bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnitude of ouabain-sensitive respiration in the liver of growing, lactating and starved sheep
Authors: McBride B. W. , Milligan L. P.
Published: September 2005

1. Oxygen consumption and ouabain-sensitive respiration was measured for liver biopsies from lactating and non-lactating ewes and for hepatocytes isolated from mature, dry ewes. O2 consumption, ouabain-sensitive respiration and 86Rb+ uptake were also measured for hepatocytes isolated from lambs, fed adult sheep and adult sheep starved for 5 d.

2. Ouabain-sensitive respiration in the liver of ewes at peak lactation accounted for 45% of the total liver O2 consumption. This percentage was 24–37% higher (P > 0.05) than measurements made during late lactation and during the non-lactating period.

3. Total O2 consumption and ouabain-sensitive respiration rates of lamb hepatocytes were greater ( P > 0.05) than similar measurements for hepatocytes isolated from adult sheep.

4. Ouabain-sensitive 86Rb+ uptake by hepatocytes from fed sheep was up to six times greater (P > 0.05) than that by cells from starved sheep.

5. The magnitude of ouabain-sensitive respiration of hepatocytes from starved sheep was 62% lower (P > 0.05) than that for hepatocytes from fed sheep.
Dietary fibre fermentation in the rat intestinal tract: effect of adaptation period, protein and fibre levels, and particle size
Authors: Nyman Margareta , ASP Nils-Georg
Published: September 2005

1. The fermentative breakdown of one resistant type of dietary fibre (wheat bran) and one easily-fermented fibre (low-methoxyl pectin) was studied with respect to the length of the adaptation period and fibre level in the diet. The breakdown of the resistant fibre was also studied regarding the protein level in the diet and particle size of the fibre.

2. Prolongation of the adaptation period from 4 to 18 d decreased the faecal dry weight considerably. The excretion of dietary fibre however, was similar, whereas a decrease in faecal nitrogen excretion could be seen.

3. A level of dietary protein of less than 50 g/kg impaired the fermentation of wheat-bran fibre, whereas a level higher than 100 g protein/kg did not further increase the degree of fermentation of the fibre.

4. The particle size did not change the fermentability of the fibre, equal amounts of the main components of coarse and milled bran being excreted in faeces.

5. Two different levels of wheat-bran fibre (48 and 96 g/kg) in the diet did not influence the fibre breakdown. Similar results were obtained with two levels of fibre from low-methoxyl pectin (42 and 84 g/kg), but a tendency towards a decreased percentage of faecal excretion of uronic acids was seen at the lower level of low-methoxyl pectin.
Use of a nylon-bag technique for pig feed digestibility studies
Authors: Graham Hadden , Åman Per , Newman Rosemary K. , Walt Newman C. , Walt newman C.
Published: September 2005

1. The use of a nylon-bag technique for pig feed digestibility determination was studied. Bags, measuring 25 × 40 mm and containing feed samples, were introduced into the pig gastrointestinal tract through a duodenal cannula, and recovered in the faeces between 23 and 69 h later. The disappearance of organic matter and crude protein (nitrogen × 6.25) from the bags was compared with in vivo apparent digestibility, determined by conventional faecal-collection methods, and neutral-detergent-fibre content for eleven feeds. The residues left in the bags after passage through the intestine from whole-crop-pea (Pisum sativum) and barley-grain samples were analysed for starch, non-starch polysaccharide residues, Klason lignin, crude protein and ash.

2. Dry matter disappearance of barley or whole-crop peas was not influenced by increasing bag pore size from 10 to 36 μm or sample weight from 250 to 1000 mg. Pepsin (EC 3.4.2.1) pretreatment had no effect on the degradation in the bags of the feeds investigated.

3. Organic matter and crude protein disappearance from the bags exceeded in vivo apparent digestibility by up to 0.10 and 0.42 units respectively. In vivo apparent organic matter digestibility could be predicted (P < 0.001) by the organic matter disappearance from the bags and the neutral-detergent-fibre content of the feed, while in vivo apparent crude protein digestibility was highly correlated (P < 0.001) to all these indices but poorly to crude protein disappearance from the bags.

4. Klason lignin was the least degraded component measured in the whole-crop-pea and barley residues from the bags, while starch was completely digested. Of the non-starch polysaccharide residues, xylose was the most resistant to degradation in both samples whereas other sugars vaned in susceptibility to solubilization between samples.

5. Results are discussed in relation to the potential uses of the nylon-bag technique described in the present paper for studies in simple-stomached animals.
Availability of lysine in meat meal, meat and bone meal and blood meal as determined by the slope-ratio assay with growing pigs, rats and chicks and by chemical techniques
Authors: Batterham E. S. , Lowe R. F. , Darnell R. E. , Major E. J.
Published: September 2005

1. The availability of lysine in four meat meals (MMs), four meat and bone meals (MBMs) and two blood meals was determined using the slope-ratio assay with growing pigs, rats and chicks and with two chemical techniques.

2. The availability of lysine (proportion of total) in the eight MMs or MBMs ranged from 0.48 to 0.88 for pigs, from 0.49 to 0.88 for rats and from 0.68 to 0.88 for chicks. There was no apparent relation between the availability estimates for pigs, rats and chicks for the individual meals.

3. For the two blood meals, availability estimates were 1.03 and 1.13 for pigs, 0.81 and 0.80 for rats and 1.07 and 1.02 for chicks.

4. Values for the indirect and direct 1-fluoro-2, 4-dinitrobenzene-‘available’-lysineassays ranged from 0.77 to 0.88 and 0.78 to 0.93 respectively for the eight MMs and MBMs. There appeared to be no relation between these values and the pig estimates.
Effect of pressure and temperature on the availability of lysine in meat and bone meal as determined by slope-ratio assays with growing pigs, rats and chicks and by chemical techniques
Authors: Batterham E. S. , Darnell R.E. , Herbert L. S. , Major E. J.
Published: September 2005

1. The availability of lysine for pigs, rats and chicks was determined using samples of meat and bone meal (MBM) subjected to different pressure and temperature treatments during dry-rendering processing. The relation between slope-ratio estimates and three chemical tests for estimating ‘available’ lysine was assessed.

2. The availability of lysine (proportion of total) for pigs was 0.97 in the control. Pressure (275 kPa gauge, 141°, for 30 min) in the early stage of rendering reduced availability to 0.74 and, in the late stage, to 0.46. Maintaining the final temperature at 125° for 4 h had little effect (0.84) whereas a higher temperature of 150° for 4 h reduced availability to 0.38.

3. Availability estimates for rats were lower than those of the pig, ranging from 0.88 in the control to 0.21 for the high-temperature treatment (150° for 4 h). The effects for temperature were similar to those for the pig, whereas the effect of pressure was equally detrimental in both the early and late stages (0.45 and 0.43 respectively).

4. For chicks, availability estimates were similar to those for the pig for the control (0.93) and the two temperature treatments (0.86 and 0.31 for the 125° and 150° treatments respectively). The chick was less susceptible to the effect of pressure applied to the MBM (0.78 and 0.63 for the early-and late-stage treatments respectively).

5. Values for the indirect-and direct-1-fluoro-2, 4-dinitrobenzene-(FDNB)-‘available’-lysine assays decreased from 0.86 and 0.74 to 0.57 and 0.54 for the control and 150° for 4 h treatments respectively, indicating that approximately half the reduced availability involved reactions with the ε-amino group of lysine. There was little relation between the FDNB values and lysine availability for the treatments involving changes in pressure.

6. There was little or no relation between dye-binding capacity of the meals, as assessed by the Acid Orange-12 dye-binding procedure (Hurrell et al. 1979), and lysine availability for the three species.
Intestinal microflora, morphology and enzyme activity in zinc-deficient and Zn-supplemented rats
Authors: Southon Susan , Gee Jennifer M. , Bayliss Catherine E. , Wyatt G. M. , Horn Nikki , Johnson I. T.
Published: September 2005

1. Immature, male Wistar rats were given a low-zinc diet (2 mg/kg) for 22–24 d. Control groups received a similar diet supplemented with 58 mg Zn/kg eitherad lib., or in amounts matched to the consumption of the Zn-deficient group. Food consumption, rate of growth and food conversion efficiency were markedly lower in the Zn-deficient group of rats compared with controls. Appetite, growth rate and food utilization improved dramatically over a subsequent 4 d period of Zn supplementation.

2. Morphological examination of samples of jejunum and ileum confirmed that Zn deficiency in the rat is accompanied by a reduction in villous dimensions and increase in villous density. After a short period of Zn supplementation, villous density and the basal width and maximum height of individual villi in the jejunum returned to normal. Similar changes occurred in the ileum but to a lesser extent.

3. Mucosal alkaline phosphatase (EC3.1.3.1) activity was significantly lower in the small intestine of Zn-deficient rats compared with Zn-supplemented rats. Disaccharidase activities were lower in the Zn-deficient group, compared with their feed-restricted counterparts, but were similar to values forad lib.-fed controls. Tissue alkaline phosphatase and disaccharidase activitities were consistently higher after a 4 d period of Zn supplementation, compared with non-supplemented animals, but this increase was only significant for alkaline phosphatase.

4. Although there were striking similarities in the mucosal characteristics of gnotobiotic and Zn-deficient rats, there was no indication that even severe dietary Zn depletion reduced the numbers of viable bacteria present in either the small or large intestine. Changes in intestinal structure and function resulting from variation in dietary Zn intake appear, therefore, to be unrelated to changes in the intestinal flora.
A mechanism for the hypocholesterolaemic activity of saponins
Authors: Sidhu G. S. , Oakenfull D. G.
Published: September 2005

1. Saponins are steroid or triterpene glycosides which occur in a number of important food plants, including such staples as soya beans (Glycine max) and chickpeas (Cicer arietinurn). They are known to be hypocholesterolaemic.

2. Some saponins form an insoluble complex with cholesterol which prevents its absorption from the small intestine. Others cause an increase in the faecal excretion of bile acids, an indirect route for elimination of cholesterol.

3. We have investigated the effects of different saponins on absorption of the bile salt sodium cholate from perfused loops of small intestine, in vivo, in the rat. Purified saponins from soapwort (Suponaria Officinalis), soya beans and quillaia (Quillata suponaria) reduced the rate of absorption of the bile salt; soya-bean and soapwort saponins substantially so but quillaia saponin to a much lesser extent.

4. These results were explained by the formation of large mixed micelles by bile acid and saponin molecules in aqueous solution. These aggregates can have molecular weights in excess of 106daltons, consequently the bile acid molecules incorporated in them are not available for absorption.

5. Control of plasma cholesterol and nutrient absorption through dietary saponins could provide substantial health and nutritional benefits in humans.
Influence of dietary protein concentration on the oxidation of phenylalanine by the young pig
Authors: Ball Ronald O. , Bayley Henry S.
Published: September 2005

1. Piglets were weaned at 3 d of age and reared to 2.5 kg on a liquid diet in which the protein was supplied by dried skim milk and a mixture of free amino acids. The oxidation of L-[l-14C]phenyIalanine was measured as an indication of the partition of amino acids between retention and catabolism in pigs (2.5 kg) offered meals containing vaned concentrations of crude protein (nitrogen x 6.25).

2. The dietary protein concentration was varied either by increasing the inclusion of a mixture of free amino acids in a series of diets containing 100 g protein/kg from skim milk, or by increasing the level of inclusion of the skim milk in a series of diets containing the equivalent of 100 g protein/kg from the free amino acid mixture.

3. The oxidation of phenylalanine was minimized by dietary protein concentrations of 240 and 258 g/kg for the diets containing increasing concentrations of free amino acids or skim milk respectively.

4. These results show that a mixture of free amino acids is used more effectively than intact protein for promoting retention of essential amino acids.

5. The recovery of radioactivity in expired carbon dioxide was inversely related to the recovery of radioactivity in liver tissue when the concentration of dietary crude protein was increased from deficient to adequate, demonstrating that the fractional oxidation of the indicator amino acid was inversely related to protein synthesis.
Taurine concentrations in the diet, plasma, urine and breast milk of vegans compared with omnivores
Authors: Rana Surinder K. , Sanders T. A. B.
Published: September 2005

1. The concentration of taurine in the diets, plasma, urine and breast milk were measured in vegans and age- and sex-matched omnivore controls. Plasma and urinary amino acid concentrations were also determined

2. Taurine was absent from the vegan diet and occurred in variable amounts in the diets of the omnivores. Urinary taurine levels were less than half those of the omnivores but plasma and breast-milk levels were only slightly lower.

3. Dietary energy intakes were similar in the vegans and omnivores, but protein intakes tended to be lower in the vegans.
Perrcentage body fat and prevalence of obesity in a UK offshore population
Authors: Light I. M. , Gibson M
Published: September 2005

1. Body-weight, body height and skinfold measurements were taken in 419 adult males working in the UK offshsore oil industry. Percentage body fat was estimated from skinfold thicknesses and the Quetelet index (weight: height2) determined.

2. The prevalence of overweightness, assessed from the Quetelet index, in the age groups 20–29, 30–39 and 40–49 years was 31.6, 50.0 and 66.2% respectively. The Office of Population Census and Surveys (1981) showed that for age-matched groups, the incidence of overweightness in an onshore population was 26, 40 and 50% respectively.

3. The percentage body fat for each respective age group was greater than that reported for an age-matched onshore population.

4. The Quetelet index was significantly related to body fat (r 0.765, P < 0.0001) and poorly correlated with height, thus this weight: height relation may be utilized in the assessment of overweightness in offshore personnel.

5. In conclusion it appears that the offshore population had a higher percentage body fat than their onshore peers and that the prevalence of overweightness was also greater.
The influence of riboflavin deficiency on absorption and liver storage of iron in the growing rat
Authors: Adelekan Delana A. , Thurnham David I.
Published: September 2005

1. Iron absorption was measured in weanling riboflavin-deficient (RD) rats or weight-matched (WM) controls fed on appropriate diets for 7 weeks. Concentrations of radio-Fe (68Fe) in plasma were monitored every 30 min for 4 h following intragastric administration.

2. Total Fe absorption in RD rats was significantly lower than that in WM controls, and the tissues of the stomach and small intestine of RD rats retained significantly (P < 0.001) more 68Fe by comparison with WM groups.

3. In a separate experiment, ferritin-Fe concentrations were measured in the livers of four groups of rats (adlib. (C), pair-fed (PF) and WM controls and RD) at day 0, and subsequently at days 14, 21, 28, 35 and 49.

4. Liver ferritin-Fe concentration was significantly lower (P < 0.05) in RD rats than in all other controls after 3 weeks on the respective diets and remained lower for the remainder of the experiment.
Estimation of tissue protein synthesis in sheep during sustained elevation of plasma leucine concentration by intravenous infusion
Authors: Schaefer A. L. , Davis S. R. , Hughson G. A.
Published: September 2005

1. The fractional rate of protein synthesis (FSR) was determined in skeletal muscle, liver, rumen and cardiac muscle of wether sheep by continuous intravenous infusion of L–[4,5–3H]leucine accompanied by infusion of 0, 7.6, 15.2 or 22.8 mmol leucine/h (three sheep per treatment). FSR was calculated assuming plasma (ksp) or intracellular (ksi) leucine-specific radioactivity (SRA) was representative of the leucine precursor pool SRA for protein synthesis.

2. Plasma leucine concentration (plateau) was linearly related to leucine infusion rate, 22.8 mmol/h evoking tenfold increase in plasma concentration.

3. Difference between plasma leucine SRA and intracellular leucine SRA in all tissues diminished as plasma leucine concentration increased.

4. There were significant differences between ksiand kapestimates for liver and rumen in control sheep.

5. As leucine infusion rate increased, differences between kriand kag, diminished in all tissues. With increasing leucine infusion, in liver kstdecreased and kspwas increased, in rumen kgedecreased and kspwas stable, while in cardiac and skeletal muscle ksiand kspboth increased.

6. At a leucine infusion rate of 22.8 mmol/h, mean kap, and kstrespectively were: rumen 1 1 (SE 2), 13 (SE 1); liver 19 (SE 2), 21 (SE 2); cardiac muscle 3–6 (SE 0.4), 3.8 (SE 0.3); skeletal muscle 4.1 (SE 0.2), 4.5 (SE 0.5) and did not differ significantly in any tissue.
Longitudinal changes in nutritional habits of teenagers: differences in intake between schooldays and weekend days
Authors: Post Bertheke , Kemper Han C. G. , Strom-Van Essen Lucienne
Published: September 2005

1. Longitudinal changes in nutritional habits were studied in Dutch adolescents from 12 to 17 years of age (131 girls and 102 boys). The dietary differences on schooldays and weekend days are reported.

2. In girls only small changes in nutritional habits were seen as they grew older. In boys there was a gradual increase in food intake with age.

3. Overall, higher nutrient intakes could be seen on weekend days. The energy intake on weekend days was consistently higher for girls and boys in all age-groups. The proportional intakes of fat and sugar were rather high, especially on weekend days. The alcohol consumption increased with age for girls as well as boys, and was for some individuals extremely high (boys) on weekend days.

4. The observed levels of intake compared with the recommendations showed a rather low intake of polyunsaturated fatty acids, polysaccharides and iron.
In vitro estimation of iron availability from a range of plant foods: influence of phytate, ascorbate and citrate
Authors: Hazell T. , Johnson I. T.
Published: September 2005

1. Plant foods were digested in vitro and the proportion of iron which diffused across a ssemi-permeable membrane was used as an index of Fe availability.

2. The mean (with SEM) Fe diffusibility from a group of eighteen cereals, legumes and nuts was very low, 2.1 (0.25)%, whereas from a group of sixteen fruits and vegetables it was high, 13.7 (1.09)%. The difference between the two food groups was highly significant (P< 0.001).

3. The results for Fe diffusibility correlated well with literature values for the in vivo absorption of Fe from similar foods (r0.84,P< 0.01).

4. When phytate, citrate and ascorbate were added to selected foods in amounts corresponding to endogenous levels, only phytate and citrate gave the expected effects on Fe diffusibility. Ascorbate only enhanced Fe diffusibility to the expected extent when it was added in much larger amounts, not normally found in foods.

5. When added to cereal foods, orange juice was found to enhance greatly Fe diffusibility even when its content of ascorbate was completely destroyed by boiling followed by prolonged storage. When citrate and ascorbate were added to cereal foods in amounts equivalent to those found in fresh orange juice, both enhanced Fe diffusibility but citrate was far more effective.

6. It is concluded that phytate is a major inhibitor of Fe diffusibility in cereals, legumes and nuts. However, citrate rather than ascorbate would appear to be the major enhancer of Fe diffusibility from many fruits and vegetables.

7. The implications of the present results are discussed in relation to the relative influence of phytate, citrate and ascorbate on dietary Fe availability.
Methane excretion in the growing pig
Authors: Christensen Kirsten , Thorbek Grete
Published: September 2005

1. Total methane excretion (CH4 in breath+flatus) was measured in two experiments with thirty-six castrated male pigs (Danish Landrace) during the growth period from 20 to 120 kg live weight (LW). In Expt A, twenty-eight pigs were fed on a commercial diet alternately at high (HFL; metabolizable energy (ME) 1234 (SE 41) kJ/kg LW0.75) or low (LFL; ME 784 (SE 31) kJ/kg LW0.75) feed levels in different weight classes. In Expt B, eight pigs were constantly fed on a semi-purified diet at HFL without (-oil) or with 90 g soya-bean oil/kg diet (foil) corresponding to daily intakes of ME of 1339 (SE 11) and 1413 (SE 8) kJ/kg LW0.75 respectively.

2. CH4 excretion was measured during 24 h respiration trials in open-air-circulation chambers.

3. About 1 litre CH4 was excreted per day at 20–25 kg LW increasing to a maximum of 12 litres at 120 kg LW, which corresponded to no more than 1.2% of dietary gross energy.

4. In Expt A, CH4 excretion increased linearly with LW, while in Expt B the increase was linear until about 70 kg LW, when it reached a plateau. On average LFL reduced CH, excretion by 23% compared with HFL. When related to dry matter (DM) intake, however, the pigs on LFL excreted 3.1 litres CH4/kg dietary DM and those on HFL 2.5 litres CH4/kg dietary DM, the difference being significant (P < 0.05). In Expt B the inclusion of soya-bean oil in the basal diet (+oil) reduced CH, excretion by 26% compared with the diet without oil (-oil). The pigs receiving the basal diet excreted 5.2 litres CH4/kg DM and the pigs receiving soya-bean oil 4.3 litres CH4/kg DM, the difference being highly significant (P < 0.001). All differences between Expt A and B in CH4 excretion based on DM intake were highly significant (P < 0.001).

5. The results are discussed in relation to gas production in ruminants, rats and humans. It is suggested that flatus production may not only be reduced by changing the composition of the dietary carbohydrates, but also by inclusion of a polyunsaturated oil in the diet of simple-stomached animals and humans.
The role of rumen protozoa in the utilization of paspalum (Paspalum dilatatum) hay by cattle
Authors: Punia B. S. , Leibholz Jane , Faichney G. J.
Published: September 2005

1.Six Friesian heifers (250 kg live weight) with permanent cannulas in the rumen and abomasum were allocated at random into two groups of three. One group was treated with Teric GN9 (ICI (Aust.) Ltd) to defaunate the animals during the first two of the four periods of the experiment, after which they were refaunated. The second group was treated with Teric at the end of the first two periods. The dietary treatments were: paspalum (Paspalum dilatatum) hay (4.1 kg/d) given alone and the hay supplemented with urea (20 g/kg dry matter).

2. Defaunation was not complete but the approximate volume of protozoa in the rumen of treated animals was less than 6% of that in the untreated animals.

3. The amount of organic matter (OM) digested in the stomach was lower (P< 0.01) in animals with reduced fauna than in those with normal fauna. There were reductions in both the apparent OM digestibility in the total tract (from 0.56 to 0.52,P< 0.01) and the proportion of the digestible OM digested in the rumen (from 0.82 to 0.79, not significant) of animals with reduced fauna. Apparent digestibilities of acid-detergent fibre and neutral-detergent fibre were significantly lower (P< 0.01) in animals with reduced fauna.

4. The amount of nitrogen disappearing from the stomach was significantly higher (P< 0.01) with the urea supplement; effects due to concentrations of protozoa were not significant. The flow of non-ammonia-N from the abomasum was higher (P< 0.05) in animals with reduced fauna than in animals with normal fauna. The flows of bacterial N from the abomasum and the efficiencies of bacterial N synthesis were not significantly affected by the treatments. N retention was higher (P< 0.01) in animals receiving the urea supplement but differences due to protozoa were not significant.

5. Protozoal contribution to the microbial N flowing from the rumen of animals with normal fauna was estimated to be 24 and 27% with and without the urea supplement respectively.

6. Concentrations of rumen-fluid ammonia-N were reduced (P< 0.05) and those of volatile fatty acids were increased (P< 0.01) with reduction in protozoal numbers. Molar proportions of propionic acid increased (P< 0.05) and of butyric acid decreased (P< 0.01) with reduced rumen fauna.

7. Rumen water volume was lower (P< 0.05) and the mean retention time of indigestible acid-detergent lignin tended to be higher in animals with reduced fauna. Rumen dry-matter pool and mean retention time of CrEDTA were not significantly different between treatments.
Effects of a β-agonist (clenbuterol) on growth, carcass composition, protein and energy metabolism of veal calves
Authors: Williams P. E. V. , Pagliani L. , Innes G.M. , Pennie K. , Harris C. I. , Garthwaite P.
Published: September 2005

1. Twenty-two British Friesian bull calves were used in a comparative slaughter experiment to determine the effects of a β-agonist (clenbuterol) on body composition and energy retention. Four calves were slaughtered at 18 d of age and constituted the initial slaughter group. Of the remaining calves, eight (group A, controls) were given milk replacer only, and ten calves (groups B and C, five calves per group) were given milk replacer plus clenbuterol(O.1 and 1.0 mg clenbuterol/kg milk replacer equivalent to approximately 2 and 20 μg/kg body-weight respectively over the 105±3 d of the experimental period). Calves were slaughtered over the weight range 146–177 kg.

2. Clenbuterol had no significant effect on dry matter (DM) intake, daily live-weight gain or feed conversion ratio. DM digestibility of the milk replacer was not affected by treatment. Nitrogen balance was measured on three separate occasions starting when the calves weighed approximately 60, 110 and 130 kg. N retention was increased over the experimental period in clenbuterol-treated calves, although the effect only achieved significance in calves weighing approximately 110 kg live weight (P< 0.05).

3. Clenbuterol (20 μg/kg body-weight) increased estimated mean daily N retention in the carcass of the calves from 22 to 25 g whilst N retention in the non-carcass components decreased from 10 to 8 g/d. Effects of clenbuterol on N retention occurred mainly in skeletal muscle. Fat in both carcass and non-carcass components was reduced by treatment with clenbuterol. The total energy content of live-weight gain was reduced from 1077 to 897 MJ in clenbuterol-treated calves and mean daily heat production was estimated to increase from 23.1 in controls to 25.9 MJ/d in calves in group C.

4. In calves of mean live weight during balance of 120 and 136 kg, clenbuterol significantly increased daily urinary creatinine excretion and in 120 kg calves NT-methylhistidine was significantly decreased (P< 0.05). Based on estimates of muscle mass from urinary creatinine and protein degradation fromN7-methylhistidine NT-methylhistidine excretion, the fractional breakdown rate of muscle protein in clenbuterol-treated calves was only 0.66 of that in the controls when the calves weighed 120 kg.
Effect of fasting and of methionine deficiency on L-methionine, DL-methionine and DL-2-hydroxy-4-methylthiobutanoic acid metabolism in broiler chicks
Authors: Saunderson C. Linda
Published: September 2005

1. Metabolism of L-[1-14C]methionine, DL-[l-14C]methionine and DL-[ 1-14C]2-hydroxy-4-methylthiobutanoic acid (DL-HMB) by broiler chicks which had been fasted overnight or given a methionine-deficient diet was compared with fed (control) birds.

2. The excretion of14C-labelled material, total14CO2exhaled,14C incorporation into tissue proteins and the14C-labelled material in perchloric-acid-soluble tissue fractions were measured 6 h after injection of the14C-labelled materials.

3. The incorporation of14C into tissue proteins and the relative rates of conversion of D-methionine and DL-HMB to L-methionine in tissues under different nutritional regimens were compared using protein-bound14C:protein-free14C values.

4. Fasted birds exhaled more14CO2than control birds but excreted less14C, while methionine-deficient birds behaved very similarly to the control animals in these respects.

5. Fasted birds incorporated much less14C into proteins of tissues other than liver and kidney from all three labelled tracers. The values for protein-bound14C: protein-free14C were lower in all tissues.

6. Methionine-deficient birds had similar levels of14C in tissue proteins but lower values for protein bound14C: protein-free14C.

7. Examination of the values for protein-bound14C:protein-free14C suggest that brain and probably liver tissues from fasted and methionine-deficient birds showed improved rates of conversion of D-methionine and DL-HMB to L-methionine compared with control animals.
Porto-arterial plasma concentration differences of urea and ammonia-nitrogen in growing pigs given high-and low-fibre diets
Authors: Malmlöf Kjell
Published: September 2005

1. The effects of a high-(HF) and a low-(LF) fibre diet on porto-arterial plasma concentration differences and plasma levels of urea and ammonia-nitrogen were compared in six Swedish Landrace x Yorkshire pigs (30–52 kg). Portal and arterial blood samples were drawn during 8 h following two consecutive meals, given at 08.00 and 16.00 hours.

2. The HF diet, in comparison with the LF diet, was found to produce significantly lower portal plasma urea levels. However, concomitant arterial plasma levels were equally depressed, consequently leaving the porto-arterial urea differences unchanged.

3. In no instance during the 16 h studied could negative porto-arterial urea differences clearly be observed. It was thus concluded that none of the diets induced an important net flux of plasma urea directly from the circulation into the gastrointestinal tract.

4. The significantly lower circulating plasma urea levels that were observed when the pigs received the HF diet were also associated with significantly lower urinary excretions of urea.

5. The HF and LF diets had similar effects on portal and arterial plasma levels of ammonia-N. This was also true with regard to porto-arterial ammonia-N differences.
The vitamin D status of East Indian Punjabi immigrants to Canada
Authors: Gibson R. S. , Bindra G. S. , Nizan P. , Draper H. H.
Published: September 2005

1. Serum 25-hydroxyvitamin D (25-OHD), calcium and alkaline phosphatase (EC3.1.3.1) levels and vitamin D intakes (from 3 d weighed dietary records) were determined in a cohort of fifty-nine male East Indian Punjabi immigrants (37.7 (SD 10.5) years) and fifty-four females (33.3 (SD 7.4) years).

2. Females had somewhat lower mean serum 25-OHD levels (12.3 (SD 5.0) v. 14.2 (SD 5.1) ng/ml,P< 0.05) and serum Ca levels (88 (SD 8) v. 91 (SD 6) mg/l) than males (P< 0.05) whereas serum alkaline phosphatase values (males 167 (SD 63), females 169 (SD 43) IU/l) and dietary vitamin D intakes (males 3.5 (SD 1.8), females 3.3 (SD 2.0) μg/d) were similar.

3. 22% Of the females and 12% of the males had serum 25-OHD levels below 9.0 ng/ml but none had serum 25-OHD levels within the range associated with clinically overt disease.

4. In the males, serum 25-OHD levels were negatively correlated with dietary fibre intakes (g/d; r–0.29;P< 0.05).

5. Multiple-regression analysis indicated that log serum 25-OHD levels were not related to dietary vitamin D intakes. Instead they were associated with sex and dietary fibre intakes (g/MJ) (F3.71;P= 0.03). These two variables explained 8% of the variance.
The importance of the body's need for zinc in determining Zn availability in food: a principle demonstrated in the rat
Authors: Hallmans Göran , Nilsson Ulf , Sjöström Rolf , Wetter Lars , Wing Kenneth
Published: September 2005

1. The hypothesis that the availability of zinc in a food is limited by factors in the food was tested against the hypothesis that Zn absorption is homeostatically regulated by the body according to its need for Zn.

2. The experimental model used was the short-term administration to rats of a parenteral nutrition solution with no added Zn in an attempt to increase their need for Zn in an anabolic phase.

3. The absorption and retention of65Zn from a piece of endosperm-wheat crisp-bread in rats injected intraperitoneally with the parenteral nutrition solution was more than 40% higher than that in a control group injected with physiological saline (9 g sodium chloride/l).

4. The results indicate that the availability of Zn in the bread is not fixed but variable and dependent on the body's need for Zn.
Relative contribution of cysteine and methionine to glutathione content and thyroid hormone levels in the rat
Authors: Suberville C. , Higueret P. , Taruoura D. , Garcin H. , Higueret D.
Published: September 2005

1. For a period of 24 d rats were given diets containing either casein or pea (Pisum sativum) protein at two different concentrations (180 and 120 g/kg) without or with cysteine or cysteine + methionine supplementation.

2. The effects of these diets on levels of blood and liver reduced glutathione (GSH) and serum thyroid hormones were studied.

3. When compared with the 180 g casein/kg diet, the 120 g casein/kg diet decreased liver GSH and serum thyroid hormone concentrations. These changes were related to dietary cysteine supply since supplementation induced an increase in these variables.

4. When compared with 180 g pea protein/kg diet, the 120 g pea protein/kg diet decreased liver GSH and serum thyroid hormone concentrations. These changes could not be corrected by cysteine or cysteine + methionine supplementation.
Determination of protein degradation rates using a rumen in vitro system containing inhibitors of microbial nitrogen metabolism
Authors: Broderick Glen A.
Published: September 2005

1. A previously reported rumen in vitro system (Broderick, 1978) was modified to include chloramphenicol (CAP) with hydrazine sulphate (HS) to give quantitative recovery of protein breakdown products. Degradation rates were determined by regression v. time of log proportion remaining undegraded (computed by subtracting from added nitrogen the amount of N recovered as ammonia and amino acids). Concentrations of reagents giving optimal N recoveries and estimated degradation rates for casein and expeller soya-bean-meal (SBM) were: 1.0 mM-HS, 30 μg CAP/ml, 20 mM-mercaptoethanol, 3.3 mg maltose/ml, when protein was added at 0125 mg N/ml.

2. Digestion of azo-casein and azo-albumin, solubilization of radioactivity from 14C-labelled casein, ovalbumin and bovine serum albumin (BSA), and hydrolysis of benzoyl-L-tyrosine p-nitroanilide and benzoyl-L-arginine p-nitroanilide were not significantly decreased by HS and CAP. This suggests that the inhibitors did not reduce microbial proteolysis.

3. Mean fractional degradation rates (/h) were: 0395 casein, 0.135 BSA, 0.159 solvent-SBM, 0.045 expeller-SBM, 0.061 meat meal, 0070 lucerne (Medicago sativa) hay. Extents of protein escape, estimated assuming rumen passage of 0.06/h, were 13, 28, 56 and 40% for casein, solvent-SBM, expeller-SBM and lucerne hay respectively. This method appears more reliable for assessing rumen degradability than buffer N solubility and protein digestibility with ficin protease.

4. Azo-dye treatment slowed the rate of casein degradation, measured by ammonia plus amino acid release, but did not alter digestion of BSA.

5. The validity of the inhibitor in vitro method for estimating protein degradability, as well as potential problems in its application, are discussed. The complete procedure may be limited to laboratories with automated analytical equipment, but a simplified version of the method may be more generally applicable.
Effect of sugar fatty acid esters on rumen fermentation in vitro
Authors: Wakita M. , Hoshino S.
Published: September 2005

1.The effect of sugar fatty acid esters (SFEs; currently used as food additives for human consumption) on rumen volatile fatty acids (VFA) and gas production was studied with sheep rumen contents in vitro.

2. Some SFEs having monoester contents of more than 70 % increased the molar proportion of propionate in conjunction with reduction in the acetate: propionate ratio when the individual SFE was added to rumen contents in a final concentration of 4 g/l. Laurate sugar ester was the most potent propionate enhancer and rumen gas depressor, the effective dose being as low as 1 g/l in a final concentration. Fatty acid esters other than SFEs had little, if any, effect on rumen VFA production and their molar proportions.

3. Approximately 50% of laurate sugar ester was hydrolysed by in vitro incubation with rumen fluid for 2 h. The addition of fatty acids and sucrose was also effective in the alterations of rumen VFA and gas production. However, the effect of SFEs on in vitro rumen fermentation was significantly greater than that of their constituent fatty acids or sucrose, or both. Accordingly, the effect appeared to be ascribed to the complex action of SFE itself and to its constituents, free fatty acids and sucrose.

4. SFEs, at the level of 4 g/l, reduced substantially the froth formation (ingesta volume increase) and seemed to be effective for the prevention of bloat.
Effects of substitution of tricaproin for tallow and of protein concentration in milk substitutes on nitrogen and energy balance in the preruminant lamb
Authors: Aurousseau Bernard
Published: September 2005

1. Results of 138 nitrogen balance studies from experiments with forty male Limousin and nineteen male Ile de France preruminant lambs were used to estimate total N requirements and to assess the effects of dietary tricaproin inclusion, protein concentration, lysine and methionine supplementation and the age of lambs on protein retention. In addition, energy balances were obtained in twenty-four of the Limousin lambs from birth up to 3 weeks of age by means of a slaughter technique.

2. For milk substitute unsupplemented with amino acids, tricaproin inclusion increased N balance slightly (P < 0.001) when a medium-protein concentration (260 g/kg dry matter (DM)) was used, in 2-week-old lambs (+4.3%) and in 5-week-old Limousin lambs (+5.3%), or very markedly when a high-protein concentration (320 g/kg DM) was used, in 2-week-old lambs (+14.5%) and in 5-week-old lambs (+18.6%). Protein requirements decreased from 300 g/kg DM in 3-week-old lambs to 270 g/kg DM in 5-week-old lambs for the control milk containing tallow-coconut oil mixture (0.67:0.33 by wt) and was increased above 300 g/kg DM at all ages in the case of experimental milk containing tallow-coconut oil-tricaproin mixture (0.33:0.33:0.33, by wt).

3. For milk containing either a medium- or a high-protein concentration and supplemented with lysine and methionine, inclusion of tricaproin increased N balance (P < 0.01) to a similar extent (+8.5 up to +14.3 %) in 1 to 2- and 3-week-old Limousin lambs. An increase in N concentration in the milk had no effect in 1 - and 2-week-old lambs, but led to a decreased N balance in 3-week-old lambs. Protein requirements decreased from 310 g/kg DM in 1-week-old lambs to 190 g/kg DM in 3-week-old lambs for the milk containing tallow-coconut oil or from 300 g/kg DM in 2-week-old lambs to 210 g/kg DM in 3-week-old lambs for the milk containing tallow-coconut oil-tricaproin.

4. For the Ile de France lambs given milk supplemented with lysine and methionine, tricaproin inclusion did not alter N balance. Protein requirements decreased from 370 g/kg DM in 2-week-old lambs to 270 g/kg DM in 4-week-old lambs for milk containing both kinds of fat mixtures.

5. Between birth and 3 weeks of age, efficiency of metabolizable energy (ME) utilization in the Limousin lambs was not dependent on the nature of the milk fat or the protein concentration of the diet (ME efficiency for tissue deposition varying from 0.672 to 0.698) whilst ME efficiency for protein deposition was 0.52 and ME efficiency for lipid deposition was close to 1; daily maintenance expenditure was 553 kJ/kg body-weight0.75
Influence of starches of low digestibility on the rat caecal microflora
Authors: Mallett A. K. , Bearne C. A. , Young P. J. , Rowland I. R. , Berry C.
Published: September 2005

1. Male Sprague-Dawley rats were fed on either a purified, fibre-free diet or a diet in which half the maize starch was replaced with uncooked amylomaize or potato starch (equivalent to 100 or 200 g amylase-resistant starch (ARS)/kg diet respectively). Changes in short-chain fatty acids (SCFA), pH, ammonia and a number of bacterial variables in caecal contents were then assessed.

2. Both ARS supplements decreased caecal content pH by approximately 1–2 units, with an associated reduction in ammonia concentration. Potato starch significantly decreased the concentration of SCFA in the hind-gut, while amylomaize supplementation increased propionic and butyric acids but decreased the occurrence of minor, branched-chain fatty acids.

3. Caecal bacterial biotransformation activities (β-glucosidase (EC3.2.1.21), β-glucuronidase (EC3.2.1.31), reduction ofp-nitrobenzoic acid, apparent ammonia formation) were consistently decreased by both ARS sources.

4. The results demonstrate that amylase-resistant carbohydrate altered toxicologically important functions in the large-intestinal flora of the rat.
Importance of body tissues as sources of nutrients for milk synthesis in the cow, using 13C as a marker
Authors: Wilson G. F. , Mackenzie D. D. S. , Brookes I. M. , Lyon G. L.
Published: September 2005

1. The proportions of carbon in individual milk constituents derived from feed and body tissues in dairy cows, were estimated by taking advantage of the natural variations which occur in the ratio, 13C:12C present in C3- and C4-plant species.

2. Four cows, which had previously grazed C3 plants (ryegrass (Lolium spp.) and white clover (Trifolium repens)), were accustomed to indoor feeding on a ration of C3-plant material (cut pastures and barley meal). The ration was then changed abruptly to one of C4-plant material (paspalum (Paspalum dilatatum) hay, maize silage and meal) for a period of 8 or 9 d in early and again in late lactation.

3. During early lactation it was estimated that 54% of the C in milk fat was derived from the body fat reserves of high genetic merit cows. Corresponding values for casein and lactose were 34 and 24% respectively, if it is assumed they were derived from body protein reserves. In contrast steam-volatile fatty acids in milk fat were almost entirely derived from dietary sources.

4. The proportional contribution of body-tissue C to individual milk constituents varied considerably between animals, possibly associated with genetic merit or the size of the body reserves available for mobilization.

5. In late lactation, when cows were close to energy and protein balance, contributions of body-tissue C to milk fat, casein and lactose ranged up to 19, 19 and 8% respectively.

6. Estimates of endogenous losses of C in faeces averaged 12 and 9% in early and late lactation respectively, and corresponding values for endogenous urinary C were 23 and 15%.
Energy-sparing adaptations in human pregnancy assessed by whole-body calorimetry
Authors: Prentice A. M. , Goldberg G. R. , Davies H. L. , Murgatroyd P. R. , Scott W.
Published: September 2005

The hypothesis that the energy cost of human pregnancy can be minimized by energy-sparing metabolic adaptations was tested using serial 24 h whole-body calorimetry. Eight healthy, well-nourished women were studied prepregnant and at 6, 12, 18, 24, 30 and 36 weeks gestation. Basal metabolic rate (BMR) showed highly characteristic changes within each subject and large inter-individual differences (F 3.5, P < 0.01). Some subjects showed a highly significant depression of metabolism up to 24 weeks gestation in support of the initial hypothesis. At 36 weeks BMR ranged from +8.6 to +35.4% relative to the prepregnant baseline. This wide variability was not explained by differences in the amount of lean tissue gained. Women displaying the energy-sparing suppression of BMR tended to be thin, suggesting that changes in metabolism may be responsive to initial energy status (ΔBMR ν. prepregnant body fat: r 0.84, P < 0.005). Changes in 24 h energy expenditure closely paralleled changes in BMR (r 0.98, P < 0.001), since the energy cost of minor voluntary activity and thermogenesis remained very constant within each individual. Pregnancy decreased the net cost of weight-dependent and weight-independent standard exercises when expressed per kg body-weight: stepping – 10 (sd 2)%, P < 0.001 at 18–36 weeks, cycling - 26 (sd 7)%, P < 0.01 at 12–36 weeks. The average integrated maintenance costs of pregnancy matched previous group estimates from well-nourished women, but individual estimates ranged from - 16 to + 276 MJ (coefficient of variation 93%). This high level of variability has important implications for the prescription of incremental energy intakes during pregnancy. It may also have had evolutionary significance.
The effect of dietary zinc deficiency on pancreatic γ-glutamyl hydrolase (EC3.4.22.12) activity and on the absorption of pteroylpolyglutamate in rats
Authors: Canton Mary C. , Cotter B. M. , Cremin F. M. , Morrissey P. A.
Published: September 2005

The effect of dietary zinc deficiency on γ-glutamyl hydrolase (EC3.4.22.12) activity and on pteroylpolyglutamate absorption was investigated in rats. Enzyme activity was determined in pancreas and gut lumen washings. Pteroylpolyglutamate absorption was studied by determining the rise in plasma folate levels following pteroylpolyglutamate ingestion. Two experiments were performed; in each purified diets were given to three groups of immature male Wistar rats for approximately 2 weeks. One group was given a Zn-deficient dietad lib.(ZD), the second was pair-fed daily with this group on a Zn-adequate diet (PF) and the third was given the Zn-adequate dietad lib.(AL). In Expt 1, significantly reduced pancreatic γ-glutamyl hydrolase activity was observed in ZD rats. In Expt 2, pteroylpolyglutamate was administered on day 14 and in the 3 h period following pteroylpolyglutamate ingestion, lumen γ-glutamyl hydrolase activity and plasma folate levels were significantly lower in ZD rats. Pancreas is reported as the source of lumen γ-glutamyl hydrolase in rats. The results presented indicate that the pancreatic enzyme is Zn-sensitive. It was concluded that, as a result, γ-glutamyl hydrolase activity was reduced in the lumen of ZD rats. Consequently the hydrolysis and subsequent absorption of pteroylpolyglutamate was impaired in ZD rats, as indicated by the smaller rise in plasma folate levels that occurred following pteroylpolyglutamate ingestion. Results of this study concur with previous observations in human beings and rats that Zn deficiency has an adverse effect on folate metabolism.