Biological Energetics Flashcards

1
Q

What is the estimation of apparent energy with high fat and high starch?

A

Usually underestimate the apparent digestible energy

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2
Q

What is the estimation of apparent energy with high protein and fiber?

A

Tends to overestimate the apparent digestible energy

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3
Q

Net energy

A

Recognized as the closest estimate of true energy values because it takes the heat increment from digestive process and metabolism of feeds into account

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4
Q

Metabolizable energy

A

The energy absorbed by the animal from feed that remains in the animal for metabolism
*accounts for the energy that is absorbed and loss

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5
Q

What are the losses that metabolizable energy accounts for?

A

-urinary energy (urea, uric acid)

-gaseous energy (methane, hydrogen, hydrogen sulfide, carbon monoxide)

-gill energy (ammonia)

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6
Q

Metabolizable energy eqn

A

ME= DE- (urinary E + Gaseous E + Gil E)

*Remember: DE accounts for fecal energy loss

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7
Q

Which animals is ME widely used for?

A

-poultry, dog, cats

**important because of the energy intensive process of urea and uric acid
AND the high protein diets of dogs and cats

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8
Q

Excretion of nitrogenous wastes by birds

A

Nitrogenous waste excreted as uric acid in birds
-excreted directly into the cloaca and mixed with feces therefore cannot be separated

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9
Q

Heat increment

A

Accounts for the energy lost as heat during digestion and metabolism
-includes heat produced/energy used during digestion of feed, metabolism of nutrients and excretion of waste

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10
Q

Components of heat increment

A

-work of digestion
-heat of fermentation
-nutrient metabolism

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11
Q

What are the two ways that heat increment can be measured?

A
  1. direct calorimetry
  2. indirect calorimetry
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12
Q

Direct calorimetry

A

Heat production measured directly
-animal in chamber measuring heat

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13
Q

Indirect calorimetry

A

Use gaseous exchange (O2 consumption, CO2 output) to estimate heat loss
-animal in chamber measuring the gases

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14
Q

How can you take into account what heat is coming from basal metabolism and what is the actual heat increment?

A

Measure the animals heat in a chamber after fasting (basal metabolism) and after being fed (heat increment) and then calculate the difference

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15
Q

Heat increment eqn

A

= Total heat production fed- total heat production fasting

HI= ME- NE

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16
Q

Advantages to net energy

A

-takes account of the metabolic cost of nutrient metabolism

-allows for a better prediction of animal performance based on diet formulation

17
Q

Disadvantages of net energy

A

-expensive and time consuming to measure NE

18
Q

Two components of net energy

A
  1. Maintenance component
  2. Production component
19
Q

Maintenance component of net energy

A

-basal metabolism
-thermoregulation
-voluntary activity associated with maintenance

20
Q

Production component of Net energy

A

-growth
-fat deposition
-offspring
-milk
-eggs
etc!

21
Q

How to measure Growth energy?

A

Measure the increase in the energy contained in the animals body

22
Q

How to measure the Milk energy?

A

Measure the energy content of the milk

23
Q

How to measure Egg energy?

A

Measure the energy content of the egg

24
Q

Energy systems used in pigs

A

-DE commonly used
-urine, gaseous losses are low

25
Q

Energy system used in aquaculture

A

-DE
-protein metabolism is very efficient

26
Q

Energy system used in poultry

A

-ME commonly used
-fecal and urine are excreted together

27
Q

Energy system used in ruminants

A

NE used
-gaseous losses, HI is large