bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of guar gum on intestinal cholesterol transport in the rat
Authors: Gee Jennifer M. , Blackburn N. A. , Johnson I. T.
Published: September 2005

1. Everted sacs of rat proximal small intestine were used to determine the effect of guar gum (5 g/l) on the uptake of cholesterol (0·1 mM) from a solution of micelles.

2. The uptake of cholesterol was found to be linear both in the presence and absence of guar gum. When guar was present throughout the whole of the incubation medium, the uptake of cholesterol was reduced to approximately 40% of control values. Sacs which had been pre-incubated in guar gum before exposure to cholesterol in a guar-free medium also showed a reduction in cholesterol uptake but this was less pronounced.

3. A two-stage perfusion technique, previously described (Blackburn & Johnson, 1981), was used to determine the effect of a guar layer adsorbed to the mucosal surface on cholesterol absorption in vivo. Such a layer leads to a reduction of approximately 36%: itwas concluded that guar slows the absorption of cholesterol from micelles by a mechanism, or mechanisms, involving an increased resistance to diffusion in the aqueous medium.

4. Groups of rats were meal-fed for at least 30 d on semi-synthetic diets with or without the inclusion of guar gum (20 g/kg). Rates of intestinal absorption of cholesterol, glucose and fluid were then determined by the perfusion technique in vivo. There was no reduction in absorption in the test animals compared with the controls.

5. It is proposed that guar gum is able to slow the intestinal transport of cholesterol from a suspension of pre-formed micelles, but only when both are present in the lumen together. No evidence was obtained to suggest that the consumption by rats of a diet containing guar gum, at a level similar to that used in human studies, leads to any adaptive reduction in their rates of cholesterol or glucose absorption.
Effects of trenbolone acetate and zeranol on protein metabolism in male castrate andfemale lambs
Authors: Sinnett-Smith Patrick A. , Dumelow Nicola W. , Buttery Peter J.
Published: September 2005

1. Tissue composition and skeletal muscle cathepsin D (EC3.4.23.5) activity weremeasured in wether lambs treated with trenbolone acetate (TBA) and oestradiol-17β (Oe) in combination and female lambs treated with TBA or zeranol. Muscle and liver protein fractional synthesis rates and plasma leucine flux were measured in the female lambs.

2. Male castrate lambs treated with TBA plus Oe showed increased growth rate, improvedfood conversion efficiency, decreased muscle RNA concentration and decreased total cathepsin D activity in muscle.

3. Female lambs treated with TBA or zeranol showed increased weight gain, improved food conversion efficiency, decreased muscle RNA and DNA concentrations and decreased free cathepsin D activity in muscle. Mixed muscle protein fractional synthesis rate was decreasedafter TBA treatment. Plasma leucine flux, not corrected for oxidation or food intake, wasnot increased by TBA or zeranol treatment.

4. Treatment of female lambs with TBA or zeranol caused increased growth rate. This increased growth rate is probably due in part to decreased muscle protein degradation, since evidence was obtained that muscle protein synthesis is decreased by TBA and zeranol treatment.
Tissue glucose and lactate metabolism and interconversions in pregnant and lactating sheep
Authors: van der Walt J. G. , Baird G. D. , Bergman E. N.
Published: September 2005

1. Continuous infusions of [14C]glucose and [14C]lactate on separate days, and measurements of blood flow-rate, were used to obtain values for rates of unidirectional metabolism and of interconversion of glucose and lactate in the portal-drained viscera, liver and hind-quarters of ewes during late pregnancy and early lactation. All infusions were made within 5 h after the morning meal, when steady-state conditions appeared to exist.

2. Use was made of ewes that had been appropriately catherized during pregnancy, and whose catheter remained patent through into lactation.

3. The liver was the main source of glucose production (67–70%) during both pregnancy and lactation. Other sources were the portal-drained viscera (absorbed glucose) and, presumably, the kidneys. Over 80% of the glucose was utilized by the peripheral tissues with approximately 35–40% of utilization being attributable to the hind-quarters.

4. Of the total lactate production, 76% occurred in the peripheral tissues during pregnancy but only 36% during lactation. While the liver utilized 73% of lactate during pregnancy, this value fell to only 42% during lactation, at which time the portal-drained viscera utilized 26% of the lactate.

5. During pregnancy, approximately 80% of the lactate arose from glucose, chiefly in peripheral tissues, while at least 12% of the glucose arose from lactate, chiefly in the liver. During lactation the extent of these interconversions was decreased.

6. Despite the interconversions, whole-body turnover rates for glucose and lactate were under- or overestimated by only 4–10% and 2–5% respectively. Furthermore, a comparison of turnover rates obtained with [U-14C]- and [6−3H]glucose indicated that there was only 6 and 2% recycling of glucose-C during pregnancy and lactation respectively.

7. Under the conditions employed in this study, lactate does not appear to be a major precursor of glucose in the ruminant, and most of the lactate taken up by the liver must be used for purposes other than gluconeogenesis, such as oxidation or alternative anabolic pathways.
Copper metabolism in growing sheep given kale (Brassica oleracea) and ryegrass (Lolium perenne)–clover (Trifolium repens) fresh forage diets
Authors: Barry T. N. , Millar K. R. , Bond G. , Duncan S. J.
Published: September 2005

1. Kale (Brassica oleracea) and ryegrass (Lolium perenne)–clover (Trifolium repens) pasture grown under similar soil conditions were grazed in the vegetative state by growing lambs of 23·6 kg initial live weight for 24 weeks. Forty-eight lambs grazed each forage. The kale and pasture contained respectively 4 and 14 mg copper/kg dry matter (DM), 7·2 and 3·1 g total sulphur/kg DM and 0·4 and 1·1 mg molybdenum/kg DM.

2. Subcutaneous injections of Cu (12 mg) were given to half the animals grazing each forage during weeks 1, 6, 12 and 18.

3. All ninety-six animals were slaughtered at the end of the experiment and an additional group of twelve animals was slaughtered when the experiment commenced. Liver Cu was determined on all slaughtered animals and heart muscle cytochrome oxidase (EC1.9.3.1) activity on those slaughtered at week 24. Blood samples removed at 6-week intervals were assayed for activity of superoxide dismutase (EC1.15.1.1; SOD) and serum Cu concentration determined. Wool growth, live-weight gain and cytochrome oxidase activity of biopsied hind-limb muscle were also measured at 6-week intervals.

4. Control animals grazing pasture showed an accumulation of total liver Cu during the experiment. Animals grazing this diet and given Cu injections showed an additional accumulation of liver Cu equivalent to the supplementary Cu administered, but Cu supplementationdid not affect the activity of any of the Cu-containing enzymes measured and did not affect live-weight gain or wool growth.

5. Control animals grazing kale showed a depletion of total liver Cu and reductions in serum Cu concentrations during weeks 18 and 24. However, cytochrome oxidase activity inheart and hind-limb muscle was similar to that of pasture-fed lambs. Blood SOD activity was reduced by kale feeding, but a laboratory study showed this enzyme was not inactivatedby dimethyl disulphide produced from rumen fermentation of S-methyl-L-cysteine sulphoxide(SMCO) which occurs in kale.

6. Cu supplementation of kale-fed lambs had no effect on hind-limb cytochrome oxidaseactivity, but considerably increased total cytochrome oxidase activity in the heart and minimized the reduction in blood SOD activity. Both are considered to represent defence mechanisms against the haemolytic anaemia caused by SMCO. However, Cu supplementation did not affect live-weight gain or wool growth.

7. The proportion of injected Cu not recovered in the liver at slaughter was greater for lambs grazing kale than ryegrass–clover pasture and the same result was calculated from Barryet al.(1981) for growing cattle. It was therefore concluded that Cu requirements must be greater for growing sheep and cattle grazing kale than ryegrass-clover pasture.
Glucose production and utilization in non-pregnant, pregnant and lactating ewes
Authors: Wilson Stephen , MacRae J. C. , Buttery P. J.
Published: September 2005

1. By using continuous infusions of 3H- and 14C-labelled substrates, three-pool models, incorporating rumen propionate, plasma glucose and blood carbon dioxide were constructed to determine the contribution of propionate to glucose in non-pregnant, pregnant (mid and late) and lactating hill ewes.

2. Although the intakes of non-pregnant and pregnant ewes were the same (1200 g driedgrass/d) and resulted in similar levels of propionate production (33 g C/d), glucose production rate (GPR) increased from 44 g C/d in the non-pregnant ewes to 62 g C/d in the ewes carrying twins in late pregnancy. In lactating ewes given 2500 g dried grass/d, propionate production increased to 56 g C/d and GPR increased to 93 and 104 g C/d in ewes suckling single and twin lambs respectively.

3. There was an increase in the percentage of the propionate resource which was diverted to glucose, from 37% in the non-pregnant ewes and ewes in mid-pregnancy, to 55% in late pregnancy and 60% in lactation. In spite of this apparent metabolic adaptation to the additional requirements for glucose, approximately 55% of the glucose-C was supplied by metabolites other than propionate and CO2.

4. From the determination of plasma glycerol concentrations it was estimated that themaximum possible contribution of glycerol-C to glucose was only 8–12 g C/d. Theremaining 40% of the glucose-C could not be accounted for and could have been derived from non-essential amino acids (NEAA).

5. In the non-pregnant and pregnant ewes only 62% of the GPR was oxidized to CO2. In the lactating ewes only 49 and 30% of the GPR was oxidized to CO2 in the ewes suckling single and twin lambs respectively.

6. In the majority of cases there was a marked similarity between the amounts of glucose-C apparently derived from NEAA and the amount of glucose-C which was not oxidized to CO2.
Amino acid oxidation by young pigs receiving diets with varying levels of sulphur amino acids
Authors: Kim Kyu-Il , Bayley Henry S.
Published: September 2005

1. Piglets were weaned at 3 d of age and were introduced to liquid diets in which 400 g/kg protein was supplied as skim-milk powder and the balance as a mixture of free amino acids. The skim milk contributed 2·3 g methionine and 1·4 g cystine/kg diet; the experimental diets were made by supplementing these levels with free amino acids.

2. The adequacy of the test level of the amino acid in the diet was assessed by measuring the oxidation of [1−14]phenylalanine as an indicator of the partition of the essential amino acids between incorporation into protein and degradation. Radioactivity recovered as carbon dioxide was used as a measure of catabolism.

3. Addition of 0·2, 0·4, 0·7, 1·2 and 1·7 g L-methione/kg to a diet containing 5 g cystine and 3 g choline chloride/kg showed that phenylalanine catabolism was minimal for the diet with 2·7 g methionine/kg indicating that this is the dietary requirement for methionine to serve as a source of methionine residues for protein synthesis.

4. Addition of D-methionine to produce a series of diets with graded levels of methionine showed that the D-isomer was less effective than the L-isomer in reducing phenylalanine catabolism: the addition of 0·8 g D-methionine/kg diet was needed to produce the same effect as 0·4 g L-methionine/kg diet showing that the replacement value of D-methionine for L-methionine was 50% in the young pig.

5. To investigate the influence of cystine on methionine requirement, diets with varying levels of methionine and cystine were prepared. Oxidation of [U-14C]methionine was used as an indication of an excess of methionine, and the results showed that increasing the dietary methionine level above 3·0 g/kg in diets containing 1·4 g cystine/kg provided an excess of methionine for oxidation. This indicated a sulphur amino acid requirement of 4·4 g/kg, one-third of this being supplied as cystine.
Oxidation of an indicator amino acid by young pigs receiving diets with varying levels of lysine or threonine, and an assessment of amino acid requirements
Authors: Kim Kyu-Il , Elliott James I. , Bayley Henry S.
Published: September 2005

1. The catabolism of [14C]phenylalanine was used to indicate the effects of varying the dietary level of lysine and threonine on the retention of dietary amino acids by 2-week-old pigs receiving diets containing skim milk and a mixture of free amino acids.

2. Reducing the dietary level of lysine from 16 to 12 g/kg had no influence on phenylalanine oxidation, reducing the lysine level from 12 to 11 then to 10 g/kg caused an almost linear increase in phenylalanine oxidation whereas further reduction to 9 or 8 g/kg resulted in a less-marked increase in phenylalanine oxidation. This showed that 12 g lysine/kg was required to maximize amino acid retention and indicated that lysine was conserved more effectively at low dietary concentrations than at dietary concentrations approaching the requirement.

3. Reducing the dietary level of threonine from 8 to 6 g/kg had no influence on phenylalanine oxidation, whereas further reduction to 4 g/kg caused a linear increase in phenylalanine catabolism showing that 6 g threonine/kg was required to maximize amino acid retention.

4. Reduction of the levels of lysine, threonine and methionine from the generous levels characteristic of a diet containing 240 g protein from skim milk/kg, to the requirement levels determined separately in the presence of the generous levels of all the other amino acids, resulted in a twofold increase in phenylalanine catabolism. This shows that the pig seems able to conserve limiting intakes of a single amino acid, but not if the intakes of two or three amino acids are limiting.
Vitamin A absorption and metabolism in the chick: response to high dietary intake and to tocopherol
Authors: Sklan David
Published: September 2005

1. Absorption of14C-labelled retinol was determined along the gastrointestinal tract of chicks, using141Cerium as a non-absorbed reference substance, as influenced by high dietary vitamin A and the addition of tocopherol to the diet.

2. The site of major vitamin A absorption was the proximal small intestine and high intake of vitamin A reduced slightly the percentage over-all absorption.

3. Labelled glucuronides were secreted into the duodenum and were 50–60% reabsorbed in the small intestines. High-vitamin-A intakes enhanced the duodenal flow of retinyl glucuronides.

4. In vitro hepatic retinol esterification and glucuronide production were enhanced in chicks given high dietary vitamin A.

5. Plasma transport and clearance of retinol were enhanced by feeding high levels of vitamin A and further enhanced when tocopherol at high concentrations was present in the diet.

6. Dietary tocopherol had no effect on absorption, increased hepatic vitamin A stores and in vitro retinol esterification, and decreased retinyl glucuronide flows through the duodenum.
Factors influencing the digestion of dietary carbohydrates between the mouth and abomasum of steers
Authors: McAllan A. B. , Smith R. H.
Published: September 2005

1. Six protozoa-free steers with simple rumen and abomasal cannulas were given basal diets consisting of a concentrate mixture of flaked maize and tapioca with either barley straw (BS) or alkali-treated barley straw (BSA). Other diets used were supplemented with urea (BSU and BSAU respectively) or contained fish meal in place of tapioca BSF and BSAF (respectively). The diets were given in a 6 × 6 Latin square design. Diets were isoenergetic and provided sufficient metabolizable energy (ME) to support a growth rate of approximately 0·5 kg/d. Basal diets, urea- and fish-meal-supplemented diets had estimated rumen-degradable nitrogen (RDN): ME values (g/MJ) of 0·5, 1·2 and 0·8 respectively. 103Ruthenium and polyethylene glycol were given as flow markers, and flows (g/24 h) at the abomasum of organic matter (OM) and carbohydrate components were calculated.

2. True digestibility coefficients of OM between mouth and abomasum were significantly greater for diets containing alkali-treated straw (approximately 0·63) than for those containing untreated straw (approximately 0·55) but were not significantly affected by N supplementation.

3. Digestibility coefficients of the neutral-sugar components of dietary polysaccharides between mouth and abomasum were 0·28, 0·34, 0·31, 0·23, 0·31 and 0·87 for mannose, galactose arabinose, xylose, cellulose-glucose and starch-glucose respectively for diet BS. Corresponding values were 0·37, 0·42, 0·56, 0·51, 0·40 and 0·88 for diet BSA. All but the mannose and starch-glucose values were significantly greater for the latter diet. N supplementation also led to increases in digestibility of all neutral sugars except mannose and starch-glucose. Fish meal produced a markedly greater effect than urea but only significantly so for cellulose-glucose. Thus, the highest digestibilities were seen for diet BSAF and were 0·68, 0·67, 0·74 and 0·64 for galactose, arabinose, xylose and cellulose-glucose respectively. Of all these sugars xylose consistently showed the greatest response in digestibility to sodium hydroxide treatment or N supplementation.
Protein, essential amino acids and glycine requirements of the growing gosling (Anser cireneus)
Authors: Nitsan Zafrira , Dvorin A. , Nir I.
Published: September 2005

1. The dietary requirements for protein and amino acids of the growing gosling (0–7 weeks) were calculated according to body composition, maintenance needs and the absorption rate of amino acids from feeds.

2. The diets were formulated by least-cost linear programming, using the calculated requirements for amino acids, with or without minimal glycine + serine requirements. The diets formulated without minimal requirements of glycine + serine were supplemented with various amounts of glycine, and fed to growing goslings.

3. The calculated requirements for protein and essential amino acids were lower than those suggested for growing broilers and turkeys. The requirements (g/MJ metabolizable energy) at 0–2, 2–4 and 4–7 weeks of age respectively, were: lysine 0·88, 0·48, 0·43; methionine + cystine 0·48, 0·38, 0·29; protein 14·5, 9·3, 7·6.

4. The goslings did not respond to glycine supplementation of the diet.
The nutritive value of rumen micro-organisms in ruminants
Authors: Storm E. , Ørskov E. R.
Published: September 2005

1. A method is described whereby a large quantity of rumen microbial dry matter of high purity was isolated from whole rumen contents obtained from abattoirs, by means of a continuous process of one filtration through four sieves followed by three differential centrifugations.

2. The contents of ash, carbohydrate, lipid, nitrogen, RNA, DNA and individual amino acids of the three centrifugal fractions are given and compared with values summarized from more than sixty published reports on the chemical composition of rumen micro-organisms isolated from both whole rumen contents and pure cultures.

3. The amino acid composition of isolated rumen micro-organisms, in particular that of the bacteria, was found to be remarkably constant.
Short-term dietary selenium restriction in young adults: quantitative studies with the stable isotope 74SeO32−
Authors: Kasper Lynda J. , Young Vernon R. , Janghorbani Morteza
Published: September 2005

1. A 45 d metabolic study was carried out in four young adult male North American residents consuming a controlled diet based on an amino acid mixture. During the initial 10 d, total daily selenium intake was adjusted to 107.7 (SE 0.1) μg/d, which was reduced to 11.4 (SE 0.1) μg/d for the remaining 35 d.

2. Two doses of a stable isotope (74SeO32-) were administered orally in the post-absorptive state on days 4 and 39 of the study.

3. Se balance (faecal + urinary excretion) as well as stable isotope excretion studies were carried out for the entire 45 d period; blood plasma and erythrocyte Se concentrations were also monitored.

4. Plasma Se concentrations (μg/ml) fell progressively from the initial value of 0.132 (SE 0.007) to 0.083 (SE 0.008) at the end of the study. The erythrocyte concentrations of Se did not vary in a consistent manner (average value for the entire study 0.147 (SE 0.002) μg/ml).

5. Faecal excretion of unenriched Se decreased from 66 (SE 6) μg/d for days 1–10 to 10.2 (SE 0.8) μg/d for days 14–40. Mean urinary excretions of the unenriched Se were 43.9 (SE 2.8) μg/d (days 1–10) and 26.9 (SE 4.6) μg/d (days 14–40). Total balance (intake - faecal excretion - urinary excretion) for unenriched Se was μg/d):-18 (SE 7) days 10–19, -17 (SE 2) days 19–39, -5 (SE 1) days 38–45.

6. Fractional absorption of the ingested label was 0.529 (SE 0.032) and 0.542 (SE 0.038) for the Se-adequate and Se-restricted phases of the study. However, urinary excretion of the absorbed label was reduced from 6.57 (SE 0.73)% for day 1 of the Se-adequate phase to only 3.32 (SE 0.26)% for day 1 of the Se-restricted phase. Similar observations were also made for day 7 of each phase.

7. These findings indicate that immediate contribution of ingested Se to the urinary Se pool is small.
Nutrient intake of pregnant Asian women at Sorrento Maternity Hospital, Birmingham
Authors: Eaton P. M. , Wharton P. A. , Wharton B. A.
Published: September 2005

1. The dietary intake of pregnant Asian women (that is originating from the Indian subcontinent) attending Sorrento Maternity Hospital in Birmingham was determined, using the weighed and recall techniques, at five-weekly intervals from 18 to 38 weeks of pregnancy.

2. Mean energy intake of the group was 7.1 MJ (1700 kcal)/d. The intakes of most nutrients were substantially below those consumed by pregnant European women in Britain, a little below those of expectant Pakistani mothers in Islamabad, and about the same as those of expectant East London mothers. Intakes of vitamin D, total folate, vitamin B6, zinc and magnesium were particularly low.

3. These observations suggest that a number of Asian women in Birmingham are likely to experience nutritional stress in pregnancy, and there is some anthropometric and biochemical evidence from Sorrento, published elsewhere (Bissenden et al. 1981), to support this.

4. A possibly beneficial feature of the diet was a low sodium intake (2 g/d). Previous work at this hospital has noted a lower prevalence of hypertension in pregnant Asian women (Wharton et al. 1980; Bissenden et al. 1981).
Subethnic variation in the diets of Moslem, Sikh and Hindu pregnant women at Sorrento Maternity Hospital, Birmingham
Authors: Wharton P. A. , Eaton P. M. , Wharton B. A.
Published: September 2005

1. The previous paper (Eaton et al. 1984) described the nutrient intake of pregnant Asian women attending Sorrento Maternity Hospital, Birmingham using the weighed and recall methods. The present paper describes the subethnic variation in nutrient intake by comparing the results from Pakistanis, Sikhs, Hindus and Bangladeshis and also describes food eaten by the pregnant women.

2. Generally. Sikhs had the highest intake of most nutrients (mean energy 7.5 MJ (1800 kcal)/d) and the greatest variety of foods; they ate chapatti and paratha but few ate meat. Hindus had a very similar diet but more ate meat, chicken and rice. Pakistanis had an energy intake about 10% below that of the Sikhs and Hindus; meat was eaten, and intake of fruit, and therefore vitamin C, was quite large. Bangladeshis were the smallest women; they had the lowest intake of energy (mean energy 6.5 MJ (1555 kcal)/d) and most nutrients, except for protein, so that 15% of energy was provided by protein. Fish, rice and a low-fat intake were other features of their diet.

3. From a nutritional standpoint, peoples coming from the Asian subcontinent should be divided into subethnic groups; the collective term ‘Asian’ is insufficient.

4. It is not clear whether these differences have any effect on the life and health of the individuals. Comparison of groups does not suggest an obvious relationship between dietary intake and fetal growth; however, there is other evidence to implicate the possible role of deficiencies of protein, energy, zinc and pyridoxine.

5. The results provide some support for the community nutritional policies of (a) offering vitamin D supplements to all pregnant Asian women and (b) fortifying bread with calcium, thiamin and nicotinic acid. There is probably no need to offer vitamin A and C supplements but they are harmless. Indications for iron supplementation are no different from those for white English women.
The irreversible loss of alanine and of glycine in fetal and sucking lambs
Authors: Hatfield G. M. , Joyce Jenny , Jeacock Marjorie K. , Shepherd D. A. L.
Published: September 2005

1. Estimates have been made of the irreversible loss of alanine and of glycine in chronically catheterized fetal lambs and in sucking lambs using [U-14C]-labelled radioisotopes. The experiments in the fetal lambs were carried out at least 5 d after implantation of catheters.

2. The mean concentration of glycine in fetal femoral arterial blood between 102 and 129 d conceptual age was 755 μmol/l and this was not significantly different from that in maternal venous blood. The mean concentration of alanine in fetal femoral arterial blood during the same period of gestation was 229μmol/l and this was significantly greater than that in maternal venous blood.

3. Assuming a catenary model, the mean irreversible loss of glycine, determined using the single-injection technique, in three fetal lambs of 107, 111 and 127 d conceptual age was 17 μmol/min per kg, whereas in two fetal lambs aged 106 and 109 d into which the isotope was infused continuously the mean irreversible loss, calculated from the specific activity of glycine 5 h after the start of infusion of the tracer ('pseudo plateau'), was 12 μmol/min per kg. In a sucking lamb, 9 d after birth, the irreversible loss of glycine was 11 μmol/min per kg. The mean irreversible loss of alanine, determined by the single-injection technique assuming a catenary model in five fetuses between 112 and 121 d conceptual age was 14μmol/min per kg, and in two sucking lambs, 9 and 11 d after birth, it was 5.1 μmol/min per kg.

4. When a two-pool model was assumed in which entry of metabolite was not directly into the sampling pool but was by way of the second pool, then the mean irreversible loss of glycine in the three fetuses was 23 μmol/min per kg and of alanine in the five fetuses was 32 μmol/min per kg. Calculations based on the alternative two-pool model did not alter appreciably the rates of irreversible loss of either alanine or glycine in the sucking lambs.

5. From a comparison of the specific activities of the amino acids and of carbon dioxide in blood during the course of the experiments, it was found that in the fetuses 0.96% of the CO2present in blood was derived from alanine and only 0.12% was derived from glycine. It was calculated that not more than 1.6 μmol lanine/min per kg and 0.29 μmol glycine/min per kg could have been converted to CO2in the fetal lambs.

6. It is concluded that since glycine in fetal blood originates from fetal tissues and not from direct transfer across the placenta the upper value for the irreversible loss describes metabolism best. In the case of alanine, which is derived from both the maternal circulation and from metabolism in fetal tissues, the true rate of irreversible loss must lie between the values predicted by the two models.
Growth and zinc homeostasis in the severely Zn-deficient rat
Authors: Giugliano R. , Millward D. J.
Published: September 2005

1. Male weanling rats were fed on diets either adequate (55 mg/kg), or severely deficient (0.4 mg/kg) in zinc, either ad lib. or in restricted amounts in four experiments. Measurements were made of growth rates and Zn contents of muscle and several individual tissues.

2. Zn-deficient rats exhibited the expected symptoms of deficiency including growth retardation, cyclic changes in food intake and body-weight.

3. Zn deficiency specifically reduced whole body and muscle growth rates as indicated by the fact that (a) growth rates were lower in ad lib.-fed Zn-deficient rats compared with rats pair-fed on the control diet in two experiments, (b) Zn supplementation increased body-weights of Zn-deficient rats given a restricted amount of diet at a level at which they maintained weight if unsupplemented, (c) Zn supplementation maintained body-weights of Zn-deficient rats fed a restricted amount of diet at a level at which they lost weight if unsupplemented (d) since the ratio, muscle mass:body-weight was lower in the Zn-deficient rats than in the pair-fed control groups, the reduction in muscle mass was greater than the reduction in body-weight.

4. Zn concentrations were maintained in muscle, spleen and thymus, reduced in comparison to some but not all control groups in liver, kidney, testis and intestine, and markedly reduced in plasma and bone. In plasma, Zn concentrations varied inversely with the rate of change of body-weight during the cyclic changes in body-weight.

5. Calculation of the total Zn in the tissues examined showed a marked increase in muscle Zn with a similar loss from bone, indicating that Zn can be redistributed from bone to allow the growth of other tissues.

6. The magnitude of the increase in muscle Zn in the severely Zn-deficient rat, together with the magnitude of the total losses of muscle tissue during the catabolic phases of the cycling, indicate that in the Zn-deficient rat Zn may be highly conserved in catabolic states.
Undernutrition in sheep. The effect of supplementation with protein on protein accretion
Authors: Fattet I. , Hovell F. D. Deb. , Ørskov E. R. , Kyle D. J. , Pennie K. , Smart R. I.
Published: September 2005

1. In a comparative-slaughter experiment, individually rationed wether lambs initially of 42 kg were given 235, 362 or 456 kJ metabolizable energy (ME)/kg live weight (LW)0.75 per d as sodium hydroxide-treated barley straw with urea (six lambs per treatment), or NaOH-treated barley straw with urea plus 125 g/d white-fish meal to give 307 or 488 kJ ME/kg LW0.75 per d (seven lambs per treatment) for 92 d.

2. All unsupplemented lambs lost both fat and body protein. The changes in fat were – 3.53, – 2.75 and – 1.40 (SE 0.59) kg (initial value 8.6 kg), and the changes in body protein were –0.47, –0.09 and –0.14 (SE 0.13) kg (initial value 4.9 kg) for the three unsupplemented groups respectively. When supplemented with fish meal, fat was again lost as –1.53 and –0.93 (SE 0.55) kg, but wool-free body protein was increased, and gains were 0.48 and 0.89 (SE 0.12) kg for the two supplemented groups respectively. All animals lost wool-free body energy, total changes being –150, – 111, – 59 and –49 and – 16 MJ respectively. When corrected to an equal ME intake the supplemented lambs, when compared with the unsupplemented lambs, gained (instead of losing) body protein (P < 0.001) and lost less fat (P < 0.05). Wool growth did not respond to supplemental protein, but was related to ME intake with an increase of 0.78 g wool fibre for each additional MJ ME.

3. The maintenance requirements of the unsupplemented and supplemented groups respectively were estimated by regression analysis to be 554 and 496 kJ ME/kg LW0.75 per d. The apparent utilization of ME below energy equilibrium (km) was 0.31 (SE 0.08) for the unsupplemented animals, and 0.12 (SE 0.10) for the supplemented animals, well below akm, of 0.70 which current UK standards (Agricultural Research Council, 1980) would predict. Most of these differences could be reconciled if basal metabolism was assumed not to be constant.

4. It is concluded that lambs in negative energy balance can continue lean body growth at the expense of body fat, provided sufficient dietary protein is available. It is also concluded that since the animals at the lowest ME intakes required less ME than predicted by current feeding standards, the effect was that it would have been difficult to distinguish between the apparent utilization of ME for maintenance (km) and for fattening (kf).
Metabolism of cryptoxanthin in freshwater fish
Authors: Goswami Umesh C.
Published: September 2005

1. In search of other provitamins A, the metabolism of cryptoxanthin was studied in several species of freshwater fish, i.e. Chunna gachua, Labeo boga (retinol-rich) and Heteropneustes fossilis (dehydroretinol-rich). The fish were either allowed to starve for 20–25 d to make their intestines free from carotenoids and vitamin A or kept on a vitamin-A-deficient diet for 140–150 d to deplete the initial reserve of vitamin A in the livers.

2. Retinol-rich freshwater fish such as C. gachua and L. boga converted cryptoxanthin into retinol and no 3-dehydroretinol or 3-hydroxyretinol could be isolated from those fish that received cryptoxanthin.

3. 3-Hydroxyretinol and 3-dehydroretinol were isolated from the vitamin-A-deficient H. fossilis, a 3-dehydro-retinol-rich freshwater siluroid, after the administration of cryptoxanthin.
Leucine and isoleucine requirements of the kitten
Authors: Hargrove Diane M. , Rogers Quinton R. , Morris James G.
Published: September 2005

1. In separate experiments the isoleucine and leucine requirements of the kitten were determined on the basis of growth and nitrogen retention. The dietary concentrations of isoleucine tested were (g/kg diet) 1.4, 2.2, 3.0, 3.8, 4.6 and 9.0 with adequate (12.0 g/kg diet) leucine. The levels of leucine tested were (g/kg diet) 5.0, 7.5, 9.0, 10.5, 12.0 and 20.0 in diets containing adequate (9.0 g/kg diet) isoleucine. In both experiments six male and six female kittens received each dietary level of isoleucine or leucine for periods of 10 d in a balanced 6 x 6 Latin-square experimental design.

2. Asymptotic curves were fitted to the response relationships and the minimal dietary requirements for maximal response were estimated from the values at 0.95 of the asymptote. On this basis, the requirements for maximal growth were 6.2 g isoleucine/kg and 7.8 g leucine/kg diet. The requirements for maximal N retention were higher; 8.4 g isoleucine and 10.6 g leucine/kg diet. The isoleucine requirements suggested by this method are probably overestimations and might be slightly above 4.6 g/kg diet.

3. Plasma isoleucine and leucine concentrations were not useful in estimating the requirements. Plasma leucine increased rectilinearly with increasing dietary leucine while the response of plasma isoleucine to increasing dietary isoleucine was non-rectilinear. Neither response relationship exhibited a breakpoint at the level of requirement. Below the suggested minimal requirement for leucine there were significant increases in the concentrations of isoleucine and valine in the plasma. Dietary isoleucine below the level of requirement had no effect on plasma valine and leucine. Dietary leucine had no effect on the plasma concentrations of methionine, phenylalanine and threonine, suggesting that the effect of decreasing dietary leucine on plasma isoleucine and valine is a result of decreased oxidation rather than decreased protein anabolism.

4. In a separate experiment six kittens, presented a diet containing 2.2 g isoleucine/kg, developed crusty exudates around their eyes within 27 d and six kittens, presented diets containing 3.8 g isoleucine/kg, showed this clinical sign but with less severity within 47 d. Cultures of conjunctival swabs taken from the most severely affected kittens showed the presence of staphylococcal species, suggesting that in isoleucine-deficient kittens there was impaired resistance to these dermal microbes.
Further studies on the effects of the presence or absence of protozoa in the rumen on live-weight gain and wool growth of sheep
Authors: Bird S. H. , Leng R. A.
Published: September 2005

1. Lambs were given a diet of oaten chaff-sucrose-fishmeal(48:48:4, w/w) and either 60 (diet A) or 120 (diet B) g urea/kg sucrose in the diet. All animals were defaunated and half were refaunated. Each group of lambs (faunated and defaunated) was then divided into two groups and given diet A or diet B. Feed intake, wool growth and live-weight change were monitored over a 182 d period.

2. The level of urea supplementation had no effect on wool growth or live-weight gain.

3. Defaunated lambs gained live weight at a higher rate (9%,P< 0.06) and grew 37% more wool (P< 0.01) than the lambs with large populations of protozoa in their rumens.
Simulation of the metabolism of absorbed energy-yielding nutrients in young sheep
Authors: Gill Margaret , Thornley J. H. M. , Black J. L. , Oldham J. D. , Beever D. E.
Published: September 2005

1. A mathematical model is described, which simulates the metabolism of absorbed nutrients (amino acids, acetic acid, butyric acid, glucose, lipid and propionic acid) in growing sheep.

2. The basic assumption of the model is that each nutrient is partitioned between synthetic, oxidative or intermediate reactions with rates of reaction which are described using enzyme kinetics. These rates depend on the relationship between maximum reaction rates, constants of affinity and inhibition and the concentrations of metabolites as determined by the model.

3. Synthetic reactions calculate fat and protein deposition while intermediate reactions involve the production of ATP and NADPH. There is a total of twelve state variables and the model, programmed in CSMP and ACSL, is solved by integration of twelve differential equations.

4. The model calculates the efficiency of utilization of metabolizable energy for different nutrient inputs and the results may be interpreted in terns of fluxes through the metabolite pools. Simulations using inputs representing forage- and concentrate-based diets indicated decreased efficiency for the forage at high levels of intake and possible reasons for this were further studied in simulations where the inputs of protein and glucose were varied.
Plasma concentrations ofN-acetylneuraminic acid in severe malnutrition
Authors: Hibbert Jacqueline M. , Jackson Alan A. , Grantham-Mcgregor Sally M.
Published: September 2005

1. In rat studies, circulating concentrations of N-acetylneuraminic acid (NANA) have been shown to be an indicator of NANA concentrations in the brain and functional brain activity, in relation to nutritional state and stimulation. Abnormal behaviour can be improved with exogenous NANA. In the present study, the plasma NANA concentration has been measured in children with severe malnutrition and compared with that in controls.

2. NANA was measured colorimetrically in the plasma of twenty-three severely malnourished children (mean age 11.43 (SD 6.05) months) before and after recovery, and in thirty-four controls (mean age 14.28 (SD 7.32) months). In thirteen of the malnourished children, NANA was measured after infections had been treated with a course of antibiotics.

3. Mean plasma NANA concentration was significantly higher in protein-energy malnutrition (PEM)(2.89 (SD 0,58)μmol/ml; n 23) compared with controls (2.13(SD 0.37)μmol/ml; n 34,P< 0.001). The levels remained high in PEM after infections had been treated (2.87(SD 0.43) μmol/ml, n 13) but returned to control levels at recovery from PEM (2.14(SD 0.24)μmol/ml).

4. In contrast to the findings in rats, in malnourished children plasma NANA concentrations were not reduced and did not relate directly to nutritional state or, by inference, brain function. These findings do not provide any support for the use of exogenous NANA supplements to improve brain function in humans.
Effect of in vitro fermentation using human faecal inoculum on the water-holding capacity of dietary fibre
Authors: McBurney M. I. , Horvath P. J. , Jeraci J. L. , Van soest P. J.
Published: September 2005

1. The water-holding capacities (WHC) of four sources of fibre were measured using dialysis membranes and osmotic-suction pressures of 45, 89 and 178 mosmol/l (1, 2 and 4 atm). At all pressures, pectin had the highest WHC, followed by cabbage (Brussicu oleruceu) and lucerne (Medicago sativu) and then cellulose. A suction pressure of 89 mosmol/l (2 atm) was used in the subsequent fermentation study since it had the lowest standard error of the mean and most closely approximated physiological conditions.

2. The four fibres were anaerobically fermented in vitro with human faecal inoculum for 24 h. The WHC of the fermentation residues were measured. The potential water-holding capacity (PWHC), a function of the extent of fermentability and the WHC of the fermentation residues, was highest for lucerne, followed by cellulose, then cabbage and, finally, pectin. Only the PWHC values ranked the four fibres in the same order as in vivo values.

3. It was concluded that the ethanol-insoluble residues containing unfermented fibre organic matter and microbial organic matter, both of which hold water, should be used to calculate PWHC and to predict the effect of fibre on rate of passage and faecal mass in humans.
The effect of amino-acid-supplemented wheat gluten on cholesterol metabolism in the rat
Authors: Bassat M. , Mokady S.
Published: September 2005

1. The effect of lysine- and threonine-supplemented wheat gluten on cholesterol metabolism was studied using male weanling rats. Animals were fed on cholesterol-free diets containing 100 or 200 g gluten/kg with or without amino acid supplementation, and compared with animals given 50, 100 and 200 g casein/kg diets, for 3 weeks.

2. A hypocholesterolaemic effect observed with the wheat gluten-fed rats, compared with the animals given 100 and 200 g casein/kg diets, was accompanied by increased turnover of cholesterol as expressed by enhanced cholesterol biosynthesis and increased faecal excretion of cholesterol and bile acids. This effect was not abolished by lysine and threonine supplementation.

3. Low levels of blood cholesterol were also observed in the rats fed on the 50 g casein/kg diet. However, a different mechanism, related to impairment of cholesterol transport from the liver, was most likely responsible for the hypocholesterolaemia found in these protein-malnourished animals.

4. The effect on cholesterol metabolism produced by dietary wheat gluten was independent of the low quality of the protein and of its specific deficiency in lysine and threonine.
Reduction of the phytate content of bran by leavening in bread and its effect on zinc absorption in man
Authors: Barbro Nävert , Brittmarie Sandström , ÅKE Cederblad
Published: September 2005

1. The effect of leavening of bread containing bran on the phytic acid content and on zinc absorption in man was studied.

2. Twenty breads with leavening times varying from 0 to 120 h were prepared. The breads contained 250 g wheat bran/kg flour. The phytic acid content was determined after baking.

3. The phytic acid content of bread containing bran was reduced to about 40% after 2 h of leavening and to 15 % after 2 d. No further decrease was observed.

4. Zn absorption from single meals was determined using a radioisotope technique. Forty-two students volunteered for these studies. They were served a breakfast of milk, butter, bread and 10, 16 or 30 g bran served either raw or baked into the bread with fermentation times of 15 min, 45 min, 3 h or 16 h. One meal contained no bran, but phytate and Zn were added in amounts equivalent to the content of 10 g bran.

5. The amount and percentage of Zn absorbed increased at each bran level as fermentation was prolonged. The percentage of Zn absorbed was reduced by increased bran content in the meal.

6. It is concluded that the fermentation of bread containing bran reduces the phytic acid content and increases Zn absorption from such bread. This may be of importance to people subjected to diets with a high cereal content, especially in combination with a low animal-protein intake.
Reactions of proteins with oxidizing lipids
Authors: Nlelsen Henrik K. , Löliger J. , Hurrell R. F.
Published: September 2005

1. The reactions between protein-bound amino acids and oxidizing lipid were investigated in a whey protein-methyl linolenate (C18.3)–water model system. The extent of fat oxidation was followed by measuring oxygen uptake, hydroperoxide formation and hydrocarbon (ethane and pentane) formation.

2. Significant losses occurred with lysine (up to 71 %), tryptophan (up to 31 %) and histidine (up to 57%). Methionine was extensively oxidized to its sulphoxide but less than 2% was further oxidized to the sulphone. No other amino acids were affected.

3. Increasing storage temperature (20°, 37°, 55°) resulted in an enhancement of fat oxidation reactions and amino acid degradation.

4. Increasing water activity (0.28, 0.65, 0.90) increased losses of lysine and tryptophan but had no influence on the oxidation of methionine, the level of remaining hydroperoxides or 02uptake. Hydrocarbons were decreased.

5. Limitation of 02uptake to 1 mol/mol lipid instead of excess 02(02uptake about 2.5 mol/mol lipid in 4 weeks) significantly reduced the degradation of lysine and tryptophan but had less influence on the oxidation of methionine. The level of remaining hydroperoxides was increased but hydrocarbons were unaffected.
Reactions of proteins with oxidizing lipids
Authors: Nielsen Henrik K. , Finot P. A. , Hurrell R. F.
Published: September 2005

1. The consequences of reactions between protein and oxidizing lipids on the nutritional quality of food proteins have been investigated using a whey protein–methyl linolenate-water model system.

2. In rat assays, significant reductions were observed in protein efficiency ratio, net protein ratio, net protein utilization, biological value and true nitrogen digestibility, especially when the reaction had taken place at high moisture content, high temperature and in the presence of excess oxygen.

3. The losses of bioavailable lysine and tryptophan as measured by rat assays followed a similar pattern. The chemical value of each amino acid multiplied by the true N digestibility closely resembled the rat assay value. In general, the reaction products of lysine and tryptophan formed during lipid oxidation were biologically unavailable.

4. The bioavailabilities of methionine and of ‘methionine plus cyst(e)ine’ were determined in separate assays. Cyst(e)ine was calculated as ‘methionine plus cyst(e)ine’ minus methionine. In whey protein which had reacted with oxidizing methyl linolenate, the bioavailable methionine content was not significantly reduced even though 82% of the methionine residues were present as methionine sulphoxide. In hydrogen peroxide-treated casein in which all methionine residues were oxidized to the sulphoxide, methionine sulphoxide was found to be 96% as utilizable as a methionine source to the rat. Free methionine sulphoxide was 87% utilizable.

5. Cyst(e)ine appeared to be as sensitive as lysine to reactions with lipid oxidation products. In whey protein which had reacted with oxidizing methyl linolenate, the bioavailabilities of cyst(e)ine, lysine, tryptophan and methionine were reduced by 28, 24, 11 and 8% respectively and true N digestibility by 9%. These results are discussed in relation to food products.