Nutrition lecture 3 - energy
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Is energy a nutrient?
Nope a property
What 3 nutrients have energy?
Do vitamins and minerals have energy?
Bomb calorimetry measures?
Gross energy of a feedstuff
Eneergy during bomb calorimetry is obtained via?
Combustion or oxidation of the nutrients containing energy
4 parts of a bomb calorimeter?
- Bomb which should be pressurized
- Bucket which contains a known amount of water
- water jacket surrounding bomb which picks up heat produced
- Thermocouples to measure heat
What do we do to feed before we burn it in a bomb calorimeter?
Pellet because dusty feed sucks
Why would we pressurize the bomb with O2
So thatthe feedstuff and not O2 is limiting in the reaction
What are the 3 units of measuring eneergy?
- Calorie - Amount of energy to raise temp of 1 g of water 1 degree celcius
- British thermal unit - amount of energy to raise temp of 1 lb of water 1 degree farenheit
- Joule - Work done by 1 newton exerted over a distance of 1 meter
how many joules in a calorie?
Why a lump of coal has a good GE hwo is its DE?
Extremely low or 0
Define gross energy?
Amount of heat released when a substance is completely oxidized in a bomb calorimeter
GE is synonyous with?
HEat of combustion
Ge while giving us the total energy in the feed it does not tell us?
How much of the energy is accesible or can even be utilized
What is often the single biggest loss of energy from thje food?
How do we test energy in the feces?
Bomb calorimeter it
Formular for DE?
= GE - Feces energy
Composition of GE that DE takes up in pigs reminants on concentrate and ruminants on roughage
What does metabolizable energy take into consideration?
- Urinary losses
- Gaseous losses
What is the main gaseous loss of digestion?
Can you combust urine?
Where do urine losses come from?>
End products of protein metabolism such as urea and uric acid
What is the range for urinary energy loss in animals?
Where do most gaseous losses come from?
3 main gases lost from metabolism?
- Hydrogen sulfide
- Carbon monoxide
Do monogastrics have high energy loss due to gas?
No not even 1%
How do you measure gas loss in a cow
Measure gas produced during flatulence and eructation
What is the usual conversion to go from DE to ME?
ME = DE *0.82
What type of energy do we use to formulate diet in pigs? Poultry? Cows?
- Digestible energy , losses in urine and gas are low
- ME although urinary is small, urine and feces are together....
- ME energy loss of urine and gas is too large to ignore and could be even as high as 10-15%
What is taken into account to get net energy?
Heat incremenet or the heat loss
While NE is ideal why isnt it often used?
Super intensive to get data for
Formula for NE?
= ME - heat incremenet
So define net energy?
The part of the feed that is completely useful to the animal to maintain itself or produce meat milk or eggs
2 componenets of net energy?
- Maintenance component - basal metabolism, heat for body warmth, voluntary maintenance activity
- Production componenet - growth, fat deposition, repro, milk, work, eggs
2 ways to measure heat loss?
- Direct calorimetry - measure heat loss directly, very sophisticated and expensive, very few labs
- Indirect calorimetry - uses gas exchange to estimate. primarily O2 and CO2
What was used prior to the bomb calorimeter to estimate energy content?
Total dirgestible nutrients (TDN) - uses proximate analysis to estimate energy content
What is the formular for TDN?
= Digestible crude protein + digestible crude fiber + digestible nitrogen free extract +digestible ether extract *2.25
How is TDN usually expressed?
As a % of the ration
Does water contribute any TDN?
Nope acts a diluent
IS TDN general or species specific?
Should be species specific as different animals can access different fractions
What are 5 factors affecting TDN?
- % dry matter
- Digestibility of dry matter
- Amount of fat
- Amount of ash
- Species fed
What form of energy does TDN roughly estimate?
1 kg of TDN is equal to how much DE?
How does a 76% TDN translate into a tonnage ration feed?
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