Lecture 2 - Energy Requirements Flashcards
The property of matter and radiation which is manifested as a capacity to perform work (such as causing motion or interaction between molecules)
Energy
What is the first law of thermodynamics?
Energy can neither be created nor destroyed, only transferred or changed from one form to another
How is energy stored and released?
Energy is stored in chemical bonds between atoms and released with oxidation reactions in cells
What is glycolysis?
An ATP-producing pathway that occurs in almost all cells
What happens to pyruvates produced by glycolysis?
They become Acetyl CoA, which plays an important role in the Kreb’s cycle (TCA cycle)
How does the body utilize excess acetyl CoA from increased glucose or carbohydrate ingestion, and what impact does this ultimately have on the body?
It is used for fatty acid synthesis/lipogenesis, and this can lead to adiposity (fat tissue accumulation)
Why is energy required by animals (5 reasons)?
Basic metabolism, thermoregulation, activity, growth (young animals), and reproduction
The energy in food if you were to burn it in a bomb calorimeter
Gross energy (GE)
The energy that is available for use after metabolic costs (digestion, gas, urine production, etc.) are subtracted
Metabolizable energy
The amount of energy required to heat 1 gram of water by 1 degree Celsius
Calories
What is the numerical value for Calories (capital “C”) listed on foods?
1000 calories, kcal, or kilocalories
(Also, 1000 kcal = 1 megacalorie or Mcal)
The standard international unit for energy (SI), equivalent to one watt of power radiated or dissipated for one second
Joule
(Remember: 4.184 joules = 1 calorie)
What are resting energy requirements?
The energy intake required to maintain an animal in complete rest (solely for respiration, basic metabolism, and cell function)
What is the equation for Kleiber’s Law (to calculate resting energy requirements (RER) in kcal)?
BW(in kg)^0.75 x 70
Can also use (BW(in kg) x 30) +70, but other equation is generally preferred
How are metabolic/daily energy requirements calculated?
RER is multiplied by a factor according to:
- Life stage, body condition, neuter status (MER factors)
- Work (DER factor)
What are some variables that affect energy requirements in bovine and other production animals?
Maintenance, lactation, growth, and reproduction
What is the rate of metabolism primarily determined by?
The rate of heat loss from the body into the environment
True or False: Smaller size = higher metabolic rate requirement
True
Weight gain, hyperlipidemia, hepatic disease, pancreatitis, and lipoma/xanthoma are all negative impacts on the body caused by energy ___________.
Excess
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 ___________.
Deficiency
Which two age groups (generally) have the highest risk of being underweight?
Young animals and senior animals
What are some consequences young animals can face when they are underweight?
- Higher susceptibility to disease and poor response to treatment if nutritional needs remain neglected
- Poor hair-coat and stunted growth
True or False: Underweight young animals often respond well to supportive care and proper feeding
True
When an older animal is underweight, what are two important chronic medical concerns to rule out?
Cancer and metabolic disease
What are other possible reasons for an older animal to be underweight, once chronic medical problems are ruled out?
Decreased appetite with aging and decreased sense acuity
How is gross energy measured?
Bomb calorimeter
What is the biggest drawback to a gross energy (GE) calculation using a bomb calorimeter?
The value tells us nothing about how well or poorly the feedstuff can by used by the animal’s body
Why is digestion not 100% efficient for extracting energy for the body?
There will always be losses in heat production, stool, urine, and gas
When does most energy loss occur, and why?
During protein digestion because the body cannot oxidize the nitrogen component
What must happen to nitrogen in order for it to be excreted from the body?
It must be combined with hydrogen to form urea, which is excreted in urine (loss of hydrogen in this process = energy loss)
What are averaged Atwater factors?
An approximation of the number of kcal (ME) produced by a gram of protein, fat, and carbohydrate
What are the three Standard Atwater Factors (numerical values)?
Protein (1g) = 4 kcal ME
Fat (1g) = 9 kcal ME
Carbohydrate = 4 kcal ME
