Energy

Gross energy (GE)

…. is total energy content in a dietary source

complete oxidation

Gross energy in feedstuffs is measured by the …. of the feedstuff by combustion

bomb calorimeter

A …. is used for measuring GE

nutrient composition

Gross energy in feedstuffs varies depending on ….

Carbohydrates

…. contain 4.10 kcal/g and proteins contain 5.65 kcal/g.

Lipids

… contain 9.45 kcal/g

available

GE does not provide nutritionally meaningful values because not all energy will be …. to animals for utilization

limited portion of cellulose

For example, starch and cellulose have the same GE even though only a …. can be used by microorganisms in animal’s gastrointestinal tract.

Digestible energy (DE)

…. is the energy content in a dietary source that is digested

DE = IE − FE

Digestible energy is obtained by subtracting the energy lost in feces (FE) from the intake of feed GE (IE=intake energy):

animal trials

Digestible energy in feedstuffs is measured from ….

crate

Briefly, an animal is temporarily housed in a …. individually

entire fecal sample

A known amount of feed will be provided and the …. will be collected

IE − FE

Gross energy in the feed and feces will be measured by combustion to obtain IE and FE. Now, DE can be calculated by ….

animal species

Digestible energy in feedstuffs varies depending on ….. and diet

Birds

…. excrete a combination of urine and feces and therefore the feces cannot be separated to determine DE.

Metabolizable energy (ME)

…. is the amount of energy in feedstuffs that can be retained in an animal body

heat increment

However, not all ME will be retained in the body because energy spent for …. during digestion and metabolism is a part of ME which would not be retained

accurate energy value

Metabolizable energy provides a more …. than DE in feeding animals

formulating

Metabolizable energy is, therefore, widely used in …. animal diets

ME = DE − (UE + GasE) = (IE − FE) − (UE + GasE)

Metabolizable energy is obtained by subtracting energy loss in urine (UE) and combustible gases (GasE) from DE:

measured

Metabolizable energy in feedstuffs is also …. from animal trials

separated urine collection

It is similar to what is described in DE, but …. is required when fecal sample is collected

carnivores and omnivores

For …, gaseous energy is usually ignored because the amount is relatively small

methane

Herbivores have significant fermentation that produces …. For herbivores collection of gas is needed to measure ME. Metabolizable energy in feedstuffs varies depending on animal species.

horses

Note that there are no ME values for ….

Energy values

…. are obtained from animal trials.

small number of trials

Only a …. have been conducted with horses to obtain these values and therefore, they are not available.

Net energy (NE)

… is the amount of energy in feedstuffs that is retained in an animal body.

heat increment (or heat production)

It does not include energy spent for …. associated with nutrient digestion and metabolism above the heat production prior to feed ingestion

NE = ME − HI − HF = (IE − FE − UE − GasE) − HI − HF

Net energy is obtained by subtracting energy spent for the heat increment (HI) and the heat of fermentation (HF) from ME:

NE

Thus, …. in a feedstuff is the portion of energy that is available to the animal for maintenance (NE_m) and various productive purposes (NE_p)

maintenance

Examples of energy used for …. (NE_m) are energy used for basal metabolism, voluntary activity, product formation, thermal regulation, and waste formation and excretion

Energy for basal metabolism

…. is defined as the minimal amount of energy that is expended to sustain the body in the post-absorptive state, state of muscular repose, and thermo-neutral environment.

NE_p

Examples of energy used for production (…..) are tissue energy, energy in milk, energy in the fetus and associated tissues, energy in eggs, energy in wool, hair and feathers, and energy to do work.

Measurement of total heat production

….. is an essential step for determining NE of feedstuffs

calorimetry

Heat production is measured by …. or comparative slaughter

calorimetry method

A …. measures NE by measuring ME intake and determining heat from gas exchange

comparative slaughter method

A …. directly measures NE_p in growing animals by determining ME intake and changes in body energy content over a time period allowing accumulation of body energy

destructive

However, both methods require expensive, laborious, and … processes

prior

Accurate measurements of NE in various feedstuffs for different animal species need to be done …. to the application of NE in feeding animals.

Energy partition

This scheme is the basis for animal feeding systems

energy content

When formulating diets for animals, …. is the first consideration

basis

Depending on the species DE, ME, or NE will be the …. of the requirements.