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
What is conversion efficiency factor?
- What would a big K factor mean?
- What would a small K factor mean?
- How would you calculate the conversion efficiency of energy (k factor)?
it represents how efficiently energy is used
little heat energy was lost during digestion and metabolism
lots of heat energy was lost during digestion and metabolism
NE/ME
k Factor: What is k suffixed with and for what? (5)
m for maintenance
l for lactation
g for growth
p for pregnancy
What is meant by ‘heat increment’?
- State example of processes which cost energy and increase the heat increment
the difference between metabolisable energy and net energy
chewing
rumination
other digestive motor activity
production and secretion of digestive juices
hydrolysis and metabolism of nutrients in the lumen
active transport across the wall of the GIT
metabolism of absorbed nutrients and synthesis of macromolecules in tissues including liver
Why is the k factor not a constant? (compare km and kp)
because a lot more energy
What factors affect k? (2)
- explain what effect each factor has on k
increase in feed quality (q) increases the value of k - fibrous feed decreases k as it is more difficult to digest so the animal must work harder to extract the energy so more energy is used to access the available energy
increase in level in production decreases the value of k - this is because more food must be eaton to sustain the increase in production, so gut transit time decreases and less time is available to extract the nutrients
What is q?
- how can you calculate q?
diet quality or metabolisability
the proportion of GE that is metabolisable
ME/GE
What happens to the value of K as the value of q (metabolisability of the diet) increases?
the value of k increases as q increases
What does APL stand for?
- What does it mean?
animal production level
how hard an animal is working above maintenance requirements
Define metabolic rate
the expenditure of energy per given time
Describe what happens when protein enters the rumen (up until the proteins are broken down into amino acids) (5)
some proteins cannot be degraded by the bugs in the rumen
this proteins passes through the abomasum where it is digested
some proteins can be degraded in the rumen
these proteins are broken down by bugs to peptides
the peptides are broken down into amino acids
Describe what happens to amino acids in the rumen (up until fermentable metabolic energy obtained)
the amino acids need to be converted into microbial proteins
some amino acids will be directly converted into microbial protein
some amino acids will be converted into ammonia, which can also be converted into microbial protein
however this process requires energy
the energy for these processes is fermentable metabolic energy, which is energy available in the rumen from rapidly fermentable sources like sugars and starches.
Why might ammonia not be converted into microbial protein in the rumen?
- describe the fate of the ammonia if this is the case (5)
if there is not enough fermentable metabolic energy in the rumen
or if the ammonia is in close proximity to the rumen wall
the ammonia is absorbed into the blood stream
the ammonia will be processed by the liver into urea and excreted by the kidneys in urine
some urea will be taken up by the salivary glands, secreted in saliva and go to the rumen with the dietary intake.
the urea can then be converted into ammonia
the ammonia can be processed into microbial protein if sufficient fermentable metabolic energy is available
Rumen Degradable proteins can be split into 2 groups - quickly degradable and slowly degradable.
- What is a quickly degradable protein?
- Give examples of quickly degradable proteins
- What is a slowly degradable protein?
a protein that can be used straight away
amino acids
ammonia
urea
a protein that requires fermentation by rumen microbes to be broken down
What is the amount of rumen undegraded protein depend on? (2) - describe each
rumen outflow rate which is proportional to the animal production level
the protein source as some proteins are more resistant to digestion
The rumen undegradable protein is ends up in the abomasum
- What 2 things can this protein be split into?
- what is the fate of the digestible undegradable protein?
- what is the fate of the acid detergent insoluble nitrogen?
digestible undegradable protein
acid detergent insoluble nitrogen
it is metabolisable protein and can be used as energy for metabolic processes
it has no nutritional value and is excreted in the faeces
Which 2 elements make up metabolisable protein?
- How can you calculate Metabolisable protein? (MP)
- Why do we multiply MCP by 0.64?
microbial crude protein
digestible undegradable protein
digestible undegradable protein + (microbial crude protein x 0.64)
MCP is not 100% efficient so only 64% of it can actually be used as metabolisable protein
State the 4 things metabolisable energy can be used for
maintenance
lactation
pregnancy
growth
How much nitrogen does typical protein contain (%)?
- How can we calculate crude protein?
- What is the general value of the conversion factor?
- Why does the conversion factor differ between different feedstuffs?
- why is measuring crude protein this way not measuring ‘True protein’?
16
16 x conversion factor
6.25
because different proteins contain slightly different amounts of nitrogen
because this method also measures the nitrogen in other non protein substances such as glycolipids and nucleic acids
State the names of substances that when digested in the rumen, are 100% utilisable in the Intestines (in order of quickest degraded in the rumen to slowest) (3)
globulin
albumins
glutelins
State the names of substances that are take a long time to be degraded in the rumen and are only 80% digestible in the intestines (3)
prolamins
cell wall proteins
denatured proteins
State the names of 2 substances that are not degradable in the rumen or digestible in the intestines
maillard products
lignin
In pigs, what do ideal proteins contain? (2)
- why are these amino acids essential?
- along with these 2, which extra amino acid is limiting in poultry?
- How can we use this information clinically?
lysine or methionine
because they cannot be synthesised by the body so are limiting
tryptophan
we can measure the amount of these amino acids to assess protein quality as all amino acids are maintained in the same proportion to lysine
What is colostrum?
- What does it contain high levels of? (4)
the first milk produced after parturition
immunoglobulins
immune cells
fat
sugars
Why is Colostrum so immunologically important for farm animals? (3)
because these neonates can only obtain maternal immunoglobulins via colostrum so are hypogammaglobulinemic
so they are immunologically naive
increased susceptibility to disease
For Rabbits and monkeys, how do they obtain maternal IgG?
- what about for dogs, cats and most domestic species?
- what about for farm animal/large animal species?
all maternal IgG is transferred across the placenta
maternal IgG is transferred through the placenta and via colostrum
all maternal IgG is transferred via colostrum
Why else is colostrum important for certain farm animal neonates? (use pigs as an example)
to protect against hypothermia as some neonates have only a small amount of adipose tissue and cannot properly thermoregulate
State 3 general broad reasons why colostrum is important to neonates and explain them
immunity - contains immunoglobulins and other immune cells to reduce the risk of infection and mortality rates
nutrition - contains higher fat, protein, mineral and growth factor than normal dam milk
gut health - introduces gut friendly microbes to stimulate the neonates immature digestive system
Colostrum Antibodies: State the 3 types of immunoglobulins found in colostrum
- By percentage, which immunoglobulin is most prevalent in the colostrum?
- Describe the role of IgG in a neonate (2)
IgG
IgA
IgM
IgG at about 90%
it is the only immunoglobulin that can cross the placental barrier in species where transplacental immunity occurs
it is absorbed across the gastrointestinal tract to provide systematic protection
By percentage, what proportion of all immunoglobulins does IgA take up in colostrum?
- Describe the role of IgA in a neonate
5%
it provides mucosal protection by preventing pathogen attachment and prevents pathogens penetrating epithelial cells
By percentage, what proportion of all immunoglobulins does IgM take up in colostrum?
- Describe the role of IgM in a neonate (2)
7%
it is the first antibody to interact with pathogens
it causes agglutination of bacteria when it binds to their surface epitope
By which process is colostral IgG absorbed?
- Describe this process
pinocytosis
cells engulf the antibody form the intestinal lumen and transfer then across the gastrointestinal tract into the lymphoreticular system
Once absorbed and in the lymphoreticular system, what happens to the IgG?
- State the names of the 2 isoforms of IgG
- What does each do?
it enters the blood stream intact and remains in circulation
IgG1
IgG2
IgG1 is re secreted back into the gastrointestinal lumen
IgG2 remains in circulation
Are the pinocytotic cells everlasting?
- When do they fully stop absorbing IgG?
no they have a short life span
24 hours of age
What happens to the colostrum levels of IgG over the first 24 hours after birth?
- What is the legal requirement associated with colostrum feeding?
- Describe the absorption of IgG at 6 hours post birth
they exponentially decrease
must have been fed colostrum by 6 hours of age
the ability for the neonate the absorb IgG through the gastrointestinal tract has reduced to about 30%
What is passive transfer?
the process by which a neonate acquires immunity via absorption of immunoglobulins
When can a neonate be classified as having ‘ Successful passive transfer’ of maternal antibodies?
- what about ‘failure of passive transfer’ of maternal antibodies?
when the neonate consumes an adequate amount of immunoglobulins
when the neonate is deprived of adequate colostrum
State the 5 Q’s of colostrum and briefly explain each
quality - colostrum must contain at least 50g IgG per litre
quantity - colostrum must contain at least 150g IgG per sachet if using a colostrum replacer
quickly - colostrum should be ideally given within 2 hours of birth and legally by 6 hours
quite clean - colostrum must have less than 100,000 colony forming bacteria per ml
quantify - neonate should have at least 10g IgG per litre in serum after 24 hours
Why is it important for colostrum to be ‘Quite Clean)? (3)
some bacteria can multiply very quickly
bacteria may bind to the IgG, preventing the IgG from binding to intestinal cells, preventing absorption of IgG
some unbound bacteria may be absorbed alongside the IgG and become systematic
What is the best source of colostrum?
- What other sources of colostrum are available? (List in order from best alternative to worst) (4)
dam
fresh colostrum from a different dam in the same holding
stored colostrum
colostrum replacer not supplement
colostrum from a different animal species
Why is fresh colostrum from a different dam a good alternative to dam colostrum?
- Which 2 ways can colostrum be stored?
- Do all colostrum replacers contain IgG?
- What is the biggest risk in giving a lamb bovine colostrum?
because the dam is likely to have the same disease status and vaccination history as the original dam
refrigerated
frozen
no
it could cause haemolytic anaemia in lambs
Delivering Colostrum: Is solely leaving the neonate with the dam enough for some species? (use an example) (2)
- What temperature should colostrum be fed at?
- Should colostrum be bucket fed or bottle fed and why?
no, calves are 2.4 times more likely to receive insufficient antibodies if left to suckle the dam
it takes a calf at least 20 minutes of constant sucking to obtain a sufficient volume of colostrum
body temperature so 38 degrees
bottle feeding because we want the suckle reflex to stimulate the opening of the oesophageal groove to divert the colostrum into the abomasum instead of the rumen
Why is it important that the colostrum is diverted into the abomasum instead of the rumen?
- should you stomach tube the colostrum?
in the rumen it will be fermented to form volatile fatty acids and can cause luminal acidosis
only if the lamb shows no willingness to suckle
Why is it bad to pool colostrum when storing it?
because you don’t want to dilute really good colostrum
Storing colostrum: at what temperature should you refrigerate colostrum?
- How long does it last in the fridge?
- At what temperature should you freeze colostrum?
- At what temperature should you defrost colostrum?
- How long can you store frozen colostrum for?
4 degrees
ideally 24 hours but no more than 48 hours
-18 degrees
less than 50 degrees
ideally 6 months but no more than 1 year
How do you pasteurise colostrum?
- why is pasteurisation important?
- Give one limitation of pasteurisation
treat it at 60 degrees for 30-60 minutes
bacteria can double every 20 minutes at room temperature and can interfere with IgG absorption
it will not eliminate MAP which causes Johnes disease
Give advantages of Passive Transfer occurring (5)
reduced pre weaning and post weaning mortality due to infectious disease
increases daily live weight gain
better feed efficiency conversion
breeding animals have better fertility
dairy cows, goats and sheep have increased milk production in the first and second lactation
What are the implications of Failure of Passive Transfer? (3)
- Which diseases in particular is the young animal more at risk of? (2)
increased risk of disease
increased risk of pre weaning and post weaning mortality
stunted growth and development
neonatal scours
sepsis
State 2 different instruments we can use to measure colostrum quality
colostrometer
brix refractometer
How does a Colostrometer work when measuring colostrum quality?
- What conditions are required for accurate readings?
- What is deemed as good quality colostrum?
- What is deemed as poor quality colostrum to be discarded?
it uses specific gravity which can be directly related to IgG content
colostrum must be at 22 degrees
no froth on top of the colostrum
more than 50mg per ml
less than 20mg per ml
How can we measure colostral antibody transfer in a neonate?
- What reading would suggest PT?
- What reading would suggest FPT?
- When can you perform this test and why?
- What piece of kit has been developed to perform this test in foals?
using a brix refractometer to measure the protein fraction from a neonates serum sample
more than 10 grams per litre
less than 10 grams per litre
24 hours after colostrum ingestion
foal IgG snap tests
