42 terms

Nutrition Lecture 13 Factors Affecting Feed Intake/Consumption

What is voluntary feed intake?
Voluntary feed intake is the amount of feed eaten by an animal when the feed is given to it without restriction
What is the performance of an animal directly dependent on?
the feed intake in terms of quality and quantity
What are the factors affecting feed intake?
animal associated factors
feed associated factors
environmental factors
What are some animal factors that affect feed intake?
physiological status of animal
body weight
fatness of animal
genetic potential of animal
How does the physiological status of an animal affect the animals feed intake?
animal based on energy demand. Animal with high demand for energy will have higher appetite and therefore high VFI.
What are some examples of how the physiological status of an animal affects the feed intake?
A lactating animal has higher demand for energy than a dry animal

Growing animal eats more feed per unit body weight than adult animal.They have "biological urge" to grow that can not be easily impeded.
How does body weight affect feed intake?
Body weight will therefore determine feed intake depending on the lean: fat ratio of the animal body.
What is the relationship between body weight and requirements of energy?
The requirements of energy by adult animal is expressed as Body Weight to the 0.75 power.
How does the fatness of an animal affect the feed intake?
Fatness reduces feed intake in animals because fat animals have physiologically less demand for fattening energy than similar thin animal. (Lean: fat ratio)
Is the intake per unit of metabolic body weight tend to be high in lean or fat animals?
What can excess fat in the abdominal cavity lead to?
Excess fat in the abdominal cavity may reduce the volume into which the rumen or stomach may extend and reduce the bulk of feed intake such as roughage.
Do males or females have faster growth?
Do males or females tend to have a higher feed intake and why?
Males have higher feed intake due to higher physiological energy demand.
What are the effects of pregnancy on feed intake?
Increased demand of nutrients for fetus development increases feed intake.

Towards the end of pregnancy, effective volume of abdomen reduces intake of bulky feed.
What does the genetic potential of an animal affect feed intake?
Animal with higher production potential will have higher physiological demand for nutrient and thus higher feed intake
How do diseases affect feed intake?
Restricted feed consumption due to loss of appetite manifests number of diseases ranging from metabolic , infectious or internal parasites.
Do healthier or sicker animals have a higher appetite?
What are the feed factors that affect feed intake?
feed palatibility
deficiency of nutrients
physical form of feed
digestibility of feed
chemical composition of feed
ratio of concentrate to roughage
What is feed palatibility?
overall acceptance and level of willingness with which an animal eats its feed.
What determines feed palatibility?
Free from contamination
Why is both odor and smell on that previous list?
Look, English isn't his first language
How does nutrient deficiency affect feed intake?
Nutrient inbalance is known to reduce feed intake in animals
What do nutrient deficiencies do to the rumen microbes?
Nutrient deficiencies reduces the activity of rumen microorganism and therefore liable to reduce feed intake
What is the most common nutrient deficiency and how is it corrected?
The most common is protein or nitrogen deficiency which can be corrected with supplementation of rumen degradable protein or urea.
Besides protein, what are some other nutrient deficiencies liable to restrict feed intake in ruminant animals?
vitamin A
vitamin D
vitamin E
In monogastrics, how does concentration of energy correlate with feed intake?
In monogastrics, normally, the higher concentration of energy the lower the feed intake and vice versa.
What can you do to silage to increase intake?
Fine chopping of silage will increase intake
What can you do to low quality roughage to increase intake and why?
Grinding will increase intake of low quality roughage due to increased rate of fermentation and passage
What makes dusty feeds less acceptable?
Dusty feeds are less acceptable than when water is added
Are feeds with low digestibility consumed in smaller or larger quantities and why?
Feeds with low digestibility (e.g. low quality roughage) are consumed in smaller quantities due to their low rate of passage through GIT.
In ruminants, what is the relationship between digestibility of feed and their intake?
In ruminants there is a positive relationship between digestibility of feed and their intake
What chemical composition of feeds determines their rate of digestion?
The chemical component of feeds that determines their rate of digestion is neutral detergent fibre, which itself is a measure of cell wall content.
What substances in feed can depress feed intake?
Presence of toxic substances in the feed such as alkaloids or tannins contribute to depressed feed intake.
What does concentration supplementation do to roughage intake and why?
Concentrate supplementation may reduce roughage intake, due to inhibition of cellulose digestion by rumen microorganisms due to lowered rumen pH common with high concentrate rations.
What are some environmental factors that affect feed intake?
sward density
rainfall and relative humidity
stresses and vices
poor design of feeders
How does sward density affect feed intake?
Animal will consume more DM in a pasture with short dense swards of digestible herbage.
How does temp affect feed intake?
Feed intake decreases at high temperatures and increase at low temperatures
At what temp do certain breeds of cattle cease to eat?
above 40 C
How does relative humidity affect feed intake?
increases heat stress in animals lowering feed intake.
How does rain reduce feed intake?
Grazing animals especially cattle and goats reduce grazing during heavy rains period
What are some stresses and vices that affect feed intake?
Poor health
Gatro-internal parasites such as ascarids, or metabolic ones such as ketosis, bloat.
Excessive handling
How do poorly designed feeders affect feed intake?
Poorly designed feeders/drinkers may add to feed contamination leading to feed rejection