Lecture 2 - Energy Requirements

Question 1

The property of matter and radiation which is manifested as a capacity to perform work (such as causing motion or interaction between molecules)

Answer 1

Energy

Question 2

What is the first law of thermodynamics?

Answer 2

Energy can neither be created nor destroyed, only transferred or changed from one form to another

Question 3

How is energy stored and released?

Answer 3

Energy is stored in chemical bonds between atoms and released with oxidation reactions in cells

Question 4

What is glycolysis?

Answer 4

An ATP-producing pathway that occurs in almost all cells

Question 5

What happens to pyruvates produced by glycolysis?

Answer 5

They become Acetyl CoA, which plays an important role in the Kreb’s cycle (TCA cycle)

Question 6

How does the body utilize excess acetyl CoA from increased glucose or carbohydrate ingestion, and what impact does this ultimately have on the body?

Answer 6

It is used for fatty acid synthesis/lipogenesis, and this can lead to adiposity (fat tissue accumulation)

Question 7

Why is energy required by animals (5 reasons)?

Answer 7

Basic metabolism, thermoregulation, activity, growth (young animals), and reproduction

Question 8

The energy in food if you were to burn it in a bomb calorimeter

Answer 8

Gross energy (GE)

Question 9

The energy that is available for use after metabolic costs (digestion, gas, urine production, etc.) are subtracted

Answer 9

Metabolizable energy

Question 10

The amount of energy required to heat 1 gram of water by 1 degree Celsius

Answer 10

Calories

Question 11

What is the numerical value for Calories (capital “C”) listed on foods?

Answer 11

1000 calories, kcal, or kilocalories

(Also, 1000 kcal = 1 megacalorie or Mcal)

Question 12

The standard international unit for energy (SI), equivalent to one watt of power radiated or dissipated for one second

Answer 12

Joule

(Remember: 4.184 joules = 1 calorie)

Question 13

What are resting energy requirements?

Answer 13

The energy intake required to maintain an animal in complete rest (solely for respiration, basic metabolism, and cell function)

Question 14

What is the equation for Kleiber’s Law (to calculate resting energy requirements (RER) in kcal)?

Answer 14

BW(in kg)^0.75 x 70

Can also use (BW(in kg) x 30) +70, but other equation is generally preferred

Question 15

How are metabolic/daily energy requirements calculated?

Answer 15

RER is multiplied by a factor according to:
- Life stage, body condition, neuter status (MER factors)
- Work (DER factor)

Question 16

What are some variables that affect energy requirements in bovine and other production animals?

Answer 16

Maintenance, lactation, growth, and reproduction

Question 17

What is the rate of metabolism primarily determined by?

Answer 17

The rate of heat loss from the body into the environment

Question 18

True or False: Smaller size = higher metabolic rate requirement

Answer 18

True

Question 19

Weight gain, hyperlipidemia, hepatic disease, pancreatitis, and lipoma/xanthoma are all negative impacts on the body caused by energy ___________.

Answer 19

Excess

Question 20

Weight loss, loss of internal organ mass, decline in healing/immune function, and a shift to using protein/fat stores for energy are all negative impacts on the body caused by energy ___________.

Answer 20

Deficiency

Question 21

Which two age groups (generally) have the highest risk of being underweight?

Answer 21

Young animals and senior animals

Question 22

What are some consequences young animals can face when they are underweight?

Answer 22

• Higher susceptibility to disease and poor response to treatment if nutritional needs remain neglected
• Poor hair-coat and stunted growth

Question 23

True or False: Underweight young animals often respond well to supportive care and proper feeding

Answer 23

True

Question 24

When an older animal is underweight, what are two important chronic medical concerns to rule out?

Answer 24

Cancer and metabolic disease

Question 25

What are other possible reasons for an older animal to be underweight, once chronic medical problems are ruled out?

Answer 25

Decreased appetite with aging and decreased sense acuity

Question 26

How is gross energy measured?

Answer 26

Bomb calorimeter

Question 27

What is the biggest drawback to a gross energy (GE) calculation using a bomb calorimeter?

Answer 27

The value tells us nothing about how well or poorly the feedstuff can by used by the animal’s body

Question 28

Why is digestion not 100% efficient for extracting energy for the body?

Answer 28

There will always be losses in heat production, stool, urine, and gas

Question 29

When does most energy loss occur, and why?

Answer 29

During protein digestion because the body cannot oxidize the nitrogen component

Question 30

What must happen to nitrogen in order for it to be excreted from the body?

Answer 30

It must be combined with hydrogen to form urea, which is excreted in urine (loss of hydrogen in this process = energy loss)

Question 31

What are averaged Atwater factors?

Answer 31

An approximation of the number of kcal (ME) produced by a gram of protein, fat, and carbohydrate

Question 32

What are the three Standard Atwater Factors (numerical values)?

Answer 32

Protein (1g) = 4 kcal ME
Fat (1g) = 9 kcal ME
Carbohydrate = 4 kcal ME