Zusammenfassung der Ressource
Voluntary
Food Intake
- What is it?
- Factor limiting animal production
- Needs to be predicted in ration formulation
- Controlled by
- Physiological factors
- Important for ruminants
- Low Quality diets = stop eating at gut fill
- AS diet quality increases, intake goes up to an optimum point where
nutritional requirements are satisfied, then DMI is reduced to maintain
nutrient supply
- Physical factors
- Important for pigs & poultry
- Higher quality diet
- Psychological factors
- Physiological Factors
- Hunger
- Controlled by Hypothalmus
- Stimulation
- Thermostatic
- Animal monitors heat
production - eats more when
its cold to raise body
temperature
- Lipostatic
- Brain monitors body
composition and animals
eat to maintain fat levels.
Fat animals eat less. They
want to achieve there
genetically determined
body composition
- Chemostatic (most likely
- Level of circulating nutrients
drop so animals eat. Brain
monitors circulating glucose.
Also monitor VFA's, Minerals,
AA, Vits, Hormones.
- Affected by physiological state
- Pregnant
- Lactating
- Age
- Physical Factors
- Gut Fill
- Depends on
- Gut/Rumen Size
- Animal breed or Size
- Pregnant? -
Foetal mass
constricts
rumen size
- Body Composition -
fat animals eat less
than thin animals
- Rate of Passage
- Effected by chemical
composition and
physical form of diet
- Low RDP = Low microbial activity = Low DMI
- High
starch =
reduced pH
= low
microbial
acivity =
low DMI
- Particle size: chop and
grind = particle size
down = rate of passage
up = DMI up
- Poor quality forage= slow digestion = low DMI
- Add NaOH / NH3 to increase digestibility.
- Good quality forage = quick digestion = high DMI
- Generally,
D Value up
=
digestibility
up (not
linear)
- Psychological
factors
- Appetite
- Smell, taste, site, sound, texture of diet.
- Diet perception effected by: feed, animal and environment
- Prediction
- Difficult!
- Physiological, physical and
psychological components work
together