scholarly journals Simulation of the metabolism of absorbed energy-yielding nutrients in young sheep

1984 ◽  
Vol 52 (3) ◽  
pp. 621-649 ◽  
Author(s):  
Margaret Gill ◽  
J. H. M. Thornley ◽  
J. L. Black ◽  
J. D. Oldham ◽  
D. E. Beever
Keyword(s):  
Basic Assumption ◽  
Reaction Rates ◽  
Metabolizable Energy ◽  
State Variables ◽  
Nutrient Inputs ◽  
Absorbed Energy ◽  
Protein Deposition ◽  
Maximum Reaction ◽  
Synthetic Reactions ◽  
The Relationship

1. A mathematical model is described, which simulates the metabolism of absorbed nutrients (amino acids, acetic acid, butyric acid, glucose, lipid and propionic acid) in growing sheep.2. The basic assumption of the model is that each nutrient is partitioned between synthetic, oxidative or intermediate reactions with rates of reaction which are described using enzyme kinetics. These rates depend on the relationship between maximum reaction rates, constants of affinity and inhibition and the concentrations of metabolites as determined by the model.3. Synthetic reactions calculate fat and protein deposition while intermediate reactions involve the production of ATP and NADPH. There is a total of twelve state variables and the model, programmed in CSMP and ACSL, is solved by integration of twelve differential equations.4. The model calculates the efficiency of utilization of metabolizable energy for different nutrient inputs and the results may be interpreted in terns of fluxes through the metabolite pools. Simulations using inputs representing forage- and concentrate-based diets indicated decreased efficiency for the forage at high levels of intake and possible reasons for this were further studied in simulations where the inputs of protein and glucose were varied.

scholarly journals The effects of varying protein and energy intakes on the growth and body composition of pigs

1992 ◽  
Vol 68 (3) ◽  
pp. 615-625 ◽  
Author(s):  
I. Kyriazakis ◽  
G. C. Emmans
Keyword(s):  
Live Weight ◽  
Metabolizable Energy ◽  
Protein Ratio ◽  
Protein Food ◽  
Protein Nitrogen ◽  
Feeding Level ◽  
Protein Deposition ◽  
Young Pigs ◽  
Growing Pig ◽  
The Relationship

The objective of the experiment was to define the form of the relationship between varying levels of protein and energy intake and the performance of young pigs. Forty-four young pigs were assigned at 12 kg live weight for 6 weeks either to an initial slaughter group (n 8) or to one of the nine feeding treatments (n 4); three allowances of a high-protein food with 355 g crude protein (nitrogen × 6.25; CP)/kg (P1, P2, P3) at three levels of feeding (L, M and H). Each feeding level was met by supplementing the allowance of feed P with the appropriate amount of starch and each treatment had two males and two females. The rate of protein deposition was not affected by feeding level at the two lowest allowances of basal feed P (P1 and P2), but it increased with increasing the feeding level for the pigs on treatment P3. Males deposited more protein than females, but this effect was more pronounced with treatment P3. The rate of lipid deposition increased with each increase in the level of feeding and decreased with increasing the allowance of feed P. The calculated efficiency of protein utilization (ep) was expressed as a function of the energy: protein ratio in the feed (MJ metabolizable energy/kg digestible CP). The best model to describe the relationship was a linear-plateau model, with the maximum value for ep of 0.814 at 73 MJ/kg. This relationship provided the basis of a model that could predict the response of a growing pig to its diet as rates of protein and lipid retention

Does it pay off to link functional gene expression to denitrification rates via modelling?

2020 ◽  
Author(s):  
Anna Störiko ◽  
Holger Pagel ◽  
Olaf Cirpka
Keyword(s):  
Gene Expression ◽  
Mechanistic Model ◽  
Reaction Rates ◽  
Biological Data ◽  
State Variables ◽  
Turnover Rates ◽  
Using Data ◽  
Inhibition Control ◽  
Denitrification Genes ◽  
The Relationship

<p>The abundances of functional genes and transcripts have provided new insights into microbially mediated biogeochemical processes and might improve quantitative predictions of turnover rates.<br>However, the relationship between reaction rates and the gene and transcript abundances may not be a simple correlation.<br>Most mechanistic reaction models cannot predict molecular-biological data, and it is unclear how they can be informed by such data.</p><p>We developed a mechanistic model that considers transcript abundances of denitrification genes, enzyme concentrations, biomass, and solute concentrations as state variables that are interrelated by ordinary differential equations, and thus mechanistically links molecular-biological data to reaction rates.<br>Important features of transcript dynamics can be reproduced with the transcript-based model.</p><p>We calibrated the model using data from a batch experiment with a denitrifying organism at the onset of anoxia.<br>We explored the relationship between transcript abundances and reaction rates by analyzing the model results.<br>The transcript abundances reacted very quickly to substrate concentrations so that we could simplify the model by assuming a quasi steady state of the transcripts.</p><p>We compared our model to a classical Monod-type formulation, which was as good at simulating the concentrations of nitrogen species as the transcript-based model, but it cannot make use of any molecular-biological data.<br>Our results, thus, suggest that enzyme kinetics (substrate limitation, inhibition) control denitrification rates more strongly than the dynamics of gene expression.</p>

Effects of supplementary concentrates on growth and partitioning of nutrients between different body components in steers fed on grass silage at similar levels of metabolizable energy intake

2003 ◽  
Vol 141 (1) ◽  
pp. 103-112 ◽  
Author(s):  
E. J. KIM ◽  
N. D. SCOLLAN ◽  
M. S. DHANOA ◽  
P. J. BUTTERY
Keyword(s):  
Metabolizable Energy ◽  
Protein Deposition ◽  
Grass Silage ◽  
Nutrient Partitioning ◽  
Bean Meal ◽  
Metabolizable Energy Intake ◽  
Soya Bean Meal ◽  
Dietary Treatments ◽  
The Relationship ◽  
Tissue Accretion

A comparative slaughter experiment was carried out to examine the effects of feeding either grass silage alone or a mixed diet of silage and concentrate on animal performance and the partitioning of nutrients between lean and fat deposition in steers. Eighteen Hereford×Friesian steers were randomly assigned to two dietary treatments; grass silage only (S) or a mixture of grass silage and a barley/soya bean meal concentrate (80[ratio ]20 on fresh basis) in the ratio of 60[ratio ]40 (on a metabolizable energy basis; SC), and to one of three target slaughter liveweights, 250, 350 or 500 kg. Metabolizable energy (ME) intake was maintained at 800 kJ ME per kg metabolic liveweight (kg0·75) per day. The relationships between chemical composition and empty body weight (EBW) at slaughter were assessed using allometric equations (logey=logea+blogeEBW). When assessed across the slaughter weights, supplementing silage with concentrates resulted in higher rates of liveweight (P<0·001), carcass fat (P<0·05) and protein (P<0·01) gains and a reduction in time taken to reach the average slaughter weight by 57 days (P<0·001). Carcass protein deposition was relatively linear across the slaughter weights (250–500 kg) and the relationship with EBW was Y=0·2372X0·8831 across treatments and did not differ between the diets. The rate at which carcass fat was deposited in relation to weight across all steers was Y=0·0004X1·9648 and was not different between the two diets. Hence, ratios of carcass fat[ratio ]protein and carcass fat[ratio ]protein gain ratios were not different. The results suggest that the main effect of feeding grass silage compared with grass silage-concentrate at similar levels of ME intake was to increase the rate of tissue accretion, but nutrient partitioning between fat and protein deposition was unchanged. There was no evidence of increased carcass fat[ratio ]protein deposition in silage-fed animals, which suggests that there is no problem of greater fat and reduced protein deposition in animals fed higher quality grass silage.

Plasminogen Depletion during Streptokinase Treatment or Two-Chain Urokinase Incubation Correlates with Decreased Clot Lysability Ex Vivo and In Vitro

1993 ◽  
Vol 70 (06) ◽  
pp. 0998-1004 ◽  
Author(s):  
Páll T Önundarson ◽  
H Magnús Haraldsson ◽  
Lena Bergmann ◽  
Charles W Francis ◽  
Victor J Marder
Keyword(s):  
Myocardial Infarction ◽  
Ex Vivo ◽  
Time Dependent ◽  
State Variables ◽  
Thrombolytic Treatment ◽  
Direct Proportion ◽  
Plasmin Activity ◽  
Plasma Exposure ◽  
The Relationship

SummaryThe relationship between lytic state variables and ex vivo clot lysability was investigated in blood drawn from patients during streptokinase administration for acute myocardial infarction. A lytic state was already evident after 5 min of treatment and after 20 min the plasminogen concentration had decreased to 24%, antiplasmin to 7% and fibrinogen 0.2 g/1. Lysis of radiolabeled retracted clots in the patient plasmas decreased from 37 ± 8% after 5 min to 21 ± 8% at 10 min and was significantly lower (8 ± 9%, p <0.005) in samples drawn at 20, 40 and 80 min. Clot lysability correlated positively with the plasminogen concentration (r = 0.78, p = 0.003), but not with plasmin activity. Suspension of radiolabeled clots in normal plasma pre-exposed to 250 U/ml two-chain urokinase for varying time to induce an in vitro lytic state was also associated with decreasing clot lysability in direct proportion with the duration of prior plasma exposure to urokinase. The decreased lysability correlated with the time-dependent reduction in plasminogen concentration (r = 0.88, p <0.0005). Thus, clot lysability decreases in conjunction with the development of the lytic state and the associated plasminogen depletion. The lytic state may therefore limit reperfusion during thrombolytic treatment.

scholarly journals Synthesis of DHA/EPA Ethyl Esters via Lipase-Catalyzed Acidolysis Using Novozym® 435: A Kinetic Study

Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 565 ◽  
Author(s):  
Chia-Hung Kuo ◽  
Chun-Yung Huang ◽  
Chien-Liang Lee ◽  
Wen-Cheng Kuo ◽  
Shu-Ling Hsieh ◽  
...  
Keyword(s):  
Ethyl Ester ◽  
Ethyl Esters ◽  
Raw Material ◽  
Maximum Reaction Rate ◽  
Mechanism Model ◽  
Maximum Reaction ◽  
Substrate Ratio ◽  
Free Fatty Acid Form ◽  
The Relationship ◽  
Predictive Relationship

DHA/EPA ethyl ester is mainly used in the treatment of arteriosclerosis and hyperlipidemia. In this study, DHA+EPA ethyl ester was synthesized via lipase-catalyzed acidolysis of ethyl acetate (EA) with DHA+EPA concentrate in n-hexane using Novozym® 435. The DHA+EPA concentrate (in free fatty acid form), contained 54.4% DHA and 16.8% EPA, was used as raw material. A central composite design combined with response surface methodology (RSM) was used to evaluate the relationship between substrate concentrations and initial rate of DHA+EPA ethyl ester production. The results indicated that the reaction followed the ordered mechanism and as such, the ordered mechanism model was used to estimate the maximum reaction rate (Vmax) and kinetic constants. The ordered mechanism model was also combined with the batch reaction equation to simulate and predict the conversion of DHA+EPA ethyl ester in lipase-catalyzed acidolysis. The integral equation showed a good predictive relationship between the simulated and experimental results. 88–94% conversion yields were obtained from 100–400 mM DHA+EPA concentrate at a constant enzyme activity of 200 U, substrate ratio of 1:1 (DHA+EPA: EA), and reaction time of 300 min.

Modified Equation to Predict Leak/Rupture Criteria for Axially Through-Wall Notched X80 and X100 Linepipes Having Higher Charpy Energy

2004 ◽  
Author(s):  
Shinobu Kawaguchi ◽  
Naoto Hagiwara ◽  
Mitsuru Ohata ◽  
Masao Toyoda
Keyword(s):  
Fracture Toughness ◽  
Flow Stress ◽  
Pipe Material ◽  
Test Results ◽  
Absorbed Energy ◽  
Bending Tests ◽  
Full Scale Tests ◽  
Hoop Stresses ◽  
The Relationship ◽  
Modified Equation

A method of predicting the leak/rupture criteria for API 5L X80 and X100 linepipes was evaluated, based on the results of hydrostatic full-scale tests for X60, X65, X80 and X100 linepipes with an axially through-wall (TW) notch. The TW notch test results clarified the leak/rupture criteria, that is, the relationship between the initial notch lengths and the maximum hoop stresses during the TW notch tests. The obtained leak/rupture criteria were then compared to the prediction of the Charpy V-notch (CVN) absorbed energy-based equation, which has been proposed by Kiefner et al. The comparison revealed that the CVN-based equation was not applicable to the pipes having a CVN energy (Cv) greater than 130 J and flow stress greater than X65. In order to predict the leak/rupture criteria for these linepipes, the static absorbed energy for ductile cracking, (Cvs)i, was introduced as representing the fracture toughness of a pipe material. The (Cvs)i value was determined from the microscopic observation of the cut and buffed Charpy V-notch specimens after static 3-point bending tests. The CVN energy in the original CVN-based equation was replaced by an equivalent CVN energy, (Cv)eq’ which was defined as follows: (Cv)eq = 4.5 (Cvs)i. The leak/rupture criteria for the X80 and X100 linepipes with higher CVN energies were reasonably predicted by the modified equation using the (Cvs)i value.

scholarly journals The energy cost of fat and protein deposition in the rat

1977 ◽  
Vol 37 (3) ◽  
pp. 355-363 ◽  
Author(s):  
J. D. Pullar ◽  
A. J. F. Webster
Keyword(s):  
Regression Analysis ◽  
Energy Cost ◽  
Metabolizable Energy ◽  
Zucker Rats ◽  
Energy Costs ◽  
Semisynthetic Diet ◽  
Direct Calorimetry ◽  
Protein Deposition ◽  
Body Weights ◽  
Gross Energy

1. Measurements were made of energy balance by direct calorimetry, and of nitrogen balance in groups of lean and congenitally obese (‘fatty’) Zucker rats at body-weights of 200 and 350 g given a highly digestible semisynthetic diet at 14.0 or 18.4 g/rat per 24 h.2. Losses of food energy and N in faeces were very small. The fatty rats lost much more N in urine than did lean rats. Despite this the proportion of gross energy that was metabolized was 0.92 for both fatty and lean rats.3. In all trials, fatty rats lost a smaller proportion of metabolizable energy (ME) as heat and deposited less as protein than thin rats but deposited much more as fat.4. The amounts of ME required to deposit 1 kJ of protein and 1 kJ of fat respectively were shown by regression analysis to be 2.25 (±0.16) and 1.36 (±0.06) kJ respectively. These values agree extremely closely with recent, more tentative, estimates based on assumptions as to maintenance requirement which the present experiments were able to circumvent. It may be concluded with confidence that the energy costs of depositing 1 g of protein or fat are almost identical at 53 kJ ME/g.

scholarly journals Metabolizable energy levels in diets with a fixed nutrient: calorie ratio for free-range broilers

2021 ◽  
Vol 42 (6supl2) ◽  
pp. 4009-4022
Author(s):  
Thiago Rodrigues da Silva ◽  
◽  
Karina Márcia Ribeiro de Souza Nascimento ◽  
Charles Kiefer ◽  
Luanna Lopes Paiva Copat ◽  
...  
Keyword(s):  
Body Weight ◽  
Weight Gain ◽  
Energy Level ◽  
Body Fat ◽  
Feed Intake ◽  
Carcass Characteristics ◽  
Metabolizable Energy ◽  
Production Performance ◽  
Feed Conversion ◽  
Protein Deposition

The present study proposes to examine the effect of dietary levels of metabolizable energy, under a fixed nutrient:calorie ratio, on the production performance; body fat and protein deposition; and carcass characteristics of free-range broilers from 1 to 84 days of age. Nine hundred unsexed chicks were allocated to six treatments in a completely randomized design with six replicates of 25 birds each. Treatments consisted of diets with varying levels of metabolizable energy (2700, 2800, 2900, 3000, 3100 and 3200 Kcal ME/kg of diet) and a fixed proportion of nutrients relative to the energy level according to the nutritional requirements for each rearing phase. Body weight, weight gain, feed intake, feed conversion, production viability, metabolizable energy intake, protein intake, lysine intake, body fat deposition, body protein deposition and carcass characteristics were evaluated. Data were subjected to analysis of variance and, later, to regression analysis. Increasing levels of metabolizable energy, coupled with a fixed nutrient:calorie ratio, reduced feed intake, increased body weight and weight gain, improved feed conversion and did not affect carcass characteristics. In conclusion, adjusting the nutrient supply according to the dietary energy level improves production performance by improving feed conversion, ensuring adequate nutrient intake and preserving fat and protein deposition in the carcass when the metabolizable energy level is raised up to 3200 Kcal/kg in all rearing stages.

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