Bioenergetics Flashcards
What is Bioenergetics?
the study of the balance between energy intake and utilization by the animal for different life-sustaining processes (ex. Digestion, lactation, tissue synthesis, biochemical thermodynamics)
Energy intake in the animal is through feed, and energy losses are through different sources such as ________
heat, feces, urine, and other gaseous losses
Studying measurements and patronizing in animals is important for ______
ration formulation and optimizing animal production
________ are the amount of heat needed to raise 1 gram of water 1 degree
calories
how many calories are in a kilocalorie?
1000
how many joules are in one kilocalorie?
4.184 J
What is gross energy (GE)?
The total amount of chemical energy in the diet consumed. It is measured as the amount of heat liberated when a feed sample is completely burned into CO2 and H2O by a bomb calorimeter (the heat of combustion)
True/False: GE does not have much practical value
True; it does not provide much information on the nutritional value of the feed and does not account for palatability, digestibility, or other animal physiological factors
High-protein and high-fat feeds will have ____ energy than high CHO feeds, and feeds with high ash will have _____ energy than lower ash feeds
more; less
What is digestible energy (DE)>
the energy remaining in the diet after fecal energy is subtracted. DE represents the indigestible components of the feed that will be excreted in the feces, however, they still contain energy that was not utilized by the animals
______ of energy is the major source of energy loss to the animal and depends on the nature of the feed
fecal loss
diets containing high ____ may have less digestibility, and fecal loss will be higher than _______ based diets
fiber; starch
in order to measure DE you need to do _______
animal feeding trials
DE is a/n ______ value as the gi tract contributes to extra energy (ex. sloughed off cells, unused enzymes, or other microbial contributions) voided in feces
apparent
DE is most commonly done in which animal?
swine
Digestible Energy (DE)=
gross energy (GE) - fecal energy (FE)
what is metabolizable energy?
the energy remaining after urinary loss and gaseous losses arising from gi tract are subtracted from DE. values obtained reflect losses due to digestion, fermentation, and metabolism of the feed by the animal
ME represents ______ and supports ________
retained energy; tissue maintenance (all organ work) and production
_____ loss is the major one and is the total energy lost in urine. They are usually stable but can increase when high protein in included in the diet. Urine is the end product of _______, which contains energy in different compounds, such as urea.
Urinary; metabolism
Gaseous products of digestion include combustible gases produced by the digestive tract during fermentation of food by microbes including -
methane, CO, Hydrogen
In ruminants __-__% of feed energy is lost from the rumen as methane, whereas losses from gaseous loss are minor and ignored in monogastrics
4-8
ME=
DE-UE-GE
To determine ME, ________ are conducted using live animals
metabolic trials
What is used to assess gaseous losses?
breathing masks or chambers
Diets with ___ protein can increase urea loss and diets with _____ fiber can increase methane and acetate loss
high; high
ME is usually conducted in _______ because urine and feces are voided together, and gaseous loss is negligible
poultry
What is net energy?
ME minus the heat generated by the inefficiency of transforming energy from one form to another
Heat production associated with nutrient digestion, absorption, and metabolism is called the _________
Heat Increment
NE=
ME-HI
Live animals continually produce heat and HI depends on analyzing fasting versus fed animals
HI is therefore all the heat produced by the acts of ______
eating, chewing, digesting the feed, and absorbing the nutrients from the gut
When an animal is fasted, stored nutrients are used instead of absorbed nutrients
HI represents the difference in efficiency of using _______ vs ___________-
absorbed nutrients vs stored nutrients
HI=
heat loss of the eating - heat loss of the fasting animal
T/F: type of feed can affect HI
true
What is NE?
the remainder of the useful energy after all the losses available to the to the animal and could be used for both animal maintenance and production ppurposes
NE represents the fraction of total energy consumed that is utilized for _________ purposes
production
NE=
NE(maintenance) + NE(production)
Why is NE not typically measured?
cost and difficulty of determining NE values
What is daily energy requirement (DER)?
average daily energy requirement
What are the four groups of DER?
resting energy requirement, exercise energy requirement, thermic effect of food, and adaptive thermogenesis
What is resting energy requirement?
the energy needed to maintain normal body functions such as respiration
RER typically accounts for _____ of total DER
60-80%
what is exercise energy requirement?
energy exerted through muscular activity and exercise
exercise energy requirement accounts for roughly _____ of DEr in non-active humans
10-20%
what is thermic effect of food?
energy burned through digestion and absorbtion
what is active thermogenesis?
energy used to stay warm or cool
what disorder is most commonly associated with energy intake?
obesity
what is obesity?
excess dietary energy intake and is more commonly diagnosed in companion animals and equines; can decrease the QOL and length of animal’s life
The _______ the deviation from optimal BCS, the greater the incidence and severity of orthopedic disorders and cardiovascular disease
greater
what affects obesity?
genetics, diet, composition, neutering
what is the main treatment of obesity?
diet management
what is caused by inadequate energy intake?
causes bovine ketosis, ovine/caprine pregnancy toxemia, fat cow syndrome, and fatty liver
