AsFedDM Calculations

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As-Fed/DM Calculations

• AS 233

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Definitions

• As-Fed amount of a nutrient contained in the
  feed as it would be fed to the animal, including
  water
• Dry Matter amount of a nutrient contained in
  only the dry matter fraction, without water

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As-Fed Basis
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DM Basis
60 g of water have been dried off
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Monogastrics

• Usually not a concern with nonruminants since use
  feed grains by-products that are approximately
  88 dry matter
• Soybean meal (SBM) 89 DM
• Corn 87.3 DM
• Vitamins minerals gt 90 DM
• Use As-Fed for ration balancing

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Ruminants

• Eat a wide variety of feeds that contain
  different amounts of water
• Silage 37 DM
• Sun-cured brome 90.8 DM
• When balancing rations, need to calculate on a
  dry matter basis

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Example

• Alfalfa silage contains 7 CP on an As-fed basis,
  and contains 40 dry matter. What CP would the
  alfalfa have on a DM basis?
• nutrient (as-fed) nutrient (DM basis)
• feed dry matter 100 DM

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The Calculation

• 7 X
• 40 100
• 40 X 700
• X 700/40 17.5 CP on a DM basis

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Another Example

• Two samples of corn, one dry (89 DM) one high
  moisture (75), came back from the lab with CP
  s of 8.8 and 7.4 CP on an as-fed basis,
  respectively. Since you are going to feed them
  to sheep, which grain contains the most CP on a
  DM basis?

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The Calculation

• Dry corn 8.8 X
• 89 100
• 89 X 880 X 880/89 9.89 CP
• High Moisture corn 7.4 X
• 75 100
• 75X 740 X 740/75 9.87 CP
• They are almost equal on a DM basis

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The Bottom Line

• As-fed should have lower nutrient levels since
  they are diluted by water

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Converting AS-FED ration to DM basis

• How many kg of a ration dry matter are consumed
  if a steer is fed the following ration?
• Corn silage 10 kg 40 DM
• Corn grain 4.0 kg 89 DM
• Supplement .5 kg 92 DM
• Total 14.5 kg as-fed ration

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Converting AS-FED ration to DM basis

• Parts DM Feed Parts As-fed DM in feed

Feed kg, AF DM kg DM Corn
silage 10.0 0.40 4.00 Corn grain
4.0 0.89 3.56 Supplement 0.5
0.92 0.46 Total 14.5 kg as-fed 8.02 kg
DM
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Rules to work these calculations

• Converting As-Fed to Dry Matter
• Nutrient concentrations will increase
• Weight will decrease
• Converting Dry Matter to As-Fed
• Nutrient concentrations will decrease
• Weight will increase