ANSC 318 1st Edition Lecture 5 Outline of Last Lecture I. Function and Digestion of Proteins, Vitamins, and Minerals; Analysis of FeedstuffsOutline of Current Lecture II. Methods of Evaluating Feedstuffsa. Chemical-basedb. Nondestructivec. Animal-basedd. MicrobiologicalIII. Proximate Analysis Systema. Backgroundb. Steps of Analysisc. Weaknessesd. Components of FractionsIV. Van Soest Systema. Backgroundb. Componentsc. Proximate Analysis vs. Van SoestV. Additional Chemical AnalysisVI. Near-Infrared Spectroscopy (NIRS)a. Backgroundb. Advantagesc. DisadvantagesCurrent LectureMethods Used to Evaluate FeedstuffsChemical Analysis:I. Proximate Analysis SystemII. Van Soest Analysis SystemIII. Specific chemical analyses (minerals, vitamins, etc.)Nondestructive Analysis:I. Near-Infrared Reflectance (NIR) SpectroscopyAnimal-Based Methods:I. Metabolism trialsII. Feeding ExperimentsIII. In vivo methods (cannula: single of multiple)Microbiological Methods:These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.I. Nylon bag procedures (in situ)II. In vitro proceduresProximate AnalysisBackground:-most common chemical method used-method of evaluating feed quality without having to conduct metabolism trials orfeeding experiments-Developed by Weende Experiment Station in Germany during the 1850’s-the basis for the Total Digestible Nutrients (TDN) system to evaluate energy availabilitySeparates Sample into 6 Different Fractions:1. Water-feed samples heated to 105˚C for 24 hours-Water content calculated by beginning weight – end weight2. Crude Protein (CP)-Kjeldahl method = older nitrogen analytical method-CP content = N content x 6.25-6.25 Factor = inverse of 16% (N content of plant CP)-Leco Nitrogen Method = newer nitrogen analytical methodWeakness of CP Analysis:-not all protein contains 16% N-nitrogen analysis doesn’t distinguish between non-protein nitrogen (NPN), like urea,and true proteins3. Crude Fat or Ether Extractions (EE):-dry feed sample extracted with petroleum ether-Fat-soluble components are separated from rest of the feed sample-contains fats which are highly digestible (true fats)-crude fat fraction also has waxes and pigments which are less digestible-you can’t really tell the percentage of true fats vs. waxes and pigments in feed4. Ash: -inorganic matter (minerals)-sample is combusted in a muffle furnace @ 600˚C for 24 hours5. Crude Fiber (CF):-Fat-extracted sample is refluxed in a weak acid and a weak base-procedure breaks down the cell wall and then removes soluble proteins, sugars, andstarches (separate starch CHO from fiber CHO by solubilizing cell contents)-in theory, remaining components = cellulose + hemicellulose + lignin-CF = less digestible CHO** 6. Nitrogen-Free Extract (NFE):-NOT a chemical procedure ***-NFE (DM basis) = 100 – (CP + EE + CF + Ash)-cumulative errors of the other analyses**-NFE = highly digestible CHOWeakness of Proximate Analysis System:-separation of CHO into the CF and NFE components is inaccurate and inconsistent****•when breaking cell wall with acids, fiber is sometimes solubilized as well -CF assay does not recover 100% of the cellulose, hemicellulose, and lignin-some of the contents end up in the NFE fraction-variation exists between plants in recovery of fiber componentsComponents of Different Fractions of Proximate Analysis:•Ash-Macrominerals (i.e. calcium) and Microminerals (i.e. copper)•Crude Protein-protein, amino acids, amines (NPN compound), NPN, nucleic acid, nitrates (causenitrous toxicity), and B-complex vitamins•Crude Fat:-fats, oils, waxes, organic acids, pigments, and fat-soluble vitamins (A, D, E, K)•Crude Fiber:-cellulose, hemicellulose, and lignin•Nitrogen-Free Extract:-sugars, starch, pigments, fructans, pectins-some cellulose, hemicellulose, and lignin from solubilization Van Soest SystemBackground:-more accurate system of analyzing the CHO fraction (main focus) of feedstuffs ******-Developed by Peter Van Soest and coworkers at Cornell University-uses detergents to solubilize various portions of plant material-has largely replaced CF analysis (still know, still used in industry)Process:1. Grind up forage sample2. Digest with neutral detergentsa. solubilizes cell contents (protein, starch, sugars, organic acids, and pectin) b. Left with only Hemicellulose, cellulose, and lignin (NDF)3. Digest with acid detergent a. Solubilizes hemicelluloseb. Left with only cellulose and lignin (ADF)4. Digest with 72% sulfuric acida. Solubilizes celluloseb. Left with only ligninNeutral detergent fiber (NDF):-primarily cellulose, hemicellulose, and lignin-total fiber or cell wall content of feeds-highly associated with feed intake, especially in ruminants *********•higher NDF = lower feed intake (slows digestibility)Acid detergent fiber (ADF):-primarily cellulose and lignin-highly associated with digestibility of forages *******•higher ADF = lower digestibility = less energyCell Contents (non-fiber components):-not a chemical assay **-cell contents (DM) = 100 – NDF (DM)Components of Van Soest Fractions:Neutral Detergent Fiber: *****-cellulose, hemicellulose, ligninAcid Detergent Fiber: *****-cellulose and ligninCell Contents: *****-lipids, sugars, pectins, soluble protein, starch, and water-soluble matterNDF and ADF are VERY accurate!!!! **********-ideally, CF should equal NDF, it usually doesn’t because of solubilization of cell wall-analyzing fiber helps know the energy value of feedsOther Chemical AnalysisHeat Damaged Forages:-if hay is bailed before it is less than or equal to 15% moisture, it will create excess heatand impair protein quality-Maillard Reactions (Browning Reactions) are heat-induced chemical reactions betweenprotein (AAs) and sugars that render the protein less digestible ****-ADF-CP is a chemical assay used to measure heat-damaged protein (N bound tocellulose, hemicellulose, and lignin)-don’t need to know ADF-CP equationNear-Infrared-Spectroscopy (NIRS)Background:-method of analysis used to rapidly and reproducibly measure the chemical componentsof feed samples with little to no sample preparations•NIRS is based on: *******-major chemical components in a feed have a unique infrared absorption spectrum-uses vibrations to detect motions of H attached to C, N, or O atoms-near infrared region is part of the electromagnetic spectrum (800-2500 nm) and is slightly broader than visible