Metabolism calculators

metabolism = a M^{b}
(where a is the mass coefficient, M is mass, and b is the mass exponent)
This example shows an estimate of the resting metabolic rate (RMR) of
a 37.3 g bird, in units of ml O_{2}/min.
The equation was derived from a paper published by Andrew Mckechnie and
Blair Wolf (Click here for a list of the references from which allometric equations were obtained.).
Note that the mass coefficient ('a' value)
and mass exponent are shown and can be edited, and that mass can be in either grams or kilograms. Also, it is possible
to make corrections for the effect of body temperature by making the appropriate
adjustments to the value of T_{b} and
Q10 (in this example, the 'base' T_{b},
from which the equation was derived, is equal to the current T_{b}
so no temperature correction occurs). After changing values in the
edit fields, click the 'Compute' button to display the new results.
The 'Store' button 'remembers' the computed metabolism for later use (for example in other calculators). The 'Save' button, if present, lets you save the current mass coefficient and mass exponent values for future use, accessed as 'Custom coefficent and exponent' option in the Taxon popup. The 'Save' button is accessible only if the units are set to ml O2/min. NOTE: you will have to click the 'Save Current Preferences' button in the Preferences window if you want to have your custom values available the next time you run the program.
You can also adjust the activity intensity for the animal, ranging from inactive (minimal metabolism; MMR) to average daily metabolism (3 X MMR)to very vigorous activity  up to 100X MMR, which is reasonable for some large flying insects.
This window calculates the washout rates of theoretical perfectlymixed chambers as a function of volume and flow rate. The computed value is the time for X% of intial gas volume to be replaced  akin to the 'halflife' concept for radioactive decay and related phenomena. back to top
To support these calculations  which are largely based on the small pressure fluctuations induced by the warming and wetting of tidal air  you need to provide a number of variables. Several of these are selfexplanatory (at least if you know something about respiratory physiology). Abbreviations for some of the more obscure ones are:
You can use the 'waveform analysis' routines in the ANALYSIS menu to obtain breathing frequeny, calibration volts, and sample volts from recorded breathing records.
In this fairly typical example, the animal (a mouse) breathed about 6.3
times per second (not unusual for a small mammal in cold conditions) and
had a tidal volume of 0.256 ml and a minute volume of about 97 ml/min. The
oxygen extraction was about 25.7%.
Although there are a lot of data to enter,
the program makes it as easy as possible. Most values are remembered
between successive uses of the calculator, so you only have to change a
few edit fields (like VO_{2}, frequency, and
sample volts). You can tab (or hit return) to move between successive
edit fields.
Important cautions:
 For temperature data, the program's default 'assumption' is that a value of zero = bad data (or no data). If your temperatures include real values of zero, then use .001 (or some other small but nonzero number) instead of zero.
 The program will attempt to find the highest 6 and 12h readings, so the implicit assumption is that your climate data are sampled at least once per hour (higher sampling rates are OK).
For each point in the data file, the necessary metabolic rate is computed according to the following rules:
Note that if you have only one temperature measurement, or if a dayactive species never has access to sunlight (e.g., stays in deep shade), you can select the shade temperature as the sun temperature (in other words, use the shade temperature measurement twice. 
When T_{e} < LCT in the inactive part of the daily cycle, if the animal can use torpor (selected in the 'options' window), one of two calculations are performed:
 if T_{e} is at or above 1 °C less than a minimal (defended) T_{b}, the metabolic rate is reduced from BMR in proportion to how close T_{e} is to minimum T_{b}.
 if T_{e} is lower than 1°C below the minimum T_{b}, metabolic rate is computed as: (minimum T_{b}  T_{e}) * C_{th}
 NOTE: the torpor algorithms do not include the energy cost of warmup.
Flowcharts (decision trees) for calculations of environmental temperature and thermoregulatory costs are at the end of this page.
Program output includes:
 mean metabolic rate (watts)
 factorial increase of mean metabolic rate above BMR
 highest single metabolic rate (watts)
 factorial increase of highest metabolic rate above BMR
 percent of total samples for which metabolic rate = BMR (i.e., T_{e} > LCT)
 mean metabolic rate for all samples where T_{e} < LCT
 factorial increase above BMR for mean metabolic rate for all samples where T_{e} < LCT
 maximum daily average (watts), and expressed as factorial increase above BMR
 maxima over 6 and 12 hours (watts), and expressed as factorial increase above BMR
 mean metabolic rate while in torpor (watts), and expressed as factorial change from BMR
 percent of time spent in torpor
NOTE: For nightime data, if a value for shade temperature is missing, the program will attempt to use the sun temperature value instead. This substitution does not occur for daytime data.
These thermal calculations are performed in one of two ways:
One individual at a time (click the 'compute costs' button): The user enters the animal's thermal parameters in edit fields in the main program window, selects the time, sun, and shade temperature channels, and then starts calculations. Results are shown after all T_{e} data are processed:
Optionally, the computed costs for each entry in the main data file can be saved in a new channel (if the file has < 40 channels).
Multiple individuals (species) in a spreadsheet (click the 'read .csv file and save results' button): The user selects the time and two T_{e} channels (sun and shade) and then opens a spreadsheet file (comma separated variables; .csv) containing a series of thermal parameters for different species, sexes, etc. The maximum number of variables in the .csv spreadsheet is 50. Each row of the spreadsheet (up to 800) contains data for one individual or species. You need to select the columns that contain:
 an indicator (yes, no, y, n, 1, 0) of whether the animal can 'use' sunlight to warm itself. If true, the calculations use the 'sunshine' value in the main data file of temperature data.
 body temperature, in degrees C
 minimum thermal conductance, in watts/degree C (here, degrees C is the gradient between body temperature and environmental temperature).
 the Lower Critical Temperature (LCT) in degrees C.
 Basal Metabolic Rate (BMR); the units are either watts or ml O_{2}/min (selected in the 'options' window).
 an indicator (yes, no, y, n, 1, 0) of whether the animal can use torpor to save energy during the inactive phase (night or day) of its daily cycle.
 the minimum body temperature (T_{b}; degrees C) that the animal will tolerate in torpor. The lowest environmental temperature at which this is achieved without increasing metabolism is assumed to be 1 °C lower than minimum T_{b}. At lower T_{e}, the animal will increase metabolic heat production to maintain T_{b} at the minimum value. The program uses the thermal conductance value (C_{th}) to calculate this metabolic rate.
 an indicator (yes, no, y, n, 1, 0, D, d, N, n) of whether the animal's active phase is during the day (diurnal) or at night (nocturnal). A 'yes' or '1' value or equivalent means the animal is diurnal.
For both methods, the 'options' button opens a window where you can select a number of alternate ways of handling data and calculations, including:
For each spreadsheet entry, the program runs through the T_{e} channels from the main data file. The combined results can be saved, along with the raw data from the 'source' .csv file, in a userselected spreadsheet file. The program always saves a column containing the mean thermoregulatory cost in watts.
Other thermoregulatory data columns to be placed in the spreadsheet are selected from the window at right:
Note that if you elect to NOT allow torpor use, that restriction will apply globally to all entries in a .csv file. If you DO allow torpor use, each entry in a .csv file will indicate whether or not torpor is applicable to that entry. 
Times are computed using the ‘Sunrise equation’; this example shows an annual day length cycle for a tropical latitude (~ 14 ° south).
This flowchart shows how T_{e}, time, and physiological parameters are used to compute thermoregulatory energy costs:
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