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