scholarly journals Effects of the amount and quality of dietary protein on nitrogen metabolism and protein turnover of pigs

1987 ◽  
Vol 58 (2) ◽  
pp. 287-300 ◽  
Author(s):  
M. F. Fuller ◽  
P. J. Reeds ◽  
A. Cadenhead ◽  
B. Seve ◽  
T. Preston
Keyword(s):  
Dietary Protein ◽  
Protein Turnover ◽  
Growing Pigs ◽  
Whole Body ◽  
Urea Synthesis ◽  
Total N ◽  
Plasma Urea ◽  
Body Protein ◽  
N Retention

1. The interrelations between protein accretion and whole-body protein turnover were studied by varying the quantity and quality of protein given to growing pigs.2. Diets with 150 or 290g lysine-deficient protein/kg were given in hourly meals, with or without lysine supplementation, to female pigs (mean weight 47 kg).3. After the animals were adapted to the diets, a constant infusion of [14C]urea was given intra-arterially for 30 h, during the last 6 h of which an infusion of [4,5-3H] leucine was also infused at a constant rate. At the same time, yeast-protein labelled with15N was given in the diet for 50 h.4. The rate of urea synthesis was estimated from the specific radioactivity (SR) of plasma urea. The rate of leucine flux was estimated from the SR of plasma leucine. The irrevocable breakdown of leucine was estimated from the3H-labelling of body water. Total N flux was estimated from the16N-labelling of urinary urea.5. Addition of lysine to the low-protein diet significantly increased N retention, with a substantial reduction in leucine breakdown, but there was no significant change in the flux of leucine or of total N.6. Increasing the quantity of the unsupplemented protein also increased N retention significantly, with concomitant increases in leucine breakdown and in the fluxes of leucine and of total N.7. It is concluded that a doubling of protein accretion brought about by the improvement of dietary protein quality is not necessarily associated with an increased rate of whole-body protein turnover.

scholarly journals Lysine requirements and whole-body protein turnover in growing pigs

1990 ◽  
Vol 63 (3) ◽  
pp. 503-513 ◽  
Author(s):  
D. N. Salter ◽  
A. I. Montgomery ◽  
Anna Hudson ◽  
D. B. Quelch ◽  
Rosemary J. Elliott
Keyword(s):  
Protein Synthesis ◽  
Protein Turnover ◽  
Protein Quality ◽  
Growing Pigs ◽  
Whole Body ◽  
Separate Experiment ◽  
Deficient Diet ◽  
Total N ◽  
Body Protein ◽  
Biological Value

The influence on protein accretion and whole-body protein turnover of changing dietary protein quality while maintaining constant energy intake was studied by varying the degree of lysine supplementation of a lysine-deficient barley-based diet given to growing pigs. Measurements of nitrogen metabolism and whole-body protein turnover, using both classical and 15N end-product methods following a single dose of lsqb;15N]glycine, were made in 49-kg male pigs given diets containing 109 g lysine-deficient protein/kg supplemented to make them (1) 'deficient', (2) 'adequate' and (3) 'in excess' with respect to lysine. The 15N dose and protein intake values used to calculate amino N flux from the cumulative urinary excretion of 15N in urea and ammonia were corrected respectively for apparent digestibilities of [15N]glycine and total N determined in a separate experiment in pigs fitted with simple ileal cannulas. N retention and biological value were significantly increased by lysine supplementation of the deficient diet to the 'adequate' level, but were not further increased by the higher level of supplementation. Rates of growth paralleled these changes. The poorer biological value of the unsupplemented diet 1 was shown also in a significantly higher excretion of urea N compared with diets 2 and 3. N digestibility was not markedly influenced by the level of lysine supplementation. Both whole-body protein synthesis and degradation increased markedly on 'adequate' supplementation of the diet with lysine, but did not increase further with an excess of lysine. It is concluded that the increase in protein accretion rate observed on supplementation of the diet with lysine was due to a greater increase in the rate of protein synthesis than of degradation, rather than a decrease in degradation rate.

scholarly journals Urea synthesis and leucine turnover in growing pigs: changes during 2 d following the addition of carbohydrate or fat to the diet

1987 ◽  
Vol 58 (2) ◽  
pp. 301-311 ◽  
Author(s):  
P. J. Reeds ◽  
M. F. Fuller ◽  
A. Cadenhead ◽  
S. M. Hay
Keyword(s):  
Blood Glucose ◽  
Plasma Insulin ◽  
Specific Radioactivity ◽  
Growing Pigs ◽  
Whole Body ◽  
Total Amino Acid ◽  
Urea Synthesis ◽  
Hormonal Changes ◽  
Plasma Urea ◽  
Body Protein

1. Studies have been made of the time-sequence of protein metabolic and hormonal changes following an abrupt increase in carbohydrate or fat intake. [3H]leucine and [14C]urea were infused for 72 h, via the aorta, into fourteen female pigs (30–38 kg body-weight). At 24 h after the start of the infusion their feed was either changed to one of two isonitrogenous diets containing additional starch (group BS, five animals) or fat (group BF, five animals), or remained unaltered (group BB, four animals). The distribution space of urea was measured by the dilution of a single dose of [14C]urea given both 48 h before and 48 h after the change in diet. The changes in the concentration and specific radioactivity of blood leucine were used to infer changes in protein turnover and those of plasma urea to measure total amino acid catabolism. The concentrations of blood glucose and plasma insulin and cortisol were also measured at approximately two-hourly intervals for the 48 h period following the change in diet.2. Within 4 h of either change in diet blood leucine concentration was lowered and the leucine specific radioactivity was raised above that in group BB, but after 24 h both the concentration and specific radioactivity of leucine returned to values similar to those in group BB. Eventually the blood leucine specific radioactivity was slightly but not significantly reduced below that of group BB.3. The addition of starch to the diet significantly reduced the synthesis and concentration of urea within 4 h but, although the addition of fat to the diet eventually lowered the urea concentration and synthesis, both changes were delayed for 18–24 h.4. In group BS plasma glucose and insulin rose after the addition of starch, but after 24–36 h both returned to values that were the same as those in the animals that received the same diet throughout (group BB). The addition of fat to the diet altered neither blood glucose nor plasma insulin concentrations. The addition of either carbohydrate or fat to the diet eventually reduced pIasma cortisol concentrations, but the change did not occur until 24 h after the change in diet.5. The results suggest that alterations in non-protein energy supply exert their immediate effect on the degradation of whole-body protein. They do not exclude the possibility that these early changes may reflect opposing changes at different sites. The results also suggest that the rate of urea synthesis may be controlled by the balance between the concentrations of insulin and cortisol, but that under the conditions of these experiments there was little relation between these hormones and the turnover of body protein as measured by the turnover of blood leucine.

Advances in stable isotope tracer methodology part 2: new thoughts about an “old” method—measurement of whole body protein synthesis and breakdown in the fed state

2019 ◽  
Vol 68 (1) ◽  
pp. 11-15 ◽  
Author(s):  
Robert R Wolfe ◽  
Sanghee Park ◽  
Il-Young Kim ◽  
Paul J Moughan ◽  
Arny A Ferrando
Keyword(s):  
Protein Synthesis ◽  
Dietary Protein ◽  
Protein Turnover ◽  
Peripheral Circulation ◽  
Whole Body ◽  
Balance Model ◽  
Body Protein ◽  
Fed State ◽  
Isotope Tracer ◽  
Tracer Dilution

Whole-body protein turnover (protein synthesis, breakdown, and net balance) model enables quantification of the response to a variety of circumstances, including the response to meal feeding. In the fed state, the whole-body protein turnover model requires taking account of the contribution of absorbed tracee to the observed total appearance of tracee in the peripheral blood (exogenous appearance, RaEXO). There are different approaches to estimating RaEXO. The use of an intrinsically labeled dietary protein is based on the overriding assumption that the appearance in the peripheral circulation of a tracer amino acid incorporated into a dietary protein is exactly proportional to the appearance of absorbed tracee. The bioavailability approach is based on the true ileal digestibility of the dietary protein and the irreversible loss of the tracee in the splanchnic bed via hydroxylation of the tracee (phenylalanine). Finally, RaEXO can be estimated as the increase above the basal rate of appearance of the tracee using traditional tracer dilution methodology. In this paper, we discuss the pros and cons of each approach and conclude that the bioavailability method is the least likely to introduce systematic errors and is therefore the preferable approach.

Level of dietary protein impacts whole body protein turnover in trained males at rest

Metabolism ◽  
2006 ◽  
Vol 55 (4) ◽  
pp. 501-507 ◽  
Author(s):  
Patricia C. Gaine ◽  
Matthew A. Pikosky ◽  
William F. Martin ◽  
Douglas R. Bolster ◽  
Carl M. Maresh ◽  
...  
Keyword(s):  
Dietary Protein ◽  
Protein Turnover ◽  
Whole Body ◽  
Body Protein

Dietary protein requirements and body protein metabolism in endurance-trained men

1989 ◽  
Vol 66 (6) ◽  
pp. 2850-2856 ◽  
Author(s):  
C. N. Meredith ◽  
M. J. Zackin ◽  
W. R. Frontera ◽  
W. J. Evans
Keyword(s):  
Dietary Protein ◽  
Protein Turnover ◽  
Protein Intake ◽  
Whole Body ◽  
Middle Aged ◽  
Body Protein ◽  
Protein Requirements ◽  
High Quality Protein ◽  
Effect Of Age ◽  
Lower Physical Activity

The effects of regular submaximal exercise on dietary protein requirements, whole body protein turnover, and urinary 3-methylhistidine were determined in six young (26.8 +/- 1.2 yr) and six middle-aged (52.0 +/- 1.9 yr) endurance-trained men. They consumed 0.6, 0.9, or 1.2 g.kg-1.day-1 of high-quality protein over three separate 10-day periods, while maintaining training and constant body weight. Nitrogen measurements in diet, urine, and stool and estimated sweat and miscellaneous nitrogen losses showed that they were all in negative nitrogen balance at a protein intake of 0.6 g.kg-1.day-1. The estimated protein requirement was 0.94 +/- 0.05 g.kg-1.day-1 for the 12 men, with no effect of age. Whole body protein turnover, using [15N]glycine as a tracer, and 3-methylhistidine excretion were not different in the two groups, despite lower physical activity of the middle-aged men. Protein intake affected whole body protein flux and synthesis but not 3-methylhistidine excretion. These data show that habitual endurance exercise was associated with dietary protein needs greater than the current Recommended Dietary Allowance of 0.8 g.kg-1.day-1. However, whole body protein turnover and 3-methylhistidine excretion were not different from values reported for sedentary men.

scholarly journals Modulation of the gut microbiota with antibiotic treatment suppresses whole body urea production in neonatal pigs

2013 ◽  
Vol 304 (3) ◽  
pp. G300-G310 ◽  
Author(s):  
Patrycja Puiman ◽  
Barbara Stoll ◽  
Lars Mølbak ◽  
Adrianus de Bruijn ◽  
Henk Schierbeek ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Gut Microbiota ◽  
Whole Body ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Urea Synthesis ◽  
Plasma Urea ◽  
Body Protein ◽  
Neonatal Pigs

We examined whether changes in the gut microbiota induced by clinically relevant interventions would impact the bioavailability of dietary amino acids in neonates. We tested the hypothesis that modulation of the gut microbiota in neonatal pigs receiving no treatment (control), intravenously administered antibiotics, or probiotics affects whole body nitrogen and amino acid turnover. We quantified whole body urea kinetics, threonine fluxes, and threonine disposal into protein, oxidation, and tissue protein synthesis with stable isotope techniques. Compared with controls, antibiotics reduced the number and diversity of bacterial species in the distal small intestine (SI) and colon. Antibiotics decreased plasma urea concentrations via decreased urea synthesis. Antibiotics elevated threonine plasma concentrations and turnover, as well as whole body protein synthesis and proteolysis. Antibiotics decreased protein synthesis rate in the proximal SI and liver but did not affect the distal SI, colon, or muscle. Probiotics induced a bifidogenic microbiota and decreased plasma urea concentrations but did not affect whole body threonine or protein metabolism. Probiotics decreased protein synthesis in the proximal SI but not in other tissues. In conclusion, modulation of the gut microbiota by antibiotics and probiotics reduced hepatic ureagenesis and intestinal protein synthesis, but neither altered whole body net threonine balance. These findings suggest that changes in amino acid and nitrogen metabolism resulting from antibiotic- or probiotic-induced shifts in the microbiota are localized to the gut and liver and have limited impact on whole body growth and anabolism in neonatal piglets.

Influence of Dietary Protein Intake on Whole-Body Protein Turnover in Humans

Diabetes Care ◽  
1991 ◽  
Vol 14 (12) ◽  
pp. 1189-1198 ◽  
Author(s):  
P. J. Garlick ◽  
M. A. McNurlan ◽  
P. E. Ballmer
Keyword(s):  
Dietary Protein ◽  
Protein Turnover ◽  
Protein Intake ◽  
Whole Body ◽  
Dietary Protein Intake ◽  
Body Protein

scholarly journals Effects of long-term protein excess or deficiency on whole-body protein turnover in sheep nourished by intragastric infusion of nutrients

1995 ◽  
Vol 73 (6) ◽  
pp. 829-839 ◽  
Author(s):  
S. M. Liu ◽  
G. E. Lobley ◽  
N. A. Macleod ◽  
D. J. Kyle ◽  
X.B. Chen ◽  
...  
Keyword(s):  
Dietary Protein ◽  
Protein Turnover ◽  
Protein Intake ◽  
Volatile Fatty Acids ◽  
Whole Body ◽  
N Losses ◽  
Body Protein ◽  
Fractional Rate ◽  
The Difference

The effect of long-term dietary protein excess and deficit on whole-body protein-N turnover (WBPNT) was examined in lambs nourished by intragastric infusions of nutrients. Ten sheep were given 500 mg N/kg metabolic weight (W0.75) per d from casein for 2 weeks and then either 50 (L), 500 (M) or 1500 (H) mg N/kgW0.75per d for 6 weeks. Volatile fatty acids were infused at 500 kJ/kgW0.75per d. Daily WBPNT was measured by continuous intravenous infusion of [l-13C]leucine 3 d before, and on days 2, 21 and 42 after the alteration in protein intake. Whole-body protein-N synthesis (WBPNS) was calculated as the difference between WBPNT and the protein-N losses as urinary NH3and urea. Whole-body protein-N degradation (WBPNS) was then estimated from WBPNS minus protein gain determined from N balance. Fractional rates of WBPNS and WBPND were calculated against fleece-free body N content. WBPNS rates at the L, M and H intakes were respectively 35·1, 41·5 amd 6·37 g/d (P< 0.001) on average over the 6 weeks and WBPND rates were 39·5, 41·1 and 56·8 g/d (P< 0.001). The fractional rates of WBPNS were 5·01, 6·37 and 7·73% per d (P< 0.001) while those of WBPND were 5·64, 6·29 and 6·81% per d (P< 0.005) respectively. On days 2, 21 and 42, WBPNS rates at intake H were 54·0, 61·8 and 75·4 g/d (P= 0·03) respectively, and WBPND rates were 43·2, 56·4 and 70·9 g/d (P= 0.03); at intake L the amounts were 38·2, 34·2 and 32·8 g/d for WBPNS (P= 0.003) and for WBPND were 43·4, 38·0 and 36·9 g/d (P= 0·016) respectively. There were no significant (P> 0·05) differences in fractional rates of WBPNS and WBPND with time at either the L or H intake. We concluded that absolute protein turnover was affected both by dietary protein intake and by body condition while the fractional rate of turnover was predominantly influenced by intake.

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