bluuebunny/crossref_metadata_2025 huggingface dataset:
The degradation of different protein supplements in the rumen of steers and the effects of these supplements on carbohydrate digestion
Authors: McAllan A. B. , Cockburn J. E. , Williams A. P. , Smith R. H.
Published: September 2005

1. Four steers with simple rumen and abomasal cannulas were given diets consisting of ground and pelleted alkali-treated straw, rolled barley and tapioca supplemented with urea (diet U) or containing single-cell protein (diet SCP), maize-gluten meal (diet MGM) or rapeseed meal (diet RSM) in place of some of the tapioca. The isoenergetic diets were given in a 4 x 4 Latin square design in eight feeds/d at 3-h intervals and provided sufficient metabolizable energy to support a growth rate of approximately 0.5 kg/d. Chromic oxide and polyethylene glycol were given as markers and appropriate samples taken from the rumen and abomasum. Flows (g/d) at the abomasum of organic matter and nitrogenous and carbohydrate constituents were calculated.

2. Rumen ammonia levels were similar with all three protein supplements at about 9 mmol/l, which was significantly lower (P < 0.05) than that in animals on diet U (16 mmol/l). Rumen liquid outflow rates (/h) were 0.099, 0.139, 0.125 and 0.160 for diets U, SCP, MGM and RSM respectively; the difference between diet U and diet RSM was significant (P < 0.05). Corresponding values for Cr2O3 outflow rates were 0.027, 0.032, 0.027 and 0.030/h respectively, which did not differ significantly from each other.

3. RNA, 35S and diaminopimelic acid (DAP) were used as microbial markers. Efficiencies of microbial-N (MN) synthesis, expressed as g MN/kg apparently digestible organic matter, truly digestible organic matter or carbohydrate fermented, were generally not significantly affected by the diet and averaged 29, 22 and 29 respectively based on mean RNA and 35S markers. Corresponding values derived from DAP of 22, 16 and 21 g MN/kg respectively were all significantly (P < 0.001) lower. Using 35S as microbial marker, MN flows at the abomasum as a proportion of non-ammonia-nitrogen flow were 0.78, 0.64, 0.51 and 0.78 for diets U, SCP, MGM and RSM respectively. Derived true rumen degradability values (g/g intake) of the total dietary N were 0.91, 0.79, 0.69 and 0.90 for diets U, SCP, MGM and RSM respectively. Protein supplement degradabilities for single-cell protein, maize-gluten meal and rapeseed meal were 0.73, 0.51 and 0.98 respectively.

4. Mouth-to-abomasum digestibility coefficients of the main neutral-sugar components of dietary poly-saccharides were 0.68, 0.63 and 0.61 for arabinose, xylose and cellulose-glucose on diet U. These values were generally significantly increased with protein supplementation, but to different extents depending on the source. Maximum digestibility values of 0.81, 0.79 and 0.76 were obtained for arabinose, xylose and cellulose-glucose with diet RSM. Starch-glucose digestibility was high (0.90) on all diets and unaffected by supplementation.
Oxidation of methionine and 2-hydroxy 4-methylthiobutanoic acid stereoisomers in chicken tissues
Authors: Dupuis Liliane , Saunderson C. Linda , Puigserver Antoine , Brachet Patrick
Published: September 2005

Oxidation of dl-2-hydroxy 4-methylthiobutanoic acid (dl-HMB), dl-methionine (dl-MET) and l-methionine (l-MET) in chicken tissue homogenates was compared using 1-14C-labelled tracers. The pattern of oxidation of the substrates was similar at both low (0.7 mm) and high (20 mm) concentrations. The rate of conversion to 2-keto 4-methylthiobutanoic acid (KMB) was highest for dl-MET and lowest for l-MET in kidney, liver and intestinal mucosa. In breast muscle, rates for dl-MET and l-MET were similar at 0.7 mm, but dl-HMB showed the highest rate at 20 mm. Kidney contained the highest specific activity for oxidation of all three substrates. Raising the pH of liver and kidney homogenates from 7.5 to 8.6 increased the oxidation of dl-MET, exclusively. Experiments with inhibitors of D-2-hydroxy acid dehydrogenase (EC1.1.99.6) and L-2-hydroxy acid oxidase (EC1.1.3.15) suggested that d- and l-HMB were stereospecifically oxidized by the enzymes. KMB stimulated l-MET oxidation in kidney yet inhibited l-MET oxidation in liver homogenates. The effect of KMB on dl-MET and dl-HMB oxidation also varied between tissues. Amino-oxyacetate inhibited l-MET oxidation completely and dl-MET and dl-HMB oxidation almost completely in both kidney and liver. L-Cycloserine was less potent than amino-oxyacetate and decreased l-MET oxidation more in kidney than in liver. It can be calculated from the results that, at low substrate concentrations, the liver contributes principally to the whole body oxidation of both dl-HMB and dl-MET. At high (greater than physiological) concentrations, dl-HMB would be oxidized principally in skeletal muscle. At all concentrations, l-MET would be converted to KMB mainly in the muscle.
The optimum dietary amino acid pattern for growing pigs
Authors: Wang T. C. , Fuller M. F.
Published: September 2005

A series of four nitrogen-balance experiments was carried out with growing pigs to determine the optimum balance amongst the amino acids in the diet. The reduction in N retention when 20 % of a single amino acid was removed from the diet was used to calculate a dietary amino acid pattern in which each amino acid would he equally limiting. A mixture of amino acids simulating the amino acid pattern of casein was used with the same efficiency as casein. From two successive deletion experiments an optimum balance amongst the essential amino acids was derived. Expressed relative to lysine = 100 this had threonine 72, valine 75, methionine + cystine 63, isoleucine 60, leucine 110, phenylalanine + tryosine 120, tryptophan 18. No estimate was made for histidine. Essential amino acids in this pattern were mixed with non-essential amino acids in ratios of 36:64 up to 57:43. The highest efficiency of N retention was achieved with diets having a ratio of at least 45:55. This included (g/16 g N) lysine 6 5, threonine 4.7, valine 4 9, methionine + cystine 4.1, isoleucine 3 9, leucine 7.2, phenylalanine + tyrosine 7.8, tryptophan 12. The N of diets with this amino acid pattern was utilized significantly better than when the pattern proposed by the Agricultural Research Council (1981) was used. The flow of amino acids past the terminal ileum of pigs given the semi-synthetic diet with this amino acid pattern was no greater than that observed with protein-free diets. The proposed pattern thus describes the intrinsic requirements of the growing pig for absorbed amino acids.
Effect of oat gum on the physical properties of the gastrointestinal contents and on the uptake of D-galactose and cholesterol by rat small intestine in vitro
Authors: Lund E. K. , Gee J. M. , Brown J. C. , Wood P. J. , Johnson I. T.
Published: September 2005

Recent reports indicate that oats have a relatively low glycaemic effect in comparison with other carbohydrate food, and that their consumption leads to a reduction in plasma-cholesterol levels in man. These properties may be due to a soluble non-starch polysaccharide in oats. The present study was undertaken to explore the physiological properties of this material. Three groups of male Wistar rats were meal-fed on a control diet free of soluble dietary fibre for 10 d before being given a 10 g meal of either the control diet, a diet containing oat gum (β-glucan), or finely ground rolled oats. The contents of the stomach, small intestine and caecum were later recovered and the weight, water content and viscosity were measured. The small intestinal contents from oat-gum-fed or oat-fed rats had a higher wet: dry weight ratio than that of the controls, and a higher viscosity. In in vitro studies the rate of uptake of d-galactose by jejunal rings was reduced in the presence of oat gum. The estimated Michaelis-Menten constant for the carrier-mediated component in the presence of oat gum was higher than that for controls, but the maximum transport rates were similar. Cholesterol uptake by everted jejunal sacs was progressively inhibited by increasing concentrations of oat gum in the mucosal medium. It is concluded that increased viscosity of the contents of the small intestine may contribute to the low glycaemic index and hypocholesterolaemic effects of oats in man. Oats appear to be amongst the few palatable sources of viscous dietary fibre in the conventional Western diet.
Preparation and characterization of a [14C]cellulose suitable for human metabolic studies
Authors: Walters M. P. , Kelleher J. , Findlay J. M. , Srinivasan S. T.
Published: September 2005

In six normal subjects administered 5 μCi of an oral dose of a commercially available 14C-labelled cellulose, significant amounts of 14CO2 were detected in expired air within 30 min, suggesting that other 14C-labelled non-cellulosic material was present. Chemical and microscopical examination confirmed that starch was the principal contaminant. The commercial preparation was purified using amyloglucosidase (EC 3.2.1.3) digestion following gelatinization of the starch by autoclaving. Subsequent administration of the purified cellulose to a further six normal subjects decreased the expired air 14CO2 during the subsequent 10 h from 13.0 (sd 4.0) to 4.1 (sd 1.9)%. Administration of the purified product to a further group of four normal subjects, before and after a regimen of increased dietary fibre, showed a cumulative increase in expired 14CO2 over 24 h from 7.9 (sd 1.1) to 12.1 (sd 2.6) % on fibre. In six ileostomy subjects the cumulative excretion of 14CO2 was greatly decreased compared with normal controls (3.0 (sd 1.14) and 10.5 (sd 3.9) % respectively). In constipated subjects expired 14CO2 continued beyond 48 h, in contrast to normal subjects where expired 14CO2 at this time was negligible.
Modulation of postprandial glycaemia and insulinaemia by cellulose in mixed nutrient combinations
Authors: Siddhu Anupa , Sud Sudha , Bijlani R. L. , Karmarkar M. G. , Nayar Usha
Published: September 2005

The present study was designed to examine the effect of cellulose (CL) on postprandial glycaemia and insulinaemia when ingested with glucose (G), casein (CS) and maize oil (CO) in various combinations. The study was conducted on five healthy male volunteers, on each of whom five meal tolerance tests were performed. The meals were isoenergetic and consisted of G; G and CL; G, CS and CL; G, CO and CL; G, CS, CO and CL. The meals were administered after an overnight fast. In addition to a fasting venous blood sample, blood was collected 0.5, 1.0, 1.5 and 2.0 h after ingestion for measurement of serum glucose and insulin levels. The glycaemic response to G+CS+CL and G+CS+CO+CL was significantly lower, while the insulinaemic response to G+CL was significantly higher than that to G. Addition of CL to G did not alter the glycaemic response, but accentuated the insulinaemic response. Further addition of CS in isoenergetic meals attenuated the glycaemic response, which may be because of a reduction in the amount of G in the meals. Like CS, CL also seemed to have an insulinotropic effect. The mechanism of the insulinotropic effect of CL cannot be deduced from the present study, but it is possible that like G, CL also stimulates gastric inhibitory peptide (GIP) secretion from the duodenum, which in turn stimulates insulin secretion.
The availability of zinc in endosperm, whole grain and bran-enriched wheat crispbreads fed to rats on a Zn-deficient diet
Authors: Hallmans Göran , Sjöström Rolf , Wetter Lars , Wing Kenneth R.
Published: September 2005

The hypothesis that factors such as dietary fibre and phytate in wheat bran limit the availability of Zn was tested in growing rats fed on low-Zn diets with different wheat crispbreads as the major source of Zn. Six groups of six weanling male rats each were fed on 5 parts semi-synthetic Zn-deficient diet and 1 part wheat-endosperm crispbread for 1 week. At the beginning of the second week, the crispbread in the diet of five groups was exchanged for crispbread made using one of the following wheat flours: (1) whole grain, (2) bran-enriched whole grain, (3) endosperm with Zn added to the whole-grain level, (4) endosperm with Zn added to the bran-enriched level, (5) whole grain with Zn added to the bran-enriched level. These diets were given ad lib. together with deionized water for 2.5 weeks. The relative absorption of Zn was lowest from the three non-supplemented diets (75–82%). All the added Zn was absorbed. As appetite, body-weight increase, Zn absorption, Zn retention and the Zn concentrations in serum and bone differed only slightly among groups fed on diets with similar Zn concentrations, it is concluded that factors such as dietary fibre or phytate in wheat bran limit the availability of Zn in wheat crispbreads very little when all the Zn is needed for growth and development in rats.
Relation between some folate-dependent metabolic pathways and dietary folate content in chicks
Authors: Whitehead Colin C. , Rennie J. Sarah
Published: September 2005

Responses of several folate-metabolizing pathways to dietary folic acid were studied in 2-week-old chicks. Oxidation of a histidine load to carbon dioxide was impaired in folate-deficient chicks. There was a curvilinear relation between oxidation and dietary folate, and maximum oxidation occurred with 2 mg supplemental folic acid/kg. Hepatic activities of glutamic acid formiminotransferase (EC2.1.2.5) and glycineN-methyltransferase (EC2.1.1.20) were not affected significantly (P> 0.05) by dietary folic acid. The activity of dihydrofolate reductase (EC1.5.1.3) in erythrocytes was elevated in folate-deficient chicks. These studies show that the activities of two folate-dependent pathways can be used as biochemical criteria of folate status in chicks.
Selenium and vitamin E status of healthy and institutionalized elderly subjects: analysis of plasma, erythrocytes and platelets
Authors: Campbell Douglas , Bunker Valda W. , Thomas Anita J. , Clayton Barbara E.
Published: September 2005

Levels of selenium in whole blood, plasma, erythrocytes and platelets, glutathione peroxidase (EC1.11.1.9; GSH-Px) activity in erythrocytes and platelets and vitamin E, low-density-lipoprotein (LDL)-cholesterol and vitamin E: LDL cholesterol in plasma were measured in seventy-five healthy subjects aged < 65 years and twenty-eight healthy and twenty-three institutionalized elderly people aged > 65 years. Healthy elderly subjects had significantly lower levels of Se in whole blood and plasma when compared with younger subjects. Other measurements of Se status were not significantly different. In the healthy subjects plasma levels of vitamin E and LDL-cholesterol increased with age to 60 years and decreased above 80 years. Vitamin E: LDL cholesterol values were not affected by age. Measurements of Se and vitamin E status in the institutionalized elderly compared with the healthy elderly were all reduced with the exception of platelet Se levels and erythrocyte GSH-Px activity. Ageingper sehad minimal effect on Se and vitamin E status but intercurrent illness and decreased food intake can lead to reduced levels in the elderly.
Effects of potassium deficiency on growth and protein synthesis in skeletal muscle and the heart of rats
Authors: Dôrup Inge , Clausen Torben
Published: September 2005

The effects of potassium deficiency on growth, K content and protein synthesis have been compared in 4–13-week-old rats. When maintained on K-deficient fodder (1 mmol/kg) rats ceased to grow within a few days, and the incorporation of [3H]leucine into skeletal muscle protein in vivo was reduced by 28–38%. Pair-feeding experiments showed that this inhibition was not due to reduced energy intake. Following 14 d on K-deficient fodder, there was a further reduction (39–56 %) in the incorporation of [3H]leucine into skeletal muscle protein, whereas the incorporation into plasma, heart and liver proteins was not affected. The accumulation of the non-metabolized amino acid α-aminoisobutyric acid in the heart and skeletal muscles was not reduced. The inhibitory effect of K deficiency on3H-labelling of muscle protein was seen following intraperitoneal (10–240 min) as well as intravenous (10 min) injection of [3H]leucine. In addition, the incorporation of [3H]phenylalanine into skeletal muscle protein was reduced in K-depleted animals. Following acute K repletion in vivo leading to complete normalization of muscle K content, the incorporation of [3H]leucine into muscle protein showed no increase within 2 h, but reached 76 and 104% of the control level within 24 and 72 h respectively. This was associated with a rapid initial weight gain, but normal body-weight was not reached until after 7 weeks of K repletion. Following 7 d on K-deficient fodder the inhibition of growth and protein synthesis was closely correlated with the K content of the fodder (1–40 mmol/kg) and significant already at modest reductions in muscle K content. In vitro experiments with soleus muscle showed a linear relationship between the incorporation of [3H]leucine into muscle protein and K content, but the sensitivity to cellular K deficiency induced in vitro was much less pronounced than that induced in vivo. Thus, in soleus and extensor digitorum longus (EDL) muscles prepared from K-deficient rats, the incorporation of [3H]leucine was reduced by 30 and 47 % respectively. This defect was completely restored by 24 h K repletion in vivo. It is concluded that in the intact organism protein synthesis and growth are very sensitive to dietary K deficiency and that this can only partly be accounted for by the reduction in cellular K contentper se.The observations emphasize the need for adequate K supplies to ensure optimum utilization of food elements for protein synthesis and growth.
An improved method for estimating changes in whole-body fat and protein mass in man
Authors: Murgatroyd P. R. , Coward W. A.
Published: September 2005

Sequential measurements of body density or total body water yield inaccurate estimates of body composition change unless the proportions of protein, water and mineral in lean tissue remain constant. Since rates of change of bone mass in adults are likely to be small compared with those of fat or protein mass, volume and total body water measurements can be combined in a three-compartment model to estimate fat and protein changes assuming constant mineral mass. This new model minimizes the bias inherent in estimates of fat or protein changes made from separate density or total body water measurements.
The effect of food deprivation on the fatty acid and lipid profile of red seabream (Pagrus major) larvae
Authors: Tandler A. , Watanabe T. , Satoh S. , Fukusho K.
Published: September 2005

Under conditions of food deprivation the lipid fraction of red seabream (Pagrus major) larvae shows patterns of conservation or loss in the profile of fatty acids and lipids. These changes were used for qualitative formulation of the dietary requirements of this species. Red seabream larvae were deprived of food for 5 d after hatching. Their lipid was extracted, weighed and analysed by gas–liquid chromatography and iatroscan for the presence of twenty-four fatty acids includingn−3 polyunsaturated fatty acids (PUFA), four polar lipids (PL) and four neutral lipids (NL). The results show an exponential decline in lipids with food deprivation, from a mean of 27.7 down to 11.8 mg/g wet larvae weight (LW). This loss could mainly be attributed to a decline in NL from 22.4 to 7.7 mg/g LW, in triacylglycerols, from 21 to 1 mg/g LW, and a change in cholesterol, from 1.3 to 4.2 mg/g LW after 5 d of food deprivation. PL declined from 5.3 to 4.1 mg/g LW in this period. The chief components of this fraction were phosphatidyl choline, and phosphatidyl ethanolamine. Among the fatty acids, the chief decline was observed in saturates and monoenes. Carbon chain lengths of 14 to 18 made up 18.2 mg/g LW in hatched larvae, but only 4.8 mg/g LW in larvae which were deprived of food for 5 d after hatching.n−3 PUFA were lost at a slower rate, from 5.4 to 3.5 mg/g LW for the same period, suggesting that they were conserved. Finally, early larvae of red seabream showed a reduced rate of loss ofn−6 relative ton−9 fatty acids, suggesting that the latter were used preferentially as an energy source.
Intestinal distribution and absorption of biotin in the chicken
Authors: Bryden W. L.
Published: September 2005

The initial distribution and absorption of biotin in chickens was studied in vivo from either changes in the composition of intestinal contents or analysis of blood draining the gut. The progressive decline in biotin concentration and flow along the small intestine demonstrated absorption throughout this organ. Quantitatively the duodenum was the most significant site of biotin absorption when crystalline biotin was included in the diet and when dietary ingredients contained highly available biotin. In contrast, when diets of low biotin availability were given the distal segments of the small intestine contributed a relatively greater amount to biotin absorption. During passage of digesta from the ileum to the caecum there was a tenfold increase in biotin concentration. About half the amount was of ileal origin with the remainder presumably resulting from microbial synthesis. About 20% of caecal biotin was in a ‘free’ form but the degree of absorption from the caeca was not determined. The amount of biotin disappearing from the gut of birds given maize-based diets was similar to the quantity appearing in portal blood. Biotin absorption was not detected from wheat-based diets using arteriovenous differences.
Effect of experimental zinc deficiency and repletion on sodium, potassium, copper and iron concentrations in guinea-pigs
Authors: Gupta R.P. , Verma P.C. , Sadana J. R. , Gupta V. K.
Published: September 2005

Zinc, sodium, potassium, copper and iron concentrations were analysed in serum and tissues of guinea-pigs fed on a diet containing 1.25 mg Zn/kg diet over a period of 60 d. The response of the Zn-deficient (ZnD) animals to Zn supplementation (100 mg Zn/kg diet) was also studied for 15 d. Serum studies in the ZnD group revealed significant decreases in the concentrations of Zn and Na from 24 d, and increases in the concentrations of Fe and K from 36 and 48 d onwards respectively; an increase in Cu was seen on day 60 only. Zn deficiency caused significant reductions in Na, K and Zn and increases in Cu and Fe contents of liver and kidney. In testis, significant decreases were noted only in Zn, K and Fe contents. Zn supplementation of the previously ZnD group resulted in marked improvements in serum and tissue mineral levels. However, hepatic Cu and Fe and renal K did not appear to respond appreciably.
Impaired T lymphocyte immune response in vitamin A depleted rats and chicks
Authors: Friedman Aharon , Sklan David
Published: September 2005

Vitamin A deficiency results in decreased immune responses; the objective of the present study was to investigate the involvement of T lymphocytes in the depression of immune responses resulting from vitamin A depletion. This objective was achieved by evaluating antigen-specific T lymphocyte proliferative responses in vitro as vitamin A depletion developed. The evaluation was performed in both rat and chick to examine the generality of immune effects due to vitamin A depletion. Our findings show that vitamin A depletion led to severe impairment of T lymphocyte activity in both animal models, and that this was directly related to the vitamin A status in both species. Immune response impairment was found to precede other manifestations of vitamin A deficiency, and was rapidly corrected by feeding retinyl acetate boluses. This implied a possible regulatory, rather than constitutive, role of vitamin A in immune responsiveness.
Passage and rumination of inert particles varying in size and specific gravity as determined from analysis of faecal appearance using multicompartment models
Authors: Murphy M. R. , Kennedy P. M. , Welch J. G.
Published: September 2005

Plastic particles of defined length (2, 5 mm) and specific gravity (sp.gr. 1.10, 1.34, 1.77) were administered just before feeding into the reticulo-rumen of four cattle and four swamp buffaloes given a diet predominantly of rice straw ad lib. Simultaneously, doses of ground rice straw marked with Cr and Yb were likewise given. Plastic particles were recovered from faeces for 12 d after dosing, and divided into non-ruminated (NR) and ruminated (R) particles. Excretion data of plastic particles were interpreted using a four-pool model incorporating passage of NR (kp) and R from the reticulo-rumen, post-ruminal passage, rate of chewing (kr) and two lag times. An inverse relationship was found between kr and sp.gr. The kr was higher for 5 mm than that for 2 mm particles. In contrast, kp was greatest for particles of sp.gr. 1.34, with higher kp for 2 mm than for 5 mm particles. Rates of passage and rumination (kp, kr) were higher for buffaloes than for cattle. Rumination time was related to kr, most highly (r2 0.96) with kr of 2 mm, 1.10 sp.gr. particles. Fragmentation of 5 mm particles by rumination tended to increase the rate of passage from the rumen. Ruminal passage rates of Yb and Cr markers were poorly correlated with each other and with kp of any of the plastic markers. Reanalysis of published data from plastic particle studies supported the relationships between sp.gr., size, kp and kr. In view of the additional information (kr) obtained using plastic particles, we suggest their use may be appropriate in studies which investigate specific differences in digestive function, while being less suitable for investigating differences between diets.
A comparison of the digestion and reduction in particle size of lucerne hay (Medicago sativa) and Italian ryegrass hay (Loliurn italicurn) in the ovine digestive tract
Authors: Grenet E.
Published: September 2005

Four types of hay were used: an early-cut and a late-cut lucerne (Medicago sativa) and an early-cut and a late-cut ryegrass (Lolium italicum). Digestibility and voluntary intake were measured on six adult sheep maintained in metabolism crates and fed 10% above the previous day's consumption, in equal portions at 08.00 and 16.30 hours. Lucerne intake was higher than that of ryegrass at similar digestibilities. The rate of digestion of the four hays was measured using nylon bags and the rates of digestion of dry matter for late-cut lucerne were faster than those for the late-cut ryegrass. Eleven adult sheep fitted with oesophageal (four), rumen (four) or duodenal (three) fistulas were used for collecting digesta samples at the different sites. They were fed successively with the four hay types. Each was offered to appetite, once daily, in a meal taken over 4 h. The rumen of rumen-fistulated sheep was completely emptied by hand once before feeding (08.00 hours) and once after removal of refusals (12.00 hours). The number of times the ingested hay was chewed during the meal and the time spent masticating was greater for the late-cut hays and greater for the ryegrass compared with the lucerne hays. The particle size of the boluses was greater than that of the rumen contents, which in turn was greater than that of the duodenal contents and faeces. The percentage of particles > 8 mm in the boluses from the ryegrass was higher than that of lucerne, and that of the early-cut ryegrass was greater than that of the late-cut ryegrass. This was also the case for the percentage of particles > 1.6 mm in the rumen contents after the meal. The rate at which dry matter disappeared from the rumen was greatest during the meal except with late-cut ryegrass; it was particularly high with late-cut lucerne, a little less with early-cut ryegrass and much lower with the other two hays. When nylon bags containing food boluses were placed in the rumen, it was apparent that without rumination, with the exception of the very digestible early-cut ryegrass, microbial degradation alone did not reduce the particle size.
Problems in estimating the extent of coprophagy in the rat
Authors: Fajardo Gladys , Hörnicke H.
Published: September 2005

The quantity of re-ingested faeces was calculated by comparing faecal dry matter of unrestricted rats and coprophagy-restricted rats after correcting for differences in food intake. Due to high day-to-day variations of produced and re-ingested faeces it was not possible to calculate precisely the extent of coprophagy of an individual rat at a particular day with this difference method. Reliable quantitative estimates require at least two rats and a collection period of 7 d. When fed on a nutritionally complete diet, rats re-ingested 0-11 % of their faeces. When fed on low-protein diets (66 g egg albumin/kg) or diets diluted with 200 g cellulose/kg, coprophagy was not significantly increased. A high re-ingestion rate (6–25 %) was observed with thiamin and pantothenic acid deficiencies. After re-ingestion of faeces had been prevented for 1 week, the amount of faeces re-ingested during the subsequent week without tail-cups was increased twofold. It is concluded that rats are able to regulate the amount of faeces eaten precisely according to their requirements.
Mechanism whereby holotrich ciliates are retained in the reticulo-rumen of cattle
Authors: Abe Matanobu , Iriki Tsunenori
Published: September 2005

The concentrations of holotrichs, reducing sugars and fermentation end-products, and the fluid dilution rates, in the cranial (CR), ventral (V) and caudal (CA) regions of the reticulo-rumen of cows were compared. Additionally, holotrich numbers in fluid and solid digesta samples taken from the dorsal (D) region were determined at different time-intervals. Holotrich numbers expressed per ml fluid at site D were almost twofold those expressed per g solid digesta, and the fluctuation of their numbers in fluid preceded that in solid digesta. Holotrich concentrations at site CR were higher before feeding than after feeding, while those at sites V and CA were lower before feeding than for a few hours after feeding. At sites V and CA, holotrich concentrations fluctuated in good agreement with reducing sugar concentrations, but the increase in the former always preceded that in the latter. The concentration of volatile fatty acids (VFA) tended to decrease from site CA to site CR, while the dilution rate was highest in site CR. The results suggest that migration of holotrichs from the reticulum to the rumen and vice versa are the cause of fluctuation in their numbers, and also the mechanism by which they are retained in the rumen of cattle.
Nutrient supply and growth of cattle offered straw-based diets
Authors: Ortigues Isabelle , Smith T. , Oldham J. D. , McAllan A. B. , Siviter J. W.
Published: September 2005

An experiment was conducted using steers cannulated at the rumen, duodenum and ileum to study the effects of increasing the levels of barley and fishmeal in straw-based diets. Diets A, B, C and D contained ammonia-treated straw, barley and fishmeal in the ratios, 67:33:0, 66:23:11, 53:47:0 and 52:36:12 (by weight) and were offered in daily amounts of 3·9, 3·9, 4·8 and 4·8 kg dry matter. The effects of barley were attributable to increased intakes of digestible organic matter and consequently to increased flows of microbial matter to the duodenum. There were no modifications in the balance of energy to nitrogen-yielding nutrients available for absorption. Introducing fishmeal into diets improved digestibility of cellulose and xylose by up to 6.7 and 4.7 % respectively, and shifted digestion towards the large intestine. Second, it increased amino acid N supply to the small intestine which averaged 52·2, 63·2, 68·8 and 84·0 g/d with diets A, B, C and D. Some changes were also noted in the balance of amino acids absorbed. Consequently, the contribution of amino acids to metabolizable energy intake increased with the proportion of fishmeal in diets (0·17, 0·20, 0·18 and 0·21 for diets A, B, C and D).

Growth rates measured in heifers amounted to 259, 431, 522 and 615 g/d for diets A, B, C and D. They appeared to be related to intestinal amino acid supply.
Energy expenditure in early infancy
Authors: Davies Peter. S. W. , Ewing G. , Lucas A.
Published: September 2005

The measurement of energy expenditure has wide applications in clinical and scientific studies. Ethical and practical problems, however, have limited the acquisition of information on total energy expenditure in infancy. The doubly-labelled-water technique, recently validated for use in infants, has now been used to measure, non-invasively, total energy expenditure in a cohort of forty-one normal, full-term infants at or close to 1·5, 3 and 6 months of age. Mean total energy expenditure was 270, 280 and 330 kJ/kg per d at these ages. Centiles for total energy expenditure in early infancy are presented; it is suggested such data are most appropriately expressed as kJ/√ (kg body-weight per d). These findings will be of importance in the re-evaluation of energy requirements in infancy and in the study of lesions in energy metabolism in disease states at this age.
The effect of environmental temperature on prandial changes in leucocyte sodium transport in man
Authors: Ng L. L. , Hockaday T. D. R.
Published: September 2005

Cellular sodium transport via the Na+, K+-ATPase contributes significantly to daily energy expenditure. The effect of a meal on leucocyte Na+transport and intracellular electrolytes was therefore investigated in lean normal subjects at room temperatures of 23° and 33°, to determine if the Na pump responds to the need for thermogenesis. In the fasting state, the ouabain-sensitive efflux rate which reflects active Na+transport, and the intracellular electrolytes were similar. At 2 h after eating a 4·2 MJ (1000 kcal) meal, the ouabain-sensitive efflux rate constant rose when the room temperature was 23° but not at 33°. The ouabain-sensitive Na+efflux rate, an index of active Na+transport, 0rose post-prandially at 23° only. The post-prandial activation of leucocyte active Na efflux in normal subjects was blunted at higher environmental temperatures, when the need for thermogenesis was reduced.
Effect of frequency of feeding of diets containing free or protein-bound lysine on the oxidation of [14C]lysine or [14C]phenylalanine by growing pigs
Authors: Batterham E. S. , Bayley H. S.
Published: September 2005

The effect of frequency of feeding (once daily or six equal portions at intervals of 3 h) of diets containing lysine (6.4 g/kg) supplied as either protein-bound or free lysine on the metabolism of essential amino acids was investigated in pigs over the 23–34 kg weight range. The amounts of radioactivity from14CO2produced by the pigs given oral doses of [14C]lysine or [14C]phenylalanine were determined. [14C]Lysine was confirmed to be unsuitable presumably because the oral dose was diluted by the dietary free lysine or was absorbed ahead of the protein-bound lysine, or both. With [14C]phenylalanine addition, there was a significantly (P< 0.01) greater production of14CO2by pigs fed once daily on the diet containing free lysine. However, with frequent feeding, there was no significant difference (P> 0.05) in the amount of14CO2produced by pigs from [14C]phenylalanine for either diet. Growth responses of the pigs were lower when the diet containing free lysine was given once daily (P< 0.01) but were similar when the diets were given frequently. It is concluded that the more rapid absorption of free lysine by growing pigs fed once daily results in an imbalance of amino acids at the sites of metabolism. This leads to greater oxidation of essential amino acids than occurs when all the amino acids are supplied in the protein-bound form. With frequent feeding, a better balanced supply of amino acids is absorbed, leading to similar rates of oxidation of excess essential amino acids from diets containing either free or protein-bound lysine.
Energy expenditure associated with sodium/potassium transport and protein synthesis in skeletal muscle and isolated hepatocytes from hyperthyroid sheep
Authors: McBride Brian W. , Early Richard J.
Published: September 2005

The object of the present study was to determine the effect of thyroxine (T4) treatment of sheep on protein synthesis and associated energy costs in skeletal muscle and hepatocytes. Protein synthesis, and ouabain-sensitive and cycloheximide-sensitive respiration in isolated intercostal muscle and hepatocytes were determined in sheep after 5 weeks of daily injections of either saline or T4. Plasma T4 and total triiodothyronine (T3) concentrations were doubled and free T3 concentrations were quadrupled by T4 injections. The fractional rates of protein synthesis increased in isolated external intercostal muscle and hepatocytes from hyperthyroid sheep. Fractional rates of protein synthesis in isolated external intercostal muscle and hepatocytes were linearly correlated with plasma free T3 concentrations. Total oxygen consumption of muscle and hepatocytes was unaffected by T4 injections. Ouabain-sensitive respiration increased in hepatocytes and muscle of T4-treated animals. Cycloheximide-sensitive respiration was elevated in hepatocytes from hyperthyroid sheep. Cycloheximide-sensitive respiration in muscle was unaffected by T4 treatment. The present experiment demonstrates that T4 increases protein synthesis in ruminants. The energy expenditure in support of Na+, K+-ATPase and protein synthesis in skeletal muscle and hepatocytes may account for 34–60% of total cellular energy expenditure.
Effect of oral glutathione on hepatic glutathione levels in rats and mice
Authors: Viña Jose , Perez Carmen , Furukawa Tadayasu , Palacin Manuel , Viña Juan R.
Published: September 2005

Administration of oral glutathione (GSH) increases hepatic GSH levels in fasted rats, in mice treated with GSH depletors such as diethyl maleate and in mice treated with high doses of paracetamol. An increase in hepatic GSH levels after administration of oral GSH does not occur in animals treated with buthionine sulphoximine, an inhibitor of GSH synthesis. Administration of oral GSH leads to an increase in the concentration of l-cysteine, a precursor of GSH, in portal blood plasma. Oral administration of l-methionine produced a significant decrease of hepatic ATP in fasted rats, but not in fed rats. Administration ofN−acetylcysteine or GSH did not affect the hepatic ATP levels. The results show that the oral intake of GSH is a safe and efficient form of administration of its constituent amino acids in cases when GSH synthesis is required to replete hepatic GSH levels.
The effect of differences in dietary iron intake on59Fe absorption and duodenal morphology in pregnant rats
Authors: Southon Susan , Wright A. J. A. , Fairweather-Tait Susan J.
Published: September 2005

The effect of iron intake on59Fe absorption throughout pregnancy, and on maternal and fetal Fe status towards the end of pregnancy, was investigated in rats. The influence of pregnancy and dietary Fe on duodenal morphology was also studied. Female rats were fed on a diet containing 17 or 100 mg Fe/kg for 2 weeks before and throughout pregnancy.59Fe absorption was measured on days 1 or 2, 8 or 9 and 17 or 18 of pregnancy, and maternal and fetal Fe status was determined on days 18 or 19. Pregnancy resulted in a fall in haemoglobin (Hb) concentration. Compared with non-pregnant counterparts, total liver Fe was reduced in the low-Fe group, but not in the high-Fe group, indicating that the fall in Hb in the high-Fe rats was not associated with an Fe-deficient state.59Fe absorption in rats fed on both diets increased throughout pregnancy, demonstrating that Fe supplementation of the diet, to a level that prevented the development of Fe-deficiency, failed to suppress an increase in absorption. Fetal weight appeared to be an important determinant of the efficiency of Fe absorption in late pregnancy. Poor maternal Fe status was accompanied by a reduction in fetal Fe concentration but results also suggested that fetuses were partly protected from maternal Fe-deficiency. Pregnancy resulted in increased duodenal circumference and villus dimensions, whilst high dietary Fe reduced duodenal growth in both pregnant and non-pregnant animals. The relevance of this finding is discussed. It was concluded that, in rats, pregnancyper secauses an enhancement in Fe absorption and that the degree of enhancement is in part related to fetal mass.
Methylmalonic acid in the diagnosis of cobalt deficiency in barley-fed lambs
Authors: O'Harte F.P.M. , Kennedy D. G. , Blanchflower W. J. , Rice D. A.
Published: September 2005

Eight lambs were fed on a cobalt-deficient whole-barley diet supplemented with urea, vitamins and minerals. Four control lambs were fed on the same diet which had been further supplemented with Co. Plasma vitamin B12levels in the Co-depleted group declined rapidly, falling below the normal range within 5 weeks. Differences between the live weights of the animals in the two groups approached statistical significance by week 14. However, methylmalonic acid (MMA) rose above normal levels in the Co-depleted group within 7 weeks. This suggested that an elevated plasma concentration of MMA is a comparatively early indicator of functional vitamin B12deficiency. It is recommended that 10 μmol/l be the upper level of normality for plasma MMA concentration in barley-fed animals, in contrast with the level of 5 μmol/l for grass-fed animals. Changes in the plasma concentrations of MMA and ethylmalonic acid associated with feeding the barley-based dietper sedid not significantly affect the validity of the gas-liquid chromatographic assay for MMA.
The effect of Maillard reaction products on zinc metabolism in the rat
Authors: Furniss D. E. , Vuichoud J. , Finot P. A. , Hurrell R. F.
Published: September 2005

The effect of giving Maillard reaction products (MRP) on zinc metabolism was investigated in the rat. In Expt 1, MRP were prepared by incubating casein with either glucose or lactose under controlled reaction conditions, and were quantified as either ‘early’ or ‘advanced’ after estimation of lysine loss and lysine destruction respectively. In Expt 2, the effect of the purified early MRP fructose–lysine (FL) on Zn metabolism was studied. The experimental diets containing 20 mg Zn/kg were given to weanling rats for 21 d. Zn balance was assessed over 9–14 d (Expt 1), or 1–14 d (Expt 2). Femur, liver, kidney and serum Zn concentrations were determined at 21 d. The major effect of the MRP in the casein-sugar mixtures was on urinary Zn excretion. The casein-glucose MRP induced up to a 6-fold increase in the quantity of Zn excreted in the urine. The magnitude of the hyperzincuria increased with the extent of the Maillard reaction. Similar dietary levels of casein-lactose MRP increased urinary Zn loss 2-fold. Free FL had no effect on urinary Zn. Faecal Zn, Zn retention, liver, femur and serum Zn were generally not influenced by giving MRP from casein-sugar mixtures or by giving free FL, although kidney Zn was decreased in rats fed on FL. It was concluded that although urinary Zn excretion can be increased by the presence of MRP in the diet, this is only a minor excretory pathway and would have little influence on overall Zn nutrition in individuals fed on a diet adequate in Zn.
Biotin studies in pigs
Authors: Kopinski J. S. , Leibholz Jane
Published: September 2005

Twenty pigs weaned at 5 d were given pelleted diets based on maize flour and casein and supplemented with 0,50,100,150 or 200 μg biotin/kg diet. The performance of the pigs was not influenced by the biotin content of the diets. Typical biotin deficiency symptoms (foot lesions and skin pustules) were observed in pigs given the unsupplemented diet and the diet supplemented with 50 μg biotin/kg diet. Tissue biotin concentration plateaued when 100 μg biotin/kg was added to the diet. Faecal biotin excretion was independent of dietary biotin intake, but increased with age. Urine biotin excretion at 102 d was significantly lower for the unsupplemented pigs than for the pigs given various levels of dietary biotin supplements. A dietary requirement of biotin for young pigs between 50 and 100 μg/kg diet is suggested from the results of the present experiment.
Biotin studies in pigs
Authors: Kopinski J. S. , Leibholz Jane , Leibholz Jane , Bryden W. L.
Published: September 2005

Six pigs (initial weight 30 kg) were fitted with T-shaped cannulas in the ileum, 0.3 m from the ileocaecal junction. Each pig was given each of seven diets for a 10 d period. The diets contained wheat (var. Banks and Egret), barley, sorghum, meat meal, soya-bean meal or casein as test feedstuffs. The apparent digestibilities of biotin to the ileum of the pigs were 0.06, -0.03, -1.23, 0.18, 0.82, 0.12 and 0.95 for the diets containing wheat (var. Banks), wheat (var. Egret), sorghum, barley, meat meal, soya-bean meal and casein respectively. The same diets were given to 168 chickens. Digesta were collected from the terminal ileum after 7 d. The apparent digestibilities of biotin to the ileum of the chickens were 0.11, −0.10, −0.73, 0.05, 0.69, 0.28 and 0.75 for the diets containing wheat (var. Banks), wheat (var. Egret), sorghum, barley, meat meal, soya-bean meal and casein respectively.
The effect of exercise and improved physical fitness on basal metabolic rate
Authors: Bingham S. A. , Goldberg G. R. , Coward W. A. , Prentice A. M. , Cummings J. H.
Published: September 2005

1. The suggestion that there is a sustained enhancement in metabolic rate after exercise was investigated during the course of a study in which six normal-weight volunteers (three men, three women) took part in a 9-week training programme. Baseline values were assessed in a 3-5 week control period of minimal activity before training. At the end of the study the subjects were capable of running for I h/d, 5 d/week.

2. Throughout the entire study the subjects were maintained on a constant diet. Measurement of energy expenditure by the doubly-labelled water (2H218O) method showed that the subjects had an energy imbalance of +3% in the control and -20% at the end of the training period. The subjects were in positive (1·1 (se 0·2) g) nitrogen balance in the second week of the control, and in negative (-0·6 (se 0·3) g) N balance in the last week of the exercise period.

3. Over the course of the study maximum oxygen consumption (Vo2max) and high-density-lipoprotein-cholesterol levels increased by 30%. Heart rate at rest and when performing a standard step test fell significantly.

4. Body composition was assessed weekly by40K counting and skinfold thickness measurements, in addition to2H2dilution at the beginning and end of the study. Fat-free mass was apparently gained in the early phases of the study, but there was lack of agreement between the different methods of assessing body composition. Changes in body-weight were not significant.

5. Basal metabolic rate (BMR), overnight metabolic rate (OMR) and sleeping metabolic rate (SMR) were measured on three occasions: in the control period, and the beginning and end of the training periods. Average BMR in the control period was 5·91 (se 0·39) MJ/24 h and was not changed with activity. There were no changes in OMR (5·71 (se 0·27) MJ/24 h in the control) nor in SMR (5·18 (se 027) MJ/24 h in the control), nor in BMR, OMR or SMR when expressed per kg body-weight, or per kg fat-free mass.

6. These results do not support the suggestion that there is a sustained increase in BMR following exercise that can usefully assist in weight-loss programmes.