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CHEMICAL ANALYSIS OF FEEDSTUFFS Pages 87-93

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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CHEMICAL ANALYSIS OF FEEDSTUFFS Pages 87-93

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  1. CHEMICAL ANALYSIS OF FEEDSTUFFSPages 87-93

  2. 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

  3. FEED NUTRIENTS

  4. 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

  5. PROXIMATE ANALYSIS COMPONENTS • Dry matter • Ash • Crude protein • Ether extract • Crude fiber • Nitrogen-free extract

  6. 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)

  7. 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

  8. 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.

  9. 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

  10. 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

  11. What form(s) of crude protein can be used to meet the crude protein requirement of a 120 lb growing gilt? • Chains of amino acids • Ammonia • Biuret • Urea • All of the above

  12. What form(s) of crude protein can be used to meet the crude protein requirement of a 800 lb growing steer? • Chains of amino acids • Ammonia • Biuret • Urea • All of the above

  13. Crude protein says 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

  14. 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

  15. Ether extract (EE) • 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

  16. Crude fiber (CF) • 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

  17. Nitrogen-free extract (NFE) • 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

  18. WHY IS PROXIMATE ANALYSIS SYSTEM STILL USED?

  19. DETERGENT ANALYSIS SYSTEM

  20. Neutral detergent fiber (NDF) • 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

  21. 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

  22. 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)

  23. OTHER ANALYTICAL PROCEDURES • 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

  24. Atomic absorption spectroscopy • 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

  25. 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 Melamine

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