Neutral Detergent Fiber

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Neutral Detergent Fiber

• Why It Is Important in Rations

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Two Sources of Energy in Forages

• Cell contents contain sugars, starches, proteins,
  etc
• gt90 digestible, rapidly available
• Cell walls contain cellulose, lignin
  hemicellulose, etc
• 40-70 digestible, more slowly available by
  fiber-digesting bacteria

Photo courtesy of Pioneer Hi-Bred International,
Inc.
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Plant Carbohydrates
Completely Digestible
Less Digestible/ Indigestible
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Plant Carbohydrates
Cell wall
Cell contents
Plant cell
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Plant Carbohydrates
Non-Fiber Carbohydrates NFC or Non-Structural
Carbohydrates - NSC
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Plant Carbohydrates
Measured as
Neutral Detergent Fiber NDF
Hemicellulose Cellulose Lignin
Acid Detergent Fiber ADF
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Plant Carbohydrates
Hemicellulose - more digestible Cellulose -
less digestible Lignin - indigestible
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Plant Composition
Key Concepts!
Related to Dry Matter Intake!
Hemicellulose Cellulose Lignin
NDF
ADF
Related to fiber digestibility!
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Understanding Forage Fiber

• To talk about Forage Quality we need to
  understand Fiber
• Fiber is a plant carbohydrate
• Fiber is the cell wall portion of the plant
  cell that holds the plant up
• Fiber is food for the rumen microbes and helps
  the cow maintain rumen health (cud chewing
  saliva, higher rumen pH)
• As plants mature, the ratio of cell wall to cell
  content goes up and the cell wall becomes less
  digestible
• There is only so much fiber the cow can consume
  (only so much space in the rumen)

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NDF Cell Walls

• The measure of plant fiber that is most useful in
  balancing rumen-healthy rations and in predicting
  how much forage a cow can consume is
• NDF Neutral Detergent Fiber
• NDF is the best single measure of Forage Quality

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NDF intakes
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NDF intakes
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A Good Working Definition of High Forage Diet
What forage NDF is needed to achieve these level
of intake?
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NDF Guidelines for forages
corn silage NDF may be deceiving as grain
content may be 20 - 60. A diet that is 50 corn
silage as sole forage source, with corn silage
that is 50 grain is technically only 25 forage.