal weight, arm circumference and skinfold thickness measurements tended to decrease with increase in the period of lactation, growth performance of entirely breast-fed babies was satisfactory as at the 12th week post-partum.
Essential fatty acids in the liver and adipose tissue of genetically obese mice: effect of supplemental linoleic and γ-linolenic acids
Authors: Cunnane S. C , Manku M. S. , Horrobin D. F.
Published: May 2005

1. Genetically obese mice (ob/ob) and their lean litter-mates were given diets iso-energetically supplemented with sucrose, hydrogenated coconut oil, safflower oil or evening primrose (Oenothera biennis) oil.

2. Weight gain over 15 weeks was significantly greater in the evening primrose oil-supplemented obese mice than in the other groups.

3. In all the groups of obese mice, liver total phospholipids contained proportionally less linoleic acid and more dihomo-γ-linolenic acid and arachidonic acid than did the lean controls.

4. As a percentage of total fatty acids, n-3 essential fatty acids (EFA) in liver and adipose tissue lipids were significantly lower in the obese mice than in the lean controls.

5. Supplementation with EFA-rich oils (safflower and evening primrose oil) increased the proportional composition of n-6 EFA and decreased the n-3 EFA more in the liver total phospholipids of the lean than the obese mice.
Abnormal essential fatty acid composition of tissue lipids in genetically diabetic mice is partially corrected by dietary linoleic and γ-linolenic acids
Authors: Cunnane S. C. , Manku M. S. , Horrobin D. F.
Published: May 2005

1. Genetically diabetic mice (db/db)and their non-diabetic litter-mates were maintained for 15 weeks on diets supplemented with safflower oil or evening primrose (Oenothera bienis) oil, both essential fatty acid (EFA)-rich sources, or hydrogenated coconut oil (devoid of EFA).

2. Plasma glucose was higher in the diabetic mice supplemented with the oils than in the unsupplemented diabetic mice. In the oil-supplemented non-diabetic mice, plasma glucose did not differ compared with the unsupplemented non-diabetic mice.

3. The proportional content of arachidonic acid in the phospholipids of the pancreas was significantly decreased in diabetic mice, an effect which was completely prevented by supplementation with safflower or evening primrose oil but not hydrogenated coconut oil.

4. In the liver phospholipids of the diabetic mice, dihomo-γ-linolenic acid was proportionally increased, an effect reduced by supplementation with safflower oil but not evening primrose or hydrogenated coconut oils.

5. In the liver triglycerides of the diabetic mice, γ-linolenic acid, dihomo-γ-linolenic acid and arachidonic acid were all proportionally decreased, effects which were also prevented by safflower or evening primrose oil but not hydrogenated coconut oil.

6. Alopecia and dry scaly skin were prominent in the diabetic mice but less extensive in the diabetic mice supplemented with EFA.
The effect of guar gum on carbohydrate-, fat- and protein-stimulated gut hormone secretion: modification of postprandial gastric inhibitory polypeptide and gastrin responses
Authors: Morgan L. M. , Tredger J. A. , Madden A. , Kwasowski P. , Marks V.
Published: May 2005

1. The effect of incorporating guar gum into predominantly single-component meals of carbohydrate, fat or protein on liquid gastric emptying and on the secretion of gastric inhibitory polypeptide (GIP), gastrin and motilin, was studied in healthy human volunteers.

2. Volunteers were given either 80 ml Hycal (carbohydrate meal), 150 g cooked lean minced beef (protein meal) or 200 ml double cream (fat meal) either with or without 5 or 6 g guar gum. Liquid gastric emptying was monitored in the fat and protein meals by taking 1.5 g paracetamol, consumed in water, with the meals and monitoring its appearance in circulation.

3. Postprandial insulin and GIP levels were both significantly reduced by addition of guar gum to the carbohydrate meal. Postprandial GIP secretion was also reduced by addition of guar gum to the protein meal, but protein-stimulated gastrin secretion was enhanced by guar gum. There was a significant negative correlation between peak circulating gastrin levels and the corresponding GIP levels. Postprandial GIP secretion and plasma motilin levels were unaffected by addition of guar gum to the fat meal.

4. 5 and 10 g guar gum/l solutions in water possessed buffering capacities between pH 2.75 and 5.5.

5. Guar gum at 5 g/l caused no detectable change in liquid gastric-emptying time.

6. The observed augmentation of gastrin secretion by guar gum following a protein meal could be due either to the buffering capacity of guar gum or to the attenuation of GIP secretion. It is possible that the chronic use of guar gum could be associated with changes in gastric acid secretion.
Prediction of body density from skinfold measurements in lactating women
Authors: Butte Nancy F. , Wills Cathy , Smith E. O'Brian , Garza Cutberto
Published: May 2005

1. Regression equations predicting body density from skinfold measurements were derived for a group of lactating women.

2. It was concluded that specific equations for lactation were not necessary, since the resultant equations were not significantly different from those published for non-lactating women.

3. The ability to predict an individual's body density from skinfold thickness measurements was unsatisfactory for either clinical or research applications.
The effect of catabolic doses of corticosterone on heat production in the growing rat
Authors: Coyer Penny , Cox M. , Rivers J. P. W. , Millward D. J.
Published: May 2005

1. The effect of corticosterone treatment on energy balance and heat production was investigated in growing rats. Animals were treated with daily subcutaneous injections of a vehicle containing 0, 50 or 100 mg corticosterone/kg for 5 d.

2. Measurements of digestible energy intake and urinary energy losses showed that corticosterone treatment resulted in a depression of metabolizable energy intake due to elevated urinary energy losses resulting from massive glucosuria.

3. Measurements of the metabolizable energy intake and the change in carcass energy indicated that at 50 mg/kg energy deposition and heat production were reduced, whilst at 100 mg/kg energy deposition was completely abolished with heat production increased. Postprandial oxygen consumption was unchanged at 50 mg/kg and increased at 100 mg/kg.

4. Factorial analysis of these results based on reported values for the energy cost of protein and fat deposition indicated that (a) the depression of total heat production at 50 mg/kg could be entirely accounted for by the concomitant suppression of growth, and (b) the elevation of total and postprandial heat production at 100 mg/kg reflected a specific influence of corticosterone on thermogenesis.

5. The significance of these findings is discussed in the light of reports that corticosterone in low doses suppresses heat production.
The nitrogen requirement of the weanling kitten
Authors: Smalley Katherine A. , Rogers Quinton R. , Morris James G. , Eslinger Loren L.
Published: May 2005

1. The nitrogen requirement of the weanling kitten was determined in a series of three experiments. In each experiment, diets were formulated to provide the growing kitten with the essential amino acids at or above the level of requirement. Expt 1 utilized a 4 x 4 balanced Latin square design with two groups of kittens (four male and four female). The crystalline L-amino acid diets were presented at four levels of dietary crude protein (N x 6.25) of 140, 160, 180 and 200 g/kg diet. The design for Expts 2 and 3 was a 6 x 6 balanced Latin square. For each of these experiments, groups of six male and six female kittens were assigned to diets. The six levels of dietary crude protein were 120, 140, 160, 180, 200 and 220 g/kg diet; dietary N was supplied by crystalline L-amino acids for Expt 2 and casein plus a supplementary amino acid mix for Expt 3. Food intake, weight gain and N retention were determined in each experiment.

2. A sigmoidal model y =P1+ P2/[1 +e(p2+p4. x)] was fitted to the response of weight gain and N retention to dietary N. The calculated requirement (95% of the upper asymptote, P1 + P2) for these experiments varied from 170 to 230 g protein/kg diet with the majority of these values falling between 180 and 200 g protein/kg.

3. On the basis of these three experiments, the kitten's requirement for dietary crude protein is between 180 and 200 g/kg diet (28.8–32.0 gN/kg) for purified diets which provide a calculated 21 MJ metabolizable energ//kg diet.
The digestion of fibre by pigs
Authors: Stanogias George , Pearce G. R.
Published: May 2005

1. The effect of including lupin (Lupinussp.) hulls, maize cobs, wheat bran and lucerne (Medicago sutiva) stems in a basal fibre-free diet on the concentrations and the relative proportions of volatile fatty acids (VFA) in the proximal colon of pigs, 17–18 h after feeding, was studied.

2. Concentrations of total VFA in the proximal colon increased with increasing levels of neutral-detergent fibre (NDF) intake, and this increase was highly dependent on the source of NDF in the diet.

3. Molar proportions of the VFA were significantly affected by the level of NDF intake only in the cases of acetic and butyric acids, whereas the source of dietary NDF had a marked influence on the molar proportions of all acids.

4. The results indicate that the extent of fermentative breakdown of fibre in the pig intestine can be influenced substantially by the type and the level of fibre in the diet.
The digestion of fibre by pigs
Authors: Stanogias George , Pearce G. R.
Published: May 2005

1. The aim of the study was to determine the relative effects of feeding growing pigs with graded amounts of neutral-detergent fibre (NDF) from various sources on the empty wet weight of segments of the pig gastrointestinal tract, on the weight and moisture content of their digesta, and on the pattern of digesta movement in them.

2. Increased NDF intakes were associated with significantly higher wet weights of all gastrointestinal segments and increased lengths of the caecum. The lengths of both the small and the large intestines were unaffected by the ingestion by the pigs of different amounts of NDF from various sources. However, the caecum responded to these increased intakes of NDF by significant increases in length. The source of NDF in the diet was a factor that markedly influenced both the length and the weight of the distal colon. The nature of these increases in weight and length morphologically and their biological significance have not been determined.

3. Despite some significant differences, neither the type nor the level of dietary NDF had any appreciable effect on the dry weight and on the proportion of dry matter (DM) of the contents in the stomach. As the level of NDF intake was increased, more undigested dietary material was found in all segments of the digestive tract of the pigs. The proportion of DM in the residues decreased progressively from the caecal contents to the contents of the distal colon. In most cases the degree to which the level of NDF intake affected the weight of the contents and the proportion of DM in them was highly dependent on the source of NDF in the diet.

4. The distribution of the feed consumed in the morning and in the evening, as measured with stained feed particles and polyethylene beads, was extremely variable. It is concluded that prolonged intakes by pigs of diets containing high levels of fibre may lead to a hypertrophy and hence increased weight of segments of the gastrointestinal tract.
The effect of indigestible particles on digestive transit time and colonic motility in dogs and pigs
Authors: Cherbut Ch. , Ruckebusch Y.
Published: May 2005

1. The myoelectric activity of the colon was examined in three dogs and three pigs when they were given a basal diet or a basal diet plus indigestible particles (IP), 2 mm in diameter, at 100 g/kg dry matter. The mean retention time was determined using coloured discs as a marker added to the daily meal.

2. Colonic electromyograms of dogs and pigs given IP revealed a 30% reduction in the number of long spike bursts (LSB) when compared with controls. The other components, propulsive migrating spike bursts (MSB) or non-propulsive short spike bursts (SSB), were unchanged. Mean retention time was decreased from 28.6 h to 17.6 h in dogs and from 129 h to 94.2 h in pigs.

3. These changes developed progressively during 3–4 d in both species, suggesting that the reduction in motor activity was an adaptation to the changes in bulk contents.

4. From the decreased motility of the colon linked to the reduction of LSB and paralleled by an increased transit time, it was concluded that one of the functions of the LSB is to impede the passage of digesta.
Retention time of chromium-labelled feed particles and of water in the gut of sheep given hay and concentrate at maintenance
Authors: Lindberg J. E.
Published: May 2005

1. Sheep were given a diet of 400 g chopped grass hay/d and 500 g crushed barley/d in three equal meals. The mean retention time in the whole gut (MRT) and the rumen retention time (RRT) of chromium-labelled feed particles and of water were estimated from marker concentrations in faecal samples.

2. MRT of Cr-labelled hay (Cr-H), barley hulls (Cr-Bh), crushed peas (Pisum sativum) (Cr-CP) and rapeseed meal (Cr-RSM) were 53.5, 52.3, 44.3 and 37.0 h respectively when estimated from total faecal collections. The estimates obtained from spot samples of faeces were almost identical.

3. RRT of Cr-H, Cr-Bh, Cr-CP, Cr-RSM (Expts 1, 2 and 3) and Cr-labelled cottonseed meal (Cr-CSM) was 35.9, 36.7, 25.3, 18.8, 19.8, 22.8 and 25.3 h respectively.

4. The Cr-labelled feed particles showed marked variations in density in water (Dω). However, both MRT and RRT were closely related to Dω, (r—0.88 and —0.95 respectively).

5. Rumen outflow rates of Cr-RSM in individual animals were related to the rumen outflow rates of water (r 0.76).
The threshold growth response ofLactobacillus caseito 5-methyl-tetrahydrofolic acid: implications for folate assays
Authors: Wright A. J. A. , Phillips D. R.
Published: May 2005

1. The comparative and absolute growth response of Lactobacillus casei was measured nephelometrically for time periods of 17–23 h in the microbiological assay of folic acid and 5-methyl-tetrahydrofolic acid at concentrations of 0–8 ng/10 ml basal medium at pH 6.8.

2. At concentrations of 0–1 ng/10 ml the comparative growth response to 5-methyl-tetrahydrofolic acid was markedly depressed whereas growth was the same at 2 ng/10 ml and above. Comparative growth was unaffected by the length of assay incubation, depressed growth being due to differences in log-phase growth rates with the rate-plot for 5-methyl-tetrahydrofolic acid being sigmoidal and for folk acid being a rectangular hyperbola with linearity only in the 0–1 ng/10 ml range. The reciprocal rate-plot for folic acid was linear whereas that for 5-methyl-tetrahydrofolic acid was coincidental only in part, giving rise to the same estimate of maximum velocity and substrate concentration for half-maximum velocity, with the exhibition of a strong threshold at low concentration.

3. A previous observation (Phillips & Wright, 1982) that the L. casei growth response to 5-methyl-tetrahydrofolic acid may be significantly less than that to folic acid is confirmed as is the long-established view that the response to both folates may be equal. In the light of current knowledge regarding folate-binding, transport and metabolism by L. casei, it is argued that the intracellular oxidation of 5-methyl-tetrahydrofolic acid to 5, 10-methylene-tetrahydrofolic acid is a rate-limiting step at low substrate concentrations, subsequently giving rise to a threshold growth response peculiar to 5-methyl-tetrahydrofolic acid. Since the rate of L. cusei growth with folk acid is not linearabove 1 ng/10 ml, it is recommended that microbiological folate assays be conducted only in the 0–1 ng/10 ml range and at a pH that elicits the same growth response from L. casei to 5-methyl-tetrahydrofolic acid as to folic acid and other folate monoglutamates.
The retention of 59Fe and 65Zn by preruminant lambs given milk-substitutes based on either casein or soya-bean-protein isolate
Authors: Hill R. , Walker D. M.
Published: May 2005

1. Eight newborn lambs were given milk-substitutes based on casein (n 4) or a soya-bean-protein isolate (n 4). On the morning before a 10 d collection period, the milk-substitutes were supplemented with 59Fe as ferric chloride and 5Zn as zinc chloride. Faeces and urine were collected daily and determinations of 59Fe and 65Zn were made on these separately. During a second 10 d period the dosing procedure and collection were repeated but the diet of each lamb was reversed.

2. Mean retention of 59Fe in lambs given the casein diet was 0.50 (SE 0.12) and in those given the soya-bean-protein diet 0.06 (SE 0.05). There were large variations among animals but the treatment effect was significant at P < 0.05. Retention of 65Zn was significantly greater than that of 59Fe for all lambs but the effect of dietary treatment was similar to that for Fe. 65Zn retention values for casein and soya-bean-protein diets were 0.84 (E 0.06) and 0.52 (SE 0.03) respectively, and the difference was significant at P < 0.01.

3. There were only very small amounts of 59Fe and 65Zn in urine, representing 0.002–0.003 of the dose.
Intestinal cellular proliferation and protein synthesis in zinc-deficient rats
Authors: Livesey Susan Southon G. , Gee Jennifer M. , Johnson I. T.
Published: May 2005

1. Immature male Wistar rats were given a low-zinc semi-synthetic diet (2 mg Zn/kg) for 28 d. Control groups received a similar diet supplemented with 58 mg Zn/kg either adlib.or in amounts matched to the consumption of the Zn-deficient group. Rates of growth, food consumption and small intestinal length were significantly reduced in the Zn-depleted rats.

2. Zn deficiency in the rat was associated with a reduction in the ratio, crypt:villus and a lower rate of crypt cell division in the jejunum. This resulted in a substantial decrease in the net influx of new cells into the villi of the Zn-deficient animals compared with controls.

3. The fractional rates of protein synthesis in jejunal mucosa were measured by a technique based on the determination of L-[4-3H]phenylalanine incorporation. There was no evidence of a decline in the protein synthetic rate in total mucosa from Zn-deficient rats.

4. It is suggested that a reduction in cell influx into the villi may be responsible for the morphological and functional changes observed in the small intestine of rats fed on a low-Zn diet.
Influence of feed intake and starvation on the magnitude of Na+,K+-ATPase(EC 3.6.1.3)-dependent respiration in duodenal mucosa of sheep
Authors: McBride B. W. , Milligan L. P.
Published: May 2005

1. Oxygen consumption and Na+,K+-ATPase(EC 3.6.1.3)-dependent (ouabain-sensitive) and -independent respiration were measured for duodenal mucosa biopsies from 10-month-old sheep given two levels of digestible energy (DE) intake (7.6–7.7 and 14.8 MJ lucerne (Medicago sativa) pellets/d) and following 48 h of starvation.

2. The mucosal biopsies were determined to be structurally intact and free of adherent bacteria on histological and scanning-electron-microscope examinations.

3. The use of D-glucose as a substrate during incubations did not elevate (P > 0.05) the respiration indices of the biopsies over those measured during acetate incubations.

4. Glucose uptake did not (P > 0.05) influence the Na+,K+-ATPase-dependent respiration of the mucosal biopsies.

5. Na+,K+-ATPase-dependent respiration accounted for 50% of the total O2, consumption of the mucosal biopsies of sheep given the lower level of DE.

6. Total O2, consumption of the duodenalmucosa was not (P > 0.05) increased when sheep were given the higher level of DE but Na+,K+-ATPase-dependent respiration of the mucosa was elevated (P < 0.01) by 37% during this period.

7. When sheep were starved for 48 h, total O2, consumption of the mucosal biopsies was not (P > 0.05) affected, however, Na+,K+-ATPase-dependent respiration of the biopsies dropped (P < 0.01) by 45%.

8. Na+,K+-ATPase-dependknt respiration accounted for 61.3% of the O2, uptakes of mucosa from the sheep given the higher level of DE and 28.3% of the 02, uptake of mucosa from fasted sheep.
Effects of undernutrition and exercise during late pregnancy on uterine, fetal and uteroplacental metabolism in the ewe
Authors: Chandler K. D. , Leury B. J , Bird A. R. , Bell A. W.
Published: May 2005

1. Uterine, umbilical and, by difference, uteroplacental net uptakes of oxygen, glucose, lactate and 3-hydroxybutyrate (uterine uptake only) were measured in single-pregnant ewes which were either well-fed throughout, or severely undernourished for 8–20 d during late pregnancy. All animals were studied while standing at rest and then while walking on a treadmill at 0.7 m/s on a 10° slope for 60 min.

2. Undernutrition did not significantly affect fetal or placental weights at 143 d gestation but caused a 14% decrease in maternal live weight. Uterine blood flow was decreased by 32% and was associated with a significant decrease in uteroplacental oxygen uptake; neither umbilical blood flow nor fetal O2, uptake were affected by maternal plane of nutrition. Maternal and fetal hypoglycaemia in underfed ewes was accompanied by 46–63 % decreases in uterine, umbilical and uteroplacental net uptakes of glucose, and similar declines in uterine and umbilical glucose/O, quotients. Moderate maternal hyperketonaemia was associated with 2.5-fold and 3-fold increases in uterine net uptake of 3-hydroxybutyrate and 3-hydroxybutyrate/O2quotient respectively.

3. Exercise caused significant decreases in uterine blood flow in fed and underfed ewes but did not affect uterine or umbilical O2uptakes; uterine net glucose uptake increased in most ewes but umbilical uptake was not significantly affected. Umbilical net uptake of lactate was significantly reduced. In underfed ewes, the extent of hyperketonaemia was significantly reduced by exercise.

4. Contrary to earlier proposals, the ovine pregnant uterus is sensitive and adaptable to long- and short-term alterations in maternal energy balance, as achieved by chronic undernutrition and exercise respectively. Thus, the fetus and placenta significantly add to, but do not necessarily have priority over the energy demands of other tissues of the ewe.
Utilization of low-quality roughage by Bos taurus and Bos indicus cattle
Authors: Hunter R. A. , Siebert S. D.
Published: May 2005

1. Six Hereford and six Brahman steers were fed ad lib. Pangola grass (Digztaria decumbens) and Spear grass (Heteropogon contortus) hay alone and supplemented with rumen-degradable nitrogen and sulphur and minerals. The rumen digestion of the two feeds was determined by reference to the disappearance of substrate from nylon bags suspended in the rumen and withdrawn after intervals ranging from 8 to 120 h.

2. The digestion of the unsupplemented Pangola grass diet occurred more rapidly in Brahmans than in Herefords and was associated with higher rumen ammonia concentrations in Brahmans (40 v. 16 mg/l). The rumen NH3, concentrations were increased to over 100 mg/l by supplementation. The digestion rate increased in both breeds after supplementation and the breed difference disappeared. Increases in digestion rate were not achieved above NH3, concentrations of 60–80 mg/l.

3. Spear grass, especially the cell-wall-constituent fraction, was more resistant to digestion than Pangola grass. Digestion of the unsupplemented Spear grass diet proceeded more rapidly in Brahmans than in Herefords. The digestion rate in Brahmans were similar irrespective of whether the diet was supplemented or not. Supplementation increased digestion rate in Herefords.
A multicompartmental model to describe marker excretion patterns in ruminant faeces
Authors: Dhanoa M. S. , Siddons R. C. , France J. , Gale D. L.
Published: May 2005

1. A multicornpartmental model, which assumes first-order kinetics, is proposed to describe digesta flow along the gastrointestinal tract of ruminants.

2. Solution of the model yields a multiplicative equation, containing a single-exponential term and a double-exponential term, for describing faecal outflow rate.

3. The logarithmic transformation of the equation was fitted to eighty-two excretion curves obtained after the administration of marker into the rumen of cattle and sheep, and compared with other published models.

4. It was found to be superior to the other models in that it fitted all the data sets successfully.
Digestion, absorption and utilization of single-cell protein by the preruminant calf
Authors: Sedgman Cynthia A. , Roy J. H. B. , Thomas Joanne
Published: May 2005

1. Two experiments of Latin square design, with four Friesian bull calves fitted with re-entrant duodenal cannulas at 4–10 d of age, were made to study the effect of giving varying levels of single-cell protein on the abomasal outflow and composition of digesta.

2. In Expt 1, diets in which 0,220,440, and 660 g/kg milk protein were replaced by the bacterial protein Pruteen were compared from 14 d of age. In Expt 2, which began at about 61 d of age, a comparison was made of diets in which 0, 220, 440 and 660 g/kg milk protein were replaced by the yeast protein Toprina.

3. Collection of abomasal outflow was made for 8 h after feeding for 2 d within each 6 d period of the Latin square design experiment. The amount of diet offered daily was 50 g dry matter/kg body-weight0.75.Polyethylene glycol (PEG), which was used as an indigestible marker, total nitrogen (TN), protein-N (PN), fat, and potassium, sodium and chloride ion outflows were measured together with pepsin (EC 3.4.23.1) and chymosin (EC 3.4.23.4) activities, pH and titratable acidity.

4. In Expt 1 there was little difference in the outflow of liquid digesta between diets and about 0.9 of the dietary PEG was recovered within the 8 h collection period. With increasing amounts of Pruteen in the diet, outflows of TN, PN, fat and Na+increased, and the pH of digesta increased. However, the volume of 'apparent secretion' into the abomasum (outflow - intake), pepsin activity, chymosin activity, titratable acidity, (outflow of C1--outflow of Na+) as a measure of outflow of HC1, and outflows of K+and of C1-were reduced. All outflows decreased with the time interval after feeding, except (Cl--Na+) outflow.

5. In Expt 2, the same trends as in Expt 1 were apparent, but since one calf had to be slaughtered and the experiment had to be analysed as a randomized block, only PN and K+outflows and pH were significantly affected by dietary treatment, with K+outflow increasing, rather than decreasing, with increasing concentration of single- cell protein in the diet.

6. Reduced proteolysis in the abomasum, associated with a faster and greater outflow of protein as a result of poor or no coagulation of protein in the abomasum, and a reduction in secretion of enzymes and in acidity may partly explain the poor protein digestibility and growth rate obtained in other experiments when diets containing more than 100 g single-cell protein/kg diet (about 200 g protein/kg total protein) were given to young calves.
Description of a human direct calorimeter, with a note on the energy cost of clerical work
Authors: Webster Joan D. , Welsh Gillian , Garrow J. S.
Published: May 2005

1. A heat-sink calorimeter, suitable for the measurement of energy expenditure in human subjects over periods up to 26 h, is described.

2. The performance of the calorimeter is illustrated by a study of four normal subjects at rest or performing clerical work for a period of 7.5 h. Each condition was measured in duplicate in each subject. On the resting days the subjects were recumbent, and on the working days they were seated throughout the measurement period. Heart rate was monitored by infra-red telemetry and physical activity by an ultrasound movement detector. Urinary cortisol excretion was also measured as an indicator of stress.

3. In each subject the mean heat loss on working days was higher than that on resting days: the increase ranged from 5.1 % to 16.7, with a mean value of 10.0% (P = 0.015). There was no significant difference between resting and working days in heart rate, physical activity or urinary cortisol excretion.

4. The present study confirms that tiring clerical work has very little effect on 24 h energy expenditure.
Changes in plasma fibronectin during acute nutritional deprivation in healthy human subjects
Authors: Chadwick S. J. D. , Sim A. J. W. , Dudley H. A. F.
Published: May 2005

1. Plasma fibronectin, a glycoprotein, is an opsonin of the reticuloendothelial system.

2. In ten healthy volunteers starved for 4.5 d, daily measurements showed a rapid reduction in plasma fibronectin, no alteration in either C3 or plasma transferrin and, at the end of the starvation period, an elevated serum albumin.

3. On refeeding, plasma fibronectin rapidly returned to its prestarvation level but plasma transferrin was significantly reduced and did not recover by the end of the study.

4. Changes in plasma fibronectin may be a sensitive index of nutritional status. The reduction of plasma fibronectin in short-term starvation may compromise host defence tolerance of injury and sepsis.