VET380 Lecture Notes - Lecture 2: Calorimeter, Exercise Intensity, Great Dane
Energy
Role of energy
Energy is the primary “nutrient” that is the essential dirver of maintenance, growth
and production in all animals
Its not actually a nutrient, but is the ability to do work.
Calorie vs. Joule vs. Kilojoule
Calorie = amount of heat needed to raise the temperature of 1g of H2O from 14.5 C
to 15.5 C.
o1 calorie = 4.184 joules
Joule = metric unit to describe the energy yield from combustion.
o1 joule = 0.239 calories
Kilojoule = 1000 joules.
Systems used to describe energy
Gross energy (GE) – total energy content of feed
Measured by complete combustion of food in a bomb calorimeter
Digestible energy (DE) – amount of energy absorbed from the GIT and available for use
Only PARTIALLY accounts for energy losses that occur during nutrient utilisation
DE = GE – faecal energy
Apparent DE = no corrections have been made for endogenous contributions to
faecal energy
oApparent DE = GE – FE
True DE = accounts for endogenous contributions (not from diet) from GIT, bacteria,
protozoa etc.
oTrue DE = GE – (FE – endogenous FE)
Metabolizable energy (ME) – amount of chemical energy available for use by cells
ME = DE – energy lost in urine and gasses
Measuring energy lost in urine + gasses is difficult, so conversion formulae are often
used
oSubject to error
oDifferent conversion factors for different species
find more resources at oneclass.com
find more resources at oneclass.com
Net energy (NE) – true amount of energy available for maintenance, work and production
NE = ME – Heat increment
Difficult to measure directly
oPredicted values are used so subject to error
Heat increment (energy lost through heat) has 4 sources:
1. Heat of digestion
2. Heat of fermentation
3. Heat of waste product formation
4. Heat of nutrient metabolism
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Energy is the primary nutrient that is the essential dirver of maintenance, growth and production in all animals. Its not actually a nutrient, but is the ability to do work. Calorie = amount of heat needed to raise the temperature of 1g of h2o from 14. 5 c to 15. 5 c: 1 calorie = 4. 184 joules. Joule = metric unit to describe the energy yield from combustion: 1 joule = 0. 239 calories. Gross energy (ge) total energy content of feed. Measured by complete combustion of food in a bomb calorimeter. Digestible energy (de) amount of energy absorbed from the git and available for use. Only partially accounts for energy losses that occur during nutrient utilisation. Apparent de = no corrections have been made for endogenous contributions to faecal energy: apparent de = ge fe. True de = accounts for endogenous contributions (not from diet) from git, bacteria, protozoa etc: true de = ge (fe endogenous fe)
