Basics of ruminant nutrition Flashcards
What side of the body is the rumen?
LHS
What are the bugs in the rumen?
- 10 billion / ml bacteria
- 1 million / ml protozoa
1 thousand / ml fungi
What is the ratio of primary to secondary rumen contractions?
2 primary : 1 secondary
(mixing) (belching/regurgitating)
What is milk production determined by?
- Genetic merit
- Nutrition
- Health
What order should be followed when formulating diet?
- Dry matter intake
- Energy
- Protein
- Minerals (macro + trace elements)
- Vitamins
What activities should be considered with the animal?
- Maintenance
- Activity
- Lactation
- Growth
- Pregnancy
How much dry matter does a cow need?
- Maintenance = 2% - 2.5% BW = 14kg in 700kg cow
- If lactating = more = 3% BW (higher yielding = more)
- If heavily preg = less
What influences dry matter intake?
- body weight & fatness – “fat cows eat less”
- milk yield “the more she milks the more she eats”
- stage of production cycle e.g. dry cow, calving, fresh calved (all have reduced DMI).
- type of food (digestibility / rate of passage).
- palatability (mixed forages).
- access - feed barrier, electric fence etc.
- availability - TMR versus parlour feed etc.
- social factors e.g. bullying of heifers.
- stress / pain e.g lameness.
- rumen health - “the right bugs & healthy bugs”
What are energy foods?
- Carbohydrates
- long chain = slow fermentation = fibre (cellulose)
- short chain = fast fermentation = sugars, starches
- Fats
- Protein
What does fermentation of carbohydrates produce?
- Volatile fatty acids = acetate, butyrate, propionate
- CO2
- CH4
What happens to VFA’s?
- Absorbed across rumen wall - health of papillae
- Enter krebbs cycle - energy
- Glucose synthesis - from propionate, MILK
What is the fate of fats + oils?
- Absorbed in small intestine - protected fats
All lactating cows in early lactation lose roughly 0.5 - 1 condition score (50kg)
How can you cope with this?
- Eat more - increased her DMI
- Metabolise body tissues - fat + muscle
- Reduce milk yield
How much energy does a cow need?
- Maintenance = 65-70MJ / day
- Production = 5MJ / litre milk
- Pregnancy = only important in last few weeks
- Weight gain/loss = 30MJ/Kg BW
What is protein metabolism in cows?
- Rumen degradable protein - N containing compounds = fermented to NH4, used by bugs = forms microbial protein
- Rumen undegradable protein = passed through rumen, digested in abomasum + SI (e.g. Soya)
How much protein does a cow need?
- > 8,000L = 18% protein
- <8,000L = 16% protein
How can you maximise DMI in lactating cows?
- maximise intakes in dry period
- palatable diet – mixed forages
- avoid SARA = forage:concentrate ratio,
- change diets slowly – 3 week “rumen adaption” period
- dry cow management = avoid getting fat
- environment = comfort, feed barrier – space – 30” per cow, social aspects – hierarchies, bullying etc
- health e.g lameness
What is the dry matter % + energy in clamp grass silage?
- DM = 20 - 35%
- 10-12 MJ ME/Kg DM (average 10.5)
What is the dry matter % + energy in maize silage?
- DM = 30-35%
- 11-11.5 MJ ME/Kg DM - high starch + low protein
What is the dry matter % + energy in big bale silage?
- DM = 30-35%
- 8.5 - 10.5 MJ ME/Kg DM
What is the dry matter % + energy in hay?
- DM = 85%
- 8-9 MJ ME/Kg DM
What is the dry matter % + energy in straw?
- DM = 85%
- 5.5-6.5 MJ ME/Kg DM
What is the dry matter % + energy in grass?
- DM = 20% or less
- 10-12.5 MJ ME/Kg DM
What is the dry matter % + energy in concentrates / cake/ blend?
- DM = 88-90%
- 12.5 MJ ME/Kg
