ANSC 318 1st Edition Lecture 5 Outline of Last Lecture I Function and Digestion of Proteins Vitamins and Minerals Analysis of Feedstuffs Outline of Current Lecture II Methods of Evaluating Feedstuffs a Chemical based b Nondestructive c Animal based d Microbiological III Proximate Analysis System a Background b Steps of Analysis c Weaknesses d Components of Fractions IV Van Soest System a Background b Components c Proximate Analysis vs Van Soest V Additional Chemical Analysis VI Near Infrared Spectroscopy NIRS a Background b Advantages c Disadvantages Current Lecture Methods Used to Evaluate Feedstuffs Chemical Analysis I Proximate Analysis System II Van Soest Analysis System III Specific chemical analyses minerals vitamins etc Nondestructive Analysis I Near Infrared Reflectance NIR Spectroscopy Animal Based Methods I Metabolism trials II Feeding Experiments III 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 II Nylon bag procedures in situ In vitro procedures Proximate Analysis Background most common chemical method used method of evaluating feed quality without having to conduct metabolism trials or feeding experiments Developed by Weende Experiment Station in Germany during the 1850 s the basis for the Total Digestible Nutrients TDN system to evaluate energy availability Separates Sample into 6 Different Fractions 1 Water feed samples heated to 105 C for 24 hours Water content calculated by beginning weight end weight 2 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 method Weakness of CP Analysis not all protein contains 16 N nitrogen analysis doesn t distinguish between non protein nitrogen NPN like urea and true proteins 3 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 feed 4 Ash inorganic matter minerals sample is combusted in a muffle furnace 600 C for 24 hours 5 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 and starches 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 CHO Weakness 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 components Components 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 cause nitrous 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 System Background 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 sample 2 Digest with neutral detergents a 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 hemicellulose b Left with only cellulose and lignin ADF 4 Digest with 72 sulfuric acid a Solubilizes cellulose b Left with only lignin Neutral 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 energy Cell Contents non fiber components not a chemical assay cell contents DM 100 NDF DM Components of Van Soest Fractions Neutral Detergent Fiber cellulose hemicellulose lignin Acid Detergent Fiber cellulose and lignin Cell Contents lipids sugars pectins soluble protein starch and water soluble matter NDF 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 feeds Other Chemical Analysis Heat Damaged Forages if hay is bailed before it is less than or equal to 15 moisture it will create excess heat and impair protein quality Maillard Reactions Browning Reactions are heat induced chemical reactions between protein AAs and sugars that render the protein less digestible ADF CP is a chemical assay used to measure heat damaged protein N bound to cellulose hemicellulose and lignin don t need to know ADF CP equation Near Infrared Spectroscopy NIRS Background method of analysis used to rapidly and reproducibly measure the chemical components of 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 light multiple reflectance measurements are obtained for each chemical constituent reflectance measurements are then related statistically to the actual chemical constituents based on complex equations uses a database calibration of these equations is the key component to accurate analysis with NIRS nothing is directly