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Is energy a nutrient?
Nope a property
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What 3 nutrients have energy?
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Do vitamins and minerals have energy?
No
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Bomb calorimetry measures?
Gross energy of a feedstuff
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Eneergy during bomb calorimetry is obtained via?
Combustion or oxidation of the nutrients containing energy
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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
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What do we do to feed before we burn it in a bomb calorimeter?
Pellet because dusty feed sucks
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Why would we pressurize the bomb with O2
So thatthe feedstuff and not O2 is limiting in the reaction
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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
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how many joules in a calorie?
4.184
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Why a lump of coal has a good GE hwo is its DE?
Extremely low or 0
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Define gross energy?
Amount of heat released when a substance is completely oxidized in a bomb calorimeter
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GE is synonyous with?
HEat of combustion
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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
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What is often the single biggest loss of energy from thje food?
Feces losses
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How do we test energy in the feces?
Bomb calorimeter it
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Formular for DE?
= GE - Feces energy
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Composition of GE that DE takes up in pigs reminants on concentrate and ruminants on roughage
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What does metabolizable energy take into consideration?
- Urinary losses
- Gaseous losses
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What is the main gaseous loss of digestion?
Methane
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Can you combust urine?
Yes
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Where do urine losses come from?>
End products of protein metabolism such as urea and uric acid
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What is the range for urinary energy loss in animals?
2-5%
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Where do most gaseous losses come from?
Bacterial fermentation
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3 main gases lost from metabolism?
- Methane
- Hydrogen sulfide
- Carbon monoxide
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Do monogastrics have high energy loss due to gas?
No not even 1%
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How do you measure gas loss in a cow
Measure gas produced during flatulence and eructation
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What is the usual conversion to go from DE to ME?
ME = DE *0.82
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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%
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What is taken into account to get net energy?
Heat incremenet or the heat loss
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While NE is ideal why isnt it often used?
Super intensive to get data for
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Formula for NE?
= ME - heat incremenet
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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
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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
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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
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What was used prior to the bomb calorimeter to estimate energy content?
Total dirgestible nutrients (TDN) - uses proximate analysis to estimate energy content
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What is the formular for TDN?
= Digestible crude protein + digestible crude fiber + digestible nitrogen free extract +digestible ether extract *2.25
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How is TDN usually expressed?
As a % of the ration
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Does water contribute any TDN?
Nope acts a diluent
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IS TDN general or species specific?
Should be species specific as different animals can access different fractions
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What are 5 factors affecting TDN?
- % dry matter
- Digestibility of dry matter
- Amount of fat
- Amount of ash
- Species fed
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What form of energy does TDN roughly estimate?
DE
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1 kg of TDN is equal to how much DE?
4.4kcal DE
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How does a 76% TDN translate into a tonnage ration feed?
760kg/tonne
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