Animal Energetics 2 Flashcards
Why is BMR not constant?
Because the body composition changes over the year- there is phenotypic variability within animals
Why measure field metabolism?
To look at the energy fluxes between an animal and it’s environment
To estimate the energy required for various behaviours
To estimate the actual food consumption of individual animals
To estimate food requirements of populations
How do you measure an animals metabolism in the lab?
Food intake
Calorimetry
Respirometry
How do you measure an animals metabolism in the wild?
Time energy budget
Doubly labelled water
Heart rate
Accelerometry
How do you measure time energy budget?
Continuously record the animals behaviour
Measure how long the animal spent performing each behaviour
Assign energy values to each behaviour
Calculate the overall energy expenditure
What are the pros of time energy budget?
It’s technically easy
What are the cons of time energy budget?
The metabolic rate of individual behaviours has to be known
It’s difficult to use accurately as other factors will affect MR
Need to conform to standard operative temperature
It can be labour intensive
What is doubly labelled water?
Inject with water labelled O18 and deuterium, which is a heavy isotope of oxygen- this then disperses around the body
The rate at which O18 is lost compared to deuterium indicates the amount of carbon dioxide being lost
Can then measure the energy expenditure of the animal
Give a summary of the field technique used in doubly labelled water
Catch the animal
Inject the animal with labelled water and deuterium
Allow injectate to equilibriate with body water
Take a sample and release the animal
Recapture after a specified interval
Take a final body water sample
Analyse water samples using a mass spectrometer
What are the potential drawbacks of doubly labelled water?
Only estimates the mean energy expenditure over the measuring period
Can’t measure over short time resolution
Reduced precision in very active animals
There can be problems trying to convert CO2 production to estimates of energy expenditure
What principle is heart rate based on?
The fick principle and the amount of oxygen the animal uses
How can heart rate be measured?
Animals can be put in a treadmill to measure heart rate and oxygen consumption over a period of time
