A snapshot of nitrogen balance in endurance-trained women

2014 ◽  
Vol 39 (2) ◽  
pp. 219-225 ◽  
Author(s):  
Stuart Douglas Houltham ◽  
David S. Rowlands
Keyword(s):  
Nitrogen Balance ◽  
Dietary Protein ◽  
Nitrogen Loss ◽  
Fold Increase ◽  
Food Samples ◽  
Follicular Phase ◽  
Protein Requirement ◽  
Nitrogen Intake ◽  
The Mean ◽  
Urinary Nitrogen

Indirect estimates of the mean daily protein requirement for female endurance athletes are 1.2–1.4 g·kg−1·day−1; however, an empirical estimate using nitrogen balance is absent. A 72-h nitrogen balance was determined during the mid-follicular phase of 10 female cyclists and triathletes training for 10.8 h·week−1 (SD 2.8) following 2 habituated protein intakes: (i) normal habitual (NH) (protein 85 g·day−1), and (ii) isocaloric high-protein (HP) (∼2-fold increase in protein). Total 72-h nitrogen intake was determined from Leco total combustion of ingested food samples. Nitrogen loss was determined from micro-Kjeldahl analysis of 72-h total urinary nitrogen and representative resting and exercise sweat output, plus estimates for fecal and miscellaneous losses. Habituated (steady state) protein requirement was estimated from the mean regression of adapted nitrogen balance vs nitrogen intake. Mean (SD) 24-h dietary protein and energy intake was NH: 1.4 g·kg−1·day−1 (0.2), energy: 9078 kJ·day−1 (1492), HP: 2.7 g·kg−1·day−1 (0.3) 8909 kJ·day−1 (1411). Average 24-h urinary nitrogen and sweat urea nitrogen outputs were 13.2 g·day−1 (2.4) and 0.33 g·day−1 (0.08) in NH; 21.5 g·day−1 (3.9) and 0.54 g·day−1 (0.12) in HP, respectively. Nitrogen balance was negative in NH (−0.59 gN·day−1 SD 1.64) but positive in HP (2.69 gN·day−1 SD 3.09). Estimated mean protein requirement was 1.63 g·kg−1·day−1 (95% confidence interval: 1.1–3.8). In conclusion the snapshot of follicular phase dietary protein requirement conformed with previous estimates for men, but was higher than previous nonempirical estimates for endurance-training women; low self-selected energy and carbohydrate intakes may explain the higher than expected nitrogen turnover, and consequently protein requirement.

Utilization of grass-silage nitrogen by growing sheep

1983 ◽  
Vol 100 (1) ◽  
pp. 43-62 ◽  
Author(s):  
Elisabeth Grenet
Keyword(s):  
Organic Matter ◽  
Formic Acid ◽  
Nitrogen Balance ◽  
Crude Protein ◽  
Nitrogen Loss ◽  
Nitrogen Retention ◽  
Protein Digestibility ◽  
Water Soluble ◽  
Nitrogen Intake ◽  
Green Fodder

SUMMARYThe digestibility, the voluntary intake and the nitrogen balance of 108 diets corresponding to 94 silages prepared from 20 fresh crops were measured in growing sheep. Series of silages were made from the same fresh forage. Each series included two controls: a direct-cut silage without additive and a direct-cut silage with formic acid, with a variable number of experimental silages with different additives.Rumen ammonia concentration, measured on rumen-fistulated sheep, decreased when an additive was used. It increased with nitrogen intake and was inversely related to the organic-matter digestibility and the crude-fibre digestibility. It varied with the silage composition.The crude-protein digestibility of direct-cut silages without additives was similar to or slightly higher than the crude-protein digestibility of the fresh crops. The addition of formic acid depressed the digestibility, but the addition of formaldehyde decreased it even more. The urinary nitrogen loss was higher for silages without additive than for the fresh crops and was decreased by the addition of formic acid. The addition of formaldehyde to formic acid had an additive effect.Retained nitrogen was lower in silages without additives (12% of nitrogen intake) than in parent crops (15·7%). It increased when formic acid (15·8%) was added. The addition of formaldehyde at a low rate (1·5 l/t green fodder) to the formic acid did not increase the nitrogen retention whether expressed in g/day or as percentage of nitrogen intake, but the addition of formaldehyde at a high rate (3·5 l/t green fodder) to formic acid decreased nitrogen retention. The other additives based on cereals or whey did not improve the nitrogen balance compared with formic acid. Nitrogen retention differed according to plant species.Retained nitrogen increased with digestible organic-matter intake and nitrogen intake. It increased with the silage water-soluble carbohydrate content. The higher the silage fermentation product content (ammonia, lactic acid, propionic acid), the lower the retained nitrogen. It appears that the nitrogen value of silages can be high provided that the silages are well preserved and that excessive protein breakdown is avoided.

scholarly journals Augmented Renal Clearance, Muscle Catabolism and Urinary Nitrogen Loss: Implications for Nutritional Support in Critically Ill Trauma Patients

Nutrients ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 3554
Author(s):  
Guilhem Dreydemy ◽  
Alexis Coussy ◽  
Alexandre Lannou ◽  
Laurent Petit ◽  
Matthieu Biais ◽  
...  
Keyword(s):  
Renal Clearance ◽  
Critically Ill ◽  
Nitrogen Balance ◽  
Protein Intake ◽  
Nitrogen Loss ◽  
Secondary Outcome ◽  
Trauma Patients ◽  
Augmented Renal Clearance ◽  
Abdominal Ct ◽  
Urinary Nitrogen

The main objective of this pilot study was to determine the association between augmented renal clearance (ARC), urinary nitrogen loss and muscle wasting in critically ill trauma patients. We conducted a retrospective analysis of a local database in 162 critically ill trauma patients without chronic renal dysfunction. Nutritional-related parameters and 24 h urinary biochemical analyses were prospectively collected and averaged over the first ten days after admission. Augmented renal clearance was defined by a mean creatinine clearance (CLCR) > 130 mL/min/1.73 m2. The main outcome was the cumulated nitrogen balance at day 10. The secondary outcome was the variation of muscle psoas cross-sectional area (ΔCSA) calculated in the subgroup of patients who underwent at least two abdominal CT scans during the ICU length of stay. Overall, there was a significant correlation between mean CLCR and mean urinary nitrogen loss (normalized coefficient: 0.47 ± 0.07, p < 0.0001). ARC was associated with a significantly higher urinary nitrogen loss (17 ± 5 vs. 14 ± 4 g/day, p < 0.0001) and a lower nitrogen balance (−6 ± 5 vs. −4 ± 5 g/day, p = 0.0002), without difference regarding the mean protein intake (0.7 ± 0.2 vs. 0.7 ± 0.3 g/kg/day, p = 0.260). In the subgroup of patients who underwent a second abdominal CT scan (N = 47), both ΔCSA and %ΔCSA were higher in ARC patients (−33 [−41; −25] vs. −15 [−29; −5] mm2/day, p = 0.010 and −3 [−3; −2] vs. −1 [−3; −1] %/day, p = 0.008). Critically ill trauma patients with ARC are thus characterized by a lower nitrogen balance and increased muscle loss over the 10 first days after ICU admission. The interest of an increased protein intake (>1.5 g/kg/day) in such patients remains a matter of controversy and must be confirmed by further randomized trials.

Studies on marsupial nutrition. VI. The utilization of dietry urea by the Euro or Hill Kangaroo, Macropus robustus (Gould)

1969 ◽  
Vol 17 (2) ◽  
pp. 187 ◽  
Author(s):  
GD Brown
Keyword(s):  
Nitrogen Balance ◽  
Dietary Protein ◽  
Nitrogen Retention ◽  
Nitrogen Excretion ◽  
Microbial Protein ◽  
Digestive Physiology ◽  
Protein Nitrogen ◽  
Feeding Trials ◽  
Urinary Nitrogen Excretion ◽  
Urinary Nitrogen

Macropod marsupials, the kangaroos and wallabies, are characterized by a ruminant-like digestive physiology. One feature of digestion in eutherian species of ruminants is the ability of these animals to utilize non-protein nitrogen through the conversion of such nitrogen to microbial protein by the microorganisms in the rumen. In the present experiments with the euro or hill kangaroo (M. robustus), the utilization of dietary protein (casein) and non-protein nitrogen (urea) has been compared by means of nitrogen balance feeding trials. No consistent differences between the levels of nitrogen retention and urinary nitrogen excretion were observed for euros fed rations supplemented with either casein or urea. It is suggested that the digestion of nitrogen by the ruminant-like macropod marsupials is similar to that of eutherian species of ruminant herbivores.

Pyrochemiluminescence: real-time, cost-effective method for determining total urinary nitrogen in clinical nitrogen-balance studies.

1988 ◽  
Vol 34 (12) ◽  
pp. 2518-2520 ◽  
Author(s):  
F N Konstantinides ◽  
K A Boehm ◽  
W J Radmer ◽  
M C Storm ◽  
J T Adderly ◽  
...  
Keyword(s):  
Nitrogen Balance ◽  
Nitrogen Loss ◽  
Linear Regression Analysis ◽  
Cost Effective ◽  
Nitrogen Excretion ◽  
Disease States ◽  
Clinical Laboratories ◽  
Wide Availability ◽  
Kjeldahl Method ◽  
Urinary Nitrogen

Abstract Total urinary nitrogen (TUN) determinations for nitrogen-balance studies were traditionally performed by the Kjeldahl method, but this method is laborious, hazardous, prone to error, and no longer widely available in most clinical laboratories. During the last several decades, urinary urea nitrogen (UUN) determinations have replaced TUN as an index of urinary nitrogen excretion in many clinical laboratories, owing to its ease of determination, decreased cost, and wide availability. However, the validity of using UUN for estimating nitrogen loss has been questioned in many disease states, owing to wide variations in the proportional amount of urea found in TUN. Chemiluminescence has been proposed as an alternative to the Kjeldahl method for TUN. TUN values obtained from 24-h urine collections measured by both micro-Kjeldahl (x) and Pyrochemiluminescence (y) (Antek Instruments, Inc.) techniques were comparable by linear regression analysis: n = 97; r = 0.996; r2 = 0.992; y = 1.048x - 0.606; P less than 0.001. Automated induction of samples and calculation of results allows up to 42 samples to be run unattended. This dramatically reduces labor and overall costs for TUN determinations, while providing a more accurate and economical assessment of nitrogen excretion than UUN in a clinical setting.

scholarly journals Dietary protein requirements and adaptive advantages in athletes

2012 ◽  
Vol 108 (S2) ◽  
pp. S158-S167 ◽  
Author(s):  
Stuart M. Phillips
Keyword(s):  
G Protein ◽  
Nitrogen Balance ◽  
Dietary Protein ◽  
Daily Intake ◽  
Dietary Guidelines ◽  
Protein Requirements ◽  
Dietary Reference Intakes ◽  
The Us ◽  
Nitrogen Intake ◽  
Practical Recommendations

Dietary guidelines from a variety of sources are generally congruent that an adequate dietary protein intake for persons over the age of 19 is between 0·8–0·9 g protein/kg body weight/d. According to the US/Canadian Dietary Reference Intakes, the RDA for protein of 0·8 g protein/kg/d is “…the average daily intake level that is sufficient to meet the nutrient requirement of nearly all [~98 %]… healthy individuals…” The panel also states that “…no additional dietary protein is suggested for healthy adults undertaking resistance or endurance exercise.” These recommendations are in contrast to recommendations from the US and Canadian Dietetic Association: “Protein recommendations for endurance and strength trained athletes range from 1·2 to 1·7 g/kg/d.” The disparity between those setting dietary protein requirements and those who might be considered to be making practical recommendations for athletes is substantial. This may reflect a situation where an adaptive advantage of protein intakes higher than recommended protein requirements exists. That population protein requirements are still based on nitrogen balance may also be a point of contention since achieving balanced nitrogen intake and excretion likely means little to an athlete who has the primary goal of exercise performance. The goal of the present review is to critically analyse evidence from both acute and chronic dietary protein-based studies in which athletic performance, or correlates thereof, have been measured. An attempt will be made to distinguish between protein requirements set by data from nitrogen balance studies, and a potential adaptive ‘advantage’ for athletes of dietary protein in excess of the RDA.

scholarly journals STUDIES ON PROTEIN REQUIREMENTS OF STEERS

2021 ◽  
Vol 6 ◽  
pp. 88-93
Author(s):  
U. J. Ikhatua ◽  
F. O. Olubajo
Keyword(s):  
Crude Protein ◽  
Nitrogen Loss ◽  
N Balance ◽  
Mean Values ◽  
Protein Requirements ◽  
N Metabolism ◽  
Digestible Crude Protein ◽  
The Mean ◽  
White Fulani ◽  
Urinary Nitrogen

Comparative studies lasting between 59 - 63 days were carried out using the N-balance method to investigate the effect of groundnut cake supplementation on N-metabolism and digestible crude protein (DCP)requirements of three breeds of steers maintained on all-roughage rations of hay and fresh dry of Cynodon rulenfuensis var robustus The results indicated that N intake (/day) Increased ed appreciably with supplementation. The percentage Increases li the intake were 16.4.40.0 and 18.0 for the White Fulani, crossbred and German Brown Steer respectively. Apparent digestibility coefficients for N also increased by 10%0.6.8% and 7.1% for these steers respectively. Faucal nitrogen output (/day) Increased slightly with supplementation with all breedy of steen, while urinary nitrogen loss decreased with the White Fulani, increased with the German Brown and showed no difference with the crossbreed. Absorbed nitrogen (g/day), N-balance (g/day) und N-retention (%) all increased with supplementations Mean values for both metabolic f al ultrogen (MEN) (N/kgDM consumed und endogenous urinary nitrogen (EUN) (/day/wkg 0.75) decreased with supplementation while the mean Hological value (BV) (197) Increased. The values were 2.4 6N/kg DM consumed, 0.11/dm/wg 0.75 and 75.87 respectively. Digestible crude protein requirements (DCP) decreed with supplementation in all the breeds of steen. The values were 1.06, 0.38 and 0.81 (0.75 + 0.20)/day/wkg 0.75) by the N-balance methods and 1.08, 0.51 und 1.20 (0.93 = 0.21) 2DCP/day/wkg 0.75 by the Nuctoriul methody. The DCP requirements therefore range from 0.75 - 0.93 /day/weg 0.75 for these breeds of steers, While there were decreases of approximately 13.14%. 1.99 and 6.4% In the mean DM Intake.

scholarly journals Effect of slow release urea in sheep feed on nitrogen balance

2018 ◽  
Vol 39 (2) ◽  
pp. 683
Author(s):  
Luiz Juliano Valério Geron ◽  
Jocilaine Garcia ◽  
Sílvia Cristina de Aguiar ◽  
Fabiana Gomes da Costa ◽  
Ana Paula da Silva ◽  
...  
Keyword(s):  
Nitrogen Balance ◽  
Slow Release ◽  
Latin Square ◽  
Average Value ◽  
Maximum Value ◽  
Nitrogen Intake ◽  
Slow Release Urea ◽  
Different Levels ◽  
Average Body ◽  
Urinary Nitrogen

The aim of this study was to evaluate the effect of inclusion of 0.0%, 0.4%, 0.8%, and 1.2% slow release urea (SRU) in sheep feed on nitrogen balance (intake, fecal and urinary excretion, nitrogen absorbed and retained and/or nitrogen balance). Four sheep with an average body weight (BW) of 30.8 ± 1.7 kg were distributed using a Latin square experimental design. Sheep were allocated in metabolic cages and received two meals a day. The data were subjected to analysis of variance and differences were tested using a regression equation with a 5% probability. The inclusion of 0.0%, 0.4%, 0.8%, and 1.2% SRU in sheep diets did not change (p > 0.05) nitrogen intake (NI), with an average value of 20.49 g animal day-1 and 1.57 g (kg0.75)-1. The inclusion of 0.0%, 0.4%, 0.8%, and 1.2% SRU in sheep diets did not affect (p > 0.05) fecal nitrogen (FN) in g (kg0.75)-1, with an average value of 0.65 g (kg0.75)-1. However, the inclusion of SRU changed (p < 0.05) the FN, expressed as g animal day-1, and % BW, in a quadratic manner. The lowest FN excretion was 7.63 g animal day-1 and 36.41% NI, and it was obtained at inclusion levels of 0.82% and 0.66% SRU, respectively. The inclusion of 0.0%, 0.4%, 0.8%, and 1.2% SRU in sheep diets had a quadratic effect (p < 0.05) in urinary nitrogen (UN), expressed as g animal day-1, g (kg0.75)-1, and % of NI. The minimum values calculated with the equations for UN were 0.86 g animal day-1, 0.06 g (kg0.75)-1, and 0.28% NI for SRU inclusion levels of 0.79%, 0.76%, and 0.71%, respectively. The inclusion of 0.0%, 0.4%, 0.8%, and 1.2% SRU in sheep diets did not change (p > 0.05) the NB expressed as g animal day-1 (10.86) and g (kg0.75)-1 (0.82). However, the NB expressed as % NI or in relation to the NI responded in a quadratic manner (p < 0.05) to the inclusion of different levels of SRU in sheep food. The maximum value for NB was 59.68% NI and it was obtained at 0.68% SRU. Thus, the inclusion of 0.6% to 0.8% slow release urea in sheep diets provides the lowest fecal and urinary nitrogen losses. In addition, these levels provide the best NB values, expressed as a percentage of NI.

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