Chemical analysis of feedstuffs pages 87 93
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CHEMICAL ANALYSIS OF FEEDSTUFFS Pages 87-93. Question. Why have some foreign feed companies added the compound below to some feed ingredients? Increase the energy concentration Increase the crude protein concentration Supply an essential amino acid Supply a required vitamin.

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Question
Question

  • Why have some foreign feed companies added the compound below to some feed ingredients?

  • Increase the energy concentration

  • Increase the crude protein concentration

  • Supply an essential amino acid

  • Supply a required vitamin



Feed analysis systems
FEED ANALYSIS SYSTEMS

  • Needed to rationally group feed nutrients and requirements

    • Makes analysis relatively easy and cost-effective

  • Feed analysis systems

    • Proximate analysis system (Weende system)

      • Developed in 1864 at Weende Experiment Station in Germany

    • Detergent analysis system (Van Soest system)

      • Developed in 1964 at USDA Beltsville Research Center


Proximate analysis components
PROXIMATE ANALYSIS COMPONENTS

  • Dry matter

  • Ash

  • Crude protein

  • Ether extract

  • Crude fiber

  • Nitrogen-free extract


  • Dry matter (DM)

    • Material remaining after a feed is dried in a 100oC oven for 24 hours

      • DM,% = wt after drying/wt before drying x 100%

      • % moisture = 100 – DM,%

    • Problems with method

      • Errors from losses of volatile components

        • Particularly a problem with fermented feeds

        • Can be avoided by toluene distillation or freeze drying

      • Drying at 100oC destroys sample for further analysis

        • Can be avoided by freeze drying or drying at 65oC for 48 hours in preparation for analysis (Still need to run a total DM analysis on part of sample)


  • Significance of DM

    • Considerable variation in the DM, % of feedstuffs

      • Corn grain, 88% DM

      • Alfalfa hay, 90% DM

      • Alfalfa silage, 45% DM

      • Alfalfa pasture, 26% DM

      • Whey, 7%

    • Other nutrients are present within the dry matter

      • Affects expression of concentrations of nutrients in feedstuffs

      • Example Crude protein, %

        DM,%Wet basisDM basis

        • Dried distillers grains 93 27.9 30

        • Modified distillers grains 50 15.0 30

        • Wet distillers grain 40 12.0 30

    • Affects storage properties of feedstuffs


  • Ash

    • Material remaining after oxidation of a sample at 600oC for 2 hours in a muffle furnace

      • % Ash = wt after ashing/sample wt x 100%

      • % Organic matter = 100 - % ash

    • Problems

      • No indication of amounts of individual minerals

      • Some minerals (Sulfur, Selenium, Zinc, Iodine are lost)

    • Significance

      • May indicate soil contamination or adulteration of feedstuff or diet.


  • Crude protein (CP)

    • % Crude protein = %N x 6.25

    • %N determination

      • Kjeldahl N

        Sample→Boil in conc. H2SO4→(NH4)2SO4→Add conc. NaOH, → Titrate

        distill NH3, and trap NH4 borate

        in boric acid

      • N analyzer

        Sample→Pyrrolize sample at high temp.→Measure N2 w/detector

    • Factor of 6.25 assumes that most proteins contain 16% N

      CP,% = measured mg N/100 mg sample x 100 mg protein/16 mg N

      = measured mg N/100 mg/sample x 6.25


  • Problems with crude protein procedure

    • Sources of N

      • True protein

        • Chains of amino acids bound by peptide linkages

        • Can meet the protein requirements of either nonruminant or ruminant animals

      • Nonprotein nitrogen

        • Forms

          • Free amino acids

          • Nucleic acids

          • Ammonia

          • Urea

          • Biuret




  • Crude protein says protein requirement of a 800 nothing about the amino acid composition of the feed source

    • Commonly assume that the concentration of individual amino acids is constant within the protein a given feedstuff

    • Can analyze for individual amino acids


  • Crude protein says nothing about the digestibility of a protein

    • Varies with feedstuff

      % Crude protein% Protein Digestibility

      Soybean meal 45 90

      Feather meal 80 75

    • Varies with heat damage

      • When overheated, protein will bind to the cell wall carbohydrates particularly across lysine

      • Causes

        • Molding of forages

        • Over-heating during processing

        • Over-drying of grains or soybeans

      • Referred to as the Maillard or Browning Reaction

      • Results

        % Crude protein% Protein Digestibility

        Well-preserved alfalfa hay 18 90

        Heat-damaged alfalfa hay 18 60


  • Ether extract (EE) protein

    • Also called crude fat

    • Material removed by refluxing ether through a feed sample for 4 hours

      % Ether extract = (Sample wt-residue after ether extract)/Sample wt x 100%

    • Theoretically represents fat content of the feedstuff

      • A high ether extract content should indicate a high energy concentration

    • Problem with procedure

      • Ether extract consists of:

        • True lipids

          • Fats and oils

        • Non-nutritional ether soluble components

          • Fat-soluble vitamins

          • Chlorophyll

          • Pigments

          • Volatile oils

          • Waxes


  • Crude fiber (CF) protein

    • Procedure

      Sample→Extract with dilute H2SO4 →Residue→Burn at 600oC→Ash

      followed by dilute NaOH

      % CF = (Residue wt-Ash wt)/sample wt x 100%

    • Theoretically represents

      • the structural carbohydrates (Cellulose and hemicellulose)

        • Limited digestibility in ruminants

        • Poor digestibility in nonruminants

      • Lignin

        • Indigestible by ruminants and nonruminants

    • Problems with procedure

      • Poor recovery of components

        % recovered

        • Cellulose 90

        • Hemicellulose 50-60

        • Lignin 13-70


  • Nitrogen-free extract (NFE) protein

    • No actual analysis

    • Calculation by difference

      • %NFE = %DM – (%ash+%CP+%EE+%CF)

    • Theoretically represents:

      • Starch

      • Sugars

    • Problems:

      • Contains all of the errors from other analyses

        • Largest error is unrecovered lignin will be placed in NFE




  • Neutral detergent fiber (NDF) protein

    • Consists of hemicellulose, cellulose, lignin, cell wall bound protein and insoluble ash

    • Significance:

      • Highly related to feed intake

      • DMI, % BW = 120/% NDF

  • Acid detergent fiber (ADF)

    • Consists of cellulose, lignin, poorly digested protein, and insoluble ash

    • Significance:

      • Highly related to digestibility and energy concentration

      • DDM% = 88.9 – (.779 x %ADF)

      • NEl, Mcal/lb (for legumes) = 1.011 – (0.0113 x %ADF)

    • Combination of DDM (determined from ADF) and DMI (determined from NDF) is used to determine Relative Feed Value (RFV)

      • RFV=DDM x DMI / 1.29

      • Used for hay marketing


  • Nitrogen bound to acid detergent fiber is a measure of heat-damaged protein

    • Called ADIN or ADF-CP

  • Procedure

    Sample→Extract with AD→ADF→Analyze N by

    Kjeldahl procedure

    ADF-CP, % of total CP= %ADFN x 6.25/%CP x 100%

  • Relationship to protein digestibility (called adjusted CP)

    • Traditional adjustment

      • If ADF-CP, % of total CP < 10%

        • Adjusted CP = CP

      • If ADF-CP, % of total CP > 10%

        • Adjusted CP = (100 – ADF-CP, % of CP) x CP

    • Modern adjustment

      • If ADF-CP, % of total CP <14, ADIN is considered digestible

        • Adjusted CP = CP

      • If ADF-CP, % of total CP is >14 and <20

        • Adjusted CP = ((100 – (ADF-CP, % of CP – 7))/100) x CP

      • If ADF-CP, % of total CP is > 20

        • Adjusted CP = CP – ADF-CP, % of CP X CP


  • N bound to NDF and ADF used to determine rumen degradable, rumen undegradable, and indigestible fractions

    Rumen degradable protein = Total CP – (NDFCP, % of CP xTotal CP)

    Rumen undegradable protein = (NDFCP, % of CP xTotal CP) –

    (ADFCP, % of CP xTotal CP)

    Indigestible protein = (ADFCP, % of CP xTotal CP)


Other analytical procedures
OTHER ANALYTICAL PROCEDURES rumen

  • Near infrared reflectance spectroscopy

    • Determines the concentrations of protein, amino acids, lipids, and carbohydrates based on absorption of near infrared light

    • Advantages

      • Rapid

      • Used by most commercial labs

    • Limitations

      • Requires calibration

      • Inability to measure heterogeneous molecules like lignin

      • Inability to measure minerals


  • Atomic absorption spectroscopy rumen

    • Used for mineral analysis

    • Procedure

      • Sample ashed and extracted into a solvent

      • Dissolved sample sucked into a flame with a light at a specific wavelength going through it

      • Absorption of light directly proportional to absorption of light

    • Limitation

      • Expense

  • High performance liquid chromatography

    • Used of amino acids and vitamins

    • Procedure

      • Sample dissolved in organic solvent injected into column

      • Column differentially separates components

      • Detector measures components as they through the column

    • Limitation

      • Expense


Question1
Question rumen

  • Why have some foreign feed companies added the compound below to some feed ingredients?

  • Increase the energy concentration

  • Increase the crude protein concentration

  • Supply an essential amino acid

  • Supply a required vitamin

Melamine


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