Dairy Nutrition 3 Flashcards
What are the energy needs for dry cows
- Maintenance
- Fetal growth
- Colostrum production
What are the goals for feeding dry cows
Goals
* Control BCS
* Optimize dry matter intake
* Ruminal adaptation for lactation
* Reduce metabolic disorders post-birth
What is the timeline for a year for a dairy cow? How is nutrition and BCS impacted
- 0d = calve
o Decreased DMI close to calving - 0 – 30d = rest post-parturition – then begin breeding
- 100d = breed (9 months before drying out) – should be pregnant
- 1-305d = milk production
o Start with 15L/d – slowing increase production (peak at 60d)
Most susceptible period
o 1st 2 month (pre-peak production) = low DMI (negative energy balance) = low BCS
o After they reach peak milk production – they eat more DMI than energy expended = regain BCS - 305 - 365d = dry (60d)
o ‘dry out’ cow by reducing milking
What to consider when feeding a dry cow? How does the timeline of the cow affect feeding?
- Control energy intake – will eat more than they need
- Far off group: 60d before calving
o 1.2 Mcal/kg with 12-13% CP
o Minimal grain – high forage - Close up group: 21d before calving
o 1.5 Mcal/kg with 14-15% CP
o Lower dry matter intake, higher energy requirement
o Silage based (higher grain)
What is the max BCS loss you should see for a dairy cow
1 point
ideally 0.5 - 0.75
in a _/5 scale
What is the transition peroid for a dairy cow and why is it important
- 3 weeks before calving and 3 weeks after
- Lots of physiologic and metabolic changes = high risk for disease
What is critical for a transitioning dairy cow
- Dry matter intake critical
o Good: >13 kg
o Meh: 10-13 kg
o Bad: <10 kg
What is the ideal BCS for dairy cows drying off, calving, and breeding
o Drying off = 3.25 – 3.75
o Calving = 3.25 – 3.75
o Breeding = 0 – 3.5
What are the goals for feeding a lactating cow
Goals
* Prevent BCS loss
* Maximize DMII and milk production
* Return to reproductive function
What are the energy requirements of a lactating cow
- Maintenance
- Growth (if in 1st lactation)
- Milk production
- Reproduction
What factors impact nutritional requirements for lactating cows
- Parity (number of prior lactations)
- Days in milk
- Milk yield and composition
- Cow wight
- Activity/environment
- Gestational phase
How should you feed a fresh cow
Early lactation
* Fresh cow (transition)
* Feed separately from main lactation herd
What are the nutritional requirements of a fresh cow? Why is it important
- Nutritionally
o High fibre/NDF
o Low starch
o Bypass rumen for amino acids and fat
o Molasses - Should be getting pregnant after ~ 90 days in milk
What are 2 reasons why a cow isn’t getting pregnant
- If not pregnant
o Negative energy balance: delay first ovulation
o Increased dietary crude protein: excess urea in plasma = change uterine environment
What are the requirements of a cow in late lactation? What are 2 things to consider when feeding
Late lactation
* Low nutrient demand
* Low milk yield
- High DMI – recover BCS but don’t overcondition
- No negative energy balance
Why is overconditioning dry cows a problem
- Excess = reduced DMI near calving and higher risk of metabolic disorders
What is Negative energy balance and Low dietary fibre associated with in the transition period respectively
- Negative energy balance associated with ketosis and fatty liver
- Low dietary fibre = acidosis and displaced abomasum
What type of feed do you use for lactating cows
- TMR: single ration for all lactating cows + avoids social distress and competition
How is concentrate and forage balanced in lactating cow TMR? Why
o Forage: high cellulose that facilitate rumination
Ruminal pH = 6-7
Acetate : Propionate (4 : 1)
More = milk fat/acetate/fatty acids
Less = milk volume
o Concentrate: starch, less rumination
Ruminal pH = 5.5 - 6
Acetate : Propionate (2 : 1)
More = propionate/glucose/lactose/milk volume
Less = milk fat
o Should have a ratio of 60 : 40 (forage : concentrate)
Compare structural and non structural carbs for lactating cows
o Structural: from rumination (acetate VFA), microbial protein and milk fat
Particle size is important: minimum size to stimulate rumination
NDF or ‘physically effective’ NDF (physical effectiveness based on particle size)
o Non-structural: propionate VFA, microbial protein, lactose, milk volume
Via non-thermal processing: roll/crack/grind
finer ground is more digestible but higher risk of acidosis
* Increase surface area and break pericarp = make endosperm accessible
How do automated milking systems influence lactating cow diets
- Automated Milking system:
o Partial mixed ration between milkings
o Concentrate when milking (grain)
How is protein given to dairy cows
- Protein: Nitrogen
o Low in diet – most from microbial protein synthesis
o In diet: focus on bypass protein and amino acids (methionine and lysine) – plant based
How is lipid utilized in dairy cows? What is their max amount allowed in diet?
- Lipid: not fermented
o Max dietary = 7%
o Can bypass rumen to allow utilization
What is the law of minimum in the context of dairy nutrition
o Law of minimum: require all amino acids to make protein, rate limiting amino acids = methionine and lysine
