Forage Quality Evaluation

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Forage Quality Evaluation

• Tim Dietz
• Research Assistant
• MSU Crop and Soil Science
• Modified lecture given by Dr. H. Bucholtz
• MSU Animal Science

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Overview

• Why feed forages?
• Why test forage quality (FQ)?
• How to sample?
• What are the measurements of FQ?
• DM, CP, NDF, ADF, CF, RFV, RFQ, NDFd, dNDF,
  ISDMD, NFC, NSC, IVDMD, TDN, ADL, NEg, NEL,
  NDICP, ADICP, NDSC, RDP, TNC, .

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Why Feed Forages?

• Supply source of nutrients
• a) Energy
• b) Fiber
• c) Minerals
• Ruminants Require FIBER
• a) Rumen Environment (acidic)
• b) Cud Chewing gt saliva production gt buffers
• gt maintain rumen pH

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Forage Evaluation - - Why ? ?

• Cash Crop Forage Producer -
• 1. To Market a Commodity
• 2. Help Establish a Selling Price
• 3. Quality Control of Forage Production Program
  
• 4. Establish a Reputation
• Dairy, Livestock, Equine Producer -
• 1. To Decide which animal to feed
• 2. Use Analysis for Ration Formulation /
  Evaluation
• 3. Decide whether to purchase
• 4. To Establish a Purchase Price

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How to Sample

• Bales sampled randomly, but with common sense
• Representative sampling

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120-250
or make your own. Key is a serrated tip
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Proper hay sampling

• A minimum of 20 cores should be taken
• 5 grab samples 3 SE
• 10 grab samples 2.1
• 20 core samples 1.1
• Combine, mix and save 0.75 lb

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Haylage / Silage sampling

• 3-5 handfuls during unloading and refrigerate
  (not freeze)
• 1-2 lb sample
• Express ship to the lab

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Forage Evaluation Methods

• Non-Analytical Observations non-quantitative
• Visual - Forage Species - (grass - alfalfa
  mixed)
• Color of Forage, Molds / dust / weeds
• Smell
• Feel
• Analytical Analysis Measurement of a
  concentration,
• amount
• On Farm - dry matter
• Laboratory - Wet - Chemical Analysis
• NIRS - (Near Infrared Spectroscopy)

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Laboratory Analysis

• Wet Chemistry in vitro vs. in situ (in vivo)
• Accurate (if done correctly)
• Takes more time
• More costly (40 up)
• NIRS Near-infrared Reflectance Spectroscopy
• Accurate (if done correctly)
• Very repeatable
• Requires wet-chemistry to develop equations
• Fast
• Cost (15 - 20)

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Labs Typically Analyze Forages for

• Dry Matter - Moisture
• Fiber - NDF ADF Lignin
• Protein
• Lipids Fat
• Minerals - Ash
• Vitamins

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1) Dry Matter Moisture Testing of Forages

• Why Test for Dry Matter ?
• 1. For ration evaluation / formulation
• 2. To determine when to harvest
• Dry Hay - Before / during baling will hay
  keep
• Silage - Before / during chopping
• - Silage DM is very important for
• Silage fermentation process in bunkers,
  tower silos, bag silage, bale silages
• How -
• 1. Run DM on Farm using
• Forced Air Drier (Koster Tester) or Microwave

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Koster Moisture Tester
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Microwave determination

• Place forage sample (large handful) on paper
  plate and weigh
• Place sample in microwave with cup of water
• Microwave for 2 minutes and mix/invert the sample
• Microwave for 1 minutes and weigh
• Microwave for 1 minute and weigh, if no change,
  do the math, otherwise nuke again

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(2) - Fiber - Analysis

• Fiber Chemical Fractions
• 1. NDF - - neutral detergent fiber
• 2. ADF - - acid detergent fiber
• 3. Lignin

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NDF - ADF

• NDF ADF - Measures of plant fiber
• NDF - neutral detergent fiber - analytical
  method
• hemicelluloses cellulose lignin
• used as predictor of feed intake
• ADF - acid detergent fiber analytical
  method
• cellulose lignin
• used as predictor / estimator of energy

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Plant Carbohydrate

• Total Carbohydrate
• Non-Cell Wall Cell Wall
• Sugar Starch Pectin Cellulose
  Hemicellulose Lignin
• ADF Cellulose Lignin
• NDF Hemicellulose ADF

Fiber
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NDF Neutral Detergent FiberADF Acid
Detergent Fiber

• Plant Carbohydrate
• NDF
• Crude Fiber
• ADF

Cell Solubles
Hemicellulose
Cellulose
Lignin
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Plant Carbohydrate Digestibility

• Cell Contents - nearly completely digestible
• Cell Wall - 30-80 digestible

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Lignin (part of the cell wall)

• Lignin is not digestible
• is like re-rod helps hold the plant
  up
• Reported as lignin of the NDF
• Alfalfa - lt 16 lignin / NDF - desirable
• Corn Silage - lt 6 lignin / NDF desirable
• Some commercial feed testing labs do lignin

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Fiber Composition of Various Feeds

• Forage
• Component Alfalfa Corn Silage Timothy
• NDF 40 51 61
• ADF 30 28 32
• Lignin 7 4 4

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Differences in Grass LegumeFiber Components

• - Grass - -Legume -
• Cell Solubles
• Pectin
• Hemicellulose
• Cellulose
• Lignin

Although grass has more fibrous material, it is
more digestible than alfalfa fiber Tomlin et
al,,1965
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(3) Protein - Analysis

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Ruminant Protein Nutrition Terms

• 1. Crude Protein - Total nitrogen X 6.25
• Protein contains 16 nitrogen
• 2. NPN - Non-Protein Nitrogen - does not contain
  amino acids
• 3. Soluble Protein - Proteins NPN that are
  in rumen fluid
• 4. Insoluble Protein - Not soluble in rumen
  fluid
• 5. Amino Acid - Contains NH2 C
• 6. Bound Protein - Not available to animal

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Ruminant Protein Nutrition Terms

• 7. Microbial Crude Protein (MCP) - Protein
  synthesized
• in rumen by bacteria protozoa
• 8. Rumen Degradable Protein (RDP) - Protein that
  can be degraded to NH3 in the rumen by
  enzymes secreted by the rumen microbes
• 9. Rumen Undegradable Protein (RUP) - Protein
  that is not degraded in the rumen. Not degraded
  by rumen microbial enzymes. Referred to as
  by-pass protein
• Metabolizable Protein Protein (MCP RUP) that
  is digested in small intestine to amino acids.
  Amino acids then are absorbed.

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(5) - Analysis for Other Forage Nutrients

• Dry Matter - Moisture
• Fiber - NDF ADF Lignin
• Fiber digestibility
• Protein
• Soluble - Bound P - RDP RUP
• Lipids Fat
• Minerals
• Vitamins

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Lipids - Fat

• For some livestock ration formulation
• knowing the fat content may be important
• Some commercial labs will analyze for fat

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Minerals

• Macro - Needed in large amount Micro - Needed
  in small - Trace
• in diet. amount in diet.
• As - of DM - grams - pounds As - PPM
  parts / million
• Analysis wet chemistry Analysis Not a
  routine analysis
• NIRS Not an acceptable because
  variability is high
• method for minerals
• Macro Minerals Micro Minerals
• Calcium Iron
• Phosphorus Copper
• Sodium Manganese
• Chloride Zinc
• Magnesium Iodine
• Potassium Cobalt
• Sulfur Selenium

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Vitamins

• Vitamins - A, D, E
• 1. Fat soluble
• 2. A,D,E - Need to be supplemented in diet
• 3. Feed ingredients not normally analyzed for
  vitamins
• B-Vitamins
• Are synthesized by rumen microorganisms
• Feed ingredients not normally analyzed for
  B-vitamins
• 2. With high producing and stressed cows there is
  limited research that supplemental B-Vitamins
  are helpful

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Other Forage Quality Measures

• Relative Feed Value (RFV)
• Relative Forage Quality (RFQ)
• Non Fiber Carbohydrate (NFC)
• Non Structural Carbohydrate (NSC)

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Relative Feed Value - for Forages

• Relative Feed Value (RFV) - Is an indexing method
  used to rank forages based on estimate of
  digestibility and animal intake potential.
• Limitations of RFV -
• ADF NDF are only laboratory values used
• DDM DMI - are assumed constants for all feeds
• Crude Protein content of forage is not used
• RFV is not used in ration formulation or
  evaluation
• RFV DDM X DMI DDM digestible
  dry matter
• 1.29 DMI dry matter intake
• DDM 88.9 - ( ADF X 0.779)
• DMI 120
  / NDF

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NFC Non-Fiber CarbohydrateNSC Non-Structural
Carbohydrate

• NFC A calculated estimate of the non-fiber,
  more rapidly fermenting carbohydrate
  (starches sugars) in a feed ingredient
• NFC 100 - NDF C. Protein Fat Ash
• NSC Is a laboratory enzyme analysis of the more
  rapidly fermenting carbohydrate (starches
  sugars)

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Starch

• Starch
• - Forages contain small amounts of starch
• - Starch is found in greatest quantities in
  corn
• - Many laboratories can analyze for starch
• analysis methods may vary between labs

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NIRS

• Absorption of wavelengths in the NIRS region are
  primarily due to X-H bounds, where X is carbon,
  nitrogen or oxygen.

Wavelength sensor
sample
Sorting grate
Light source
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NIRS on-farm

• Some larger dairy farms in the Netherlands, CA,
  and AZ are testing NIRS mounted on TMR wagons
• Feed is scanned as it is loaded and adjustments
  to quantities are made on the fly

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Lit. cited

• Tomlin, D.C., RR Johnson and BA Dehority. 1965.
  J. Anim. Sci. 24161-165
• Dairy NRC. 2001.
• Mickelson et al. 1988. Alfalfa and Alfalfa
  Improvement.