scholarly journals Predicting metabolisable energy in commercial rat diets: physiological fuel values may be misleading

2010 ◽  
Vol 103 (10) ◽  
pp. 1525-1533 ◽  
Author(s):  
Maximilian Bielohuby ◽  
Karin Bodendorf ◽  
Heinz Brandstetter ◽  
Martin Bidlingmaier ◽  
Ellen Kienzle
Keyword(s):  
Experimental Approach ◽  
Average Energy ◽  
Energy Losses ◽  
Predictive Equations ◽  
Gross Energy ◽  
Metabolisable Energy ◽  
Digestible Protein ◽  
Pig Feed ◽  
Predicted Values

Knowledge about metabolisable energy (ME) intake is crucial for various experimental settings in rodent studies. ME considers faecal and renal energy losses. In particular, faecal energy excretion can vary considerably between differentially composed diets. Thus determination of faecal energy losses, i.e. apparent energy digestibility, is the most important experimental approach to determine ME. Predictive equations for ME such as Atwater factors or an equation for pigs, which are frequently employed for rodent feed, consider an average energy digestibility for nutrients and average renal losses for protein. Both equations, however, were never validated for rat feed. We therefore determined experimentally the digestibility of energy (experimentally determined digestible energy − 5·2 kJ/g digestible protein) and nutrients of eleven natural and five purified rat diets and compared the present results with the predicted values. Compared with natural diets, digestibility of gross energy (GE) and nutrients was higher by about 20 % in the purified diets (P < 0·0001). Mean GE digestibility in natural diets amounted to 71·4 % (range 53·3–83·5 %;n11). Atwater factors predicted ME with satisfactory accuracy in purified diets. In contrast, for natural diets, only the equation for pig feed gave acceptable estimates of ME. Choosing an inappropriate predictive equation for ME resulted in considerable error. For prediction of ME in mixed rat feed, we propose to use the equation for pig feed for natural diets and Atwater factors for purified diets. If the equation for pig feed cannot be applied we suggest using the lower modified Atwater factors instead of the ‘original’ Atwater factors to estimate the ME of a diet.

Partition of dietary energy by sheep fed fresh ryegrass (Lolium perenne) with a wide-ranging composition and quality

2020 ◽  
Vol 60 (8) ◽  
pp. 1008
Author(s):  
C. A. Ramírez-Restrepo ◽  
G. C. Waghorn ◽  
H. Gillespie ◽  
H. Clark
Keyword(s):  
Lolium Perenne ◽  
Sulfur Hexafluoride ◽  
Nutritive Value ◽  
Open Circuit ◽  
Energy Losses ◽  
Dietary Energy ◽  
Digestible Energy ◽  
Gross Energy ◽  
Metabolisable Energy ◽  
Predicted Values

Context Perennial ryegrass (Lolium perenne L.) is an important forage in temperate ruminant agricultural systems, but its quality and composition is highly variable and can become dominated by senescent material during summer and dry periods. Nutritive value is often predicted on the basis of chemical composition and calculated metabolisable energy (ME), which is rarely measured. Aim To measure the partition of energy from ryegrasses with widely varying proportions of leaf and senescent material, among faeces, urine and methane (CH4) in sheep. Methods Three experiments were undertaken with two groups of young wether sheep, fed seven diets of freshly cut ryegrass, at maintenance levels of intake to measure the partition of dietary energy among faeces, urine and CH4, enabling ME to be calculated. Across the seven diets, green leaf accounted for 16.0–87.6% of feed offered, whereas senescent material ranged from 2.8% to 65.0% and nitrogen (N) ranged between 8.6 and 31.2 g/kg DM. Measured ME was compared with predicted values based on digestible energy. Methane emissions were determined by both open-circuit respiration chambers and sulfur hexafluoride marker dilution. Key results Apparent digestibility (g/100 g) of DM ranged from 51.8 to 75.3 and N from 26.7 to 73.9. The percentage of the gross energy of feeds partitioned to CH4 (chamber) was 6.01–7.42, and 1.77–5.69 to urine. Effects of digestibility on CH4 yields (g/kg DM intake) were minor and the sum of energy losses to CH4 and urine were 13.5–17.6% of digestible energy (DE) intake, suggesting an underestimation of ME when predicted from DE. Use of sulfur hexafluoride substantially overestimated CH4 emissions when the permeation tubes had been in the sheep for 80 days. Conclusions A high proportion of senescent material in ryegrass had little effect on CH4 yields from sheep and energy losses to urine were mostly less than 3% of energy intake and were related to dietary N concentration. Implications Dietary ME calculated from DE is likely to be underestimated when ryegrass contains a high proportion of senescent material, due to reduced urinary energy losses, as CH4 yields are largely unaffected by maturity or senescence.

Comparison of a range of NE systems with data obtained from slaughter balance studies on 8-12 week old pigs

1998 ◽  
Vol 1998 ◽  
pp. 154-154
Author(s):  
V.E. Beattie ◽  
R.N. Weatherup ◽  
K.J. McCracken ◽  
S.G. McIlroy ◽  
R.W. Henry
Keyword(s):  
Growing Pigs ◽  
Energy Losses ◽  
European Research ◽  
Animal Performance ◽  
Feed Ingredient ◽  
Protein Sources ◽  
Wide Range ◽  
Gross Energy ◽  
Pig Feed ◽  
Research Centres

The gross energy of any pig feed is not completely available to the animal with losses occurring in faeces, urine, methane and heat. The NE system of feed evaluation should be more accurate in predicting animal performance since it takes into account these energy losses and the metabolic utilisation of energy. The NE system ascribes a relatively higher value to energy from fat and a lower value to energy from protein sources than the DE system. One method of deriving NE is to multiply DE by a factor of 0.71 (Noblet, 1996a). A wide range of more complex NE systems are currently in use involving individual feed ingredient data collected at various European research centres. This study was designed to compare a range of NE systems with data obtained from slaughter balance studies on 8-12 week old pigs using a range of diets for growing pigs differing in CP and DE levels.

scholarly journals Nonlinear Models for Relativity Effects in Electromagnetism

2009 ◽  
Vol 64 (5-6) ◽  
pp. 327-340 ◽  
Author(s):  
Santosh Devasia
Keyword(s):  
Relative Velocity ◽  
Nonlinear Models ◽  
Average Energy ◽  
High Energy ◽  
Experimental Energy ◽  
Cathode Ray Tube ◽  
Predicted Values ◽  
High Energy Particles ◽  
Energy Determination

Abstract Experimental energy measurements tend to be smaller than the predicted values in (i) the absorption of high-energy particles (in cloud chambers) and (ii) the average energy determination of the classical β -ray spectrum of radium E (using magnetic fields). To address these differences in energy measurements, we reconsider relative-velocity-dependent models in electromagnetism proposed initially by Weber before data from cathode-ray-tube (CRT) experiments was available. It is shown that identifying the nonlinear, relative-velocity terms using CRT data results in a model, which (i) captures relativity effects in optics and high-energy particles, and (ii) explains the apparent discrepancies in experimental energy measurements.

Comparison of a range of NE systems with data obtained from slaughter balance studies on 8-12 week old pigs

1998 ◽  
Vol 1998 ◽  
pp. 154-154
Author(s):  
V.E. Beattie ◽  
R.N. Weatherup ◽  
K.J. McCracken ◽  
S.G. McIlroy ◽  
R.W. Henry
Keyword(s):  
Growing Pigs ◽  
Energy Losses ◽  
European Research ◽  
Animal Performance ◽  
Feed Ingredient ◽  
Protein Sources ◽  
Wide Range ◽  
Gross Energy ◽  
Pig Feed ◽  
Research Centres

The gross energy of any pig feed is not completely available to the animal with losses occurring in faeces, urine, methane and heat. The NE system of feed evaluation should be more accurate in predicting animal performance since it takes into account these energy losses and the metabolic utilisation of energy. The NE system ascribes a relatively higher value to energy from fat and a lower value to energy from protein sources than the DE system. One method of deriving NE is to multiply DE by a factor of 0.71 (Noblet, 1996a). A wide range of more complex NE systems are currently in use involving individual feed ingredient data collected at various European research centres. This study was designed to compare a range of NE systems with data obtained from slaughter balance studies on 8-12 week old pigs using a range of diets for growing pigs differing in CP and DE levels.

Experimental Determination of the Effective Resolution Limit in Thick Specimens at High Voltages

1975 ◽  
Vol 33 ◽  
pp. 664-665
Author(s):  
Mircea Fotino
Keyword(s):  
Experimental Approach ◽  
Chromatic Aberration ◽  
Resolving Power ◽  
Biological Research ◽  
Specimen Thickness ◽  
Resolution Limit ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Resolution Level

The use of thick specimens (0.5 μm to 5.0 μm or more) is one of the most resourceful applications of high-voltage electron microscopy in biological research. However, the energy loss experienced by the electron beam in the specimen results in chromatic aberration and thus in a deterioration of the effective resolving power. This sets a limit to the maximum usable specimen thickness when investigating structures requiring a certain resolution level.An experimental approach is here described in which the deterioration of the resolving power as a function of specimen thickness is determined. In a manner similar to the Rayleigh criterion in which two image points are considered resolved at the resolution limit when their profiles overlap such that the minimum of one coincides with the maximum of the other, the resolution attainable in thick sections can be measured by the distance from minimum to maximum (or, equivalently, from 10% to 90% maximum) of the broadened profile of a well-defined step-like object placed on the specimen.

Determination of the Average Energy of Iron Ions in the Axial Direction of a Micropinch Discharge Using an Ion Collector

2019 ◽  
Vol 82 (10) ◽  
pp. 1387-1391
Author(s):  
S. A. Sarantsev ◽  
I. F. Raevskii ◽  
V. A. Kostyushin ◽  
A. S. Savelov
Keyword(s):  
Average Energy ◽  
Axial Direction ◽  
Iron Ions

Reynolds-averaged Navier–Stokes simulation of hydrofoil effects on hydrodynamic coefficients of a catamaran in forced oscillation

2016 ◽  
Vol 231 (2) ◽  
pp. 364-383
Author(s):  
Amin Najafi ◽  
Mohammad Saeed Seif
Keyword(s):  
High Speed ◽  
Experimental Approach ◽  
Navier Stokes ◽  
Hydrodynamic Coefficients ◽  
Laboratory Equipment ◽  
Factors Affecting ◽  
High Frequencies ◽  
Frequency Independent ◽  
Reynolds Averaged Navier Stokes

Determination of high-speed crafts’ hydrodynamic coefficients will help to analyze the dynamics of these kinds of vessels and the factors affecting their dynamic stabilities. Also, it can be useful and effective in controlling the vessel instabilities. The main purpose of this study is to determine the coefficients of longitudinal motions of a planing catamaran with and without a hydrofoil using Reynolds-averaged Navier–Stokes method to evaluate the foil effects on them. Determination of hydrodynamic coefficients by experimental approach is costly and requires meticulous laboratory equipment; therefore, utilizing the numerical methods and developing a virtual laboratory seem highly efficient. In this study, the numerical results for hydrodynamic coefficients of a high-speed craft are verified against Troesch’s experimental results. In the following, after determination of hydrodynamic coefficients of a planing catamaran with and without foil, the foil effects on its hydrodynamic coefficients are evaluated. The results indicate that most of the coefficients are frequency-independent especially at high frequencies.

Real-Ear-to-Coupler Difference Predictions as a Function of Age for Two Coupling Procedures

2002 ◽  
Vol 13 (08) ◽  
pp. 407-415 ◽  
Author(s):  
Marlene P. Bagatto ◽  
Susan D. Scollie ◽  
Richard C. Seewald ◽  
K. Shane Moodie ◽  
Brenda M. Hoover
Keyword(s):  
Young Children ◽  
Infants And Children ◽  
Regression Equations ◽  
Predictive Equations ◽  
Subject Variability ◽  
Predicted Values ◽  
Age Range ◽  
Infants And Young Children

The predicted real-ear-to-coupler difference (RECD) values currently used in pediatric hearing instrument prescription methods are based on 12-month age range categories and were derived from measures using standard acoustic immittance probe tips. Consequently, the purpose of this study was to develop normative RECD predicted values for foam/acoustic immittance tips and custom earmolds across the age continuum. To this end, RECD data were collected on 392 infants and children (141 with acoustic immittance tips, 251 with earmolds) to develop normative regression equations for use in deriving continuous age predictions of RECDs for foam/acoustic immittance tips and earmolds. Owing to the substantial between-subject variability observed in the data, the predictive equations of RECDs by age (in months) resulted in only gross estimates of RECD values (i.e., within ± 4.4 dB for 95% of acoustic immittance tip measures; within ± 5.4 dB in 95% of measures with custom ear molds) across frequency. Thus, it is concluded that the estimates derived from this study should not be used to replace the more precise individual RECD measurements. Relative to previously available normative RECD values for infants and young children, however, the estimates derived through this study provide somewhat more accurate predicted values for use under those circumstances for which individual RECD measurements cannot be made.

Sign in / Sign up

Export Citation Format

Share Document