Fibre fractions. Energetic evaluation of feeds Flashcards
What is fibre fractions?
Separation of hemicellulose, cellulose and lignin
How to distinguish fibre fractions?
-
Boiling in neutral detergent solution
-> cell contents dissolve (minerals, CP, EE, soluble CHs, starch, pectin): Neutral detergent fibre (NDF): hemicellulose, cellulose, lignin -
Boiling in acid detergent solution
-> hemicellulose dissolves: acid detergent fibre (ADF): cellulose, lignin -
Treatment in concentrated (72%) H2SO4
-> cellulose dissolves: acid detergent lignin (ADL): lignin
Is CF same as NDF (neutral detergent fibre)? Explain
It’s NOT the same.
NDF > CF !
They are determined by different chemical methods
Energetic evaluation of feeds. What are nutrients required for ?
- for the synthesis of body tissues and animal products
- as a source of energy (for maintenance and production)
—
nutrient ≠ energy, nutrient = source of energy
What is the purpose of determination of energy of feeds
- to express energy requirements of animals
- to express the energy contents of their feeds by the same energy terms
What are energy terms? GE? DE? ME? NEm? NEl? NEg?
- GE: gross energy
- DE: digestible energy (only nutrients the were absorbed from GIT)
- ME: metabolisable energy
- NEm: net energy for maintenance
- NEl: net energy for lactation
- NEg: net energy for gain
Diagram of energy terms
GROSS ENERGY (BRUTTO ENERGY)
— faecal energy loss
DIGESTIBLE ENERGY
— urinary and gaseous (rumen and gut) energy losses urea in mammals and uric acid in birds
METABOLISABLE ENERGY
— heat loss (is different according to way of utilisation: NEm < NEl < NEg)
NET ENERGY
Principles (1,2,3) and practice (4,5) of a modern energy evaluation system
- Energy requirement of animals and energy content of their feeds must be expressed with the same type of energy
- It should be additive (substitution of feeds by each other)
- It should be exact (positive correlation between feed energy term used and animal production)
- Simplicity (of determination)
- Practicability (easy use in the nutrition practice)
How to calculate GE?
Amount of heat arising from the oxidation of the feeds
—
Bomb calorimeter is used
Energy units of measure for monogastric animals and ruminants
Monogastric: MJ/kg of feed
Ruminants: MJ/day
—
1 kJ/g = 1MJ/kg
What energy type is used to express energy requirements and energy content of feed for swine, horse and rabbit?
SWINE, HORSE, RABBIT
—
DIGESTIBLE ENERGY is used. Further losses are not important
—
Gross energy is not used in animal nutrition because too inaccurate, we don’t know what will happen to nutrients in the body
—
Can be different in different countries
What energy type is used to express energy requirements and energy content of feed for poultry?
POULTRY
—
METABOLIZABLE energy
—
Problem is that feces and urine excreted together -> not able to distinguish
—
Same in all countries
What energy type is used to express energy requirements and energy content of feed for dogs and cats?
DOG, CAT
—
METABOLIZABLE energy
—
In dogs in cats ME is used because of urinary energy loss. Carnivores -> high protein consumption -> high urea levels. Especially in cats because in them protein is the main source of energy
—
Same in all countries
What energy type is used to express energy requirements and energy content of feed for fur bred animals?
HERBIVORE FUR BRED ( nutria, chinchilla)
DIGESTIBLE energy
—
CARNIVORE FUR BRED (polecat, mink, fox)
METABOLISABLE energy
—
Can be different in different countries
What energy type is used to express energy requirements and energy content of feed for dairy cows and dairy goats?
DAIRY COWS -> NEl
—
Gaseous losses!
—
Same in all countries
What makes possible to use NEl for both maintenance and lactation in dairy cows?
Graphs for maintenance and milk production are parallel so only one can be used
What is partial transformation factor (“k”)?
k = (NE/ME) x 100
—
70-80% for NEm
60-70% for NEl
30-50% for NEg
