bluuebunny/crossref_metadata_2025_split huggingface dataset:
Storage of milk powders under adverse conditions
Authors: Ford J. E. , Hurrell R. F. , Finot P. A. 
Published: September 2005

1. Storage of milk powder under unfavourable conditions accelerates the normally slow deterioration in nutritional quality. The effects of such storage on the water-soluble vitamin composition were examined.2. (a) Spray-dried whole milk containing 25 g water/kg was stored at 60° and 70° and sampled weekly to 9 weeks. (b) Spray-dried whole milk and skimmed milk were adjusted to contain 40 and 100 g water/kg and stored at 37° in nitrogenand in oxygen. Samples were taken for analysis at intervals during storage.3. The samples were analysed for eight B-complex vitamins and ascorbic acid, and also for total lysine, ‘reactive lysine’ and ‘lysine as lactulosyl-lysine’.4. Storage at 60° caused rapid destruction of folic acid (53% loss at 4 weeks) and slower loss of thiamin, vitamin B6 and pantothenic acid (18% at 8 weeks). There was no change in the content of riboflavin, biotin, nicotinic acid and vitamin B12. At 70° the rate of destruction of the four labile vitamins was much increased; 18% or less survived at 4 weeks.5. At 37° and 40 g water/kg there was little change in total and ‘reactive’ lysine during storage for 57 d. Lactulosyl-lysine was demonstrably present butatlow concentration. There was considerable loss of folate (72%) and ascorbate (91%) during storage for 30 d in O2, but no significant loss in N2. Thiamin fell by approximately 12% in 57 d, equally in O2 and N2. The content of the remaining vitamins was unchanged. At 100 g water/kg there were progressive Maillard changes. During 27 d in N2 the colour changed from cream to palebrown, but in O2 there was no perceptible colour change. Total lysine fell by 20% in 27 d, and ‘reactive lysine’ by 30%. Folate was stable during 16 d in N2, but largely (94%) destroyed in O2. Ascorbic acid was also destroyed in N2 as in O2. Thiamin fell by 41% in 27 d, equally in O2 and N2. Vitamin B6 was more labile, especially in N2, falling by 71% in 16d.6. With skimmed-milk powder containing 100 g water/kg, storage at 37° in O2 and N2 gave much the same results as for the corresponding whole-milk powder. The presence of milk fat had no marked effect on the stability of the water-soluble vitamins.7. Destruction of vitamins was clearly linked to the progress of Maillard-type reactions and was strongly influenced by time and temperature of storage, moisture content and, in some instances, by the presence of O2.
Effect of zinc deficiency on the pregnant ewe and developing foetus
Authors: Masters David G. , Moir R. J. 
Published: September 2005

1. Mature Merino ewes were given either a low-zinc diet (4 mg/kg) or an adequate-Zn diet (50 mg/kg) for all or part of pregnancy.2. The ewes consuming the low-Zn diet consumed 25% less feed than those given the adequate-Zn diet during the last 115 d of pregnancy.3.Zn concentration in the plasma of Zn-deficient pregnant ewes declined from 0·7 to 0·3 mg/1.4. The lambs born to Zn-deficient ewes weighed less and had reduced concentrations ofZn or less total Zn, or both, in the whole carcass, liver and pancreas.5. A reduction in activity of alkaline phosphatase (EC3.1.3.1) in the liver and a slight reduction in thymidine kinase (EC2.7.1.21) activity in the thymus was also observed in Zn-deficient lambs.6. The Zn-deficient ewes deposited approximately 63 mg Zn into each single-born lamb;this indicates that during the last third of pregnancy the developing foetuses were accumulating the equivalent of 35% of the total dietary Zn intake of the ewes.
Threonine metabolism in sheep
Authors: Egan A. R. , MacRae J. C. , Lamb C. S. 
Published: September 2005

1. In three experiments, mature Blackface wethers were given freeze-storedAgrostis festucaherbage by continuous feeder.2. In Expt 1, on separate occasions [U-14C]threonine, [U-14C]glucose and NaH14CO3were infused over 12 h periods to obtain estimates of irreversible loss rate (ILR) of threonine, glucose and carbon dioxide in the plasma and of the exchange of C between these metabolites.3. In Expts 2 and 3, during periods when glucose and threonine metabolism were examined, glucose loss across the kidneys (23–29 g/d) was induced by infusion of phloridzin.4. Results from the four sheep used in Expts 1 and 3 are presented as three-pool models. They indicate that threonine ILR (7·8 g/d; 3·1 g C/d) was approximately three times the estimated rate of absorption of exogenous threonine (1 g C/d). Glucose ILR was approximately 76 g/d (mean ± SE; 30·3 ± 0·57 g C/d). Only 0·3% of the glucose-C (0·09 g/d) was derived directly from threonine-C (i.e. 3% of the threonine-C ILR). Bicarbonate ILR was 170 ± 7·3 g C/d, and glucose contributed 11·1 ± 3·52 g C/d to this, accounting for 51 ± 4·4% of glucose-C ILR. Threonine contributed 0·20 ± 0·026 g C/d to the bicarbonate-C ILR, accounting for only 6·4 ± 0·87% of the threonine-C ILR.5. When, in Expts 2 and 3, phloridzin was infused, glucose ILR was increased by 28 ± 1·5% and bicarbonate ILR was increased by 13 ± 2·4%. Threonine ILR (3·1 g C/d) was not increased, but the metabolic distribution of threonine-C was altered. The transfer of threonine-C into glucose and CO2was increased by 39 and 69% respectively to 0·125 and 0·45 g C/d, accounting for 4 and 13% of the threonine ILR respectively.6. Both technical and metabolic considerations which affect interpretation of these results in terms of rates of catabolism of threonine and of quantitative estimates of gluconeogenesis from threonine are discussed.
Threonine metabolism in sheep
Authors: Macrae J. C. , Egan† A. R. 
Published: September 2005

1. The irreversible loss rate (ILR) of glucose, bicarbonate and threonine were determined in six twin- and triplet-bearing ewes on three occasions during the last 6 weeks of gestation.2. Three of the ewes (group S) were given conventional rations of hay plus concentrates so that their blood ketone levels did not rise over this period. The other three ewes (group H) were given a fixed intake of hay throughout; their blood ketone levels rose, but remained at subclinical levels.3. The results are presented in the form of three-pool open-compartment models for each period. There was an increase in the glucose ILR for both groups over the 6-week period, but the over-all increase (mean ± SE) was much greater (p < 0·001) in group S (35·1 ± 2·43 g carbon/d) than in group H (11·3 ± 1·28 g C/d). Similarly, increases in bicarbonate ILR were also higher in group S (161 ± 11·2 g C/d) than in group H (63 ± 21·7 g C/d). However, whereas with group S ewes, receiving supplementary feed, this increase was progressive throughout the 6 weeks, with the group H ewesthe increase which occurred over the last 3 weeks of gestation (56 ± 26·3 gC/d) was much greater than that which occurred over the preceding 3 weeks (7 ±4·7 g C/d). This pattern was also evident in the oxidation of glucose to CO2.4. In contrast to the previously mentioned findings, neither threonine ILR nor the amount of threonine converted to glucose or catabolized to CO2 changed significantly over the 6-week period.5. The results are discussed in the light of findings presented in the previous paper that the amount of threonine used in catabolic processes can alter if a glucose-only sinkis created in wether sheep.
The effect of free and protected oils on the digestion of dietary carbohydrates between the mouth and duodenum of sheep
Authors: McAllan A. B. , Knight R. , Sutton J. D. 
Published: September 2005

1. Sheep fitted with rumen and re-entrant duodenal cannulas were given diets of approximately 200 g hay and 400 g concentrate mixture alone, or supplemented daily with 40 g linseed or coconut oils free or protected with formaldehyde-casein in a 5 × 5 Latin-square arrangement. Chromic oxide paper was given as a marker at feeding time and passage to the duodenum of neutral-detergent fibre (NDF) and different sugars were estimated from the values for c0nstituent:marker at the duodenum. Contributions of microbial carbohydrates to these flows were estimated from amounts of RNA present.2. The carbohydrate composition of mixed rumen bacteria from sheep rumen digesta were similar regardless of diet. Of the sugars entering the duodenum all the rhamnose and ribose and 0·51, 0·24 and 0·35 of the mannose, galactose and starch-glucose respectively, were contributed by the microbes. Virtually all the arabinose, xylose and cellulose-glucose were contributed by the diet.3. For sheep receiving the basal ration, coefficients of digestibility between mouth and duodenum, corrected where necessary for microbial contribution, were 095,0·66,0·67,0·62,0·45 and 0·51 for starch-glucose, mannose, arabinose, galactose, xylose and cellulose-glucose respectively. Corresponding values when free-oil-supplemented diets were given were 0·95,035,0·38,0·55,0·01 and –0·02 respectively. Values for diets supplemented with linseed oil or coconut oil did not differ significantly. Addition of protected oils to the basal feed also resulted in depressed digestibilities of dietary structural sugars but to a far lesser extent than those observed with the free oils.4. Apparent digestibility of NDF was altered in the same direction as those of the main structural sugars, averaging 0·50,0· 17 and 0·29 in animals receiving the basal, free-oil-supplemented or protected-oil-supplemented diets respectively. The reasons for the difference between NDF and discrete carbohydrate analytical totals are discussed.
The influence of the gut microflora on protein synthesis in liver and jejunal mucosa in chicks
Authors: Muramatsu T. , Coates M. E. , Hewitt D. , Salter D. N. , Garlick P. J. 
Published: September 2005

1. Protein synthesis in liver and jejunal mucosa was measured in 19-d-old germ-free (GF) and conventional (CV) chicks fed on a semi-purified casein–gelatin (SCG) diet using a massive-dose single injection of [U-14C]phenylalanine. The effect of subsequent feeding for 9 d either a nitrogen-free (NF) diet or an NF diet supplemented with L-methionine (5 g/kg) and L-arginine hydrochloride (2 g/kg) (MA diet) was investigated in both types of chick.2. In the liver, apart from the amount of DNA, the values for wet weight, protein, RNA, fractional synthesis rate (FSR) and the amount of protein synthesized were reduced after feeding the NF diet and, to a lesser extent, the MA diet. Except that the total amount of liver DNA was higher in the CV chicks than in their GF counterparts (P< 0·01), no environmental effect was significant. When expressed on a unit body-weight basis, liver weight, protein, RNA and DNA were significantly higher in the CV than in the GF chicks.3. In the jejunal mucosa, the values for wet weight, protein and RNA tended to be reduced after the NF treatment but increased after the MA treatment. Mucosal DNA and the amount of protein synthesized (μg/mm per d) were significantly reduced after the NF diet but were less affected after the MA diet. Mucosal protein FSR and the amount of protein synthesized per mg RNA were significantly reduced after both dietary treatments. No difference was found among dietary treatments in the amount of protein synthesized per mg DNA in jejunal mucosa. Mucosal DNA was significantly higher in the CV chicks and the reverse was true for mucosal protein: DNA.4. It was suggested that the increased protein synthesis in jejunal mucosa and possibly in liver on supplementation of an NF diet with methionine and arginine would partly, ifnot completely, account for the N-sparing effect of these amino acids.5. Although the protein: DNA value was smaller in CV chicks, the FSR and the amount ofprotein synthesized tended to be higher than in their GF counterparts irrespective of nutritional status. This might imply that protein degradation rate is greater in the CV state.
The effect of 1α-hydroxycholecalciferol on the placental transfer of calcium and phosphate in sheep
Authors: Durand D. , Braithwaite G. D. , Barlet J.-P. 
Published: September 2005

1. The calcium and phosphorus concentrations in foetal tissue or the placental transfer of45Ca and32P, or both, were studied in fifty-five control or 1α-hydroxycholecalciferol (1α-(OH)D3)-treated (0·1 μg/kg body-weight per d for 12 d) ewes between 77 and 140 d of gestation.2. Treatment resulted in a significant increase in the concentration of Ca and P in foetal tissues at all stages of gestation except at 140 d when, it is suggested, foetal mineralization may approach a maximum value.3. This increase in Ca and P concentration in foetal tissues was associated with an increased placental transfer of Ca, though at 111 and 120 d gestation this increase was not significant. P transfer, which was only measured at 140 d gestation, was also significantly higher in treated animals.4. The concentrations of Ca and P in both maternal and foetal plasma were increased significantly by the 1α-(OH)D3treatment.5. Whereas the concentration of Ca in the plasma of foetuses was always greater than in their dams, the concentration of plasma P in treated animals, unlike controls, was lower in foetuses than dams. This suggests that the increased placental transfer of P, unlike that of Ca, may be a passive rather than an active process.
Energy and nitrogen metabolism of lactating rabbits
Authors: Partridge G. G. , Fullera M. F. , Pullar J. D. 
Published: September 2005

1. Twelve crossbred does (New Zealand White × California) were offered a diet of high protein and metabolizable energy content (249 g/kg dry matter (DM) and 13·6 MJ/kg DM respectively) throughout a 32 d lactation at one of four feeding levels (240, 280, 320 or 360 g/d). Each feeding level was replicated three times.2. Milk output was measured by weighing the does before and after their one daily suckling period.3. The lactation was divided into four consecutive 8-d periods. Each doe was placed in a direct calorimeter for 48 h around the mid-point of each of these periods and measurements of energy exchange were made. Nitrogen balance was also measured throughout the study period.4. Milk samples were taken from a parallel group of animals and the estimates of milk composition were applied to the main group of does.5. From the second period of lactation onwards nearly all does mobilized body tissue to support milk energy secretion, although there was no loss of weight. Multiple regression analyses were used to examine the apparent efficiency with which metabolizable energy and body-tissue energy were utilized for milk production. Overall, the relationship was described by the equation:Period of lactation … 2 3 4Milk E = 0.735 me intake – 0·938Body ER –296 –280 –276(se 0-020) (se 0-039)where Milk E is the milk energy output, ME intake is the metabolizable energy intake and Body ER is the body energy retention, all expressed in kJ/kg body-weight0·75 per d.All does appeared to be in positive N balance throughout lactation on this high-protein diet.
Protein synthesis in skin and bone of the young rat
Authors: Preedy Victor R. , McNurlan Margaret A. , Garlick Peter J. 
Published: September 2005

1. Fractional rates of protein synthesis in tissues of young growing rats were estimated by injection of flooding amounts (1·5 mmol/kg body-weight) of [3H]phenylalanine. Rates of 63·6%/d and 90·4%/d respectively were obtained in the skin and bone (tibia) of fed animals. These rates were comparable to that in liver (86·3%/d) but considerably higher than in muscle (16·9%/d).2. Absolute amounts of protein synthesized in tissues of fed rats were estimated. Together the skin and bones accounted for 25% of whole-body synthesis, a value similar to the contribution of liver (15%) and muscle (25%).3. In fed rats the ratio, RNA: protein in skin and bone was lower than in liver, but much higher than in muscle. However, the amounts of protein synthesized per unit RNA in skin and bone were higher than in both liver and muscle.4. After 2 d of starvation the fractional rates of protein synthesis in skin and bone fell by 26% and 31% respectively. This was greater than the fall in liver (17%) but less than in muscle (66%). In bone the fall in synthesis was accompanied by decreases in both RNA: protein and synthesis per unit RNA, but in skin there was a fall in RNA: protein which was partially countered by an increase in the rate of synthesis per unit RNA.
Effects of a dietary excess of leucine on the metabolism of tryptophan in the rat: a mechanism for the pellagragenic action of leucine
Authors: Bender David A. 
Published: September 2005

1. In order to investigate the mechanism of the pellagragenic action of excess dietary leucine, rats were fed on diets providing a minimally-adequate amount of tryptophan, with no preformed niacin, with and without the addition of 15 g leucine/kg diet. This amount of leucine in the diet has been demonstrated previously to lead to depletion of blood and liver nicotinamide nucleotides. The metabolism of tryptophan was assessed by measurement of the production of14CO2after the administration of [methylene-14C]tryptophan to estimate the activity of kynureninase (L-kynurenine hydrolase,EC3.7.1.3) and [benzene ringU-14C]tryptophan to estimate the activity of picolinate carboxylase (aminocarboxymuconate semialdehyde decarboxylase,EC4.1.1.45).2. A dietary excess of leucine led to inhibition of kynureninase and increased the activity of picolinate carboxylase. Both of these effects would result in a reduction in the rate of metabolism of acroleylaminofumarate (aminocarboxymuconate semialdehyde) to quinolinic acid and hence to nicotinamide nucleotides. These two effects provide an explanation for the pellagragenic effect of a dietary excess of leucine in animals that are wholly or partly reliant on endogenous synthesis from tryptophan to meet their requirements for nicotinamide nucleotides, and presumably also explain the pellagragenic effect of a dietary excess of leucine in man.
Effects of oestradiol and vitamin B6on tryptophan metabolism in the rat: implications for the interpretation of the tryptophan load test for vitamin B6nutritional status
Authors: Bender David A. 
Published: September 2005

1. The effects of the administration of oestradiol and vitamin B6on tryptophan metabolism in the rat have been assessed by measurement of the release of14CO2from [14C]tryptophan, in vivo, in order to determine whether, and to what extent, the abnormalities of tryptophan metabolism that are associated with oestrogen administration can be attributed to drug-induced vitamin B6deficiency or depletion. Two positional isomers of [14C]tryptophan have been used; [ring-2-14C]tryptophan as an index of the activity of tryptophan oxygenase (L-tryptophan: oxygen oxidoreductase (decyclizing),EC1.13.11.11) and [methylene-14C]trytophan as an index of the activity of kynureninase (L-kynurenine hydrolase,EC3.7.1.3).2. The administration of 500 μg oestradiol/kg body-weight led to a reduction in the release of14CO2from both positional isomers of tryptophan, suggesting that the activities of both tryptophan oxygenase and kynureninase are reduced following oestrogen treatment. The kinetics of the release of14CO2from [methylene-14C]tryptophan after the administration of oestradiol were compatible with competitive inhibition of kynureninase by oestradiol or a metabolite.3. The administration of 10 mg pyridoxine hydrochloride/kg body-weight also reduced the production of14CO2from both positional isomers of14C]tryptophan, suggesting some toxicity of such a high dose of the vitamin.4. In animals which had received the supplementary dose of vitamin B6, the administration of oestradiol led to further reduction in the production of14CO2from [ring-2-14C]tryptophan, suggesting a further reduction in the activity of tryptophan oxygenase, and an increase in the production of14CO2from [methylen-14C]tryptophan, but with a delay in the peak of production.5. These results confirm that there is no induction of tryptophan oxygenase by oestradiol, but rather reduced activity of the enzyme after the administration of a relatively high dose of the hormone. They also confirm that the inhibition of kynureninase by oestrogen metabolites that has been reported previously in partially-purified enzyme preparations also occurs in vivo.6. It is suggested that the abnormal results of the tryptophan load test that have been reported in women receiving oestrogens, and which have been interpreted as indicating some extent of drug-induced vitamin B6deficiency, can be accounted for by the inhibition of tryptophan metabolism by oestrogens or their metabolites. Therefore it seems likely that the practice of administering supplements of vitamin B6to women receiving oestrogens may not be appropriate, and indeed may exacerbate the changes in tryptophan metabolism that result from the administration of oestrogens. The tryptophan load test would appear to be unreliable as an index of vitamin B6nutritional status in women receiving oestrogens.
Iron absorption from a malted cocoa drink fortified with ferric orthophosphate using the stable isotope58Fe as an extrinsic label
Authors: Fairweather-Tait Susan J. , Minski Margaret J. , Richardson D. P. 
Published: September 2005

1. The potential use of an extrinsic label to measure iron absorption from a ferric orthophosphate-fortified malted cocoa drink was examined by measuring the solubility of the FePO4in 0·1 M-hydrochloric acid.2. The validity of using the stable isotope58Fe as an extrinsic label was tested by comparing Fe absorption by rats from wheat flour extrinsically-labelled with58Fe or59Fe.3. Fe absorption from a malted cocoa drink (20 g powder made up with hot water) fortified with FePO4(0·5 mg Fe/g powder) was measured in human subjects using58Fe as an extrinsic label. Absorption was calculated by measuring unabsorbed58Fe in faeces. Absorptions of Fe from the drink fortified with either FePO4or ferrous sulphate were compared. The effect of the addition of ascorbic acid to the drink (1 mg/g powder) on Fe availability was also examined.4. The effect of fasting on Fe absorption from the drink was determined in rats by giving the drink to fasting animals or shortly after they had consumed a small meal.5. The FePO4was totally soluble in 0·1 M-HCl and there were no differences in absorption between58Fe- and59Fe-labelled wheat flour. In the human experiment the proportion of Fe absorbed from the drink plus FePO4and ascorbic acid was (mean with SE) 0·25 (0·02), from the drink plus FePO40·24 (0·02) and from the drink plus FeSO40·23 (0·03). Fasting had a significant effect on Fe availability; rats given the drink shortly after a small meal absorbed less than half as much Fe as those given the drink on a fasted stomach.6. It was concluded that the FePO4used to fortify the malted cocoa drink was as well absorbed as FeSO4but that the high levels of absorption were a reflection of the fasting condition of the subjects. The level of ascorbic acid was not great enough to enhance the availability of the FePO4any further.