Forage Analysis Procedures

Download: Laboratory Procedures (pdf)

Dr. Dan Undersander, University of Wisconsin
Dr. David R. Mertens, USDA-ARS US Dairy Forage Research Center
Ms. Nancy Thiex, South Dakota State University

July, 1993

Table of Contents

• Historical Development of Forage Quality Testing Proficiency

• Section A - Laboratory Sample Preparation
  • Introduction
  • 1. Sample Preparation
    • Preparing samples greater than approximately 85% dry matter for grinding
    • Preparing samples less than approximately 85% dry matter for grinding
    • 1.1 Grinding with a Cutting Mill
    • 1.2 Grinding with a Cyclone Mill (Udy, Cyclotec or equivalent)

     

• Section B - Procedures for Certification
  • Introduction
  • 2. Dry Matter Determination
    • 2.1 Single Step Total Dry Matter Determinations
      • 2.1.1 Total Dry Matter by Oven Drying for 2 hr at 135°C
      • 2.1.2 Total Dry Matter by Oven Drying at 100°C for 24 hr or 105°C for 16 hr
      • 2.1.3 Total Dry Matter by Microwave Drying to Constant Weight
    • 2.2 Two Step Total Dry Matter Determination of Wet Samples
      • 2.2.1 Partial Drying of Wet Samples
        • 2.2.1.1 Partial Dry Matter Using Forced-air Drying Ovens
        • 2.2.1.2 Partial Dry Matter Using Microwave Oven
      • 2.2.2 Laboratory Dry Matter of Partially-Dried Samples
        • 2.2.2.1 Laboratory Dry Matter by Oven Drying for 2 hr at 135°C
        • 2.2.2.2 Laboratory Dry Matter by Oven Drying at 100°C for 24 hr or 105°C for 16 hr
        • 2.2.2.3 Laboratory Dry Matter by Microwave Drying to Constant Weight
        • 2.2.2.4 Dry Matter by Near Infrared Reflectance Spectroscopy
        • 2.2.2.5 Dry Matter by Oven Drying for 3 hr at 105°C
      • 2.2.3 Determination of Sample Total Dry Matter using the Two-step Procedure
    • 2.3 Wet, Fermented Samples
      • 2.3.1 Toluene Determination of Moisture
  • 3. Nitrogen and Crude Protein Determination
    • 3.1 Nitrogen Determination by Kjeldahl
    • 3.1A Addendum to Nitrogen Determination by Kjeldahl (Rack):
      • Options for Experienced Laboratories
      • 3.1.1 Standardization of Hydrochloric Acid Standard Solution
      • 3.1.2 Standardization of Sodium Hydroxide Standard Solution
    • 3.2 Nitrogen Determination by Kjeldahl (Block Digestion)
    • 3.3 Nitrogen Determination by Combustion Method
    • 3.4 Crude Protein by Near Infrared Reflectance Spectroscopy
  • 4. Acid Detergent Fiber
    • 4.1 Determination of Acid Detergent Fiber by Refluxing
    • 4.2 Determination of Acid Detergent Fiber by Near Infrared Reflectance Spectroscopy

     

• Section C - Procedures Presented for Information
  • 5. Neutral Detergent Fiber - Amylase Procedure
    • 5.1 Determination of Amylase Neutral Detergent Fiber by Refluxing
    • 5.2 Standardizing Alpha-Amylase Activity for Neutral Detergent Fiber Determination
    • 5.3 Determination of Neutral Detergent Fiber by Near Infrared Reflectance Spectroscopy
  • 6. Acid Detergent Insoluble Nitrogen and Acid Detergent Fiber Crude Protein
  • 7. Total Ash in Forages
  • 8. Crude Fat (Ether Extract) in Forages

   

• Appendix
  • Appendix A - Calculated Values
    • Relative Feed Value Index
    • Adjusted Crude Protein
    • Estimates of Energy Availability
  • Appendix B - Predicting Minerals by NIR
  • Appendix C - Quality Assurance
  • Appendix D - Quality Control
  • Appendix E - Taking a Good Forage Sample for Analysis
  • Appendix F - Critical Conditions in Determining Detergent Fibers