unit 2: evaluating feedstuffs for farm livestock

Unit 2: Evaluating Feedstuffs Unit 2: Evaluating Feedstuffs for Farm Livestockfor Farm Livestock

Unit 2: Evaluating Feedstuffs for Unit 2: Evaluating Feedstuffs for Farm LivestockFarm Livestock

Unit 2 Objectives:Unit 2 Objectives:– Understanding of methods used to determine nutrient Understanding of methods used to determine nutrient

composition of feedscomposition of feeds– Knowledge of sample collection methodsKnowledge of sample collection methods– Identify and communicate how feed samples are Identify and communicate how feed samples are

reportedreported– Comprehension of how feedstuff digestibility is Comprehension of how feedstuff digestibility is

determineddetermined– Understand various energy measurements and how Understand various energy measurements and how

they are usedthey are used– Physical and economical evaluation of feedsPhysical and economical evaluation of feeds


Analytical Methods for Nutrient Analytical Methods for Nutrient CompositionComposition– Three general types of methods can be used Three general types of methods can be used

to determine effect of feedstuffsto determine effect of feedstuffsChemical proceduresChemical procedures

– Titration, colorimetry, etc.Titration, colorimetry, etc.

Biological proceduresBiological procedures– Feedstuff tested by a live animal (rat, chick)Feedstuff tested by a live animal (rat, chick)– More accurateMore accurate– Much more tedious and expensiveMuch more tedious and expensive


Microbiological proceduresMicrobiological procedures– Tested w/ isolated bacteriaTested w/ isolated bacteria

– Obtaining Samples for AnalysisObtaining Samples for AnalysisKey to reliable feed nutrient evaluation is a Key to reliable feed nutrient evaluation is a representative samplerepresentative sampleIdentificationIdentification

– Thoroughly identify the feed testedThoroughly identify the feed tested– What might we include in our identification?What might we include in our identification?

SamplingSampling– Grains/Mixed FeedsGrains/Mixed Feeds

Sacked feeds – 2 samples/sack, 5-7 sacks, handful Sacked feeds – 2 samples/sack, 5-7 sacks, handful eacheach


Bulk Feeds – 12 to 15 samples, widely separate Bulk Feeds – 12 to 15 samples, widely separate locations for sampling (while delivered or fed, if locations for sampling (while delivered or fed, if possible)possible)

Mix samples in a clean pail, make sure feed doesn’t Mix samples in a clean pail, make sure feed doesn’t separate, send a 1 or 2lb. sample to the labseparate, send a 1 or 2lb. sample to the lab

– HayHay

Use a core samplerUse a core sampler

Take a 12’ – 15” core sample that will include stem Take a 12’ – 15” core sample that will include stem and leavesand leaves

12 – 15 samples are needed to be accurate (1/bale)12 – 15 samples are needed to be accurate (1/bale)

Try to get to middle of the stack if possibleTry to get to middle of the stack if possible

““Grab” Samples can be used, but accuracy is Grab” Samples can be used, but accuracy is variablevariable


– Haylage or SilageHaylage or SilageUpright silos – collect during feedout, several small Upright silos – collect during feedout, several small samples, mix together for one compositesamples, mix together for one compositePit/Bunker silos – 4-5 grab samples from a fresh Pit/Bunker silos – 4-5 grab samples from a fresh face, do not collect spoiled material, do not collect face, do not collect spoiled material, do not collect within 12”-18” from edgewithin 12”-18” from edgeFreeze if you are collecting over multiple daysFreeze if you are collecting over multiple daysRefrigerate if you can’t mail immediately (what Refrigerate if you can’t mail immediately (what happens if you don’t do this?)happens if you don’t do this?)

– Harvest SamplingHarvest SamplingNot recommended for any feed <30% DMNot recommended for any feed <30% DMSame methods as discussed priorSame methods as discussed prior12-15 samples, mix for one composite12-15 samples, mix for one compositeMark different fields as feed is stored (plastic marker, Mark different fields as feed is stored (plastic marker, oats, etc.)oats, etc.)


– GeneralGeneral

Not beneficial unless you are going to use in Not beneficial unless you are going to use in designing a feeding programdesigning a feeding program

Three benefitsThree benefits to using sampling for proper balance to using sampling for proper balance of feedstuffs – 1) minimize protein supplementation of feedstuffs – 1) minimize protein supplementation and reduce cost, 2) can properly balance if a nutrient and reduce cost, 2) can properly balance if a nutrient is being underfed, 3) can confirm that a factor other is being underfed, 3) can confirm that a factor other than feed is limiting productionthan feed is limiting production

Proximate AnalysisProximate Analysis– Most generally used chemical analysis to describe Most generally used chemical analysis to describe

nutrient composition of feedsnutrient composition of feeds


– Dry Matter (DM)Dry Matter (DM)How do we determine DM content of a feedstuff?How do we determine DM content of a feedstuff?Can we do this ourselves?Can we do this ourselves?What is the benefit of knowing the DM content?What is the benefit of knowing the DM content?

– Ash (minerals)Ash (minerals)Burned sample that removes all other nutrientsBurned sample that removes all other nutrientsOnly inorganic residue remainsOnly inorganic residue remainsMay not be 100% accurateMay not be 100% accurate

– Crude Protein (CP)Crude Protein (CP)Digest to N through chemical process (Kjeldahl Digest to N through chemical process (Kjeldahl process)process)How do we determine CP content from N How do we determine CP content from N concentration?concentration?Does not distinguish between forms of NDoes not distinguish between forms of N


– Ether Extract (Fat)Ether Extract (Fat)

Use ether to extract fat contents for 4 hrsUse ether to extract fat contents for 4 hrs

Loss of wt = fat contentLoss of wt = fat content

Includes some “fats” that are of no use to animals, so Includes some “fats” that are of no use to animals, so may not be 100% accuratemay not be 100% accurate

– CHOCHO

Crude Fiber (CF) – remove water & fat; then through Crude Fiber (CF) – remove water & fat; then through chemical rxn. to remove protein, sugar, and starch; chemical rxn. to remove protein, sugar, and starch; leaves cellulose, lignin, and minerals; (how are the leaves cellulose, lignin, and minerals; (how are the minerals removed?)minerals removed?)

Nitrogen-Free Extract (NFE) – sugars and starches Nitrogen-Free Extract (NFE) – sugars and starches (maybe some hemicellulose & lignin); not determined (maybe some hemicellulose & lignin); not determined by an analysis; 100% - water, ash, protein, fiber, fatby an analysis; 100% - water, ash, protein, fiber, fat


The Van Soest MethodThe Van Soest Method– Focuses on forage fiberFocuses on forage fiber– Divides fiber into digestible and indigestible fractionsDivides fiber into digestible and indigestible fractions– Extraction w/ detergentsExtraction w/ detergents– Predicts intake – NDF – index of gut fillPredicts intake – NDF – index of gut fill– Predicts digestibility – ADF – indicates forage digestibilityPredicts digestibility – ADF – indicates forage digestibility– Heat damaged forages – can help determine the amount Heat damaged forages – can help determine the amount

of protein unavailable in feedstuff. What level of of protein unavailable in feedstuff. What level of unavailable begins to cause problems?unavailable begins to cause problems?


Near Infrared Reflectance SpectroscopyNear Infrared Reflectance Spectroscopy– Ability to sample quickly w/ little preparation (grinding); Ability to sample quickly w/ little preparation (grinding);

only uses one sampleonly uses one sample

Can be completed in <3 min.Can be completed in <3 min.

Analyze multiple components in one operationAnalyze multiple components in one operation– Measurements done by absorption/reflection of lightMeasurements done by absorption/reflection of light– Not accurate for mineralsNot accurate for minerals– Expensive equipment, must be calibrated correctlyExpensive equipment, must be calibrated correctly– Wet-chemistry analysis is more accurateWet-chemistry analysis is more accurate– InexpensiveInexpensive


Determination of VitaminsDetermination of Vitamins– No routine analysis available to determine vit contentNo routine analysis available to determine vit content– Assays can be ordered to determine specific vitamins, if Assays can be ordered to determine specific vitamins, if

neededneeded

Determination of EnergyDetermination of Energy– Bomb CalorimeterBomb Calorimeter– Sample is burned in an oxygen atmosphereSample is burned in an oxygen atmosphere– Liberated heat raises the temp of water surrounding the Liberated heat raises the temp of water surrounding the

devisedevise

This temp increase is the basis for determining the This temp increase is the basis for determining the energy concentrationenergy concentration

1 cal heat required to raise 1g water 11 cal heat required to raise 1g water 1º Cº C


– Nutrient ExpressionNutrient ExpressionDM basisDM basis

– Most accurate/common way to express nutrient levelsMost accurate/common way to express nutrient levels– Levels the playing field to compare feedsLevels the playing field to compare feeds

As-Fed basisAs-Fed basis– Amount of nutrients contained in a feed as the animal Amount of nutrients contained in a feed as the animal

would consume itwould consume it

Air-Dry basisAir-Dry basis– Assumed to be ~90% DMAssumed to be ~90% DM


Let’s practice some conversionsLet’s practice some conversions– Thumb rulesThumb rules

Nutrient concentration should increase when Nutrient concentration should increase when converting to DM basisconverting to DM basis

Wt. will decrease on DM basisWt. will decrease on DM basis

Feeding TrialsFeeding Trials– Can give information as to acceptance and Can give information as to acceptance and

performance of a feedperformance of a feed– Doesn’t tell why a feed performed the way it Doesn’t tell why a feed performed the way it

diddid


Digestion or Metabolism TrialDigestion or Metabolism Trial– Weakness of chemical analysis is that is Weakness of chemical analysis is that is

doesn’t take into account digestibility very doesn’t take into account digestibility very accuratelyaccurately

– Steps of a digestion trialSteps of a digestion trialProximate feed analysis to know what you start w/Proximate feed analysis to know what you start w/Feed a measured amount of feed, or feed at Feed a measured amount of feed, or feed at constant rateconstant rateCollect fecal matterCollect fecal matterProximate analysis on fecesProximate analysis on fecesDifference is the apparent digestibility of the feedDifference is the apparent digestibility of the feed


– Can use markers or indicators to identify Can use markers or indicators to identify feedsfeeds

– Testing can be done in metabolism stalls Testing can be done in metabolism stalls where the animal is somewhat confinedwhere the animal is somewhat confined

Attached to collection instruments for feces and/or Attached to collection instruments for feces and/or urineurine

– Usually done in 2 phasesUsually done in 2 phasesPreliminary phasePreliminary phase

– Frees digestive tract of any other types of feedsFrees digestive tract of any other types of feeds– Animal gets accustomed to the process and feedAnimal gets accustomed to the process and feed– 3-5d in pigs, 8-10d in ruminants3-5d in pigs, 8-10d in ruminants


Collection phaseCollection phase– When feed and fecal collections are measuredWhen feed and fecal collections are measured

– What are some of the chances for error in this What are some of the chances for error in this system?system?

Measures of Feedstuff EnergyMeasures of Feedstuff Energy– Total Digestible Nutrients (TDN)Total Digestible Nutrients (TDN)

General, calculated amountGeneral, calculated amount

Does not account for important losses of digestionDoes not account for important losses of digestion

Can be expressed as lbs., %, or kgCan be expressed as lbs., %, or kg


Can be extremely variable/inaccurate (usually Can be extremely variable/inaccurate (usually overestimate)overestimate)

– 1lb. TDN from 1.2 lbs. corn = 1.2 Mcal NE1lb. TDN from 1.2 lbs. corn = 1.2 Mcal NE– 1lb. TDN from 2.1 lbs. hay = 1.0 Mcal NE1lb. TDN from 2.1 lbs. hay = 1.0 Mcal NE– 1lb. TDN from 2.4 lbs. poor hay = .8 Mcal NE1lb. TDN from 2.4 lbs. poor hay = .8 Mcal NE

– Nutrient Partitioning in Digestion & Nutrient Partitioning in Digestion & MetabolismMetabolism

Energy UnitsEnergy Units– CalorieCalorie = amount of heat needed to raise 1g water 1 = amount of heat needed to raise 1g water 1ºCºC– KilocalorieKilocalorie = 1000 calories = 1000 calories– MegacalorieMegacalorie = 1000 kcal, or 1,000,000 calories (a.k.a. = 1000 kcal, or 1,000,000 calories (a.k.a.

therm)therm)


Gross Energy (GE)Gross Energy (GE)– Total potential energy of a feedstuff consumedTotal potential energy of a feedstuff consumed– Determined in a bomb calorimeterDetermined in a bomb calorimeter

Fecal Energy (FE)Fecal Energy (FE)– Undigested residue that passes through the GIUndigested residue that passes through the GI– Can be collected and tested same method as aboveCan be collected and tested same method as above

Digestible Energy (DE)Digestible Energy (DE)– DE = GE – FEDE = GE – FE– Takes account of some losses during digestionTakes account of some losses during digestion

Gasseous Products of Digestion (GPD)Gasseous Products of Digestion (GPD)– Combustible gasses that escape the body during Combustible gasses that escape the body during

digestion & absorptiondigestion & absorption– Mostly methane; some H, CO, acetone, etc.Mostly methane; some H, CO, acetone, etc.


– Most common in ruminantsMost common in ruminants– Hard to measure accuratelyHard to measure accurately

Urinary Energy (UE)Urinary Energy (UE)– Includes materials that result directly from the Includes materials that result directly from the

digestion/absorption/enzymatic processesdigestion/absorption/enzymatic processes– Many Many endogenousendogenous sources as well sources as well

Metabolizable Energy (ME)Metabolizable Energy (ME)– ME = DE – UE – GPDME = DE – UE – GPD– More accurate measure of nutritive value than DE and More accurate measure of nutritive value than DE and

TDNTDN– Easy to determine in nonruminants because of the lack Easy to determine in nonruminants because of the lack

of GPDof GPD


Heat Increment (HI)Heat Increment (HI)– Increase in heat production following feed consumptionIncrease in heat production following feed consumption– Caused by the heats of fermentation, and heats of Caused by the heats of fermentation, and heats of

nutrient metabolismnutrient metabolism– Energy is wasted unless the environmental temperature Energy is wasted unless the environmental temperature

is below the animal’s critical temperature zoneis below the animal’s critical temperature zone– If it is used for temperature regulation, becomes part of If it is used for temperature regulation, becomes part of

NEmNEm

Net Energy (NE)Net Energy (NE)– NE = ME – HINE = ME – HI– Amount of energy used for maintenance only, or for Amount of energy used for maintenance only, or for

maintenance and production purposesmaintenance and production purposes– Function should be stated clearly when Function should be stated clearly when

reporting/evaluating NEreporting/evaluating NE


– NEm (NE for Maintenance)NEm (NE for Maintenance)

Part of total NE needed to keep animal in energy Part of total NE needed to keep animal in energy equilibriumequilibrium

No gain/loss of energy in body tissueNo gain/loss of energy in body tissue

Basal Metabolism – energy needed to maintain basic Basal Metabolism – energy needed to maintain basic vital cellular activityvital cellular activity

Energy of Voluntary Activity – energy needed for Energy of Voluntary Activity – energy needed for basic movement to obtain food, water, lying down, basic movement to obtain food, water, lying down, etc.etc.

Heat to keep body warm – additional heat needed Heat to keep body warm – additional heat needed when environmental temp < animal’s critical when environmental temp < animal’s critical temperaturetemperature


Heat to keep body cool – extra energy expended Heat to keep body cool – extra energy expended when environmental temp > animal’s thermo neutral when environmental temp > animal’s thermo neutral zonezone

– NEp (NE Production)NEp (NE Production)Additional energy required above NEmAdditional energy required above NEmWhat would be considered production?What would be considered production?NEl, NEgNEl, NEg

Energy in Beef CattleEnergy in Beef Cattle– This system can be used to accurately predict energy This system can be used to accurately predict energy

needs for wt. gain under normal conditionsneeds for wt. gain under normal conditions– Make adjustments for abnormal conditionsMake adjustments for abnormal conditions– See tables 2-3, 2-4, and 2-5 for referenceSee tables 2-3, 2-4, and 2-5 for reference– We will discuss further later in the semesterWe will discuss further later in the semester


Energy in Dairy CattleEnergy in Dairy Cattle– NE values are much more accurate than any other NE values are much more accurate than any other

systemsystem– Evaluate NEm, NEg, and NElEvaluate NEm, NEg, and NEl

NEl – includes energy requirements for pregnancy, NEl – includes energy requirements for pregnancy, reproduction, and milk productionreproduction, and milk production

NEl – most often used component in ration NEl – most often used component in ration formulation and evaluationformulation and evaluation

Energy in SwineEnergy in Swine– Generally use ME or DE as their evaluating toolsGenerally use ME or DE as their evaluating tools– Will eat to energy requirements if feed ad libitumWill eat to energy requirements if feed ad libitum– Will cover further laterWill cover further later


Physical Evaluation of FeedstuffsPhysical Evaluation of Feedstuffs– Eye AppraisalEye Appraisal

Used mostly w/ foragesUsed mostly w/ forages

TypeType

ColorColor

% of leaves% of leaves

Weed contaminationWeed contamination

SpoilageSpoilage

– PalatabilityPalatability


– Factors Affecting ValueFactors Affecting ValueSoil fertilitySoil fertilityGrowing conditionsGrowing conditionsHarvestingHarvesting

– Stage of maturityStage of maturity– LossesLosses

Processing & StorageProcessing & Storage

Evaluating Feeds Cost/Unit of NutrientEvaluating Feeds Cost/Unit of Nutrient– Cost of feed/unit wt. divided by unit wt. * % Cost of feed/unit wt. divided by unit wt. * %

nutrient concentrationnutrient concentration– ExamplesExamples


Unit 2 Assignment:Unit 2 Assignment:– Review Problem Solving QuestionsReview Problem Solving Questions

1-5 1-5

Take your time!!!!Take your time!!!!

unit 2: evaluating feedstuffs for farm livestock

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