Lecture Two Flashcards
Define the term calorie:
amount of heat needed raise 1 g H20 from 14.5 to 15.5
Define the term joule:
metric unit energy yield from combustion
What is gross energy and how is it measured?
The total energy content of feed and it is measured using a bomb calorimeter.
What is meant by the term digestable energy? and how is it calculated?
Amount of energy that is absorbed from the GIT. DE = GE - faecal energy
What is meant by the term metabolisable energy? and how is it calculated?
Amount of chemical energy available for use by cells. ME = DE – energy lost in urine and gasses
What is meant by the term net energy? and how is the value calculated?
Net energy represents the true amount of energy available for work. NE = ME – heat increment (the heat produced from digestion + absorption
What is the difference between “true” and “apparent” digestible energy?
Apparent- no corrections have been made for endogenous contributions to faecal energy (DE = GE – FE)
True- accounts for endogenous contributions (not from diet) from GIT, bacteria, protozoa (DE = GE – (FE- FE endogenous )
What are the losses that are associated with the heat increment?
- Heat of digestion- chemical reactions in digestive tract
- Heat of Fermentation- chemical reactions of bacteria in digestive tract.
- Heat of waste product formation- given of from waste product production (e.g. urea)
- Heat of nutrient metabolism- all other sources
What is the approximate Atwater modified contents of Carbohydrate, Protein and Fat? (in kcal/gram)
Carbohydrate and Protein = about 3-4
Fat = double (at about 8-9)
What are the factors that contribute to maintenance energy requirements?
- Basal Metabolism
- Muscular Work
- Temperature Regulation
