bluuebunny/crossref_metadata_2025_split huggingface dataset:
Somatomedin-C and zinc status in rats as affected by Zn, protein and food intake
Authors: Cossack Zafrallah T. 
Published: September 2005

1. The objective of the present experiment was to study the level of plasma somatomedin-C (SM-C) and the status of zinc in rats as affected by three levels of Zn given in combinations with two levels of protein.2. Six groups of rats were fed, for 21 d, on six different diets based on combinations of two levels of dietary protein (low protein, 75 g/kg; high protein, 200 g/kg) and three levels of zinc (low Zn, 0.9 pglkg; moderate Zn, 55 pg/kg; high Zn, 110 pglkg). All groups were pair-fed with the group receiving the low-Zn-low-protein diet. An additional group of six rats served as an ad lib.-fed control group and was fed on a diet that contained 55 pg Zn/kg and 200 g protein/kg ad lib.3. Body-weight gain and food intake were recorded daily. Rats were killed at the end of the experimental period (21 d). Zn was assayed in plasma, tibia and liver by atomic absorption technique. Plasma SM-C was assayed by radioimmunoassay.4. In rats given the low-Zn-low-protein diet, the level of plasma SM-C increased in response to the increase in the amount of Zn or Zn and protein in the diet. However, no change was observed when the level of protein alone was increased.5. Among all groups tested, adlib.-fed rats showed the highest level of plasma SM-C. Thus it may be concluded that a balanced diet combined with adequate food intake is necessary to maintain an optimal level of plasma SM-C.
Feeding frequency for lactating cows: effects on rumen fermentation and blood metabolites and hormones
Authors: Sutton J. D. , Hart I. C. , Brosters W. H. , Elliott Rosemary J. , Schuller E. 
Published: September 2005

1. The present paper reports the effects on rumen fermentation and plasma metabolites and hormones of giving fixed rations of hay and high-cereal concentrates at different meal frequencies to lactating cows. In Expt 1 the total ration was given in two and twenty-four meals daily and in Expts 2–4 the concentrates were given in two and five or six meals and the hay in two meals daily. The diets contained 600–920 g concentrates/kg.2. In Expt I, minimum rumen pH was higher but mean pH was lower when cows were given their ration in twenty-four meals/d rather than two meals/d.3. In all the experiments, the effects of increased meal frequency on the molar proportions of rumen volatile fatty acids (VFA) were small and not significant, although there was a general tendency for the proportion of acetic acid to increase and that of propionic acid to fall. Increasing the proportion of concentrates in the diet reduced the proportion of acetic acid and increased the proportions of propionic and n-valeric acids.4. In Expt 3, more frequent feeding was found to reduce the concentration of non-esterified fatty acids in the blood, but changes in other metabolites were small and not significant. Increasing the proportion of concentrates in the diet reduced the concentrations of acetic acid and 3-hydroxybutyric acid and increased the concentrations of propionic acid and glucose.5. The mean daily concentration of insulin in the blood was reduced by more frequent feeding of the higher-concentrate diet but not of the lower-concentrate diet. The concentration of glucagon also tended to fall with more frequent feeding. Increasing the proportion of concentrates in the diet increased the concentration of insulin.6. More frequent feeding reduced the depression in milk-fat concentration caused by feeding the low-roughage diets. About three-quarters of the variation in milk-fat concentration could be related to changes in rumen VFA proportions, but the relations for the two meal frequencies had different intercepts although similar curves. The results suggest that milk-fat depression on low-roughage diets with twice-daily feeding was due to a change in rumen VFA proportions accompanied by elevated plasma insulin concentrations. The improvement in milk-fat concentration due to more frequent feeding could be explained partly by the small change in rumen VFA proportions and partly by a reduction in mean plasma insulin concentrations, but these mechanisms did not fully account for the milk-fat responses observed.
Energy and nitrogen metabolism of rabbits during pregnancy, lactation, and concurrent pregnancy and lactation
Authors: Partridge G. G. , Lobley G. E. , Fordyce R. A. 
Published: September 2005

1. In an experiment twenty-four cross-bred does were used, six in each of four physiological states: non-pregnant (NP), pregnant (P), lactating (L) or concurrently pregnant and lactating (CPL). They were offered a diet of high nutrient density (crude protein (nitrogen × 6.25) 272 g/kg dry matter (DM), metabolizable energy 15.5 MJ/kg DM) at one of two intakes on a scale based on metabolic body-weight (kg body-weight0.75). The study lasted for 24 d and was divided into three consecutive 8 d periods: ‘early’, ‘mid-’ and ‘late’ pregnancy or lactation, or concurrent pregnancy and lactation.2. Around the mid-point of each period the does were placed for 24 h in a gradient-layer calorimeter, and measurements of energy exchange were made. N balance was also measured throughout each period of the study.3. Milk output in L and CPL does was measured by weighing the does immediately before and after suckling once each day. Milk samples were taken from a parallel group of does and the estimates of milk composition applied to the experimental group.4. Milk yields and composition were similar for L and CPL does in early and mid-lactation, but in late lactation the milk output from CPL does declined rapidly. This was the period of maximal fetal growth rates. Energy and N retention increased in P and CPL does in late pregnancy.5. Regression analysis was carried out to summarize the relations between metabolizable energy intake (MEI) and energy retention (ER; MEI-heat loss) in each physiological state. The equations were:NP: ER = 0.67 (se 0.057) MEI – 208,P: ER = 0.67 (se 0.095) ME1 – 224,L: ER = 0.90 (se 0.022) ME1 – 441,CPL: ER = 0.85 (se 0.036) ME1 – 387,where all variables are expressed in kj/kg body-weight0.75 per d.
Flow of nitrogen from the rumen and abomasum in cattle and sheep given protein-free nutrients by intragastric infusion
Authors: Ørskow E. R. , MacLeod N. A. , Kyle D. J. 
Published: September 2005

1. Three experiments were conducted to determine the flow of nitrogen through the rumen and abomasum when cows, steers and lambs were totally nourished on volatile fatty acids infused into the rumen.2. In two dairy cows (650–700 kg) and two large steers (370–405 kg) the daily flow of non-ammonia-N (NAN) from the rumen was 50.7 and 58 mg/kg live weight (W)0.75respectively.3. The flows of NAN through the rumen and abomasum in four young steers (240 315 kg) were 85.0 (SE 21.0) and 195 (SE 7.0) mg/kg W0.75respectively.4. In the third experiment the effects of altering rumen pH and osmotic pressure on flow of NAN through the rumen and abomasum were investigated in lambs. While rumen pH and osmotic pressure influenced rumen volume and outflow they had no significant effect on NAN flow. The mean values for NAN outflow from the rumen and abomasum were 76 and 181 mg N/kg W0.75respectively.5. Abomasal NAN flow increased with increasing abomasal pH. When osmotic pressure was greater than about 330 mosmol/l in the rumen there was a net inflow of water, while below this value there was net loss of water.6. For all experiments the flow of N both from the rumen and abomasum was highly variable; this has to be considered if a constant value is used for endogenous N in estimating dietary N in the abomasum.7. With N-free infusion the rumen NHaconcentration varied from 50 to 120 mg NHa-N/I.8. The amino acid composition of rumen and abomasal N was also determined. Relative to tissue Nit contained a higher proportion of cysteine.
Compensatory nitrogen retention in growing pigs following a period of N deprivation
Authors: Tullis J. Bronwyn , Whittemore C. T. , Phillips Patricia 
Published: September 2005

1. Semi-synthetic diets, with dried microbial cells (Pruteen) as the nitrogen source, were used to measure N retention in 50 kg pigs given different combinations of N intake involving periods of deprivation and enhanced supply.2. Metabolic faecal N losses were 1.92 g/d (1.26 g/kg dry matter eaten) and endogenous urinary losses were 3.96 g/d for pigs given an N intake of 6.9 g/d.3. Compensatory N retention averaging 4.2 g extra N/d was observed in pigs given enhanced N supply by diets providing 31.0, 60.4 and 93.4 g N/d. In some instances enhanced N retention was maintained for 22 d.4. Pigs given enhanced N supply by extravagant N intake did not maintain the compensatory response which had been evident initially.
The effect of manipulating growth in sheep by diet or anabolic agents on plasma cortisol and muscle glucocorticoid receptors
Authors: Sharpe P. M. , Buttery P. J. , Haynes N. B. 
Published: September 2005

1. The cortisol status (total plasma cortisol concentration, free cortisol concentration, transcortin capacity) and the characteristics of skeletal muscle binding for cortisol and dexamethasone were examined in female lambs either implanted with Zeranol or trenbolone acetate or whose dietary intake was restricted.2. The skeletal muscle glucocorticoid receptor had a high affinity for the glucocorticoid triamcinolone (relative binding affinity 0.85) and cortisol (relative binding affinity 0.51) with virtually no affinity for trenbolone.3. Trenbolone acetate treatment reduced the binding capacity of sheep skeletal muscle for cortisol within 2 d of implantation. The other treatments had little effect except a small reduction in the animals where food intake was restricted. Similarly, binding capacity for dexamethasone was reduced by trenbolone acetate treatment but was not affected by the other treatments. This reduction in trenbolone acetate-treated animals is, at least in part, due to a reduction in glucocorticoid receptors.4. Transcortin capacity was elevated by Zeranol treatment but reduced with diet restriction or trenbolone treatment.5. No support for the suggestion of free cortisol concentration being important in the growth-promoting mechanism of trenbolone or Zeranol was obtained.6. Although insulin concentrations were not significantly altered by treatment (P > 0.05), when combining all the animals there was evidence of a negative correlation between total cortiso1: insulin vaue (P < 0.05) or free cortisol: insulin value and growth rate (P < 0.001). Free cortisol was negatively correlated to growth rate (P < 0.05) and transcortin capacity positively correlated (P < 0.01).
Energy metabolism in healthy black Kenyan children
Authors: Duggan Maureen B. , Milner R. D. G. 
Published: September 2005

1. Twenty-four healthy black Kenyan children, mean age 29 (SD 19) months, were studied over a 24 h period. Energy expenditure (EE) was determined using a ventilated-hood indirect calorimeter; measuring oxygen consumption and carbon dioxide production. Metabolizable energy intake was measured in twenty children. Anthropometric measurements were used to estimate surface area and lean body-weight.2. The mean daily intake of metabolizable energy was 338.4 (se28.4) kJ/kg; 70% of gross dietary energy being provided by carbohydrate. The level of postprandial EE was significantly (P > 0.05) higher than the resting level (12.6 (se0.47) and 11.38 (se0.37) kJ/kg per h respectively) while the level of the postprandial respiratory quotient (RQ) was similar to the resting level (0.94 (se0.02)) and 0.98 (se0.03 respectively). In 33% of total observations of the resting RQ the value was more than 1.0. These findings suggest that short-term fat storage may be a normal feature of metabolism in children, and also that the energy cost of (postprandial) fat synthesis is increased by a high-carbohydrate diet.3. Values for the resting metabolic rate and various estimators of body size were compared using regression analysis. It was evident that, in these young children with considerable variation in body composition, body-weight remained a satisfactory metabolic-size estimator.
The effect of protein and energy deficiency on skin glycosaminoglycan levels in the rat
Authors: Kaggwa Jane S. N. 
Published: September 2005

1. The effects of protein-deficient and energy-deficient diets on the concentrations of skin glycosaminoglycans (GAGs) and collagen were studied in young rats.2. In Expt 1, comparisons were made between animals fed on a control (C) diet (protein:energy (P:E) 0.210), a low-protein (LP) diet (P:E 0.032) and a very-low-protein (VLP) diet (P:E 0005)ad lib.Skin GAGS and collagen concentrations were determined at intervals as the animals became malnourished and when some of those fed on the VLP diet started showing signs of oedema. Concurrently, plasma albumin concentrations were determined to assess the extent of hypoalbuminaemia. With prolonged severe protein deficiency all GAGS species were reduced below normal levels. Collagen concentration decreased with prolonged protein deficiency. Protein-deficient rats developed hypoalbuminaemia.3. In Expt 2, comparisons were made between animals fed on the C, LP and VLP dietsad lib.and others given the C diet in restricted amounts sufficient to maintain body-weights identical to those fed on LP or VLP dietsad lib.Energy-deficient rats, wasting at rates similar to protein-deficient ones, had higher skin GAGs concentrations than those in protein-deficient or control animals. With prolonged malnutrition, collagen concentrations were similar in protein- and energy-deficient animals and lower than those observed in control animals. Plasma albumin concentrations in energy-deficient animals were above starting values, except in severely energy-deficient animals at the end of the experiment. Protein-deficient animals developed hypoalbuminaemia.4. In conclusion, the present study has shown that the main difference between prolonged severe protein deficiency and energy deficiency in the rat is that skin hyaluronic acid concentration is higher than normal in energy deficiency but below normal levels in prolonged severe protein deficiency. Initially skin collagen concentrations are higher than normal in both protein- and energy-deficient animals. However, with prolonged malnutrition the concentrations are reduced.
The effects of a high-animal- and a high-vegetable-protein diet on mineral balance and bowel function of young men
Authors: Dokkum W. Van , Wesstra Anneke , Luyken R. , Hermus R. J. J. 
Published: September 2005

1. Twelve young men were given for periods of 20 d, each of three mixed diets, namely a low-protein (LP) diet (9% total energy as protein, 67% of animal origin), a high-animal-protein (HA) diet (16% total energy as protein, 67% of animal origin) and a high-vegetable-protein (HV) diet (16% total energy as protein, 67% of vegetable origin). Retention of calcium, magnesium, iron, zinc and copper as well as various bowel function indices were investigated during each dietary period.2. Neither the HA diet nor the HV diet changed the retention of the minerals considerably. Only Fe balance decreased significantly on the HV diet.3. Substituting the HV diet for the HA diet resulted in significant increases in faecal wet weight (17 g/d), defaecation frequency (0.12 stools/d), faecal volatile fatty acids (2.6 mmol/d) and a decrease in faecal bile acids (128 μmol/d).4. It is concluded that a HV diet, rather than a HA diet is to be recommended with respect to bowel function, whereas the HV diet does not necessarily have a significant influence on mineral retention.
The effect of oral contraceptives on the apparent vitamin B6status in some Sudanese women
Authors: Salih Eltayeb Y. , Zein Asma A. , Bayoumi Riad A. 
Published: September 2005

1. In vitro activation of erythrocyte aspartate aminotransferase (EC2.6.1.1) activity by pyridoxal phosphate was used to assess vitamin B4nutritional status in forty Sudanese women taking combined, low-dose oral contraceptives (oestrogen-progestogen; OC) and in thirty healthy, non-pregnant women not taking OC.2. Fourteen (35%) out of forty OC users showed apparent vitamin B4deficiency.3. Side-effects associated with OC were more common among the apparently vitamin-B4-deficient OC users than among OC users and non-OC users not deficient in vitamin B4.
Abnormal fermentations in continuous cultures of rumen microorganisms given cobalt-deficient hay or barley as the food substrate
Authors: McDonald P. , Suttle N. F. 
Published: September 2005

1. Four experiments, each with four concurrent continuous cultures of rumen micro-organisms, were used to investigate the effects of inoculum, food substrate and cobalt supplementation on the course of fermentation and vitamin B12synthesis. The inocula came from sheep receiving either a Co-rich, complete diet (Ruminant A: Expts 1, 2 and 4) or a Co-deficient hay (Expt 3). In Expt 2, inocula from different donors were used for each culture but for other experiments they were pooled. Co-deficient hay was used as the initial substrate and Co-supplements were given after 8–54 d Co-depletion.2. In three of four experiments, two using a pooled inoculum, uncharacteristically low acetate (Ac) and high propionate (Pr) outputs were obtained from the hay substrate in some cultures. In all, six cultures gave Ac:Pr values in the effluent > 2: 1 and, in Expt 3, the differences remained evident for at least 6 d after a change to a Co-deficient barley substrate.3. Abnormal cultures gave lower cobalamin (cbl) and vitamin B12analogue outputs than normal cultures: when supplemented with Co they showed small responses in cbl and large responses in analogue output with a slow increase in Ac:Pr.4. We suggest that the use of Co-deficient substrates led to shifts in the microbial populations of some cultures, indicating the cbl-dependence of some species of rumen micro-organisms.
Effects of intraruminal sodium chloride infusion on rumen and renal nitrogen and electrolyte dynamics in sheep
Authors: Godwin Ian R. , Williams Vernon J. 
Published: September 2005

1. Sheep were given 800 g low-protein roughage/d at 2 h intervals and infused intraruminally with 0, 500, 750, 1000, 1250, 1500 or 2000 mmol sodium chloride/d in 436 ml water. The digestibility of various food fractions and rumen ammonia, volatile fatty acids (VFA) and liquid turnover rate were measured, along with renal haemodynamics and the renal excretory patterns of nitrogen and electrolytes. Ad lib. food intake was determined during the infusion of 0 and 2000 mmol NaCl/d.2. Infusion of NaCl up to 750 mmol/d had virtually no effect on the indices measured, except water intake and water excretion. Infusion of greater amounts caused a step-wise decrease in the digestibility of organic matter (OM) and N. Rumen liquid turnover rate was increased substantially and rumen NH2, and VFA concentrations were decreased. Ad lib. food intake was not different when either 0 or 2000 mmol NaCl/d were infused into the rumen.3. The glomerular filtration rate and effective renal plasma flow (ERPF) were substantially increased after the infusion of 1250 mmol or more NaCl/d. Extracellular fluid volume was also increased. The renal excretion of urea and uric acid+allantoin (URAL) were decreased at the higher infusion rates but the fractional excretions of both these substances were enhanced. The excretion of sodium, chloride, calcium and magnesium were markedly increased with increasing salt infusion.4. The results suggest that high NaCl inputs into the rumen increase the rumen turnover rate, which in turn decreases the digestibility of OM, particularly N. This causes lower rumen NH3, and VFA concentrations. Plasma urea and URAL concentrations are also decreased and this causes lower renal excretion of these substances despite a much higher fractional excretion resulting from the greatly enhanced urine flow rate.5. When roughages low in N are given, NaCl intake should be kept below 20 mmol/kg body-weight per d to prevent a decline in the digestibility of the food and any consequent reduction in protein available to the sheep.
Role of rumen protozoa in nitrogen digestion in sheep given two isonitrogenous diets
Authors: Ushida K. , Jouany J. P. , Thivend P. 
Published: September 2005

1. The effect of protozoa on digestion in the rumen was studied using either defaunated or faunated sheep.2. Six wethers, each fitted with rumen and simple duodenal cannulas, were given two isonitrogenous diets containing either lucerne (Medicago sativa) hay (diet L) or sodium hydroxide-treated wheat straw (diet S). The diets were given in eight equal portions per day at 3-h intervals. The mean intake of dry matter, 53 g/kg body-weight0.75per d, was similar for the two diets and each diet had a similar digestible organic matter content. Diet L promoted a large protozoal population and was rich in nitrogen sources of low rumen-degradability, while diet S supported a smaller protozoal population and was rich in rumen-degradable N.3. Digesta flow at the duodenum was estimated by means of a dual-marker technique using chromium-mordanted lucerne hay and polyethylene glycol as markers. The microbial flow at the duodenum was estimated using diaminopimelic acid (DAPA), nucleic-acid purine bases (PB) and35S incorporation simultaneously. The different microbial markers were compared in the defaunated sheep. Protozoal N contribution was estimated in faunated sheep.4. Defaunated sheep had lower rumen ammonia concentrations and molar proportions of butyric acid than faunated sheep, but they had higher molar proportions of propionic acid.5. Rumen organic matter digestion was reduced by defaunation, but this decrease was compensated for by increased intestinal digestion.6. There was a net increase of N flow (approximately 10 g/d) between mouth and duodenum in defaunated sheep. This was explained by increases in both microbial and dietary N flows from the rumen compared with faunated sheep.7. The influence of protozoa on solid- and liquid-phase retention times in the rumen is discussed, as well as the protozoal contribution to microbial N flow in the duodenum of faunated sheep.
Dynamics of large ciliate protozoa in the rumen of cattle fed on diets of freshly cut grass
Authors: Leng R. A. , Dellow D. , Waghorn G. 
Published: September 2005

1. The dynamics of large ciliate (holotrich) protozoa (Isotricha and Dasytricha spp.) in the rumen of cattle given cut, fresh ryegrass (Lolium multiflorium Lam) were studied by means of a single intrarumen injection of14C-labelled protozoa prepared in vitro by adding [Me14C]choline to rurnen fluid containing protozoa and incubating at 39° for 2 h.2. An indication of the lysis rate of protozoa in the rumen was obtained from the radioactivity apparently lost through the methane pool.3. The turnover time of the holotrich protozoa indicates that these protozoa were extensively retained in the rumen and that only a small proportion of those produced in the rumen flowed out in the digesta. This was supported by the estimation of the rate of lysis which was approximately 85% of the turnover rate in the rurnen.4. The apparent production rate of the larger protozoa indicates that they contribute only about 9% of the predicted net microbial protein synthesis in the rumen.