Nutrition 1 - Week 8 Flashcards
Give the formula to calculate Digestibility (%)
((intake-faecal)/total intake) x 100
If something was 100% digestible, what would this mean?
it would mean that everything that is consumed is utilised and therefore no faeces are produced
State 7 factors affecting Digestibility
food composition
ration composition
preparation
enzyme suplementation
individual variation
species variation
level of feeding
Digestibility: How does Food composition affect Digestibility? (3)
different nutrients have different digestibilities
some nutrients, such as glucose, are highly digestible
some nutrients, such as fibre, are less digestible
Digestibility: How does Ration Composition affect Digestibility?
- Give an example
the digestibility of some feedstuffs can be affected by other dietary components
high starch diets in ruminants decrease rumen PH and may inhibit microorganism fibre digestion
Digestibility: How does Preparation affect Digestibility?
- State 6 examples of different preparations
the preparation of the food can determine how accessible the nutrient is for digestion in the GI tract
rolling, crushing, grinding, alkali, heating, micronisation
Digestibility: How does Enzyme Supplementation affect digestibility?
- For which group of animals is this especially helpful for?
adding enzymes may increase digestibility
non ruminants
Digestibility: How does Individual variation affect Digestibility?
different individuals of the same species may find some feedstuffs more or less digestible than other individuals
Digestibility: How does Species Variation affect Digestibility? (3)
forages have higher digestibility for ruminants than non ruminants
sheep tend to digest grain better than cattle
cattle tend to digest low quality forage better than sheep
Digestibility: How does Level of Feeding affect Digestibility? Use the example of a large volume of food is ingested (4)
- Which type of component will level of feeding affect most severely? Give an example
a larger volume of food is ingested
which increases passage time
and decreases the time for digestive action of enzymes
so lowers the apparent digestibility
slowly digested components like fibre
Why does Grass digestibility decrease as grass grows longer?
- State specific nutrients affected and whether they increase or decrease (6)
because the stems and stalks are longer so the grass contains more structural carbohydrates with a lower digestibility and less storage carbohydrates with a higher digestibility
lignin content increases
cellulose content increases
hemicellulose content increases
sugar content increases
protein content decreases
lipid content decreases
Describe the structure of Lignin
- why is Lignin practically indigestible?
- What does it do to closely associated polysaccharides?
it is a complex cross linked alcohol polymer
because it has high resistance to chemical degradation
it reduces the digestibility of them
State the 3 ways of measuring amounts of different fibres in feedstuffs
natural detergent fibre
acid detergent fibre
modified acid detergent fibre
Fibre Measurement - How does NDF work?
- Which fibres does this method measure the amounts of? (3)
- What other fractions does this method measure from the forage? (4)
boil the feedstuff in sodium laurel sulphate and EDTA
lignin
cellulose
hemicellulose
sugars
lipids
soluble protein
starch
Fibre Measurement - How does ADF work?
- Which fibres does this method measure the amounts of? (2)
reflux the feedstuffs with sulphuric acid and cetyltrimethylammonium bromide
lignin
cellulose
Fibre Measurement - How does MADF work?
it is a modification of ADF with increased acid strength and increased boiling time
State 10 factors controlling food intake
physical
chemical
nervous/hormonal
physiological
palatability
deficiencies
illness
heat
obesity
availability
Food Intake: How do Physical factors affect food intake?
- Give an example of a physical factor affecting food intake
the size of the stomach, rumen or crop can limit the amount of food that can be consumed
the foetus in late pregnancy can restrict the stomach size, especially in sheep
Food Intake: How do Chemical Factors affect food intake? (2)
- Give an example of this in non-ruminants (2)
- Give an example of this in ruminants
different species have different chemicals which induce a feeling of satiation
this will reduce feed intake as the animal feels full and does not want to eat anymore
glucose
cholecystokinin
Why is it important to be able to predict/estimate food intake? (6)
diet formulation
feed availability
feed budgeting
reducing feed wastage
determining stocking densities
conservation management
State 3 different things you could use to predict food intake
animals weight
rules of thumb
nutrient requirement tables
Predicting food intake: How can we predict food intake based on the animals weight?
by using complex equations
Predicting food intake: How can we predict food intake based on rules of thumb? (in g of DM per kg /day) (7)
22 for beef cattle
28 for dairy cattle in early lactation
32 for dairy cattle in peak lactation
15 for dairy cows in dry period
1 for sheep and lambs
3 for sheep in late gestation
2kg dry matter per 100kg body weight for horses
Describe how feeding standards come up with nutrient requirement information
- Have there been many UK requirements?
- Give information surrounding the most recent UK nutrient requirement stands (2)
the findings are usually the output of a committee of experts
no
it was conducted in 2003 and was a nutrient requirement standard for pigs
published by BSAS
What nutrient requirement standards do we tend to rely on in the uk and why?
- what are the requirements usually based off?
- what do they usually contain?
American NRC series of nutrient requirements
because there have been very few conducted in the uk
the need for the majority of the population
an added safety margin
Why do we want to maximise voluntary food intake?
because if we want to maximise production at the minimum cost, we need to get the maximum production from forage so need to optimise feed intake
Optimising VFI: State 9 different ways to optimise voluntary food intake
clean troughs
ensure there is enough trough space
ensure there is always feed in front of stock
ensure there is adequate clean potable water
good quality feed
mixed forages
short chop length
increase palatability
total mixed ration
Optimising VFI: What could count as good quality feed? (2)
feed with no mould or spoilage
feed containing optimum minerals and vitamins
Optimising VFI: Why does mixed forages optimise VFI?
it has been found that providing mixed forages increases intake over a single type
Optimising VFI: How does short chop length optimise VFI?
- why is this a compromise?
a short chop length decreases transit time so the food is processed quicker
because it decreases the digestibility of the feed stuffs so the forage is not being utilised as well
Optimising VFI: How can you increase palatability?
by adding molasses
What 2 components does food consist of?
water
dry matter
What components does dry matter consist of?
- what does the inorganic component consist of?
- what does the organic component consist of? (6)
inorganic and organic components
minerals
carbohydrates
lipids
proteins
nucleic acids
organic acids
vitamins
What is the difference between fresh weight and dry weight?
fresh weight includes the weight of the water
Which of the organic components of dry matter give the animal energy? (4)
carbohydrates
lipids
proteins
organic acids
What is gross energy?
- How is it determined?
- what are its units?
the total energy the feed contains
using bomb calorimetry where the total energy content is converted into heat
MJ/Kg DM
What is digestible energy? (DE)
- how can it be calculated? (in MJ/Kg DM)
- what indigestible compounds often account for a lot of the energy lost in faeces? (2)
it is the energy the rumen microflora and ruminant can access
(GE of foodstuffs - GE of faeces)/ total DM intake per day
lignin
other indigestible compounds
Why is it difficult to calculate Digestible energy for poultry?
- do they have the same problem when calculating ME?
due to cloacal dual voiding where fatal excretion is contaminated with uric acid excretion
no because ME deducts energy from
What is Metabolisable energy?
- which energy losses does DE include that ME doesn’t? (2)
- how would you calculate ME? (MJ/Kg DM)
it is energy available for utilisation by the animal
energy lost in methane
energy lost in urine
(GE of diet - GE faeces - GE urine - GE methane)/ DM intake per day
What is net energy? (NE)
- How does NE differ from ME?
It is the proportion of ME that can be used for maintenance, growth, production of milk, production of wool or growth of a foetus
NE does not include the energy lost as heat during digestion and metabolism