2. Cow nutrient requirements and ration formulation

1
2. Cow nutrient requirements and ration
formulation

• ANIM 3028
• Tom Cowan
• Tropical Dairy Research Centre, UQ, Gatton

2
Sources of nutrients

• All feeds supply one or more
• the primary feeds (pasture, forage, grains,
  byproducts) contain all, but in varying
  quantities.
• Energy and protein come in various forms (e.g.
  starch, fibre and sugar for energy)
• (e.g. NPN, amino acid mix for protein)

3
Minerals and vitamins

• Minerals availability in feed
• associated feeds
• form of mineral
• level of animal deficiency

• Vitamins not of concern
• Most vitamins or their precursors are in feeds
• housed cows on dry feed may need A and/ or D
• Vitamin e (or Se) may protect against infection
• rumen microbes produce water soluble vitamins
  (B,C)

4
Rumen function

• Cow nutrition is largely rumen fermentation
• Optimising microbial growth
• rumen capacity (L)
• wall papillae
• development of capacity and papillae depend on
  level of feeding
• feeds produce VFA (volatile fatty acids - acetic,
  propionic, butyric)
• VFA absorbed through wall of rumen (papillae)
• acetic for milk fat/propionic for milk protein

5
Protein absorbtion

• Protein absorbed from intestines
• Mix of feed protein (UDP), and microbial protein
  (bacteria and protozoa)

VFA
Feed
Microbial protein
6
Energy and protein utilisation

• Energy
• Gross energy similar
• Primary variation due to faeces output
• urine and methane less variable
• metabolisable energy used in Australia as unit

• Protein
• very different levels in feeds
• two primary sources of variation in utilisation
• rumen ammonia and faeces

7
Maintenance and production

• Maintenance energy to maintain body
• Level of feeding multiple of maintenance
• Efficiency declines as level of feeding increases
• For simplicity usually discussed as maintenance
  (0.8 efficiency) and production (0.2 to 0.6
  efficiency)

8
Cow requirements

• Annual cycle in milk yield, dry matter intake and
  live weight
• Lactation curve is the measured cycle
• normal curve peaks at 6 to 8 weeks after
  calving, and falls at 5 a month thereafter
• in practice curves may be all shapes, depending
  on feed supply

Live weight
DMI
Milk
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Quantitative requirements

• Over the full lactation milk output is related to
  DMI
• 12L milk - 12 kg DMI
• 20L milk - 17 kg DMI
• 30L milk - 23 kg DMI
• Water needs from 20 to 120L/day

10
Ration formulation

• Essential tool in feeding cows
• enables the ration to be balanced
• enables the amount of ration to be set

Nutrient requirements of cow
Nutrient contents of feeds
Ration formulation
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Nutrients in feeds

• Need to measure in feeds
• Is not an exact science
• energy - fibre or digestibility analysis to give
  ME as MJ/kg DM
• protein - N6.25, rumen degradability
• minerals - DM/DM
• vitamins - not measured

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Simple ration formulation
E.g.
CSM 40CP
6
By subtraction, ignore sign
16
Barley grain 10CP
24
Ration needs to be 6/30 CSM and 24/30 barley
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Complex ration formulation

• Computer based
• You choose type - put in the feeds and the
  program tells you what is in the diet, then you
  decide (needs a good nutritionist)
• Optimisation type - linear program, gives diet of
  least cost, highest production, etc. (needs an
  excellent program)

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Nutrients and their description

• Energy, Megajoules of metabolosable energy (MJ
  ME)
• Protein, kg
• Minerals, g or mg
• Vitamins, International Units
• water, L