AGR 4501 PASTURE MANAGEMENT1 Nutritive Value of Pastures

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  • AGR 4501 PASTURE MANAGEMENT*Nutritive Value of Pastures

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*What is nutritive value?The capacity of a feed to generate animal products if other factors are not limiting

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*AnimalFeedProducts (meat, milk)geneticshealthenvironmentwastesquantityquality

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Good quality feedMust be able to supply the nutrients required for growth and body functions of animal

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*NutrientsEnergyProteinMineralsVitaminsWater

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*EnergyThe most important feed component if all other nutrients are adequateDetermines growth rate and productivity of animals

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Energy in feedTotal energy in feed = Gross Energy (GE) units : MJ (mega joules) per kgEnergy which can be used for growth = net energy (NE)

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*MilkGross EnergyNet Energy

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Gross Energy (GE)Digestible Energy (DE)Metabolizable Energy (ME)Net Energy (NE)FaecesUrine, methaneHeat

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Types of feed and energy contentConcentrates e.g. corn, wheat high energy feed >10 MJ/kgForages and Roughages including pasture: high fibre
  • AGR 4501 PASTURE MANAGEMENT*Measurements of Nutritive QualityDigestibilityVoluntary IntakeProtein ContentMineral & Vitamin content

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*DigestibilityEstimates the proportion of feed which can be digested (Intake-faeces)

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Factors affecting digestibilitySpeciesTemperate > TropicalC3>C4AgeDigestibility declines with ageTemperatureHigh temperature lowers digestibilityProtein ContentIf less than 7%

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Effects of cell structure on digestibilityPlant cells are comprised of:Cell contentsCell wallCell contentsComprise of soluble carbohydrate, protein, completely digestibleCell wall Partially digestible

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Cell wallCelluloseHemicelluloseLigninSilica

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*As plants matureAmount of cell wall increasesProportion of cell content decreasesPercentage of indigestible components increaseDigestibility decreases

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*At the plant levelProportion of stems increases with ageStems become harder (more lignin) as plant ageProportion of old and senescing leves increase

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Methods of measuring digestibilityIn vivoIn vitroNylon BagVan Soest analysis

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*In vivoUse real life animal Weigh feed and offer to animalWeigh uneaten feed the next dayCalculate feed intake (feed offered-feed remaining)Weigh faecesCalculate digestibility7 days adaptation 10 days measurement

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*In vitro(Tilley & Terry, 1963)Obtain rumen fluid from fistulated animalProvide anaerobic condition by infusing nitrogenIncubate ground dried feed sample 39oC for 48 hrsAdd acid pepsin and incubate in aerobic condition for 48 hrsFilter and weigh residue (undigested)

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Rumen fistulated cattle

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Nylon BagUse 6 g of dried ground sampleWrap in nylon bags 15x6 cmIntroduce into rumen via fistulaLeave for 48 hrRemove bags and incubate further in acid pepsin for 48 hrWeigh residue

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Rumen fistulated cattle

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Nylon bags filled with feed sample

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*KN4, 6 and 8 WAPAH and SBMSampled and driedgroundCP, OM, NDF and ADFdeterminationIn situ DM and CP disappearanceusing nylon bag techniqueInsertion of nylon bags into the rumenfor 72, 48, 24, 16, 12, 8 and 4h Removed,washedRuminal degradation study (Nylon bag technique)

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Intestinal digestion study (mobile bag technique) Test samples were incubated in the rumen for 16 and 24h Removed, washed and dried Each dried residual sample was fitted (0.5g) into six mobile bags and sealed Incubated in a Pepsin-HCL solution for 1hat 37 C, rinsed and then kept on ice, 4 C Introduced into duodenum of canulated steers, 20 min./bagCollected from the feces, stored at -18C, washed DM, CP, amino acid* determinationCalculation of intestinal DM, CP and amino acid* disappearances * Ruminal and intestinal residues will be analyzed for amino acids later

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Effects of protein on digestibility

    % protein% digestibility3.651.76.859.5

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Effects of protein on digestibility

    % protein% digestibility3.651.76.859.5

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Effects of minerals on digestibility

    % sulfur% digestibility0.0955.20.1560.2

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Measurements of Nutritive QualityDigestibilityVoluntary IntakeProtein ContentMineral & Vitamin content

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Voluntary IntakeThe quantity of feed ingested by animals when fed ad libitumInfluenced by animal size, breed, physiology and healthHigher quality feed should have higher intake

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Voluntary IntakeUnit of measureg/kg liveweight0.75eg. Weight of cow 150 kg, consumes 3 kg DM, V.I. = 3000/1500.75 = 3000/42.86 = 70 g/kg0.75

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Factors affecting V.I.DigestibilityParticle size of feedProtein content if
  • AGR 4501 PASTURE MANAGEMENT*Mechanism controlling intakeIntake depends on rate of passage through rumen and alimentary tractFast rate of passage, more feed can be ingestedFeed of low digestibility and low protein stays longer in rumen

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*V.I. can be improved byGrinding or chopping feed to smaller particlesAdding protein or urea to low protein feedAdding minerals which are deficient

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Leaf:stem ratio affects V.I.

    KabulabulaHamil% leaf28.053.0% digestibility55.255.5V.I. g/kg0.7549.167.3

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Sward density effects on V.I.Short, compact, grasses have higher intake needs fewer bites compared to loose swards

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Methods of measuring intakeIn vivoIndigestible markers for grazed pastureNDF is correlated with intake

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Indigestible markerChromium oxideDose animal with known amount of markerAnalyse the faeces for the markerEstimate the amount of faecesKnowing digestibility of feed, can calculate intake

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Measurements of Nutritive QualityDigestibilityVoluntary IntakeProtein ContentMineral & Vitamin content

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Protein contentProtein required by animals for growth, milk production and reproductionProtein requirements vary between stage of growth of animals, dry and lactatingCritical level is at 7% protein, below which feed intake is reduced

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Factors affecting protein contentSpecies: legumes 18-30% protein grasses 6-15% protein Age protein declines as plant mature decline is greater with grasses Nitrogen Fertiliser

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Measurement of ProteinProtein contains ~ 16% N To determine protein content, analyse N content and multiply by 6.25 (100/16=6.25) eg. 2% N = 12.5% proteinMeasurement of N by Kjeldahl method

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Mineral contentLack of minerals will results in metabolic disorderSupply mineral lick or supplements to overcome deficiencyPlants usually have low P and Na compared to animal needs

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Indirect Measurement of Nutritive ValueBased on fibre content and compositionCan be correlated with digestibility and intakeThe method is faster and less expensive

    AGR 4501 PASTURE MANAGEMENT

  • AGR 4501 PASTURE MANAGEMENT*Proximate Analysis Has been