bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of molybdenum on the conversion of sulphate to sulphide and microbial-protein-sulphur in the rumen of sheep
Authors: Gawthorne J. M. , Nader C. J. 
Published: May 2005

1. [35S]sulphate was used to measure the apparent turnover of sulphate, sulphide and microbial-protein-S in the rumen contents of four sheep that were intraruminally infused with 10 g sodium sulphate/d alone, or together with 126 mg sodium molybdate (50 mg molybdenum/d).2. Infusion of molybdate increased the concentration of sulphate in rumen fluid from 2.2 to 7.2 μg S/ml and decreased the rate of reduction of sulphate to sulphide by 50%. Although the rate of sulphide production was slower, the concentration of sulphide in rumen contents was increased. A dual role for molybdate in the metabolism of sulphide in the rumen is suggested to explain these changes.3. In animals that were not infused with molybdate, only one-third of the S (3.0 g/d) that passed through the sulphate pool in rumen fluid was converted to sulphide, decreasing to one-sixth when molybdate was infused.4. The turnover of S amino acids in microbial protein was not significantly affected by molybdate. Only 52–57% of the S amino acid content of microbial protein was synthesized de novo by way of the sulphide pool.
The induction of obesity in rodents by means of monosodium glutamate
Authors: Bunyan J. , Murrell Elspeth A. , Shah P. P. 
Published: May 2005

1. Monosodium glutamate (MSG) was administered by various methods to mice and rats of various ages and the incidence of obesity was later measured.2. Newborn mice were injected subcutaneously with 3 mg MSG/g body-weight at 1, 2, 3, 6, 7 and 8 d of age; 16% died before weaning. Of the survivors, 90% or more became markedly obese. Mean carcass lipid content was increased by about 120% in both sexes at 20–30 weeks of age. In male mice, MSG treatment increased body-weight and epididymal fat pad weight, and greatly decreased adrenaline-stimulated lipolysis in isolated fat cells. Body-weight of females was not increased significantly. Food intake was not increased in either sex from weeks 13 to 15. Blood glucose level was not generally increased by MSG but some of the male mice had abnormally high values.3. Obesity was not detected in the offspring of female mice that had received 100 g MSG/kg diet, either from 3 weeks before mating until weaning, or from the 14th day of pregnancy until weaning.4. Intraperitoneal injection of 10 mg MSG/g body-weight (in two doses) at weaning increased carcass lipid content in female mice by 34% by 23 weeks of age, but female rats were not affected.5. The addition of 20 g MSG/l to the drinking-water from weaning onwards did not increase carcass lipid content in female rats or mice.6. The addition of 20 g MSG/kg diet from weaning onwards did not alter body-weight or carcass lipid content in male and female rats by 14 weeks of age.7. The obesity induced in mice by MSG was not associated with hyperphagia, unlike genetic obesity and obesity induced by gold thioglucose (GTG).8. All types of mouse studied, obese and lean, had essentially the same linear relationship between carcass water content and carcass lipid content.9. Although MSG-obese mice could not readily be differentiated from normal mice by the increase in body-weight, which was only about 10% compared to 50–120% for genetic and GTG-induced obesity, the proposed schedule of injections in the newborn was almost 100% reliable in inducing a high extent of adiposity.
Resistance to ketosis during prolonged fasting by rats fed on a diet containing undecanoic acid, an odd-carbon-number fatty acid
Authors: Pi-Sunyer F. X. 
Published: May 2005

1. Sixty-four male rats were fed on a nutritionally complete diet containing 30% of the dietary energy as fat. For thirty-two rats (control) the fat source was maize oil; for the remaining thirty-two rats (experimental) the fat source was triundecanoin–maize oil (7:3, w/w).2. After 6 weeks, groups of control and experimental rats were fasted and killed on days 0, 1, 2 and 4 of the fasting period. In the experimental group, adipose-tissue fatty acids contained, on average, 246 mmol undecanoic acid/mol total fatty acids. In contrast, the adipose tissue of the control group did not contain odd-carbon-number fatty acids.3. Plasma glucose levels were significantly higher for all fasted experimental groups and blood ketone levels were significantly lower for these groups.4. Thus, during prolonged starvation, animals which accumulated odd-C-number fatty acids resisted the development of ketosis. It appeared that odd-C-number fatty acids mobilized from fat depots during fasting may provide their terminal three-C residues for gluconeogenesis rather than for acetyl-CoA production, thereby allowing for better maintenance of blood glucose and insulin levels than in control animals.5. It is concluded that the lower acetyl-CoA production and higher blood insulin levels reduce ketogenesis.
Protein absorption and ammonia production: the effects of dietary protein and removal of the colon
Authors: Gibson J. A. , Sladen G. E. , Dawson A. M. 
Published: May 2005

1. The effect of increasing dietary protein content on the amount of faecal nitrogen was measured in six normal subjects and five subjects without functioning colons (three with ileostomy and two with ileo-rectal anastomosis).2. There was a significant increase in the amount of faecal N with increased dietary protein content in the subjects without functioning colons.3. In normal subjects with intact colons, faecal N content was found to be lower than that in subjects without colons, and furthermore there was no significant variation with diet.4. The source of the increase in faecal N with increased dietary protein content in subjects without functioning colons is discussed and the significance of these findings in relation to the efficiency of protein absorption is considered.
Micellar solubilization of fatty acids in aqueous media containing bile salts and phospholipids
Authors: Smith A. , Lough A. K. 
Published: May 2005

1. The solubility of fatty acids in aqueous media containing bile salts alone and in admixture with either lecithin (phosphatidylcholine) or phosphatidylethanolamine was determined.2. Over the pH range 2.0–7.4, the order of fatty acid solubility in aqueous solutions containing bile salts was linoleic > oleic > elaidic > palmitic > stearic. The solubility of each fatty acid increased as the pH of the micellar solution increased.3. Addition of lecithin to aqueous solutions of bile salts greatly increased the solubility of palmitic acid and stearic acid.4. In the presence of bile salts and lecithin, the solubility of oleic acid and elaidic acid decreased with increasing pH of the micellar solution, indicating a competitive effect between the fatty acid anions and lecithin. The solubility of linoleic acid increased linearly with lecithin concentration.5. Phosphatidylethanolamine as an additive to bile salts increased the solubility of both saturated and unsaturated fatty acids in the pH range 2.0–7.4. The effectiveness of phosphatidylethanolamine as an amphiphile was similar to that of lecithin, although at pH 3.0 fatty acid solubility was greater in the presence of phosphatidylethanolamine.6. The significance of these findings is discussed in relation to the intestinal absorption of fatty acids in sheep.
Influence of the products of phospholipolysis of phosphatidylcholine on micellar solubilization of fatty acids in the presence of bile salts
Authors: Lough A. K. , Smith A. 
Published: May 2005

1. The solubility of fatty acids in aqueous solutions containing bile salts and lysolecithin at pH values between 2.0 and 7.4 was studied. Both the 1-acyl and 2-acyl isomers of lysolecithin increased the solubility of fatty acids to the same extent, the order of solubility being linoleic > oleic > elaidic > palmitic > stearic.2. The influence of the products of phospholipolysis of lecithin on palmitic acid solubility was determined. On a molar basis, lysolecithin was more effective than were bile salts in promoting the solubilization of the fatty acid.3. In bile salt solutions in which the phospholipid concentration was constant on a molar basis, the solubility of palmitic acid decreased linearly with the progressive replacement of lecithin by lysolecithin. Palmitic acid was solubilized to the same extent on replacing lecithin with lysolecithin on a constant weight basis.4. In bile salt solution containing lysolecithin and oleic acid in equimolar amounts, the solubility of palmitic acid was similar to that in bile salt solutions containing lecithin in equivalent proportion.5. The results are discussed in relation to the action of phospholipolytic activity on the intestinal absorption of fatty acids in sheep.
The effect of feeding frequency on the growth and composition of individual organs in the rat
Authors: Pocknee R. C. , Heaton F. W. 
Published: May 2005

1. The effect of consuming the same total amount of food in either one large meal or several small meals per d was studied using weanling male rats.2. The increase in total body-weight was the same in both instances, but the weights of the liver, kidneys, femur, small intestine and stomach were greater, and those of the spleen and residual carcass were smaller, in meal-eating rats than in continuously fed control animals. These differences persisted into the adult state.3. No differences in gross chemical composition were found between the corresponding organs of the two groups of rats, and the differences in weight appeared to be the result of changes in the general growth rate of individual organs.4. The hypertrophy of the kidneys in meal-eaters was due to an increase in mean cell size, but the increased weight of the liver and reduced weight of the spleen appeared to be largely the result of changes in the number of cells present.
Biotin deficiency and fatty liver and kidney syndrome in chicks given purified diets containing different fat and protein levels
Authors: Whitehead C. C. , Bannister D. W. , Evans A. J. , Siller W. G. , Wight P. A. L. 
Published: May 2005

1. The occurrence of biotin deficiency and fatty liver and kidney syndrome (FLKS) in chicks was studied using a 2 × 2 × 2 × 2 factorial-design experiment in which the variables were dietary biotin, fat and protein, and starvation.2. The severity of biotin deficiency, using growth retardation and severity of dermal lesions as criteria, was least when the low-biotin diet also contained low levels of fat and protein. Addition of fat or protein increased the severity of the deficiency. Tissue fatty acid composition was affected by biotin deficiency only in those birds given the low-protein, low-fat diet. The main change was an increase in the ratio, 16:1 fatty acids:18:0 fatty acids. Plasma glucose and free fatty acid levels in non-fasted birds were unaffected by the dietary variables.3. Mortality from FLKS with the diet containing low biotin, fat and protein levels was 52% at 28 d, but was reduced or eliminated when the dietary level of any of these ingredients was increased.4. Starvation considerably increased the incidence of FLKS in the period immediately after fasting, and also affected plasma glucose and free fatty acid concentrations. Liver fatty acid composition indicated an increase in the proportion of 18:0 at the expense of 16:1 and 18:1, irrespective of diet, except when the bird developed FLKS, when 16:1 and 18:1 concentrations increased in proportion, at the expense of 18:0.5. The relationship between biotin deficiency and FLKS, and a possible mechanism for the induction of FLKS by starvation are discussed.
Further studies of the dynamics of nitrogen metabolism in sheep
Authors: Nolan J. V. , Norton B. W. , Leng R. A. 
Published: May 2005

1. A study of ammonia and urea metabolism in sheep was made using isotope dilution techniques with (15NH4)2SO4, [15N]urea and [14C]urea in order to determine quantitatively the movements of urea-N and NH3-N throughout the body of normal, feeding sheep.2. Single injections of15N-labelled compounds were made into the rumen fluid NH3, caecal fluid NH3and the blood urea pools, in order to estimate the rates of flux through, and the transfer of N between, these and other nitrogenous pools in the body.51Cr EDTA was injected into the rumen and caecum with (15NH4)2SO4to allow estimation of fluid volumes and to provide an indication of mixing, and of times of transit of isotopes between different sampling sites in the digestive tract.3. The sheep ate approximately 22 g lucerne chaff/h and the mean dietary N intake was 16.3 g/d.4. The rate of flux of NH3through the rumen NH3pool was 15.0 g/d (i.e. 90% of the dietary N ingested; however, this amount also included N from plasma urea (1.1 g/d) and other endogenous sources including NH3derived from caecal NH3(0.4 g/d).5. Only 40% of the N in isolated rumen bacteria was derived from NH3, indicating that a considerable proportion of their N requirements were obtained from compounds other than NH3(e.g. peptides and amino acids).6. There was evidence of recycling of N between nitrogenous pools in the rumen, probably through rumen NH3→ microbial N → NH3.7. It was estimated that 5.3 g blood urea-N/d entered the digestive tract: 20% of this urea was degraded in the rumen, 25% in the caecum and the remainder was apparently degraded elsewhere; there was evidence of urea degradation in the large intestine posterior to the caecum and it is suggested that urea degradation and absorption of the resultant NH3may occur in the ileum.8. Of the 4.8 g N/d entering the caecal NH3pool, 4.2 g N/d left and did not return and the difference (0.6 g N/d) was recycled, possibly through caecal NH3→ microbial N → NH3.9. A large proportion of the NH3entering the caecal NH3pool (70% or 3.2 g N/d) was apparently derived from degradation of nitrogenous products, other than urea, including rumen microbial N (1.0 g N/d) passing undigested from the small intestine.10. Less than half the NH3-N of caecal origin entering the rumen passed through the blood urea pool; the remainder was apparently transported as other nitrogenous compounds in the blood or body fluids.11. The results of the three experiments were combined in a general three-pool, opencompartment model which formally recognizes an unlimited number of other unspecified, interconnected pools together comprising the whole-animal system. Rates of flux through, and transfer of N between these and other nitrogenous pools in the body were calculated by solving this model and the information derived has been applied to whole-animal models with a view to subsequently using these models in computer simulation studies.
Utilization of14C-labelledEscherichia coliby rats
Authors: Tong A. , Fishert R. F. 
Published: May 2005

1.Escherichia coliwas grown on14C-labelled glucose and fractions representing ‘whole cells’, ‘cell contents’ and ‘cell walls’ were administered orally to rats.2.14C appearing as14CO2in the expired air and as unidentified radioactive products in urine and faeces was measured until the cumulative recovery showed little change with time.3. All fractions were digested. The digestibility of cell waslls was less than that of the other fractions.4. There was considerable variation among individual rats.
The effects of dietary histidine, methionine and homocystine on vitamin B12and folate levels in rat liver
Authors: Williams D. L. , Spray G. H. 
Published: May 2005

1. L-histidine (20 g/kg) added to vitamin B12-deficient and cyanocobalamin-supplemented diets based on soya-bean flour reduced the growth of rats given the vitamin B12-deficient diet but stimulated growth of rats given the cyanocobalamin-supplemented diet. Liver weight (g/kg body-weight) increased, but the protein content of the livers decreased, in rats given histidine supplements. The histidine was associated with significantly higher folate concentrations in the livers of cyanocobalamin-supplemented rats.2. Vitamin B12-deficient and cyanocobalamin-supplemented rats were given diets based on a mixture of amino acids that was balanced apart from methionine, which was added in various amounts, and with the addition of homocystine. The only vitamin B12-deficient rats which had reasonable gains in weight were those receiving a diet containing 8 g L-methionine/kg. The remainder, particularly those given diets containing only homocystine, had little or no increase in weight. All the cyanocobalamin-supplemented rats gained weight; those given diets containing 2 and 8 g L-methionine/kg, or 8 g homocystine/kg, had the highest gains.3. There was a tendency for a higher concentration of either methionine or homocystine in the diet to be associated with higher concentrations of both folate and vitamin B12in the livers.4. In vitamin B12deficiency methionine appeared to increase the accumulation of folate in the liver, affecting mainly the amounts of polyglutamate derivatives.
An improved procedure for the assay of available lysine and methionine in feedstuffs using Tetrahymena pyriformis W
Authors: Shorrock C. 
Published: May 2005

1. A study was made of the assay of available lysine and available methionine using Tetrahymena pyriformis W, as applied to a variety of protein-rich feedstuffs.2. Results were strongly influenced by the conditions under which the analyses were done. With most of the test samples predigestion with papain caused a large increase in the values obtained.3. An improved assay procedure was developed which included enzymic predigestion of the test samples, ‘all-in’ sterilization of the medium constituents, and measurement of growth from extinction values. It gave results for available lysine that were broadly similar to those obtained in growth tests with rats, and in chemical tests by the method of Carpenter (1960). Values for available methionine agreed closely with those obtained in microbiological tests with Streptococcus zymogenes.
The utilization of diets containing acetate salts by growing lambs as measured by comparative slaughter and respiration calorimetry, together with rumen fermentation
Authors: Hovell F. D. Deb. , Greenhalgh J. F. D. , Wainaman F. W. 
Published: May 2005

1. In a comparative slaughter experiment, growing lambs were given concentrate diets in which 14 or 19% metabolizable energy (ME) provided by barley was replaced by sodium, calcium and potassium salts of acetic acid. As the proportion of ME as acetate was increased, energy retention decreased. ME intake was 9271, 9430 and 9217 ± 67 kJ/d and energy retention was 2698, 2422 and 2280 ± 71 kJ/d for the diets containing 0, 14 or 19% ME as acetate respectively. There were no differences in protein deposition. The efficiency of utilization of acetate for energy retention (kf) was calculated by difference to be 3 and 10 ± 13% respectively for the diets containing 14 and 19% ME as acetate.2. In a second experiment, growing lambs were given concentrate diets in which 4 or 16% ME provided by barley was replaced by salts of acetic acid, and utilization was measured by indirect calorimetry. There were no significant differences in the utilization of the diets for maintenance (km) or energy retention (kf). The km values were 82.4 ± 2.3 and 81.2 ± 0.7%, and kf values were 67.4 ± 4.5 and 65.8 ± 2.7% respectively for the diets providing 4 and 16% ME as acetate. The kf of the additional acetate in the diet providing 16% ME as acetate was calculated by difference to be 54%.3. The acetate and Ca concentrations of the rumen digesta were increased by including acetate salts in the diet, but Na and K concentrations were not affected.4. It is concluded that the best explanation for the poor utilization of acetate in the comparative slaughter experiment is that acetate was poorly utilized for lipogenesis. The calorimetry experiment contained relatively large errors, but the results suggest that acetate may be utilized efficiently in some circumstances. It is suggested that these results and apparently conflicting results in the literature may be explained by the concept that the efficient utilization of acetate is dependent upon the supply of glucose or glucose precursor.
The determination of volatile fatty acids in the caecum of the conscious rabbit
Authors: Parker D. S. , Mcmillan R. T. 
Published: May 2005

1. A method of obtaining dialysed samples from the caecum of the conscious rabbit is described.2. Values for total volatile fatty acid content and for molar proportions of individual volatile fatty acids in dialysate samples were in good agreement with those obtained from caecal material.3. The volatile fatty acid level in the caecum throughout the day was determined using two groups of animals, one group fedad lib.and the other group on a restricted food intake. These results indicated a marked diurnal fluctuation in volatile fatty acid level in the caecum of rabbits fed once/d which was not evident in those fedad lib.
The metabolism of [75Se]selenomethionine in four women
Authors: Griffiths Nora M. , Stewart R. D. H. , Robinson Marion F. 
Published: May 2005

1. The long-term fate of an oral dose of [75Se]selenomethionine was studied in four women.2. Urinary and faecal excretion, respiratory losses and whole-body retention of 75Se were measured, and also 75Se turnover in whole body, plasma and erythrocytes during a period of 33–44 weeks.3. Intestinal absorption of [75Se]selenomethionine by the four subjects was 95.5–97.3% of the administered dose.4. Urinary excretion accounted for 6–9% of absorbed 75Se in the first 2 weeks. No radioactivity was detected in expired air.5. After the initial 8 weeks during which radioactivity decreased more rapidly, whole-body retention of 75Se decreased exponentially with a half-time of 207–290 d.6. Plasma 75Se concentration reached a maximum level 3–4 h after the dose. Transient initial uptake of 75Se in erythrocytes during the first hour was followed by a gradual increase to a maximum concentration at 8–12 weeks.7. These results are compared with the results of an earlier study of the metabolism of [75Se]selenite in two of the same women. 75Se from [75Se]selenomethionine was found to be more completely absorbed, had a greater retention and smaller endogenous urinary and faecal losses than 75Se from [75Se]selenite, and these differences persisted throughout the experimental period. These findings differed from those obtained in rats in which, after an initial period, 75Se from selenite was metabolized similarly to that from selenomethionine.
Mechanisms of heat damage in proteins
Authors: Hurrell R. F. , Carpenter K. J. , Sinclair W. J. , Otterburn M. S. , Asquith R. S. 
Published: May 2005

1. Studies have been made with solvent-extracted chicken muscle, bovine plasma albumin (BPA) and other proteins, all severely heated in the absence of carbohydrates so as to cause a large decrease in their fluorodinitrobenzene (FDNB)-reactive lysine contents.2. ɛ-N-(β-L-aspartyl)-L-lysine and ɛ-N-(γ-L-glutamyl)-L-lysine isopeptides were determined after enzymic digestion of heated chicken muscle, and their content was found to increase as the material was subjected to more heat treatment. Heated chicken muscle was not found to contain lanthionine. Heated BPA, on the other hand, was found to contain lanthionine but not the isopeptides. Both lanthionine and isopeptide cross-linkages were detected in most of the other heated proteins. There was some difficulty in quantifying the amounts of isopeptides formed on heat treatment, because the enzymic digestion procedure used in their isolation appeared to be incomplete. Neither lysinoalanine nor ornithinoalanine was detected in any of the test materials.3. The severely heated chicken muscle was fed to rats, and ileal and faecal digestibilities were studied. Protein digestibility was found to be greatly reduced after heat treatment, although the isopeptides themselves appeared to be at least as digestible as the total N component, total lysine, or FDNB-reactive lysine. However, the reduction in ileal N digestibility only partly accounted for the much larger reduction in nutritive value, as measured by net protein ratio ((weight loss of N-free animals + weight gain of test animals) ÷ weight of crude protein (N × 6.25) consumed by test animals). Possible reasons for this are discussed.