9/6/20131Nutrient Analysis and UtilizationChemical Analysis Sources National Research Council (NRC)  Publications that list nutrient requirements and nutrient content of common feedstuffs for a species Laboratory analysis Specific for your sample Commercial laboratories9/6/20132Types of Laboratory Analysis Proximate Analysis Detergent Analysis System (Van Soest) Near Infrared Reflectance (NIR) Specialized Methods Bomb calorimeter Amino acid analysis Atomic absorption GC HPLCProximate Analysis Groups substances in terms of common chemical characteristics Determines: Dry Matter (Water) Ash Crude Protein (CP) Ether Extract (EE) Crude Fiber (CF) Nitrogen Free Extract (NFE)9/6/20133Dry Matter Dry sample to remove water  Difference = moisture loss Heat sample at 100 – 1050C Time and temperature affect resultsExample:100 g sample 87 g dry sample*Dry at 1000C(As Fed)(Dry Matter)*This sample was 87% DM and 13% waterCrude Protein – Kjeldahl Procedure Sample digested in sulfuric acid Converts N to ammonium sulfate Ammonium is titrated  Analysis determines N content, not CP CP must be calculated CP = N x 6.25 Does not distinguish between different types of nitrogen Gives no indication of protein quality9/6/20134Ether Extract Measures lipid content Sample extracted with ether  Lipids removed from sample Does not distinguish between nutritive (true fat) and nonnutritive (waxes, pigments) components Represents fraction of feed that is highest in energyAsh Measures total mineral content (inorganic matter) Residue after combustible material removed Heat in 500 – 6000C furnace  Little nutritional importance Soil may contaminate Volatile minerals may be lost Selenium, iodineExample:87 g DM 1 g AshHeat at 5000C9/6/20135Crude Fiber Boil in dilute acid, then dilute base, dry, ash Difference before and after ashing is CF Represents structural carbohydrates Cellulose, hemicellulose, lignin Criticized by ruminant nutritionistsNitrogen Free Extract (NFE) Calculation only Consists of difference between original sample weight and weights of water, EE, CP, CF, and Ash NFE = Sample – (water + CP + EE + CF + Ash) Represents the soluble carbohydrate fraction of the feedstuff9/6/20136SampleDry MatterWaterCF + AshCFEther ExtractFat-Free ResidueCrude ProteinDry at 1000CKjeldahlEther ExtractionBoil in Acid Boil in AlkaliAshBurn in FurnaceNFE = Sample – (Water + CP + EE + CF + Ash)Detergent Analysis SystemCell Content:SugarsStarchesSoluble CHOPectinProteinLipidsCell Wall:CelluloseHemicelluloseLignin9/6/20137Detergent Analysis  Developed for ruminant nutrition to replace CF  Uses detergent extractions to separate cell contents from cell wall Neutral Detergent Boil in detergent (sodium lauryl sulfate) Extracts cell contents Cell wall components remain (NDF) Acid Detergent Boil in detergent (cetyl trimethylammonium bromide) and acid (sulfuric) Extracts hemicellulose Cellulose and lignin remain (ADF) Forage SampleHemicelluloseCell Wall (NDF)Cell ContentLignin + Cellulose (ADF)Neutral DetergentAcid Detergent9/6/20138Near Infrared Reflectance (NIR) Uses infrared light  Instrument detects light absorbed and reflected Feed composition evaluated by pattern of reflectance High precision equipment  Requires calibration Strength of data base determines accuracy of analysisSpecialized Analytical Methods Bomb calorimeter Amino acid analysis Atomic absorption spectrophotometry Gas chromatography (GC) High-performance liquid chromatography (HPLC)9/6/20139Bomb CalorimeterSampleThermometerWaterBombIgnition WireInsulated ContainerFurther Analysis Amino acid analysis – amino acid profile Combination of chromatography and spectrophotometry More useful than CP Atomic absorption spectrophotometry –mineral profile Concentrations of individual minerals determined by unique properties as it passes through a flame More useful than ash9/6/201310Further Analysis Gas Chromatography (GC) Determines fatty acids, volatile fatty acids, fat-soluble vitamins Separates compounds by a heated column Closely related compounds separate High-performance liquid chromatography (HPLC) Determines vitamins, supplements, additives, etc. Separates compounds by liquid instead of gasMeasurement of Feed and Nutrient UtilizationMethods Growth trials Production trials Digestion/metabolism trials9/6/201311Growth & Production Trials Growth Measures Body weight, height Feed intake Feed efficiency (F/G) Production Measures Feed intake Rate of production  Eggs, milk, calf weight, conception rateDigestibility Trials Nutrient utilization – determined by digestibility Feed - FecesDigestedUndigested9/6/201312Digestibility Trials Total Collection Animals adjusted to new diet for 3-10 days Feces collected for 4-10 days Determine nutrient content of feed and feces Indicator methods Used when total collection is unavailable Uses internal (feed component) or external (added to feed) markers Digestibility calculated (Apparent digestibility)Apparent Digestibility (%) Total Collection:= Nutrient intake – Nutrient in fecesNutrient intakeX 1009/6/201313Apparent vs. True Digestibility Nutrients are excreted in the feces from endogenous sources Apparent digestibility does not take into account these endogenous sources Underestimates value of feedstuff True digestibility takes into account these endogenous sources= Nutrient intake – (Nutrient in feces – Endogenous Nutrient)Nutrient intakeX 100Balance Trials Provide information on nutrient utilization Measures total intake and total excretion Determines whether net retention or loss occurs Routes of excretion: Feces, urine, expired air, sloughed skin, shed hair, heat loss9/6/201314Rumen Digestion Techniques Batch trials Continuous fermentation Nylon bag techniqueSurgical Procedures to Study Nutrient Utilization  Fistulation Various parts of GI tract – dependent upon species Catheters in veins or arteries9/6/201315Determining Requirements – Growth TrialsFinal Weight, lb.Lysine in Diet, %Deficiency Optimum