GI - Bovine nutrition Flashcards
What are some examples of forages?
Grass (fresh forage)
Silage
Straw/hay - drying (conserved forage)
What are some examples of supplementary feeds?
High energy foods with lots of protein/starch:
Wheat
Soya
Maize
Gluten
What is NDF content?
Neutral detergent fibre - measure of the fibre in the food
Cell wall content - cellulose, hemicellulose and lignin
What is neutral detergent fibre needed for?
Scratch factor - stimulates rumination and fibre production
What is the difference between straw and wheat?
Same plant - stems vs leaves
When is grass high in fibre/dry matter?
When it goes to seed, later in season
What are the objective of grazing strategies?
Maximise DMI
Minimise damage to pasture - want third eaten, third left and third trampled into ground
What are 5 grazing strategies?
Continuous
Rotational
Strip
Zero - housed
Extended season
What is the difference between hay and haylage?
Hay is more mature grass, left to dry on the ground for longer - higher dry matter/NDF
What is the difference between round bale and clamp?
Round bale - easier production, but less capital (cheaper product)
Clamp - better quality, less energy dense, longer chop length but more spoilage risk
What is maize silage very popular in?
Dairy - higher energy and less protein so increased milk yeild/quality
How is silage made?
Anaerobic conditions allow lactobacilli to produce lactic acid
Drops pH to <4.5 - stops spoilage
What factor can stop pH of silage dropping so low?
Water content - need to wilt first, do on dry windy day in early season (may)
What happens if secondary fermentation occurs?
Air gets in - clostridia produce butyric acid and degrade protein
Rots - decreased palatability, decreased DMI, decreased nutritional content
What can you add to silage?
Acids/acid salts - to decrease pH
Sugars - increase palatability
Inoculants - bacteria to start fermentation
Enzymes - release carbohydrates
What is straw? What are the different kinds?
Stalks of cereal crops
Very high DM, very fibrous, low nutrient density
Barley straw - softer, more palatable
Wheat straw - fibrous, good for bedding, less palatable
Why are supplementary feeds fed?
To make up for deficits in forages
What are straights? What are some examples?
Single product
Primary feeds eg. soyal bean meal, wheat, sugar beet pulp
By products - brewers grains, biscuit waste
What are compounds? How is this different to a premixed blend?
Mixture of straights milled and pelleted
Blend - not pelleted, may or may not be milled
What is the first rate limiting step when feeding cows?
Voluntary feed intake - amount they eat
What factors affect voluntary feed intake?
Size of cow
Yield of cow
BCS - high BCS will eat less
Stage of pregnancy
Palatability
Access
What factors affect palatability of feed, impacting voluntary feed intake?
Quality - high NDF needs longer to digest so lower VFI
Moisture content - lower VFI if too wet or too dry
Taste
Chop length - affects gut transit time
Complete diet/mixed forage - increases VFI
How is voluntary food intake measured?
Dry matter intake basis
What is the rule of thumb formulae for predicting dry matter intake? (MUST REMEMBER)
2.5% body weight + 10% of yield
What are correction factors for DMI?
Multiply the answer by the correction factor to correct for the particular case
eg. if Holstein or if getting complete diet
What is the average daily yield of a dairy cow?
28 litres a day
After voluntary food intake, what is the next rate limiting state when feeding cattle?
Energy (joules)
What are the different sources of energy and protein available to cattle?
Simple carbohydrates
Complex carbohydrates
Fats
Protein
Which forage has the highest energy levels?
Maize silage
How are simple carbohydrates digested? What are they used for?
Rapid fermentation in the rumen
Used for Fermentable Metabolisable Energy - available for use by rumen flora to make protein and nucleic acid
How are complex carbohydrates digested? What do they produce?
Slow fermentation in the rumen
Release volatile fatty acids (VFAs) - absorbed into the blood stream
How are fats digested?
Digested in abomasum and small intestine
What are fats used for in the diet and what are the limitations?
Very high energy density
Used as glue in pelleted feeds
But they can stop the rumen microbes being able to digest the fibre - reduce milk butterfat content
How much fat is restricted to being in a cows diet?
<6% of total diet
What do we want protein to be used for?
Amino acids can be deaminated in the liver to produce glucose
But want them to use protein for growth and calf production instead
What is the gross energy?
Total energy you can get from a product eg. if you burn it
What is the metabolisable energy?
Amount of energy that is left after faecal, urine and methane energy is lost
What are the metabolisable energy requirements of a cow for maintenance? (MUST REMEMBER)
65MJ/day
What is the highest energy demand for?
Lactation
What is the energy demand for lactation? (MUST REMEMBER)
5MJ/litre of milk
eg. if producing 30litres of milk a day then needs 150MJ energy a day
What is the energy demand for pregnancy? (MUST REMEMBER)
25wks - 5MJ/day
40wks - 45MJ/day
What is conversion efficiency?
The efficiency with which metabolisable energy is converted to net energy - take away heat produced from each energy requirement
What does conversion efficiency depend on?
Use of energy
Quality of feed
Animal production level
What is the equation for the quality of the diet?
Quality = metabolisable energy / gross energy
How do you work out the animal production level?
Total energy requirement/energy for maintenance
eg. animal producing lots of milk may be 5 x maintenance
How is efficiency of digestion affected by animal production level?
If animal production level goes up then efficiency of digestion goes down because of high DMI and decreased gut transit time
How do you work out the total protein content of crude protein?
Protein is around 16% nitrogen
So Protein content = nitrogen x 6.25
What two categories does protein split into in the rumen?
Rumen degradable protein
Undegraded dietary protein
What is rumen degradable protein digested to form? What is it used for?
Digested in the rumen to form amino acids - needed to produce microbial protein
This is called Fermentable Metabolisable Energy
What does fermentable metabolisable energy provide energy for?
Synthesis of microbial crude protein, provide nutrients to the rumen microflora
What is a way that cows recycle non protein nitrogen instead of being lost in the urine as urea?
Urea goes back into salivary glands to make saliva
What protein bypasses the rumen and goes straight into the gut?
Undegraded dietary protein
Digestible undegraded protein
How does rumen outflow rate affect rumen degradable protein?
Slow outflow rate = more RDP
Animal production level increases voluntary food intake which increases outflow rate
So high animal production level = more undegraded dietary protein
What is the protein source given to cows?
Soya bean
What are the maintenance protein requirements for a cow?
300g/day
What are the lactation requirements for protein for a cow?
45g/Litre
What are the pregnancy requirements for protein for a cow?
20wks - 20g/day
40wks - 190g/day
What are the dietary crude protein requirements for a cow?
Approximately 1-2g additional crude protein/kg dry matter for every litre of milk
What can cause elevated urea levels in the blood in cows?
Dehydration
Renal disease
Excessive crude protein in the diet
Lack of fermentable metabolisable energy in the diet - so cant utilise crude protein
What is Effective Rumen Degradable Protein?
ERDP - the amount of RDP actually available to the rumen microbes
How does Effective Rumen Degradable Protein interact with Fermentable Metabolisable Energy?
ERDP relies on FME to be able to utilise the crude protein - ratio ERDP:FME crucial
(FME = simple carbs used by gut flora)
What happens to Undegraded Dietary Protein?
Either goes into faeces
Or goes as digestible undegradable protein into metabolisable protein
How does the metabolisable protein system work?
Crude protein is broken down into rumen degradable protein and undegraded dietary protein
Rumen degradable protein converted to EFFECTIVE rumen degradable protein
EFDP used with FME from simple carbs to produce microbial crude protein
This is then combined with digestible undegradable protein which bypassed the rumen to make up metabolisable protein which is used by the cow
What is the difference between rumen degradable protein and EFFECTIVE rumen degradable protein?
Some of the rumen degradable protein is lost as it is quickly degradable
So effective RDP is taking away the degraded part
What are the important factors of artificially reared calves?
Consistent milk replacement preparation
Consistent timing
Consistent presentation
Cleanliness
What makes up the compound feed given to calves?
18% crude protein with high digestible undegradable protein - want it to go through rumen and be digested by calf for growth
Eg. soya
What roughage is given to calves?
Good quality barley straw or hay
From rack - clean, off floor
What are the two different ration formations given to beef cows?
Rapidly fermentable carbohydrates - cereal/barley beef
Forage based systems - slower growing, grass/silage
What type of cow is the cereal/barley beef ration most suited to?
Late maturing breeds - early maturing beef breeds get too fat too quickly
Eg. Dairy/dairy x continental
What nutritional disorders might be associated with cereal beef?
Acidosis
Vitamin A deficiency
Bloat
How are beef suckler cows fed?
Diet rarely formulated - minimise feed costs by maximum grass grazing possible
More tolerant of a poor diet than diary
Mostly done on BCS
Winter forage - silage +/- straw
When should beef suckler cows be highest BCS?
Autumn - underfeed over winter, will gain back over summer
What are the different feeding systems used for feeding concentrate in dairy cows?
Concentrate -
In parlour
Out of parlour feeding
Mid-day feeds
In mixed ration
What are the advantages of complete diet/TMR?
Increased DMI - increased yeild
Improved rumen function - less acidosis
Cheaper
What are the disadvantages of complete diet/TMR?
Capital investment
Need to store lots of feed
Fat cows - can overeat
Slow entry to parlour - no incentive
Cash flow - money tied up in feed
What is partial mixed ration?
Mixed ration fed outside of the parlour
Small amount of concentrated fed in the parlour
Best of both worlds
What are the advantages of keeping cows in different groups depending on stage of lactation?
Avoids thin and fat cows - more precision
Improved management
Decreased standing times
What are the disadvantages of keeping cows in different groups depending on stage of lactation?
Increased bullying
Increased complexity - lots to work out
Increased time
What are the different feeding strategies used in dairy cows to decide how much nutrients the cows requires?
Feeding to yield
Flat rate feeding
Stepped feeding
What is leading and challenging in feeding to yield?
Lead - feed more concentrate to increase the yield
Challenge - after peak lactation decrease concentrate to stop cows getting fat
What is flat rate feeding?
Concentrate fed based on target yield
Same for every day of lactation - total yield similar but longer flatter lactation curve
What are the advantages and disadvantages of feeding to yield?
Simple
Avoids overfeeding/underfeeding
But increased risk of acidosis and metabolic stress
What are the advantages and disadvantages of flat rate feeding?
Simple
Less risk of metabolic stress and acidosis
But risk of overfeeding/underfeeding
Increased BCS loss around peak
What is stepped feeding?
Compromise between feeding to yield and flat rate feeding
Stepped levels of concentrates decreasing over lactation
What is the DMI in dry cows?
2% bodyweight
What BCS is the aim at drying off?
2.5-3
What happens if you have a BCS >3 at calving?
Increased calving difficulties
Decreased DMI - lower yield and increased risk of negative energy balance
What does loss of BCS in the dry period cause?
Lowered fertility
What is the average energy requirement of a cow during dry period?
100MJ/day - maintenance and pregnancy
What type of protein is important during the dry period?
Digestible undegradable protein - more protein for foetal growth
What makes up a dry cow diet?
Single ration - very high fibre
How much calcium is needed to make a litre of milk?
2g per litre of milk
What does hypocalcaemia cause in cows?
Impaired skeletal muscle contraction (milk fever)
Subclinical effects on uterus and GI tract smooth muscle
How do you prevent milk fever?
Restrict calcium - to upregulate mechanisms of Ca mobilisation in the body eg. osteoclasts
Magnesium supplements - improves calcium mobilisation, makes slightly acidotic (good)
What food is high in calcium for cows?
Grass
What is DCAD? What is it good for?
Dietary cation anion difference
Balance of cations and anions - induced mild metabolic acidosis
Good for preventing hypocalcaemia by mobilising Ca more
What is used to produce glucose for the cow?
Proprionate - makes oxalo-acetic acid in krebs cycle
What gives cows a fatty liver?
Too quick reduction in BCS - negative energy balance
Fat mobilisation - like hyperlipaemia in horses
What is type II ketosis? How is it different to type 1?
Insulin resistance, fat infiltration into liver around calving due to too high BCS in early dry period
Different to type I - too little energy intake around peak lactation
What causes ruminal acidosis?
Feeding too many carbs/high concentrate diet
Lactic acid producing bacteria - decrease pH
How can you measure ruminal acidosis?
Decreased herd performance
Rumenocentesis
Inconsistent faeces
