spongiform encephalopathies · 2007-08-02 · elizabeth mumford ernst nef lukas perler andrew...

ManageMent OF transMissible spOngiFOrM encephalOpathies in livestOck Feeds and Feeding

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Olivier Fumièredaniel guidondagmar heim

elizabeth Mumford ernst nef

lukas perlerandrew speedy

FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONSrome, 2007

CApACITy BUILDING FOR SURvEILLANCE AND pREvENTION OF BSE AND OTHER ZOONOTIC DISEASES

course manual

The designations employed and the presentation of material in this information product do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal or development status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.

All rights reserved. Reproduction and dissemination of material in this information product for educational or other non-commercial purposes are authorized without any prior written permission from the copyright holders provided the source is fully acknowledged. Reproduction of material in this information product for resale or other commercial purposes is prohibited without written permission of the copyright holders. Applications for such permission should be addressed to the Chief, Electronic Policy and Support Branch, Communication Publishing Division, FAO, Viale delle Terme di Caracalla, 00153 Rome, Italy or by e-mail to [email protected]

© FAO 2007

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CONTENTS

Foreword v

Courseobjectives vii

INTRODUCTION TO TRANSmISSIBLE SpONGIFORm ENCEpHALOpATHIES

1. transmissible spongiform encephalopathies 1

2. bovine spongiform encephalopathy 3

3. Measures for control and prevention 5

4. clinical signs of bse 10

5. diagnosis of bse 10

6. surveillance systems 14

7. risk assessment 16

8. references 17

OvERvIEw: ImpLEmENTATION OF TRANSmISSIBLE SpONGIFORm ENCEpHALOpATHIES mEASURES FOR LIvESTOCk FEEDS

1. general concepts 21

2. ban on srM in feeds 21

3. scope of feed bans 22

4. control of cross contamination 22

5. import restrictions 23

6. enforcement 23

7. references 23

pROTEIN USE IN LIvESTOCk FEEDING


2. protein sources and supplements 28

3. summary of tse-relevant concepts 31

4. references 32

INACTIvATION OF TRANSmISSIBLE SpONGIFORm ENCEpHALOpATHIES AGENTS


2. inactivation procedures 33

3. Future development of inactivation in rendering 35

4. references 36

iv

RENDERING OF ANImAL By-pRODUCTS


2. the rendering process 37

3. goals of the rendering process 38

4. Other options for animal by-product disposal 39

5. animal by-product legislation in the european Union 39

6. the future use of meat and bone meal 41


8. references 42

mANUFACTURING OF COmpOUND FEEDS FOR LIvESTOCk


2. structure of a feed production plant 43

3. Feed production processes 45

4. references 50

LIvESTOCk FEED REGULATIONS AND INDUSTRy GUIDELINES


2. international standards and national/regional regulations 52

3. implementation of international and national standards and regulations: industry guidelines 57


5. references 61

QUALITy ASSURANCE IN FEED-pRODUCING pLANTS


2. important points for quality assurance 64

3. documentation and data 69

4. complaints and product recall 70

5. sample collection 71


7. references 73

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LABORATORy ANALySIS FOR THE DETECTION OF pROHIBITED mATERIALS IN LIvESTOCk FEED


2. available test methods 76

3. comparison of tests 80


5. references 82

BSE RISk AND TRADE IN ANImAL pRODUCTS AND LIvESTOCk FEEDS


2. the effects of bse on global trade 83

3. assessing the risks of bse in trade 83

4. trade data: quality and quantity 84

5. assessing bse exposure risk 86


7. references 89

AppENDIX 1

course contributors and staff 91

AppENDIX 2

related background reading and Web links 95

AppENDIX 3

glossary of technical terms and acronyms 101

AppENDIX 4

project summary 109

vii

FOREwORD

Tosupportcountrieswitheconomiesintransitionanddevelopingcountriesinthecon-trol and prevention of bovine spongiform encephalopathy (BSE), the project CapacityBuildingforSurveillanceandPreventionofBSEandOtherZoonoticDiseases,involvingcollaboration between the Food and Agriculture Organization of the United Nations(FAO), Safe Food Solutions, (SAFOSO, Switzerland) and national veterinary offices inpartnercountries,andfundedbytheGovernmentofSwitzerland.

Theaimoftheproject istobuildcapacity,establishpreventivemeasuresandana-lyserisksforBSE.PartnercountriesarethusenabledtodecreasetheirBSErisktoanacceptablelevelordemonstratethattheirBSEriskisnegligible,andtherebyfacilitateregionalandinternationaltradeundertheAgreementontheApplicationofSanitaryandPhytosanitaryMeasures (SPS)of theWorldTradeOrganization (WTO).Abriefprojectsummaryisincludedasanappendixtothiscoursemanual.

Activitiesoftheproject:• Thespecificneedsofpartnercountriesareassessed.• Fourcomprehensivecoursesto“trainthetrainers”areprovidedtoselectedpar-

ticipantstoimproveunderstandingoftheepidemiologyofandrelevantriskfactorsfor BSE and Transmissible spongiform encephalopathies (TSE) and to developspecificknowledgeandskillsforimplementingappropriatecontrols.

• Inathirdstep, in-countrycoursesareheldbytrainednationalpersonnel inthelocallanguageandaresupportedbyanexperttrainer.

FAOhasthemandatetoraiselevelsofnutritionandstandardsofliving,toimproveagricultural productivity and the livelihoods of rural populations. Surveillance andcontrol of diseases of veterinary public health importance contribute to this objec-tive.SAFOSO,aprivateconsultingfirmbasedinSwitzerland,isprovidingthetechnicalexpertiseforthisproject.

This manual is a supplement to the training course Management of transmissiblespongiformencephalopathiesinlivestockfeedsandfeeding,whichisgivenwithintheframeworkoftheproject.ThispracticalcourseistargetedatgovernmentalandindustrypersonnelwhowillcontributetothedevelopmentandimplementationofthenationalBSEsurveillanceandcontrolprogramme,andtotheBSEriskassessmentforthepart-nercountries.

Theinformationincludedinthemanualisnotintendedtobecompleteortostandonitsown.Forfurtherreading,specificreferencesareincludedattheendofthechapters.General background material and Web links, and a glossary of terms and frequentlyusedacronymsareincludedasappendices.

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ThepreparationofthismanualwasacollaborativeeffortofthetrainersoftheMan-agementoftransmissiblespongiformencephalopathiesinlivestockfeedsandfeedingcourseofferedinSwitzerlandandtheprojectstaff.Thecontentofthemanualreflectstheexpertiseandexperienceoftheseindividuals.FAOandSAFOSOaregratefultotheprofessionalspreparingthemanualandtotheGovernmentofSwitzerlandforfundingthispublic-privatepartnershipprojectinsupportofsaferanimalproductionandtrade.

Samuel C. Jutzi Ulrich kihm Director Director FAOAnimalProductionandHealthDivision SafeFoodSolutions Rome,Italy Berne,Switzerland

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COURSE OBJECTIvES

UponcompletionofthelecturesandexercisesofthecourseonManagementoftrans-missible spongiform encephalopathies in livestock feeds and feeding, of the projectCapacityBuildingforSurveillanceandPreventionofBSEandOtherZoonoticDiseases,theparticipantsshould:

• basic informationonBSEandTSEs, including transmission,pathogenesis, riskfactors,andepidemiology;

• renderingandinactivationofTSEagents;• categorization ofanimal by-productsand knowledge of the risks of animal by-

productsinanimalfeed;• modernprocesstechnology in feedandpremixmanufacturingplants, including

controlofcrosscontaminationwithanimalby-products;• internationalandnationalregulationsinfeedmanufacturing,includingguidelines

fortheuseofanimalby-products;• qualitymanagementinfeedmanufacturing;• samplingstrategiesfortestingoffeedandprinciplesofthetests;• inspectionoffeedplants,includingBSEcontrols;• globalmarketforanimalfeed,includingassessmentandcontroloftherisks.

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INTRODUCTION TO TRANSmISSIBLE SpONGIFORm ENCEpHALOpATHIES

1. TRANSmISSIBLE SpONGIFORm ENCEpHALOpATHIESTransmissible spongiform encephalopathies (TSE) are a class of neurodegenerativediseasesofhumansandanimalscharacterizedbyspongiformdegenerationofthebrainandtheassociatedneurologicalsigns.TSEsareslowlydevelopinganduniformlyfatal.

Diseasesincludekuru,Gerstmann-Sträussler-ScheinkersyndromeandCreutzfeldt-Jakobdisease(allinhumans),scrapie(insheepandgoats),felinespongiformencepha-lopathy(FSE;incats),bovinespongiformencephalopathy(BSE;incattle),chronicwast-ingdisease(CWD;incervids)andtransmissibleminkencephalopathy(TME;inmink).MostoftheseTSEshadalreadybeenreportedbeforethefirstdetectionofBSE.(Figure1)(Lasmezas,2003).

FigUre 1

year in which the various TSEs were first reported

1700 1750 1800 1850 1900 1950 2000

Variant Creutzfeldt-Jakob disease

Feline spongiform encephalopathy

Bovine spongiform encephalopathy

Chronic wasting disease

Transmissible mink encephalopathy

Gerstmann-Sträussler-Scheinker syndrome

Creutzfeldt-Jakob disease

Kuru

Scrapie

The TSE with the longest history is scrapie, which was recognized as a disease ofsheepinGreatBritainandothercountriesofwesternEuropemorethan250yearsago(DetwilerandBaylis,2003).Scrapiehasbeenreportedinmostsheep-raisingcountriesthroughouttheworldwithfewnotableexceptions(e.g.Australia,NewZealand).

Transmissible mink encephalopathy (TME) was first described in 1947. It is a rarediseaseoffarmedminkandhasbeenrecordedincountriesincludingtheUnitedStatesofAmerica(USA),Canada,Finland,GermanyandtheRussianFederation.ContaminatedfeedissuspectedtobethemainsourceofTMEinfection.

Chronicwastingdisease(CWD)incaptiveandfree-roamingNorthAmericandeerandelkwasfirstdescribedinthe1960s.Initially,caseswereonlyreportedincaptivedeerandelkinColorado(USA),butCWDincaptiveand/orfreeroamingdeer,elkandmoosehasnowbeenreportedinseveralotherstatesintheUSAandinareasofCanada.TheoriginofCWDisstillunknown.

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Scrapie, kuru, Creutzfeldt-Jakob disease, Gerstmann-Sträussler-Scheinker syn-drome,TME,andCWDarebelievedtobedistinctfromBSE.However,straintypinghasindicatedthatsomeotherTSEsarecausedby thesamestrainof theTSEagent thatcausesBSE incattle.Only fouryearsafter the initialBSEcaseshadbeendiagnosedin cattle in the United Kingdom of Great Britain and Ireland (UK), BSE in domesticcats (feline spongiform encephalopathy / FSE) was first reported. Almost all of theapproximately100FSEcasesdiagnosedworldwideoccurredintheUK.Themostwidelyacceptedhypothesis is that theaffecteddomesticcatswereexposedtoBSE infectiv-ity throughcontaminatedcommercialcat feedor freshslaughteroffal thatcontainedbrainorspinalcordfrombovineBSEcases.SeverallargecatskeptinzooswerealsodiagnosedwithFSE.Theseincludedcheetahs,lions,ocelots,pumasandtigers.AllofthelargecatsthatwerediagnosedwithFSEoutsidetheUKoriginatedfromUKzoos.It issuspected that these largecatsacquired the infectionbybeing fedcarcassesofBSE-infectedcattle.

NotlongafterBSEwasdiagnosedincattle,sporadiccasesofBSEinexoticruminants(kudus,elands,Arabianoryx,ankolecows,nyala,gemsbockandbison)werediagnosedinBritishzoos.OnezebuinaSwisszoowasalsoBSEpositive.Inthemajorityofthesecases,exposuretoanimalfeedproducedwithanimalprotein(andthereforepotentiallycontainingBSEinfectivity)waseitherdocumentedorcouldnotbeexcluded.

Moreover, there has long been concern that sheep and goats could have beenexposed to BSE, because it has been experimentally demonstrated that BSE can beorally transmitted tosmall ruminants (SchreuderandSomerville,2003). In2005, thefirstcaseofBSE inagoatwasconfirmed inFrance (Eloit etal., 2005), though therehavebeennoconfirmedBSEcasesinsheeptodate.Itisdifficulttodistinguishbetweenscrapie and BSE in sheep, as differentiation is currently not possible by clinical orpathologicalmeans.

SeveralTSEshavebeenreportedtooccurinhumans,includingtwoformsofCreut-zfeldt-Jakobdisease(sporadicCJDandvariantCJD[vCJD]),Kuru,Gerstmann-Sträus-sler-Scheinkersyndrome,aswellas fatal familial insomnia.Of these,onlyvCJDhasbeenassociatedwithBSE.SporadicCJDwasfirstidentifiedin1920asanencephalopa-thyoccurringalmostexclusivelyinelderlypatientsworldwide.TheincidenceofsporadicCJD isapproximately0.3-1.3casespermillion individualsper year,and issimilar inmostcountries.Thedurationofthediseaseisapproximatelysixmonths.Approximately80-89%ofCJDcasesarebelievedtobesporadic,10%arefamilial(aresultofaheritablemutationinthePrPgene),andtheremainderarebelievedtobeiatrogenic.

VariantCJDwasfirstreportedinMarch1996intheUK(Willetal.,1996).IncontrasttosporadicCJD,patientsareyoung(averageage29years)andthedurationofthediseaseis longer(average22months).Epidemiologically, little isknownaboutvCJD. Insomecasesthediseasewasseeningeographicalclusters,andthereareindicationsthatspe-cialconsumptionpatternsmayhaveplayedarole.Geneticfactorsmayalsoplayaroleininfection,aspatientswithclinicaldiseasehavebeenhomozygousformethionineatcodon129oftheprionproteingene.InEurope,thisgenotypeaccountsforapproximately30%ofthepopulation.

The expected course of the vCJD epidemic is difficult to predict, since importantvariablessuchashumanexposurerate,theinfectiousdose,theincubationperiodandhumansusceptibilityarelargelyunknown.Thepredictions initiallyrangedfromafewhundredtoafewmillionexpectedcases.However,thelowerpredictionsaremoreprob-

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ablebasedonthecurrentincidenceofvCJDcases(Figure2).ThelinkbetweenBSEandvCJDiscommonlyaccepted.Initially,thetemporospatial

associationoftheoutbreakssuggestedacausalrelationship.Experimentally,inocula-tionoftheBSEagentintothebrainsofmonkeysproducesfloridplaqueshistologicallyidenticaltothosefoundinthebrainsofvCJDpatients.Inaddition,theagentsassociatedwithBSEandvCJDaresimilar,bothbyglycotyping(evaluatingtheglycosylationpattern)andbystraintyping,whereastheprionsassociatedwithotherTSEs(suchassporadicCJD,scrapieandCWD)aredifferent.

2. BOvINE SpONGIFORm ENCEpHALOpATHy2.1. Origin and spread of BSEBSEwasfirstdiagnosedincattleintheUKin1986(Wellsetal.,1987).Extensiveepide-miologicalstudieshavetracedthecauseofBSEtoanimalfeedcontaininginadequatelytreated ruminant meat and bone meal (MBM) (Wilesmith et al., 1988). Although ele-mentsofthescenarioarestilldisputed(e.g.originoftheagent;Wilesmithetal.,1991;Princeetal.,2003;SSC,2001a), itappears likely thatchanges inUKrenderingproc-essesaround1980allowedtheetiologicalagenttosurviverendering,contaminatetheMBM,andinfectcattle.SomeoftheseinfectedcattlewouldhavebeenslaughteredatanolderageandthereforewouldhavebeenapproachingtheendoftheBSEincubationperiod.Potentially,theyhadnoclinicalsignsorthesignsweresubtleandwentunrec-ognized, although the cattle would have harboured infectivity levels similar to thoseseen inclinicalBSEcases.Thewasteby-products from thesecarcasseswould thenhavebeenrecycledthroughtherenderingplants,increasingthecirculatinglevelofthepathogen(whichbynowwouldhavebecomewelladaptedtocattle)intheMBM,thuscausingtheBSEepidemic.

In1989,thefirstcasesoutsidetheUK,intheFalklandIslandsandOman,wereidenti-fiedinlivecattlethathadbeenimportedfromtheUK.In1989,Irelandreportedthefirstnon-imported(“native”or“indigenous”)caseoutsidetheUK,andin1990Switzerland

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

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20

15

10

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3

10

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18

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FigUre 2

Number of vCJD cases in the Uk over time

Source:DepartmentofHealthUK(2006)

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reportedthefirst indigenouscaseontheEuropeancontinent. IndigenouscaseswerethenreportedinmanycountriesthroughoutEurope.In2001,JapanreportedthefirstindigenouscaseoutsideEurope,andthiscasehasbeenfollowedbyindigenouscasesinIsraelandNorthAmerica.1

2.2. EpidemiologyCattletestingpositiveforBSEhaverangedfrom20monthsto19yearsofage,althoughmostofthecasesarebetween4and6yearsofage.Abreedorgeneticpredispositionhasnotbeenfound.MostcasesofBSEhavecomefromdairyherds,likelyduetodif-ferences infeedingsystemswhencomparedwithbeefcattle.Additionally,beefcattlearetypicallyyoungeratthetimeofslaughter.Becausetheaverageincubationperiodisfourtosevenyears,infectedbeefcattlewillgenerallynotlivelongenoughtodevelopclinicalsigns.

Thereisnoexperimentalorepidemiologicalevidencefordirecthorizontaltransmis-sionofBSE,andthereisstillcontroversyregardingthepotentialforverticaltransmis-sion.Noinfectivityhasthusfarbeenfoundinmilk(TAFS,2007;SSC,2001b),ova,semen,or embryos from infected cattle (SSC 2002a, 2001c; Wrathall, 1997; Wrathall et al.,2002).SomeoffspringofBSEcasesintheUKwerealsoinfected,andacohortstudyofUKcattleconcludedthatverticaltransmissioncouldnotbeexcluded.However,theroleofvariationingeneticsusceptibilityorothermechanismsinthisconclusionisunclear,andnooffspringofBSEcaseshavebeenreportedwithBSEoutside theUK. Ifsomeamountofmaternaltransmissiondoesoccur,it isclearlynotenoughtomaintaintheepidemic,evenwithintheUK.

2.3. pathogenesis Intheearly1990s,infectivitystudiesofBSEincattlewereongoing.Atthattime,experi-mentalinoculationoftissuesfromBSE-infectedcattleintomicehadonlyidentifiedinfec-tivityinbraintissue.Therefore,definitionofspecifiedriskmaterials(SRM;thosetissuesmost likely to be infective) was based on scrapie infectivity studies. Scrapie replicatesprimarilyinthelymphoreticularsystem,andscrapieinfectivityhasbeenfoundinnumer-ouslymphnodes,tonsils,spleen,lymphoidtissueassociatedwiththeintestinaltractandplacenta.Duringthelaterpreclinicalphase,infectivityisfoundinthecentralnervoussys-tem(CNS).Inaddition,scrapieinfectivityhasbeendetectedinthepituitaryandadrenalglands,bonemarrow,pancreas,thymus,liverandperipheralnerves(SSC,2002b).

The first resultsofBSEpathogenesisstudies, inwhichcalveswere intracerebrallyinoculatedwithtissuefromBSEfieldcasesandfromcattleexperimentallyinfectedbytheoral route,becameavailable in themid-1990s (Wellsetal.,1996;1998). Incattleexperimentally infectedby theoralroute,BSE infectivityhasbeen found in thedistalileumatspecificintervalsduringtheincubationperiod,startingsixmonthsafterexpo-sure(Wellsetal.,1994).Furthermore,CNS,dorsalrootgangliaandtrigeminalgangliawerefoundtobeinfectiveshortlybeforetheonsetofclinicalsigns.Recently,lowlevelsof infectivity early in the incubation period have been detected in the palatine tonsil.Inonestudy,sternalbonemarrowcollectedduringtheclinicalphaseofdiseasewasinfective;however,thisresulthasnotbeenreproduced(thereforeitmaypossiblyhavebeenduetocrosscontamination)(Wellsetal.,1999;Wells,2003).

1 CurrentthroughJanuary2007.

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2.4. TSE agentsAlthough some controversy still exists regarding the nature of the BSE agent, mostresearchersagreethataresistantprionproteinisthecauseofthedisease.Researchhasshowntheagenttobehighlyresistanttoprocessesthatdestroyothercategoriesofinfectiousagents,suchasbacteriaandviruses,andnonucleicacidhasbeenidentified.

Ineukaryoticspecies,mostcellscontainanormalprionprotein,termedPrPC(super-script “C” for “cellular”).Thisprotein isnormallydegradablebyproteases.TSEsarethoughttobecausedbyanabnormal,infectiousformofPrPC,inwhichthestericcon-formationhasbeenmodifiedandwhich ishighlyresistant toproteinasedegradation.This infectious form ismostcommonly termedPrPSc(initially for “scrapie”),butmayalsobereferredtoasPrPBSEorPrPres(fortheportionthatis“resistant”toaspecificpro-teinase,proteinaseK).Becauseprionproteinisverycloselyrelatedtothenormalcel-lularPrPCprotein,itdoesnotinducetheproductionofantibodiesininfectedanimals.

TheroleofPrPCinnormalanimalsisstillunderdiscussion.GeneticallymodifiedmicelackingthegeneforPrPC(andexpressingnoPrPC)canbeexperimentallyproduced,butthesemicehavenoobviousphysiologicalchangesthatcanbeattributedtolackingtheprotein.Theycannot,however,beinfectedexperimentallywithTSEagents.

3. mEASURES FOR CONTROL AND pREvENTION3.1. Aims of measuresTheultimateaimsofBSEcontrolandpreventionprogrammesaretoreduceexposureriskbothtocattleandtohumans(Figure3).Twolevelsofmeasuresmustthereforebeconsidered:

• thosethatblockthecycleofamplificationinthefeedchain;• thosethatpreventinfectivematerialfromenteringhumanfood.

Asaresultoftheprolongedincubationperiod,itmaybemorethanfiveyearsbetweeneffective enforcement of measures and a detectable decrease in the number of BSEcases,i.e.beforetheeffectofthemeasuresisseen.Thisintervalmaybeevenlongerifthemeasuresarenotenforcedeffectively,asisusuallythecaseforsometimeafterimplementation.

FigUre 3

Reducing BSE exposure risk to both cattle and humans

Blockamplification

EradicateBSE

Prevent the BSE agent from entering human food

Prevent animal exposure

Prevent human exposure

Recycling andamplification cycle in cattle

MeasuresIntermediate

goalsUltimate

aims

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RiskmanagementforBSEisnotgloballyharmonized.InEurope,thememberstatesoftheEuropeanUnion(EU)havecommonrulesfortheimplementationofmeasures,andothercountriesinEuropeandcountrieswantingtojointheEUareadaptingtheirmeasures accordingly. However, the implementation of these measures still variesconsiderablyfromonecountrytoanother.

3.2. measures to protect animal healthFeed bansRecognitionofMBMasasourceofinfectionledtobansonfeedingMBMtoruminantsinordertobreakthecycleofcattlereinfection(DEFRA,2004a;EC,2004;HeimandKihm,1999).Implementationofa“feedban”maymeandifferentthingsindifferentcountries.FeedscontainingMBMofruminantormammalianoriginmightbebanned,orthebanmight includeallanimalproteins (i.e.mammalianMBM, fishmealandpoultrymeal).Thebanmightprohibitfeedingofthematerialstoruminantsortoalllivestockspecies,ormightentirelyprohibituseofthematerial.

Insomecountries,afeedbanofruminantMBMtoruminantswasimplementedasthefirststep.ThebanwasthenoftenextendedtomammalianMBMduetothediffi-cultyindistinguishingbetweenheat-treatedMBMofruminantoriginandMBMofothermammalianorigin.Thisextendedbanwasgenerallyeasiertocontrolandenforce.

EvenwhennoMBMisvoluntarilyincludedincattlefeed,thereisstillariskofrecyclingtheagentthroughcrosscontaminationandcrossfeeding.ExperiencehasshownthatsmallamountsofMBMinfeedaresufficienttoinfectcattle.ThesetracesmayresultfromcrosscontaminationofMBM-freecattlefeedwithpigorpoultryfeedcontainingMBM,e.g.fromfeedmillsthatproducebothtypesoffeedinthesameproductionlines,fromtransportbythesamevehiclesorfrominappropriatefeedingpracticesonfarms.Apparently,usingflushingbatchesasasafeguardagainstsuchcrosscontaminationinfeedmills isnotsufficient.ThetracesofMBMincattlefeedthathavebeendetectedinEuropeancountriesaremostoftenbelow0.1%,whichseemstobeenoughtoinfectcattle.Therefore,aslongasfeedingofMBMtootherfarmedanimalsisallowed,crosscontaminationofcattlefeedwithMBMisverydifficulttoeliminate.Dedicatedproduc-tionlinesandtransportchannelsandcontroloftheuseandpossessionofMBMatfarmlevelarerequiredtocontrolcrosscontaminationfully. InmostEuropeancountries,abanonfeedingMBMtoallfarmanimalshasnowbeenimplemented.

Moredetailed informationonmeasures for livestock feedscanbe found insubse-quentchaptersofthiscoursemanual.

Rendering parametersRenderingofanimalby-products(e.g.bovinetissuesdiscardedattheslaughterhouse)andfallenstockintoMBM,whichisthenfedtoruminants,canrecycletheagentandallowamplification.Whenrenderingprocessesareproperlyapplied,thelevelofinfec-tivityisreduced.Ithasbeendeterminedthatbatch(ratherthencontinuous)renderingat133ºCand3barsofpressurefor20minuteseffectivelyreducesinfectivity(providingthat the particle size is less than 50 mm) although it does not completely inactivatetheagent(Tayloretal.,1994;TaylorandWoodgate,1997;2003;OIE,2005a).Therefore,using these parameters does not guarantee absolute freedom from infectivity in theMBM,especiallywhenmaterialwithhighlevelsofBSEinfectivityenterstherenderingprocess.

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More detailed information on measures for rendering can be found in subsequentchaptersofthiscoursemanual.

Specified risk materialsSpecifiedriskmaterials(SRM),aretissuesthathavebeenshown(orareassumed)tocontainBSEinfectivityininfectedanimals,andthatshouldberemovedfromthefoodand feedchains (TAFS,2004a). If thesematerialsareremovedatslaughterand thenincinerated, the risk of recycling the pathogen is markedly reduced. In addition, inordertoremoveinfectivityfurtherfromthefeedchain,carcassesfromhigh-riskcattle(e.g.fallenstock)shouldalsobetreatedasSRM.CountriesdefineSRMdifferently,anddefinitionssometimeschangeasnew informationbecomesavailable;however,mostdefinitionsincludethebrainandspinalcordofcattleover30months(Table1).

3.3. measures to prevent human exposureTheabovemeasurestoprotectanimalhealthindirectlyprotecthumanhealthbycon-trolling the amplification of the BSE agent. The most important direct measures forpreventinghumanexposure to theBSEagent in foodsaredescribed in the followingpages.

Ban of SRm and mechanically recovered meat for foodExcludingSRMandmechanically recoveredmeat (MRM) from thehuman foodchaineffectivelyminimizestheriskofhumanexposureandisthemostimportantmeasuretakentoprotectconsumers (TAFS,2004a).MRMisapastederived fromcompressed

TABLE 1. A summary of designated SRm in Europe (as of October 200�)

Species and tissue European Union Uk and portugal Switzerland

Age

CATTLE

Skull(includingbrainandeyes) >12months - >6months

Entirehead,(excludingtongue) - >6months >30months

Tonsils Allages Allages Allages

Spinalcord >12months >6months >6months

Vertebralcolumn(includingdorsalrootgangliabutNOTvertebraeoftailortransverseprocessesoflumbarandthoracicvertebrae) >24months >30months >30months(includestail)

Intestinesandmesentery Allages Allages >6months

Spleen - >6months -

Thymus - >6months -

SHEEp AND GOATS

Skull(includingbrainandeyes) >12month >12months >12months

Spinalcord >12months >12months >12months

Tonsils >12months >12months Allages

Ileum Allages Allages Allages

Spleen Allages Allages Allages

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carcasscomponentsfromwhichallnon-consumabletissueshavebeenremoved.Thesecarcasscomponentsincludebonesaswellasthevertebralcolumnwiththespinalcordanddorsalrootgangliaoftenattached.TheMRMisthenusedincookedmeatproducts,suchassausagesandmeatpies,and,ifruminantmaterialisincluded,isregardedasamajorBSEriskfactor.

BSE detection at slaughterMeasuresforminimizingrisksforhumanhealthrequiretheidentificationandelimina-tionofclinicallyaffectedanimalsbeforeslaughter,whichcanonlybeachievedthroughanadequatesurveillanceprogrammeincludinganantemorteminspectionspecificforBSE.BecausetheSRMfromclinicallyaffectedanimalsisknowntocontaininfectivity,removalanddestructionof theseanimalsprior toentering theslaughterhousehavetwoclearlypositiveeffects:

• Theriskofinfectivematerialenteringthefoodandfeedchainsisreduced.• There is lesscontaminationof theslaughterhouse,and lesspotential forcross

contaminationofnormalcarcasses.Inaddition,mostcountriesinEuropehavebeenconductinglaboratorytestingofall

slaughter cattle over 30 months of age (or even younger) for BSE since 2001 (TAFS,2004b).

Thebenefitsoftestingregularslaughtercattleare:• It identifies the very few positive animals that may not yet be showing clinical

signs.• Itdecreasestheriskofcontaminatedmaterialenteringthe foodchain in those

countrieswhereothermeasures(e.g.antemorteminspection,SRMremoval)maynotbeeffectivelyimplemented.

• Itcouldincreaseconsumerconfidenceinbeefandbeefproducts.• Itmayallowimportbanstobelifted(althoughsomeimportsbansmaybeinviola-

tionofWTOrules).Thedrawbacksare:• Itisextremelyexpensive.• Itmaygiveafalsesenseofsecuritytoconsumers.• It may diminish the incentive to implement effectively and enforce other, more

effectivemeasures(suchasantemorteminspection).• Itcouldleadtoincreasedcontaminationwithinslaughterhousesduetoprocess-

ingofagreaternumberofpositivecarcasses ifothermeasuresarenot imple-mented.

AllcurrentlyavailablemethodsfordiagnosingBSErelyonthedetectionofaccumu-latedPrPScinthebrainofinfectedanimals.Therefore,cattlemusthavealreadybeenslaughteredbeforeconfirmationofdiseasestatuscanbemade,potentiallyincreasingtheriskofcontaminationofcarcasseswithaninfectiousagent.Topreventthis,identi-ficationandremovalofclinicallyaffectedanimalsbythefarmerorveterinarianduringanantemorteminspectionareoptimalcontrolsteps.

measures to avoid cross contamination of meat with SRmIthasbeenshownthattheuseofcertaintypesofcaptiveboltgunstostuncattlepriortoslaughtercausesbraintissuetoenterthebloodstreamthatcould,bedisseminatedthroughout the carcass (including muscle). Therefore, pneumatic bolt stunning and

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pithingarenowforbiddenbymanycountriesinEuropeandelsewhere.Hygienicmeas-urestakenintheslaughterhousetoreducepotentialcontaminationofmeatwithSRMarealsoimportant.

MoredetailedinformationonSRMremovalandothermeatproductionissuescanbefoundintheCapacityBuildingforSurveillanceandPreventionofBSEandOtherZoonot-icDiseasesprojectcoursemanualentitledManagementof transmissiblespongiformencephalopathiesinmeatproduction(FAO,2007a).

3.4. On-farm measuresClassicalcontrolmeasuresforinfectiousdiseases(biosecurity,quarantine,vaccination)donotgenerallyapplytoBSE.Givenallavailableevidence,theBSEagentisnottrans-mittedhorizontallybetweencattlebutonlythroughfeed,primarilyingestionofcontami-natedMBMduringcalfhood.WhenaBSEcaseisdetected,ithasbeenshownthatothercattlewithinthatherdareunlikelytotestpositiveforBSE,despitethelikelihoodthatmanycalvesofsimilaragetothecaseallconsumedthesamecontaminatedfeed.

However,someon-farmstrategies,primarilythosethatfocusonfeedasasourceofinfection,andsomecullingprogrammesdocontributetothecontrolanderadicationofBSE.Cullingstrategiesvaryamongcountries,andoftenchangeovertime.Somediffer-entcullingstrategiesthathavebeenappliedinclude(SSC,2000;2002c).

• theindexcaseonly• allcattleonthefarmwheretheindexcasewasdiagnosed• allcattleonthefarmwheretheindexcasewasbornandraised• allcattleontheindexcasefarmandonthefarmwheretheindex casewasbornandraised• allsusceptibleanimalsontheindexcasefarm (includingsheep,goatsandcats)• “feed-cohort“(cattlethatcouldhavebeenexposedto thesamefeedastheindexcase)• “birth-cohort“(allcattlebornoneyearbeforeoroneyear aftertheindexcaseandraisedonthesamefarm)

Whileherdcullingmaybeapoliticallyexpedientmeansofincreasingconsumercon-fidenceandfacilitatingexports,itisunlikelytobeanefficientriskmanagementmeas-ure (Heim and Murray, 2004). There are significant problems in implementing suchastrategy.Farmerssee itasaradicalapproachbecause it results inaconsiderablewasteofuninfectedanimals.Althoughtheremaybesufficientcompensationforculledanimals, farmersmaynotbelieve it is reasonable tocullapparentlyhealthy,produc-tiveanimals.Inadditiontheyarelikelytolosevaluablegeneticlinesand/ortheir“life’swork”.Forthesereasons,farmersmaybelesswillingtonotifysuspectcasesifcullingoftheirentireherdcouldresult.

Evidencefromanumberofcountriesindicatesthat,inthoseherdswheremorethanonecaseofBSEhasbeendetected,theadditionalcase(s)werebornwithinoneyearoftheindexcase.Asaresult,cullingabirthcohortisamorerationalriskmanagementstrategyasitfocusesonthoseanimalswithinaherdthathavethegreatestchanceofhavingBSE.Evenso,dependingontheinitiallevelofexposureandtheoriginalsizeofthecohort,itislikelythatrelativelyfewadditionalcasesofBSEwillbedetectedinthe

Herdculling

Cohortculling

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birthcohortofaherd indexcase.Cohortculling is,however, likely tobemuchmoreacceptabletofarmerswhencomparedwithherdculling.

3.�. Import controlThebestmeansofpreventingtheintroductionofBSEistocontroltheimportofcertainBSEriskproductsfromcountrieswithBSEorcountriesthatareatriskofhavingBSE.Mostcountriesdonotbanimportsofpotentiallyinfectivematerialsuntiltheexportingcountry has reported their first BSE case. This is usually too late, however, becausethe risk already existed before the first case was detected. Materials that should beconsideredriskyforimport(unlessappropriatesafetyconditionsaremet)includeanymammalianderivedmeals (includingMBMandotherproteinmeals), feedcontainingMBM,livecattleandoffal. Importofbeefandbeefproductsforhumanconsumption,including processed beef products, whole cattle carcasses and bone-in beef, shouldalsobecontrolled,especiallyfortheexclusionofSRM.Debonedbeefmeatisgenerallyconsideredasnon-riskyforimport.

3.�. EnforcementAlthoughimplementationofeachmeasuredecreasestheoverallriskofexposure,com-biningmeasuresdecreasestheriskmoreprofoundly(HeimandKihm,2003).Forexam-ple, feedbansimplementedinconjunctionwithanSRMbanforfeedhaveastrongerimpact. Moreover, measures must be effectively implemented and enforced. Simplyissuing a regulation or ordinance without providing the necessary infrastructure andcontrolswillnotachievethedesiredgoals.Educationofallpeopleinvolvedisrequiredatalllevelsandinallsectorsinordertoimproveunderstandingandcapacity,andthusimprovecompliance.

4. CLINICAL SIGNS OF BSEIncontrasttomanyBSEcasespicturedinthemedia,mostcattlewithBSEhavesubtlesignsofdisease.Signsareprogressive,variableintypeandseverity,andmayincludedepression,abnormalbehaviour,weightloss,sensitivitytostimuli(light,sound,touch)andgaitormovementabnormalities.Othersigns thathavebeennoted insomeBSEcasesincludereducedmilkyield,bradycardiaandreducedruminalcontractions(Braunetal.,1997).

Differential diagnoses for BSE include bacterial and viral encephalitides (e.g.bornadisease,listeriosis,sporadicbovineencephalitis,rabies),brainedema,tumors,cerebrocortical-necrosis (CCN), cerebellar atrophy, metabolic diseases and intoxica-tions,aswellasothercausesofweightlossandneurologicalabnormalities.

Becausenoneof theclinical signsarespecific (pathognomonic) for thedisease,adefinitive clinical diagnosis cannot be made. With experience, however, farmers andveterinarianscanbecomeefficientatearlyidentificationofBSEsuspects.Thesesuspi-cionsshouldalwaysbeconfirmedthroughlaboratorytesting.

�. DIAGNOSIS OF BSE�.1. BiosafetyMicroorganisms are classified by the World Health Organization (WHO) accordingto their pathogenicity for humans and animals. According to this classification, pre-cautions must be taken when handling these agents primarily to protect the people

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handling them and also to protect the general human population and livestock fromaccidentalexposure.Dependingontheclassificationofthemicroorganism,precautionsalso must be taken to protect laboratory workers and the community from possibleexposureandinfection.Thus,WHOhasdefinedfourbiosafetylevel(BL)categoriesforlaboratories.ThesecategoriescorrelatesomewhatwiththeWHOriskgroupcategories,butalsoreflectwhatisbeingdonewiththemicroorganisminthelaboratory.

Themostinternationallywell-acceptedguidelineontheclassificationsystemforandthehandlingofmicroorganismsistheWHOLaboratorybiosafetymanual(WHO,2003).Thismanualdefinestheriskgroups,therequirementsforriskassessments,andtherequirementsforeachofthelaboratoryBLs.

In2000,theEUpublishedadirectivebasedontheWHOguidelines,whichdefinesanewriskgroupforBSEandrelatedanimalTSEsbasedonBSEagentcharacteristics(e.g.limitedriskforlaboratorypersonnelandthecommunity,inabilitytoexcludeaero-sol transmission). This new risk group is called 3**, which means risk group 3 withsomealleviations.Scrapie,ontheotherhand,isstillclassifiedasriskgroup2.

AccordingtotheSwissExpertCommitteeforBiosafety,differentbiosafetylevelsarerequiredwhenhandlingBSEmaterials,dependingonthetypeofmaterial(SwissExpertCommittee for Biosafety, 2006). For example, histology and Immunohistochemistry(IHC)onformicacid-inactivatedBSEmaterialcanbeperformedinaBL1laboratory,androutineBSEdiagnosticscanbeperformedinaBL2laboratorywithsomeadditionalmeasures.Areference laboratory forTSEmustbeBL3,butsomemodificationsareallowed.Attentionshouldbepaid to the fact thatBSE laboratory requirementsoftendifferamongcountries.

�.2. Sample collectionBecauseboththehighestconcentrationofPrPScandthemostprominentrelatedlesionstendtobelocatedintheareaoftheobexregionofthebrainstem(Figure4),samplingthisregionoptimizessensitivity,regardlessofthediagnostictestmethodused.Ifthis

FigUre 4

Tissue selected for testing for BSE (histopathology and rapid tests), (s), includes the obex region (o)

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regionisnotsampledcorrectly,falsenegativeresultsmaybeobtained.Thisrequiresthatindividualscollectingsamplesarefamiliarwiththeanatomyinthisregion.

All animals clinically suspected of having BSE should be examined post mortem.Optimally,severalrepresentativeareasofthebrainofclinicalsuspectsareexamined;therefore,thewholeheadoftheanimalshouldberemovedandsenttothelaboratory.Aswell,thisallowsteststobeperformedforotherdifferentialdiagnoses.Atthelabora-tory,thebrainisremovedassoonaspossibleforfurthertestingandonehalfisfixedinformalin(forhistopathologyandIHC).Theremaininghalfofthebrainisfirstsampledforrapidtestsandthenfrozenat-20°Cor-80°C.

Incasesofemergencyslaughter,fallenstockorroutinescreening,onlythecaudalbrainstem (medulla oblongata) is generally removed for testing, without opening theskull.Thecaudalendofthebrainstemshouldbevisiblethroughtheforamenmagnumafterseparationofthehead,andaspeciallydesignedspooncanbeusedtoremovethebrainstem(includingtheobexregion)throughtheforamen.Thebrainstemisthensplitlongitudinally,andonehalffixedinformalinforhistopathologyandIHCwhiletheotherhalfisreservedandsampledforrapidtests.Thefreshtissueremainingaftersamplingforrapidtestsisthenfrozenat-20°Cor-80°C.

ForneuropathologyandIHC,tissueisfixedinformalin,inactivatedwithformicacid,andthenembeddedinparaffin.Theembeddedbrainsamplesaresectionedandplacedonglassslides.Forneuropathologicexamination,sectionsarethenstainedwithstand-ardhaematoxylinandeosin(H&E)stain.

�.3. Neuropathology and immunohistochemistryVisualizationof typicalneuropathologicchangesrequires that the tissuestructurebeintact.Thereforeitmaynotbepossibletoevaluateevenslightlyautolyticsamples(e.g.samplesfromfallenstockorcadavers,samplesimproperlyfixedfortransport).Freez-ingofsamplesalsodestroysthetissuestructure.

Aftercharacterizationofthehistopathologicfeaturespresentinasample,BSEmustbedifferentiatedfromotherneuraldiseasesshowingsimilarlesions.Theterm“spongi-form” ispurelydescriptiveand issometimesused interchangeablywithother terms,suchasvacuolation,spongiosis,spongydegenerationormicrocavitation.Vacuolationoftheneuropilcanbeseeninmanydifferentdiseasesandeveninanormalbrain,sopos-siblecausesofspongiformchangesmustbedifferentiated(e.g.normalvacuolationvspathologicalvacuolationvsvacuolationfrompostmortemartifacts).“Encephalopathy”referstothefactthatthediseaseisprimarilydegenerativeand,apartfromgliosis,doesnotshowanyinflammatorychanges.

Afterneuropathologicexamination,IHCcanbeusedtoidentifyPrPScdirectly,inthesamplebylabellingitwithspecificantibodies.Insomecases,IHCmayallowadefinitivediagnosisofBSEtobemadewhenquestionableorevennoneuropathologicchangesareseen.

However,becausethenormalPrPprotein(PrPC)present inthebraincellshasthesameaminoacidsequenceasPrPSc,antibodiesnormallyusedinIHCdetectbothPrPScandPrPC.Therefore,inordertobeabletodetermineifthereisanyPrPScpresent,thetwoproteinsmustfirstbedifferentiated.ProteinaseKisanenzymethatcausestotalproteolysisofnormalPrPC,althoughPrPScisresistanttoproteolysisbyproteinaseKtoalargeextent.OnlysmallpartsatthebeginningandattheendofPrPScaredigestedand the remaining part, generally referred to as the core fragment or PrPres, is still

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detectedbytheantibodies.Therefore,proteinaseKisusedinIHCtodigesttotallythePrPCpresentinthesample,ensuringthatanyPrPdetectedwillbePrPSc.Withoutthisstep, samples could yield a false positive result because of the detection of normalPrPC.Similarly,incompletedigestioncouldleadtofalsepositiveresults.

Formostantibodiesusedintesting,therespectiveepitopeonPrPisnotaccessibleinthenativePrPconformation.Therefore,anadditionalsteptodemasktheappropriateepitopeonPrPres isrequired.Demaskingcanbeaccomplishedbydenaturationoftheproteinorbyusingnon-specificproteases.

�.4. Rapid BSE tests TestsareavailabletoanalyseBSEsuspectmaterialsrapidly(OIE,2005b).Whichrapidtestsarelicensedandapprovedinvariouscountriesthroughouttheworldarevariableandlistsareconstantlybeingupdated(EuropeanFoodSafetyAuthority,2005).

AllcurrentlylicensedBSErapidtestshaveseveralthingsincommon.First,theyusematerial from the brainstem, i.e. they are post mortem tests. Second, current rapidtestsarebasedonthesameprinciplesofhomogenization,proteinaseKdigestion(withthe exception of the IDEXX HerdChek BSE Antigen EIA), and detection. Although theprinciplesof thesestepsaresimilaramongtests, therearesignificantdifferences intheexecution.Thematerialsandproceduresarespecifictoeachtestsystemandtestperformance is validated under these specific conditions, thus protocols cannot bemodifiedorinterchangedamongtests.

Initially,thesampleofcentralnervoussystem(CNS)materialmustbehomogenizedwith a specific buffer containing stabilizers and detergents. After homogenization,proteinaseKisusedtodigestthePrPC(withtheexceptionoftheIDEXXHerdChekBSEAntigenEIA)andtheepitopeisdemasked.Then,theproteinaseKresistantfragmentofPrPSc,ifpresent,isdetectedwithspecificmonoclonalorpolyclonalantibodiesusingwesternblotorenzymelinkedimmunosorbentassay(ELISA)technology.

Althoughtherearedifferencesbetweenthetests,theoverallperformance(sensitivityandspecificity)iscomparable.Greatdifferencescanbefoundinthehandlingandtheversatilityofthetestsforhighandlowthroughputlaboratoryset-ups.

�.�. New developmentsWorkisconstantlybeingdoneonthedevelopmentofnewrapidtests.Newtestsmaybebasedontherefinementofanestablishedprocedureoronthereplacementofproce-duresbycompletelynewconcepts.

All new tests are still based on post mortem sampling as they use brain materialfromtheobexregion.Ofcourse,theabilitytodiagnoseBSEantemortemwouldbeahugeadvantage,andmuchresearchisbeingdoneinthisfield.Reportsonpossibleantemortemtestsarepublishedregularly.However,noneofthesetestshassofarpassedthe validationprocess,andan imminentbreakthrough inantemortem testing isnotforeseen.

DiagnosisofTSEsiscoveredindepth intheCapacityBuildingforSurveillanceandPreventionofBSEandOtherZoonoticDiseasesprojectcoursemanualDiagnosticTech-niquesfortransmissiblespongiformencephalopathies(FAO,2007).

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�. SURvEILLANCE SySTEmS�.1. Objectives of surveillance ThetwomajorobjectivesforBSEsurveillancearetodeterminewhetherBSEispresentinthecountryand,ifpresent,tomonitortheextentandevolutionoftheoutbreakovertime. In this way, the effectiveness of control measures in place can be monitoredandevaluated.However, thereportednumberofBSEcases inacountrycanonlybeevaluatedwithinthecontextofthequalityofthenationalsurveillancesystemandthemeasurestaken.BSEriskcanstillexist inacountry,evenifnocasesarefoundwithsurveillance.Surveillanceaimstosupplementthemorecomprehensivedataprovidedbyariskassessment(HeimandMumford,2005).

Generalguidelinesfordiseasesurveillanceandspecificguidelinesforanappropri-ate levelofBSEsurveillancefor thedifferentcategoriesofnationalriskareprovidedintheOIETerrestrialAnimalHealthCode(OIE,2005c,d).Theserecommendationsareconsidered by the WTO (WTO; World Trade Organization, 1994) and the internationalcommunityastheinternationalstandards.

�.2. passive surveillanceInmostcountriesBSEislistedasanotifiabledisease,whichisabasicrequirementforafunctioningpassive(aswellasactive)surveillancesystem.However,somecountrieshavenonationalpassivesurveillancesystemforBSE,oronlyaweaksystem.

Until1999,BSEsurveillanceinallcountrieswaslimitedtothenotificationofclinicallysuspectedcasesbyfarmersandveterinarians(andothersinvolvedinhandlinganimals)totheveterinaryauthorities(passivesurveillance).Itwasassumedthatthiswouldallowearlydetectionofanoutbreak(HeimandWilesmith,2000).However,becausepassivesurveillancereliessolelyonthereportingofclinicalsuspectsandisdependentonmanyfactors,includingperceivedconsequencesonthefarmanddiagnosticcompetence,itisnotnecessarilyconsistentorreliable.Thus,althoughpassivesurveillance isacrucialcomponentofanyBSEsurveillancesystem,ithasbecomeincreasinglyobviousthatpas-sivesurveillancealoneisnotsufficienttoestablishtherealBSEstatusofacountry.

Forapassivesystemtofunctioneffectively,severalfactorsmustbeinplace:

Veterinarystructure: Thediseasemustbenotifiable.Casedefinition: A legal definition of BSE must exist and must be broad

enoughtoincludemostpositivecases.Diseaseawareness: Theappropriate individuals (farmers,veterinarians)must

beabletorecognizeclinicalsignsofthedisease.Willingnesstoreport: There must be minimal negative consequences to the

identificationofapositivecaseatthefarmlevelandmeas-uresmustbeconsidered“reasonable”.

Compensationscheme: Thecostsofculledanimalsmustbereasonablycompen-sated.

Diagnosticcapacity: Theremustbeadequatelaboratorycompetence.

Becausethesefactorsvarygreatly,bothamongcountriesandwithincountriesovertime,theresultsofpassiveBSEsurveillancesystemsaresubjectiveandevaluationandcomparisonofreportednumbersofBSEcasesmustbemadecarefully.

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�.3. Active surveillanceTooptimizeidentificationofpositiveanimalsandimprovethesurveillancedata,thosepopulationsofcattlethatareatincreasedriskofhavingBSEshouldbeactivelytargetedwithinanationalsurveillancesystem.Withtheintroductionoftargetedsurveillanceofcattleriskpopulationsin2001,alargenumberofcountriesinEuropeandalsothefirstcountriesoutsideEuropedetectedtheirfirstBSEcases.

Cattlewithsignsofdiseasenon-specifictoBSEandcattlethatdiedorwerekilledforunknownreasonsmaybedefinedindifferentcountriesassickslaughter,emergencyslaughter,fallenstockordownercows.TheprobabilityofdetectingBSE-infectedcat-tleishigherinthesepopulations,asitmayhavebeenBSEthatledtothedebilitation,death,cullorslaughteroftheseanimals.ManyofthesecattlemayhaveexhibitedsomeoftheclinicalsignscompatiblewithBSE,whichwerenotrecognized.Theexperienceofmanycountriesinthelastyearshasshownthat,afterclinicalsuspects,thisisthesec-ondmostappropriatepopulationtotargetinordertodetectBSE.Targetedsurveillanceaimstosamplecattleintheseriskgroupsselectively,andtestingoftheseriskpopula-tionsisnowmandatoryinmostcountrieswithBSEsurveillancesystemsinplace.

Healthycattle Routineslaughter

Cattlewithnon-specificsigns(e.g. Sick/emergencyslaughter,weightloss,lossofproduction)and fallenstock,downercowscattlethatdiedforunknownreasons(onthefarm,duringtransport)

CattlewithspecificsignsofBSE BSEsuspects(orsuspicionofBSE)

Theageofthepopulationtestedisalsoimportant,astheepidemiologicaldatashowthatcattleyoungerthan30monthsrarelytestpositiveforBSE.Therefore,targetedsur-veillanceaimstosamplecattleselectivelyover30monthsofageintheriskpopulations,whichmaybeidentifiedonthefarm,attransportorattheslaughterhouse.

However,despite the fact that correctly implementedsamplingof riskpopulationswouldhypotheticallybesufficient toassessBSE inacountry, testingasubsampleofhealthyslaughteredcattleshouldbeconsidered.Thisisneededtominimizediversionofquestionablecarcassestoslaughter,i.e.toimprovecompliance.Iffarmersareawarethat randomsampling isoccurring,andwhen theprobabilityofbeing tested is largeenough,theyarelesslikelytosendsuspectanimalsdirectlytoslaughter.

Thespecificsurveillanceapproachesvaryamongthedifferentcountries.TheEUandSwitzerlandaretestingtheentireriskpopulationover24and30monthsofage,respec-tively.IntheEU,additionally,allcattlesubjecttonormalslaughterover30monthsofage are currently tested, whereas in Switzerland a random sample of approximately5%istested.CountriesoutsideEuropehaveimplementedavarietyofdifferenttestingsystems.FromtheexperiencesgainedinEurope,itisclearthatitismostefficienttoensuretheeffectiveimplementationofpassiveandtargetedsurveillanceinriskpopula-tionsratherthantofocusontestingoftheentirenormalslaughterpopulation.

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PreventionofBSEandOtherZoonoticDiseasesprojectcoursemanualentitledEpide-miology,surveillance,andriskassessmentfortransmissiblespongiformencephalopa-thies(FAO,2007).

�. RISk ASSESSmENT�.1. BSE status and international standardsFora longtime,BSEwasconsideredaproblemexclusivelyof theUK.Evenafter thedetectionofBSEcasesinseveralcountriesoutsidetheUK,theriskofhavingBSEwascategoricallydeniedbymanyothercountries.Onlyaftertheintroductionofactivesur-veillancedidseveral“BSE-free”countriesdetectBSE.

Before2005,theOIEdescribedfiveBSEcategoriesforcountries,butinMay2005anewBSEchapterwasadopted(OIE,2005d)reducingthenumberofBSEstatuscatego-riestothefollowingthree:

•Country,zoneorcompartmentwithanegligibleBSErisk•Country,zoneorcompartmentwithacontrolledBSErisk•Country,zoneorcompartmentwithanundeterminedBSEriskAccording to the OIE, a primary determinant for establishing BSE risk status of a

country,zoneorcompartmentistheoutcomeofascience-basednationalriskassess-ment.Thisassessmentmaybequalitativeorquantitative,andshouldbebasedontheprinciplesgivenintheCodeChapters1.3.1and1.3.2onRiskanalysisandtheAppendix3.8.5 on Risk analysis for BSE (OIE, 2005 e,f,g). The OIE Code Chapter on BSE (OIE,2005d) lists the followingpotential factors forBSEoccurrenceandtheirhistoricper-spectivethatmustbeconsideredinsuchanassessment:

Release assessment2

• theTSEsituationinthecountry• productionandimportofMBMorgreaves• importedliveanimals,animalfeedandfeedingredients• importedproductsofruminantoriginforhumanconsumptionandforinvivouse

incattleIn addiction, surveillance for TSEs and other epidemiological investigations (espe-

cially surveillance for BSE conducted on the cattle population) should be taken intoaccount.

Exposure assessment: • recyclingandamplificationoftheBSEagent• the use of ruminant carcasses (including from fallen stock), by-products and

slaughterhousewaste,theparametersoftherenderingprocessesandthemeth-odsofanimalfeedmanufacture

• thefeedingbansandcontrolsofcrosscontaminationandtheirimplementation• thelevelofsurveillanceforBSEandtheresultsofthatsurveillance

In addition to an assessment of BSE risk, the OIE status categorization for BSEincludesevaluationofsomeofthemeasuresinplaceinthecountry.Accordingtothe

2 In2006,theOIEBSEchapterwasmodifiedsothatonlyBSE,andnototherTSEs,isincludedintheexposureassessment.

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OIECode,factorsevaluatedintheestablishmentofBSEstatusshouldinclude:• theoutcomeofariskassessment(asdescribedabove)• disease awareness programmes to encourage reporting of all cattle showing

clinicalsignsconsistentwithBSE• compulsorynotificationandinvestigationofallcattleshowingclinicalsignscon-

sistentwithBSE• examinationinanapprovedlaboratoryofbrainsamplesfromthesurveillanceand

monitoringsystem.

�.2. The geographical BSE risk assessmentThegeographicalBSEriskassessment(GBR)isaBSEriskassessmenttooldevelopedby theScientificSteeringCommitteeof theEuropeanCommissionandbasedonOIEassessmentcriteria.TheGBRisaqualitativeindicatorofthelikelihoodofthepresenceofoneormorecattlebeinginfectedwithBSE,atagivenpointintimeinacountry,andhasbeenappliedtoanumberofcountriesthroughouttheworld.Themethodisaquali-tativeriskassessment,whichusesinformationonriskfactorsthatcontributeeithertothepotentialforintroductionofBSEintoacountryorregionortotheopportunityforrecyclingof theBSEagent inacountryorregion.The followingquestions,relatedtoreleaseandexposure,areansweredthroughtheGBR:

• Wastheagentintroducedintothecountrybyimportofpotentiallyinfectedcattleorfeed(MBM),andifsotowhatextent?

• Whatwouldhappeniftheagentwereintroducedintotheanimalproductionsys-tem,i.e.woulditbeamplifiedoreliminated?

Beforethedetectionofthefirstcasesinmany“BSE-free”countries,theGBRshowedthatariskcouldbepresent.Thisconfirmedtheconceptthataserious,comprehensiverisk assessment must be carried out to estimate the extent of the BSE problem incountries.

Thus, decisions on preventive measures should be based on such a detailed riskassessment, whether it is the GBR or another science-based assessment based onOIErecommendations.Nocountryshouldwaituntilthefirstcaseoccursbeforetakingpreventivemeasures.ThereremainmanycountrieswithanunknownBSErisk.Inordertominimizeimportrisksfromthesecountries,furtherriskassessmentsareneededtoevaluatetherealBSEdistributionworldwide.

RiskassessmentforTSEsiscoveredindepthintheCapacityBuildingforSurveillanceandPreventionofBSEandOtherZoonoticDiseasesprojectcoursemanualEpidemiol-ogy,surveillanceandriskassessmentfortransmissiblespongiformencephalophathies(FAO,2007c).

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FAO. 2007a. Management of transmissible spongiform encephalopathies in meat production.Course manual, Project Capacity Building for Surveillance and Prevention of BSE and OtherZoonoticDiseases.Rome

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encephalopathies.CapacityBuildingforSurveillanceandPreventionofBSEandOtherZoonoticDiseases.

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present.RevscitechOffintEpiz18(1),135-144

Heim D, kihm U. 2003. Risk management of transmissible spongiform encephalopathies in

Europe.RevscitechOffintEpiz22(1),179-199

Heim D, mumford E.2005.ThefutureofBSEfromtheglobalperspective.MeatScience70,555-562

Heim D, murray N.2004.Possibilities tomanage theBSEepidemic:cohortcullingversusherd

culling – experiences in Switzerland. In: Prions: a challenge for science, medicine and thepublichealthsystem,2nded.EdsHFRabaneau,JCinatl,HWDoerr.Karger,Basel,Switzerland.

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transmissible spongiform encephalopathy agents. Terrestrial Animal Health Code, Appendix

3.6.3.http://www.oie.int/eng/normes/mcode/en_chapitre_3.6.3.htm

OIE.2005c.Surveillance forbovinespongiformencephalopathy.TerrestrialAnimalHealthCode,Appendix3.8.4.http://www.oie.int/eng/normes/MCode/en_chapitre_3.8.4.htm

OIE. 2005d.Bovinespongiformencephalopathy.TerrestrialAnimalHealthCode,Chapter2.3.13.http://www.oie.int/eng/normes/MCode/en_chapitre_2.3.13.htm

OIE.2005e.Generalconsiderations(riskanalysis).TerrestrialAnimalHealthCode,Chapter1.3.1.

http://www.oie.int/eng/normes/MCode/en_chapitre_1.3.1.htm

OIE. 2005f. Import risk snalysis. Terrestrial Animal Health Code, Chapter 1.3.2. http://www.oie.

int/eng/normes/MCode/en_chapitre_1.3.2.htm

OIE. 2005g. Factors to consider in conducting the bovine spongiform encephalopathy risk

assessment recommended inchapter2.3.13.TerrestrialAnimalHealthCode,Appendix3.8.5.

http://www.oie.int/eng/normes/MCode/en_chapitre_3.8.5.htm

prince mJ, Bailey JA, Barrowman pR, Bishop kJ, Campbell GR, wood Jm.2003.Bovinespongiform

encephalopathy.RevscitechOffintEpiz22(1),37-60

Schreuder BE, Somerville RA.2003.Bovinespongiformencephalopathyinsheep?RevscitechOffintEpiz22(1),103-120

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SSC (Scientific Steering Committee of the European Commission).2000.OpinionoftheScientific

SteeringCommitteeonBSE-relatedcullingincattle.Adoptedatthemeetingof14/15September

2000.http://europa.eu.int/comm/food/fs/sc/ssc/out138_en.pdf

SSC.2001a.OpiniononhypothesesontheoriginandtransmissionofBSE.AdoptedbytheScientific

SteeringCommitteeatitsmeetingof29-30November2001.http://europa.eu.int/comm/food/fs/

sc/ssc/out236_en.pdf

SSC. 2001c. Opinion on the six BARB BSE cases in the UK since 1 August 1996. http://europa.

eu.int/comm/food/fs/sc/ssc/out237_en.pdf

SSC.2001b.SafetyofmilkwithregardtoTSE:stateofaffairs.http://europa.eu.int/comm/food/fs/

sc/ssc/out175_en.html

SSC.2002a.Thesafetyofbovineembryos.AmendmenttotheSSCopinionof18-19March1999

onthepossibleverticaltransmissionofbovinespongiformencephalopathy(BSE).http://europa.


SSC. 2002b. Update of the opinion on TSE infectivity distribution in ruminant tissues. Initially

adoptedbytheScientificSteeringCommitteeatitsmeetingof10-11January2002andamended

atitsmeetingof7-8November2002.http://europa.eu.int/comm/food/fs/sc/ssc/out296_en.pdf

SSC.2002c.OpinionoftheSSContheadditionalsafeguardprovidedbydifferentcullingschemes

under the current conditions in the UK and DE. Adopted on 11 January 2002. http://europa.


Swiss Expert Committee for Biosafety. 2006. http://www.umwelt-schweiz.ch/buwal/eng/

fachgebiete/fg_efbs/index.html

TAFS (International Forum for TSE and Food Safety).2004a.TAFSpositionpaperonspecifiedrisk

materials. http://www.tseandfoodsafety.org/position_papers/TAFS_POSITION_PAPER_SPECIFI

ED%20RISK%20MATERIALS.pdf

TAFS.2004b.TAFSpositionpaperontestingofcattleforBSE–Purposeandeffectiveness.http://

www.tseandfoodsafety.org/position_papers/TAFS_POSITION_PAPER_ON%20TESTING%20OF%

20CATTLE.pdf

TAFS.2007.TAFSpositionpaperon thesafetyofbovinemilkandbovinemilkproducts”.http://

www.tseandfoodsafety.org/position_papers/TAFS_POSITION_PAPER_ON_MILK.pdf

Taylor Dm, Fraser H, mcConnell I, Brown DA, Brown kL, Lamza kA, Smith GRA. 1994.

Decontamination studies with the agents of bovine spongiform encephalopathy and scrapie.

ArchVirol139,313–326

Taylor Dm, woodgate SL.1997.Bovinespongiformencephalopathy:thecausalroleofruminant-

derivedproteinincattlediets.RevscitechOffintEpiz16,187–198

Taylor Dm, woodgate SL.2003.Renderingpracticesandinactivationoftransmissiblespongiform

encephalopathyagents.RevscitechOffintEpiz22(1),297-310

wells GA.2003.PathogenesisofBSE.VetResCommun.Suppl1,25-28

wells GA, Scott AC, Johnson CT, Gunning RF, Hancock RD, Jeffrey m, Dawson m, Bradley R.1987.

Anovelprogressivespongiformencephalopathyincattle.VetRec121(18),419-420

wells GAH, Dawson m, Hawkins SAC, Green RB, Dexter I, Francis mE, Simmons mm, Austin AR,

Horigan mw. 1994. Infectivity in the ileum of cattle challenged orally with bovine spongiform

encephalopathy.VetRec135(2),40-41

wells GAH, Dawson m, Hawkins SAC, Austin AR, Green RB, Dexter I, Horigan mw, Simmons

mm. 1996. Preliminary observations on the pathogenesis of experimental bovine spongiform

encephalopathy. In: Bovine spongiform encephalopathy: the BSE dilemma. Ed. C.J. Gibbs,

SeronoSymposia,Norwell,USASpringer-Verlag,NewYork,Inc.pp.28-44

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wells GA, Hawkins SA, Green RB, Austin AR, Dexter I, Spencer yI, Chaplin mJ, Stack mJ, Dawson

m. 1998. Preliminary observations on the pathogenesis of experimental bovine spongiform

encephalopathy(BSE):anupdate.VetRec142(5),103-106

wells GA, Hawkins SA, Green RB, Spencer yI, Dexter I, Dawson m. 1999. Limited detection

of sternal bone marrow infectivity in the clinical phase of experimental bovine spongiform

encephalopathy(BSE).VetRec144(11),292-294

wHO (world Health Organization).2003.Laboratorybiosafetymanual.Secondedition(Revised).

ReferencenumberWHO/CDS/CSR/LYO/2003.4.http://www.who.int/csr/resources/publications/

biosafety/Labbiosafety.pdf

wilesmith Jw, wells GA, Cranwell mp, Ryan JB. 1988. Bovine spongiform encephalopathy:

epidemiologicalstudies.VetRec123(25),638-644

wilesmith Jw, Ryan JB, Atkinson mJ.1991.Bovinespongiformencephalopathy:epidemiological

studiesontheorigin.VetRec128(9),199-203

will RG, Ironside Jw, Zeidler m, Cousens SN, Estibeiro k, Alperovitch A, posers S, pocchiari m,

Hofman A, Smith pG.1996.AnewvariantofCreutzfeldt-JakobdiseaseintheUK.Lancet347,

921–925

wrathall AE.1997.Risksoftransmittingscrapieandbovinespongiformencephalopathybysemen

andembryos.RevscitechOffintEpiz16(1),240-264

wrathall AE, Brown kF, Sayers AR, wells GA, Simmons mm, Farrelly SS, Bellerby p, Squirrell

J, Spencer yI, wells m, Stack mJ, Bastiman B, pullar D, Scatcherd J, Heasman L, parker J,

Hannam DA, Helliwell Dw, Chree A, Fraser H. 2002. Studies of embryo transfer from cattle

clinicallyaffectedbybovinespongiformencephalopathy(BSE).VetRec150(12),365-378

wTO (world Trade Organization).1994.Agreementonsanitaryandphytosanitarymeasures.FinalActoftheUruguayRound,Article5.http://www.wto.org/english/docs_e/legal_e/15-sps.pdf

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Overview:

Implementation

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encephalopathy

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livestock feeds

OvERvIEw: ImpLEmENTATION OF TRANSmISSIBLE SpONGIFORm ENCEpHALOpATHy mEASURES FOR LIvESTOCk FEEDS

1. GENERAL CONCEpTSCurrently, it is well accepted that cattle are exposed to the BSE agent through theingestionofcontaminatedfeed.Therefore,akeymeasureinpreventingthespreadandrecyclingof theBSEagent is toprevent ruminant-derivedproteins frombeing fed toruminants.Ultimately,thisisthesimplegoalofanyfeedban,however,achievingthisgoalisnotsosimple.ExperienceinEuropeandelsewherehasshownthataseriesofeffectivemeasuresmustbeimplementedtoassurethatthisgoalismet.

When feed bans were first introduced in Europe, the goal of preventing ruminantmaterialfrombeingfedtoruminantswaslogicallyimplementedintheleastdisruptivemannerpossible(i.e.ruminanttoruminantbansormammaltoruminantbans).Later,“flushing”batches(batchesoffeedprocessedortransportedinbetweenfeedbatchescontainingprohibitedandnon-prohibitedmaterials)were introducedtoreducetracesof prohibited materials from the equipment and reduce cross contamination. ThesemeasuresdoindeedreducetheriskofexposureofcattletotheBSEagent;however,thecontinuedappearanceofanimalswithBSEthatwerebornaftertheimplementationoftheseinitialbans(animalsbornaftertheban,or“BAB”)showedthatthemeasureswereinsufficient(HeimandKihm,2003).

Ithasbecomeclearthatacomplementarysystemofintegratedfeedcontrolmeas-ures must include (1) a ban on including specified risk material (SRM; those animaltissuesmostlikelytocontainTSEinfectivity,includingbovinefallenstock)infeeds,(2)strictfeedbansthatareeffectivelyenforced,and(3)controlofcrosscontaminationatevery step along the feed production chain from transport of raw materials throughfeedingpracticesonthefarm,inordertoultimatelypreventexposureofruminantstopotentialinfectivity(HeimandKihm,2003).Inaddition,restrictionsonimportsofriskyproductsmustbeevaluated,toprevententryorre-entryofinfectivematerial.Enforce-mentandcontrolofallmeasuresthroughself-regulationandexternalauditsiscrucial.Finally,educationanddiseaseawarenessmustbepromotedinordertopromotecom-pliancewiththemeasuresateverystepalongthefeedproductionchain, includingatthefarmlevel.

ExactlywhichmeasuresareimplementedinacountrywilldependonnationalBSErisk(asdeterminedbyanationalBSEriskassessment),economics,trade,andcapacityavailabletoeffectivelyenforcethemeasures.Insomecases,morerestrictivemeasuresmaybeeasier toenforce,and thereforemaybemoreeconomically justifiablebutallmeasuresultimatelyaimtopreventtheingestionoftheBSEagentbyruminants.

2. BAN ON SRm IN FEEDSBecauseSRMpotentiallycontainsthehighestBSEinfectivity,itshouldbeexcludednotonlyfromthehumanfoodchain,butalsofromthefeedchain,atminimumforruminantspeciesbutoptimallyforallanimals.RenderingofSRM,evenatthestandardprocessing

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parametersof133ºCand3barsofpressurefor20minutes,doesnotentirelyinactivatetheagent(TaylorandWoodgate,2003).ThereforeremovalandsubsequentdestructionofallSRM(includingfallenstockandBSEsuspectanimals)isaveryeffectivemethodforexcludingthisinfectivityfromtheBSErecyclingsystemandsubstantiallyreducingtheriskofintentionalorinadvertentexposureofruminants.Controlsattheslaughter-house(aswellasattherenderingplantinthecaseoffallenstock)mustbeinplacetoassuretheappropriateseparationanddisposalofthedifferenttypesofmaterial.

3. SCOpE OF FEED BANSCurrently, different countries have different bans, i.e. different rules regarding whatspecificmaterialsareprohibitedinfeedsandforwhatspeciesbutallbansaimtoulti-mately prevent the ingestion of ruminant material by ruminants. Feed bans directedatparticulargroupsofanimals (ruminant to ruminant,mammalian to ruminant)aregenerally more difficult to implement and enforce than those with a broader scope(mammalian tomammalian,ormammalian toall livestock)because, inanyagricul-turalsystem,thepresenceofmaterialandfeedsprohibitedforonespeciesandnotforothersincreasestheriskforcrosscontaminationorcrossfeeding.Moreover,availablefeedtestsaregenerallymoreeffectiveatdistinguishingbetweenmaterialsthatareverydifferent (e.g.plants vs.animals,or fishvs. terrestrialanimal) thanatdifferentiatingbetweenmaterialsfromdifferentmammalianspecies.

Thus,takingintoconsiderationnationalTSErisk,insomecountriesitmaybemorefeasible to implement a broader ban. However, broader bans have greater economicconsequences, as more animal by-products must be alternately disposed of and, insomecases,substantialchangesinthemanagementofthefeedproductionlinesarerequired.

4. CONTROL OF CROSS CONTAmINATIONThe importance of cross contamination has been emphasized with the continuedappearance of BAB animals in Europe. It is known that as little as one milligram ofinfectivebrainmaterialissufficienttoinfectacalf(DannyMatthews,VeterinaryLabora-toriesAgency,UK,personalcommunication,2005).Intheproductionoffeedswithbatchsizesofaboutonetonne,eventhesmallamountsofcrosscontaminationthatnormallyoccurcouldallowthisamountofmaterialtobepresentinsubsequentbatches.There-fore,incountrieswithoutotheradequatemeasures(suchasabanonSRM)thisamountofcrosscontaminationcouldleadtoexposure(andpotentiallyinfection)ofcattle.

Currently,itisbelievedthatdedicatingseparateproductionlinesforfeedscontainingprohibitedmaterialsandthosenotcontainingprohibitedmaterials (dependingonthefeedbaninplace)isthemosteffectivemeasureforpreventingthispotentialexposure.Alternatively, entirely separate plants may be established. Certainly, if feed for petanimals isproducedusinganimal-derivedmaterials, theseproduction linesmustbeseparate.Theextentof lineseparationforotherlivestockfeedswillbedependentonthe particular feed ban in place. In addition, control of cross contamination must beimplementedateachstepalongthefeedproductionchainfromhandlingrawmateri-als throughproduction, transport,andstorage, to feedingon the farm.This requiresadequaterecord-keepingandeducationofpersonnelinalltheoperationsinvolved.

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�. ImpORT RESTRICTIONSThespreadofBSEtocountries throughout theworldhasbeenattributed to trade inlivecattle,animalby-products(primarilymeatandbonemeal/MBM)andfeedscontain-ing(orpotentiallycontaining)MBM.ThisriskisnotlimitedtoexportingcountriesthathavereportedBSEcases.Therefore,importingcountriesmustnotonlyevaluatetheirdomesticriskbutalsotheriskposedbyanyimportsoftheseriskyproducts.

�. ENFORCEmENTInordertobeeffectiveatreducingrisk,allimplementedmeasuresmustbecontrolledandenforcedthroughasystemofcontrolsandauditsintegratedateverystepalongthefeedproductionchain.Asystemforsamplingandanalysisoffeedsandfeedingredientstodetectprohibitedmaterialswhichmaybepresentduetonon-compliancewiththefeedbanorowingtocrosscontaminationmustalsobeinplace,whichincludestestingofbothdomesticallyproducedproductsandimports.Thetestingmethodchosenmustbeappropriatenotonlytothespecificfeedbaninplace,butalsototheprocessparam-etersthatwereusedorpotentiallyusedinproduction.

Thesebasicconceptsaredevelopedinfurtherdetail,inparallelwithcurrentgeneralrenderingandlivestockfeedproductionconcepts,inthefollowingcoursemanualchap-ters.Attheendofmanychapters,bulletpointsemphasizetheTSE-relevantconceptsfromtheinformationpresentedwithinthechapter.

�. REFERENCESHeim D, kihm U. 2003. Risk Management of transmissible spongiform encephalopathies in

Europe.RevscitechOffintEpiz22(1),179-199

Taylor Dm, woodgate SL.2003.Renderingpracticesandinactivationoftransmissiblespongiform

encephalopathyagents.RevscitechOffintEpiz22(1),297-310

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protein use in

livestock feeding

Protein use in livestock feeding

1. GENERAL CONCEpTS Allanimals requirecertainbasicnutrients, includingenergy (from fatsandcarbohy-drates),protein,mineralsandvitamins.Compoundfeedsareformulatedtoprovideallor most of these nutritional requirements for a particular species and/or productionclassoflivestock.Itisimportanttoconsiderproductionclasswhenformulatingrations,becauseasananimalgrowsmoreenergyisneededformaintenanceofthelargerbodymassand tosupportan increasingproportionof fatdeposition.Thus,younggrowinganimalshavegreaterrequirementsformanynutrientsthandoolderanimals.Similarly,classesofhigh-producinganimals(suchaslactatingdairycattle)willalsohavehighernutritionalrequirements.

In general, the protein requirements for animals are given as some amount ofprotein (or sometimes of specific amino acids) per unit of time, usually the amountrequiredperday.Proteinrequirementsareusuallyalsoexpressedasaconcentrationwithin the ration (diet),usuallyasg/kgof the rationas fed.Aswithothernutritionalrequirements,proteinrequirementsdiffergreatlydependingon livestockspeciesandproductionclass.Inolderanimalsboththerequiredproteinconcentrationoftherationand the protein:energy ratio decline. In addition, in older animals the voluntary feedintakeincreases,sothattheincreasedamountofproteinrequiredcanbemetwithalowerproteinconcentrationintheration.Therefore,itisimportanttobespecificwhendescribingrequirementsforprotein,aswellasforaminoacids.AdetailedreviewoftheproteinrequirementsoflivestockisavailablefromMiller(2004).

Whenformulatingrations,othernutrientsandmicronutrientscontainedinthevari-oussourcesandsupplementsmustbeconsiderednotonlybecauseoftheirnutritionalbenefit but also because, in some cases, they may be present at detrimentally highlevels. These nutrients include the major minerals, calcium (Ca), phosphorus (P),sodium(Na),potassium(K),andchlorine(Cl),aswellasvitamins(includingvitaminB12,cholineandvitaminD)andessentialfattyacids.

1.1. protein requirements for monogastric animalsAlthough many ration formulations are described in terms of crude protein (CP;Table 1), monogastric animals do not have a requirement for crude protein as such.Instead,monogastricanimalsrequireninetotenspecificaminoacidsthattheycannotsynthezise,togetherwithasourceofaminonitrogenthatcanbeusedforthesynthesisoftheremainingaminoacids.Therefore,therationmustbeformulatedinconsiderationofthoseaminoacidsthatareessentialandthosethatarelimiting.

Essentialaminoacidsare thosethatcannotbesynthesizedandthereforemustbeprovidedbytheration.Inaddition,theaminoacidscysteineandtyrosinecanbesynthe-sizedinthebodybutonlyfromtheessentialaminoacidsmethionineandphenylalanine,respectively.Consequently,cysteineandtyrosinearenotabsolutelyrequiredifsufficientmethionineandphenylalanineareavailable,andsoaretermedsemi-essential.How-ever,ifcysteineandtyrosinearealsoprovidedintheration,thenadditionalmethionine

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andphenylalaninearenotrequired.Arginine isanessentialaminoacidforbirdsandfish but is synthesized in mammals as part of the urea cycle. However, the amountavailableforproteinsynthesismaybeinadequateasmostofthesynthesizedarginineisbrokendowntoreleaseurea.Therefore,additionaldietaryargininemaypromotegrowthinyounganimals.Incertainsituations,suchasinyounganimalsandrapidlygrowingchicks,glycineandserinemaynotbesynthesized insufficientquantities,andsoaretermedconditionallyessential.

Limitingaminoacidsarethoseessentialaminoacidsforwhichtherequirementscannotbemetbecausetheaminoacidcompositionsofthedifferentproteinsourcesinarationdonotmatchtheneedsof(i.e.arenotbalancedfor)thespecificproductionclass.Not surprisingly, animal protein sources are usually better able to match the aminoacidneedsofanimals,andsobetterabletomeettherequirements.Proteinsourcesthatcloselymatchtherequirementsofaparticularspeciesorproductionclasswellaretermedhighqualityproteinsforthatclass.Inattemptingtoformulateabalancedration,theminimalaimistomeettherequirementsforthefirsttwolimitingaminoacids.Ofcourse,anoptimallybalancedrationwillmeettheanimal’sneedsforallaminoacids,howeverthisisdifficulttoachieve.

Forpoultry,methioninepluscysteine(M+C;generallyconsideredtogetherascysteinecanbederivedfrommethionine)andlysineareusuallythefirsttwolimitingaminoacidsincommonlyusedfeedingredients.Lysinerequirementsmaybemetbycomplementinglysine-deficientcerealgrainswithalysine-richlegumeproteinsuchassoya.However,

TABLE 1. Typical crude protein (Cp) concentrations in rations for various classes of monogastric livestock species (in grams per kg air-dried feed)

Class weight/age Cp g/kg

SWINE

Starter:3weekweaning 5-10kg 240 5weekweaning 10-20kg 210

Grower 20-60kg 165

Finisher 60-90kg 140

Sows: lactating 176 pregnant 130

BIRDS

Broiler: starter 0-2weeks 230 grower 2-4weeks 210 finisher 4-7weeks 190

Rearingpullets 0-6weeks 210 6-12weeks 145 12-18weeks 120

Layinghens 160

Turkey: starter 0-6weeks 300 grower 6-12weeks 260 finisher 12+weeks 180

Breedingturkeys 160

FISH

Salmonidsfry fingerlings 550 smolt 400-460

Catfish 320-360

Source:adaptedfromMillerEL,2004.

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as proteins from both of these sources are also deficient in M+C, the mixed rationremainsM+Cdeficient.This isnormallyandmosteconomicallycorrectedbysupple-mentationwithsyntheticmethionine.

For pigs, lysine is normally the first limiting amino acid. Extensive research intodietaryrequirementsforyoungpigshasdeterminedtheidealaminoacidpatternandallowedexcessesofindispensableaminoacidstobeeliminated,resultinginamaximaloverallreductioninproteinrequiredintheserations.Consequently,thiscanappearasaproportionalincreaseinrequiredlysine.Assomeoftheanimalproteinshaveveryhighlevelsoflysine,theyareoptimalforuseinbalancingtheaminoacidcompositionofthecerealcomponentoftheserationstoachievetheidealratio.

Inthepast,mostrationformulationhasbeenbasedonthechemicallydeterminedaminoacidcontentoffeeds,i.e.established“bookvalues”representativeoftheclassratherthananalysesof the individual feedbatch.Someimprovement in theseestab-lishedvaluesmaybemadebydeterminingCPcontentofthebatchandthepublishedregressionequationsofaminoacidcontentinrelationtoCP.Anadditionalproblemisthat, at the tissue level, theaminoacidschemicallydetermined tobepresent in therationmaynotbeavailabletotheanimal.Thus,itisalsonecessarytoconsideraminoacidavailability.

1.2. protein requirements for ruminantsIn the ruminant, ingested feed is fermented by microorganisms in the rumen. Vola-tile fatty acids absorbed from the rumen and omasum provide the major part of themetabolizableenergytotheanimal.Thefermenteddigesta,aswellasruminalmicro-florathenleavetherumenandarefurtherdigestedintheabomasum(truestomach)andintestines(asinthemonogastricanimal).Themajorityofaminoacidsavailabletoruminantsareprovidedbydigestionandabsorptionofmicrobialprotein in thesmallintestine.Becausetheaminoacidbalanceofmicrobialproteinisgenerallymoresimilartothatof livestockthanarecerealgrains,theaminoacidrequirementsofruminantscanbemetatmaintenancelevelbymicrobialproteinalone.Withanincreaseinenergysupplied in the ration, extra microbial protein is produced and an increased level ofproductioncanbesustained.

However, the microbial protein yield is eventually limited by the fermented energysupply,thereforeformoderateandhighlevelsofproductionthemicrobialaminoacidsupplymustbesupplementedwithdietarysourcesofprotein,orprotectedaminoacidsthat escape degradation in the rumen. The nitrogen (N) requirements of ruminantsproducingathigherproductionlevelsarethustwofold:

1. AsourceofdegradableNtomeettheneedsoftherumenalmicrobialmicroflora.Thiscanlargelybemetbynon-proteinNsources,suchasurea,whicharecon-vertedtoammoniaintherumen.However,growthofthemicrofloraisadditionallystimulatedbyasupplyofproteinpeptides.

2. A source of non-degradable N that is later digested in the small intestine andprovidesaminoacidstocomplementthemicrobialaminoacidsandmeettissueneeds(“by-passproteins”).

Hence, importantcharacteristicsforproteinsuppliedintherationaretherateandextentofdegradationintherumen,whicheffecttheprotein’scontributionnotonlytotheammoniaandpeptideneedsofthemicroflorabutalsotothesupplyofaminoacidsformeetingtissueneeds.Considerablevariationinthesecharacteristicsexistsamong

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differentproteinsources.Anotherimportantcharacteristicofproteinsisthedigestibilityoftheundegradedproteinthatleavestherumen.Microbialproteinhasatruedigest-ibilityof85%inthesmallintestine,butvaluesforfeedproteinscanrangefrom50to90%.Finally,aswithmonogastricanimals,theaminoacidcompositionofthedigestedproteinmustalsobeconsidered.

2. pROTEIN SOURCES AND SUppLEmENTS Mostrations,especially thoseforyounggrowingorhigh-producinglivestockclasses,will require balancing with an additional protein source or protein supplement. His-torically,aninexpensivesourceofproteinformanufactureoflivestockfeedshasbeenmealsmadefromrenderedby-productsofanimals(MatthewsandCooke,2003),partic-ularlymeatandbonemeal(MBM).However,aftertheemergenceofBSEandthedirectimplicationof ruminant-derivedprotein in the transmissionandrecyclingof theBSEagent, itwasdeterminedthateffectivecontrolof thediseaserequiresrestrictionsonthefeedingofsometypesofanimal-derivedproteinstosomeorallclassesoflivestock(asdescribed in the“Overview: ImplementationofTSEmeasures for livestock feeds”chapterinthiscoursemanual).OneimportantresultoftheimplementationofthefeedbansinmanycountriesworldwidehasbeenadramaticdecreaseintheuseofMBMandotheranimal-derivedmealsforlivestockfeeding.Consequently,newsourcesofproteinarebeingsoughtandoldersourcesreconsidered.

Classesofproteinsourcesincludeanimal-derivedmeals,plantproteinsources,andsyntheticaminoacids.Thesesources,aswellasotherproteinsources thatmustbeconsideredinthecontextofTSEs,aredescribedbelow.

2.1. Animal-derived mealsInadditiontoclassicMBM,whichgenerallycontainsby-productsfrommultiplespecies(including ruminants), other sources of rendered animal protein include blood meal,meatmeal,bonemeal,andfeathermeal,aswellasmealsmadefromexclusivelyfishorpoultrymaterial.Insomecountries,dedicatedrenderingplantsproduceMBMfrompureequineorporcinematerial.Animal-derivedmealstendtohaveaminoacidcom-positionsthatmatchtherequirementsofanimals(aspreviouslydescribed),aswellasbeinghighinvitaminB12.Animal-derivedmealsarealsohighinlysine,whichisimpor-tantbecauselysineisthefirstlimitingaminoacidinfeedsformanylivestockclasses.

Unfortunately, thedefinitionsappliedtovariousmealsproducedthroughrenderingarenotalwaysconsistentbetweencountries,whichcausessomeconfusion.Forexam-ple,iftheashcontentishigh,thismayindicatethatthemealcontainssomeamountofbone,andsoitisreferredtoasMBM.Iftheashcontentisloweritmaybereferredtoasmeatmeal.Theterm“meatmeal”inthecontextofinternationaltradealsooftencoversarangeofproducts(e.g.meatmeal,MBM,bonemeal,bloodmeal,feathermeal)frommanyspecies(e.g.includingbovine,ovine,porcine,avian,pets,andwild/zooanimals).Therecanalsobeawidevariationinwhatexactlygoesintothemealthatisbeingpre-pared,notonlybetweenrenderingplantsbutalsobetweenindividualbatcheswithinaplant. Insomecases,spillageandwaste fromother industries (suchas thepet foodindustry)isalsorendered.Somegeneraldescriptionsaregivenhere.

Meatandbonemeal(MBM)hasawell-balancedaminoacidprofileand,priortotheappearance of BSE, was considered an excellent source of supplemental protein foranimalfeeds.Itiswellsuitedforfeedingmonogastricanimals,asitisnotonlyawell-

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balancedproteinsource,butalsoasourceofavailablecalcium,phosphorusandothernutrients(e.g.potassium,magnesium,sodium).

ThedigestibilityoftheMBMproteinfractionisnormallyhigh(81to87%).Theproteinqualityislowerthanthatoffishmealorsoyabeanmeal,limitingitsusefulnessasaCPsupplementincereal-basedrationsformonogastricanimals.However,becausetheCPislessdegradableintherumencomparedtomanyothersupplementalproteinsources,inruminantsitcanbeusedtoreplacemostothersupplementalproteins.MBMhasbeenconsideredagoodsourceofby-passproteinforruminants,andparticularlyvaluableinrationsforhigh-producingdairycows.

SupplementationofrationswithMBMhasbeensuccessfullyusedtopromoteproduc-tioninotherlivestockclasses,includingfish.ReplacingsoyabeanmealorfishmealwithMBMalsomayincreaseproductioninpigs,mainlybecauseofitshighlysinecontent.

Othermeatmealsandbonemealsaredefinedaccording to therelativeconcentra-tionsofthesecomponents,andthesedefinitionsdifferwidely.Theusefulnessofthesespecificproducts for feedingvariouslivestockproductionclasseswilldependontheirexactcomposition.

Fishmealhasbeenwidelyusedasasupplementalproteinsourceformanyyears,pri-marilyformonogastricanimals.Theaminoacidqualityoffishmealisexcellentformostproductionclasses,althoughthecomposition(e.g.CP,ash,energy)canvarydependingupontheexactsubstrateandprocessingmethod.Itisoftenusedasaby-passproteinsourceforfeedinglactatingdairycattle.Themainconstraintontheuseoffishmealbythefeedindustryisitsrelativelyhighcost.Fishmealisgenerallyprocessedseparatelyfrommaterialofruminantanimals,thereforemaybeconsideredofnegligibleBSEriskifcrosscontaminationiscontrolledduringtransportandstorage.

Poultrymeal isnutritionallysimilar toMBM,but isderivedentirely fromavianspe-cies.This is important inthecontextofBSE,becausegenerallypoultryslaughterandproduction isentirelyseparatedfromthatofruminantanimals.Thus, if therenderingprocess,transport,andstoragearealsoseparated,thentheriskofpoultrymealbeingcrosscontaminatedwithruminantproteinsisextremelylow.

Feathermeal,hornmeal,andmealfromswinebristlesarealsoseparatelyavailable.These products are generally used as supplements for the protein creatine, but theirdigestibilityisquitelow.TheyaregenerallynotconsideredariskforBSEifcrosscon-taminationiscontrolledasabove.

Bloodmealmayalsobeusedasasourceofprotein.Thisproduct isalsogenerallynotconsideredarisk forBSE ifspecificstunningmethodsareforbidden,and ifcrosscontaminationiscontrolledasabove.

2.2. plant protein sourcesPlantproteinsourcesvarywidelyintheirabilitytomeetthenutritionalrequirementsoflivestock.Inalmostallcases,plantsourcesmustbecombinedtoachieveanadequatebalanceofnutrients,particularlyaminoacids.

Soybeanmealorcakeisavaluablesourceofvegetableprotein,andiswidelyusedinrationsforpoultry,pigsandruminants.Theaminoacidcompositioniscomparabletothatofmilkprotein.Whenusingsoybeanmealasasubstitute foranimalproteins incom-poundfeeds,however,itisimportanttoconsiderthatsomemineralsarepresentonlyinsmallquantities.Inaddition,althoughsoybeanmealisagoodsourceofsomevitamins,itlacksvitaminB12,whichislikelythevitaminmostcommonlylackinginpoultryrations.

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Cottonseedmealisavaluableproteinsupplementforadultcattle.Thepresenceofgossypol(apolyphenolictoxin)notonlylimitsitsusefulnessforpigs,poultryandimma-tureruminants,butalsohaspublichealthimplications.Adultruminantsareprotectedfromgossypoltoxicityduetodenaturationofthetoxinintherumen.Cottonseedmealhasaconstipatingeffectoncattle,whichisbeneficialinfeedswithhighmolassescon-tent.Cottonseedmealhasrelativelylowrumendegradabilityandisthereforeausefulsourceofby-passprotein.

Groundnut (peanut)cakeisthematerial leftafteroilextractionofgroundnuts. It isasafefeedforallclassesoflivestockandhasagoodaminoacidbalance.Formatureruminantstherearenorestrictionsontheuseofgroundnutcake.Itmaybedecorticatedorundecorticated,andthehighfibrecontentofundecorticatedcakemakesitausefulcorrectiveforcattlefeedingongrassthatislowinfibre.Theresidualoilingroundnutcake may cause soft fat in bacon pigs; therefore, the extracted decorticated meal ispreferableforpigfeeding.Becauseofthelowfibreandhighproteincontentofdecorti-catedgroundnutmeal,itisavaluableingredientinpoultryrations.

Maize gluten meal is the by-product of the wet milling of maize (corn) and has ahigherproteincontentthanmostcerealgrains.Asitisnotverypalatableitcannotbefedalone,anditsrelativelyunbalancedaminoacidcompositionrestrictsitsuseinbothpoultry and pig rations, with maximum recommended levels of 10 to 16%. However,becauseitretainstheyellowcolouringpigmentofthegrainitisavaluableadditiontopoultryrations.

Other plant sources of protein include meals and cakes of coconut, palm kernel,rapeseed,lupin(e),safflower,sesame,mustardandlinseed,aswellaspeasandbeans,eachwithspecificlimitationsontheiruse(FAO,2004).

2.3. Synthetic amino acids Syntheticaminoacidshavebeenusedforover40years,startingwithDL-Methioninepro-ducedbychemicalsynthesisinthelate1950sand60sandL-Lysineproducedbyfermen-tation in the1960s. In the late1980s,L-ThreonineandL-Tryptophanwere introduced.With progress in biotechnology, the cost of production of each amino acid has beensignificantlyreduced,akeyfactorintheexpansionofaminoaciduseinanimalfeed.

2.4. Other protein sources that must be considered in the context of TSEs WiththeemergenceofBSE,therisksofotherfeedcomponentshavehadtobeconsid-eredandpreviouslycommonfeedingpracticesre-evaluated.

Pet foodspillageoftencontainsanimal-derivedproteinsthatmaybeprohibitedforlivestockspeciesbecause inmanycountriespet food isexemptfromaspectsof feedbans. Pet food that spills or is otherwise considered unfit for feeding pets may beintentionally or inadvertently fed to livestock on the farm. Moreover, these materialsaresometimessentback through the renderingprocessasaby-productofpet foodmanufacturing.

Catering(table)wastealsooftencontainsanimal-derivedproteins(suchasbeef)thatmaybeotherwiseprohibitedforlivestockspecies.However,becauseallcateringwastewas at one time deemed fit for human consumption, it should pose no risk if otheradequateTSEcontrolmeasuresareinplace.Forexample,eventhoughthefeedingofruminantproteintoruminantsisprohibitedbyallfeedbans,ifSRMsareexcludedfromthe human food chain and appropriate slaughter methods are used, then beef meat

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shouldposeanegligiblerisk.Thisproductismostimportantinthecontextofthespreadofotheranimaldiseases,suchasfootandmouthdisease(FMD).

Milkreplacers,tallow,andotherfat-basedproductshavebeensuspectedtoberiskfactorsfortheintroductionofBSEintosomecountries,althoughthishasneverbeenproven.FatitselfisnotconsideredtobeSRM.RenderedtallowisconsiderednegligibleriskifSRMisexcludedfromtherenderingprocess,andifrestrictionsonthecontentofproteinsandothersolidsinthefatsandotherprocessingguidelinesaimedtoreducetheriskofBSEinfectivityarecompliedwith.Milk-basedproductsareconsideredtobeofnegligibleriskOIE,2005).

Poultry litter includes excreta, bedding, unconsumed feed, and feathers, and hasbeenusedasasourceoffreenitrogenandofproteinpeptidesinlivestockfeeds,pri-marilyasaninexpensivemethodofdisposal.AlthoughpoultryspeciesarenotknowntobesusceptibletoTSEs,ithasbeensuggestedthatprionspotentiallypresentinpoultryfeedsmightpassthroughthedigestivetractandbepresentinthelitter.Thiscouldposeaverysmallriskifthelitterwasthenfedtoruminants.

2.�. Impact of the BSE feed bans on animal nutritionInEurope,andsubsequentlyinothercountries,theMBMbanshaveresultedinaneedtofindalternativeproteinsourcesforlivestockfeed.AccordingtoAbeletal.(2002),foralltheprotein(andaminoacids)previouslysuppliedby2.3milliontonnes(MT)ofMBMtobereplacedintheEU,about2.3MTsoyabeanmeal,4.6MTpeas,3.9MTbeansor2.8MTlupin(e)swouldbeneeded.However,theseauthorsalsosuggestthatplantmealsare inferiortoanimalmealswithregardtovariousothercomponents,andthatplantmealsmaycontainanti-nutritive factors thatcannegativelyaffect feed intakeand/ornutrient availability. In some countries, differences in costs of the different sourcesmustalsobeconsidered.However,moreaccuratelivestockfeedingsystems(e.g.phasefeeding)withadjusteddietaryaminoacidconcentrationshaverecentlybeendevelopedthatallowforproteinstoremainatlevelssimilartothatcontributedbyMBM.Consider-ingthis,MBMbanscouldberegardedaminorprobleminsomecountriesintermsofensuringaminoacidsupply.

Anadditionalconsequenceofthefeedban,atleastintheEU(whichhashadatotalfeedbansince2001), isanoverall reduction inphosphorous (P) supply,which isnotcompensatedbytheuseofplantmeals.Anadditional100000tonnesofinorganicPforfeedisnowneededintheEU(Abeletal.,2002).Atpresent,thisissuppliedbyincreasedminingofrockphosphates.Useofmicrobialphytaseenzyme(whichincreasestheavail-abilityofPfromplantmaterials)inlivestockrationscouldhelptosolvethisprobleminthefuture.

3. SUmmARy OF TSE-RELEvANT CONCEpTS• Fromanutritionalandeconomicstandpoint,animalby-productswereconsidered

agoodandplentifulsourceofproteinforlivestockfeeds.• BecausetotheemergenceofBSE,appropriatealternateproteinsourcesforlive-

stockfeedshavehadtobefound,whichisnutritionallymorechallengingforpigandpoultryfeedsthanitisforruminantfeeds.

• TherisksofMBMfromsomeregionsmadefromcertainhigh-riskmaterialsarewell documented, but alternative protein sources (including some that are notprohibitedinfeeds)mayalsostillposesomeBSErisk.

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• Someproductsthatposenoinherentriskmaystillcontaininfectivityduetocrosscontaminationduringproduction.

4. REFERENCESAbel Hj, Rodehutscord m, Friedt w, wenk C, Flachowsky G, Ahlgrimm H-J, Johnke B, kühl

R, Breves G. 2002. The ban of by-products from terrestrial animals in livestock feeding:

consequences for feeding, plant production, and alternative disposal ways. Proc Soc NutrPhysiol 11,201-229

FAO.2004.AnimalFeedResourcesInformationSystem(AFRIS).http://www.fao.org/ag/AGA/AGAP/

FRG/AFRIS/index_en.htm

matthews D, Cooke BC.2003.Thepotentialfortransmissiblespongiformencephalopathiesinnon-

ruminantlivestockandfish,RevscitechnOffintEpiz,22(1),283-296

miller EL.2004.Proteinnutritionrequirementsoffarmedlivestockanddietarysupply.In:Proteinsourcesfortheanimalfeed industry.ExpertConsultationandWorkshop.Bangkok,29April-3May 2002. http://www.fao.org/documents/show_cdr.asp?url_file=/docrep/007/y5019e/y5019e00.

htm

OIE (world Organization for Animal Health).2005.Bovinespongiformencephalopathy.TerrestrialAnimalHealthCode,Chapter2.3.13.http://www.oie.int/eng/normes/MCode/en_chapitre_2.3.13.

htm

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Inactivation of

TSE agents

inactivation of tse agents

1. GENERAL CONCEpTSAlthoughthereremainquestionsaboutthecharacteristicsandpathophysiologyoftheprionsthatarethediseaseagentsofTSEs,theirinfectivityisknowntobehighlyresist-ant tomany formsof inactivation.This resistance to inactivation is important,as thepresenceofinfectiveagentinrenderedanimalby-productssubsequentlyfedtoanimalshasbeentheprimaryfactorintheexpansionofBSEintheworld.Therefore,controlofboth theprocessingparameters for renderingofanimalby-productsand thesubse-quentuseoftheprocessedproductsinanimalfeedarecrucialcomponentsofanyTSEcontrolprogram.

Moreover,manyexamplesof inadvertent transmissionofotherTSEs throughcon-taminatedmaterialsexist.SporadicCreuzfeldt-Jakobdisease(CJD)isdocumentedtohavebeentransmittedfrompatienttopatientthroughtheuseofinadequatelydecon-taminatedneurosurgicalequipment(Bernoullietal.,1997).Scrapiehasbeentransmit-ted to sheep and goats through the survival of this agent in formol-treated vaccines(Agrimietal.,1999).

Foreffectivedevelopmentandimplementationofcontrols,somefundamentalfactsaboutTSEagentinactivationmustbetakeninaccount.

2. INACTIvATION pROCEDURES Rendering isusedtomanufacturemeatandbonemeal (MBM)fromanimalby-prod-uctsprimarily,butnotexclusively,forinclusioninanimalfeed.Therenderingprocessisdescribedinthe“Renderingofanimalby-products”chapterinthiscoursemanual.However,BSEinfectivityhasbeendocumentedtoremaininmaterialafterbeingsub-jectedtothecommonrenderingprocessesusedworldwide(TaylorandWoodgate,2003).It isthissituationthat iscreditedwiththeexpansionoftheBSEoutbreakthroughoutEuropeandtheworld.

Worldwide,oneormoreofthefollowinginactivationprocedureshavegenerallybeenusedformaterialpotentiallycontainingprions:

• batchautoclavingat134-138ºCfor18minutes(Europe);• exposure tosodiumhypochloritesolution (20000ppm)available inchlorine for

onehour(Europe);• exposureto1Msodiumhydroxideforonehour(USA);• continuousautoclavingat132ºCforonehour(USA).

Some of these methods have been incorporated into formal recommendations onreducingTSEinfectivity(OIE,2005;EU,2002),althoughthereisstillsomequestionasto their actual effectiveness in certain situations. Because different research studiesofinactivationandinfectivityusedifferentTSEagentsandstrainsofagents,thereareoftendiscrepanciesbetweenstudyresults,andthereforeinterpretationsmustbemadecarefully.

Inactivationproceduresrelyingsolelyonheatandpressureareusedonalargescaleintherenderingindustry,whereaschemicalinactivationmostoftenisappliedtomate-

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rialfromdiagnosticlaboratoriesorfromresearch.Inmanylaboratoriesacombinationofbothproceduresisapplied.Thesetwoproceduresarebrieflydiscussedbelow.

2.1. Heat/pressure inactivationAlthoughheatiscommonlyusedinanattempttoinactivateprions,ithasbeenreportedthatdryheatmaynotbeveryeffective.Inonestudy,dryheatattemperaturesupto180ºCforonehourdidnotinactivatetheME7strainofscrapieagentandsomeinfectivityremainedevenafterexposuretodryheatat160ºCfor24hours.However,aone-hourtreatment of dry heat at 200 ºC was effective with certain TSE strains (Taylor et al.,1996)

InmorerecentstudiescarriedoutbyBrownetal.(2000)itwasreportedthattracesofscrapieinfectivitycouldstillbedetectedafterbraintissueinfectedwith263K(anotherstrainofscrapieagent)hadbeenexposedtodryheatat600ºCfor15minutes.Ithasbeen speculated that this is due to the persistence of an inorganic skeleton of theinfectiveprionevenafterheatingto600ºC,andthatthisskeletonmightstillbeabletotriggertheconversionofnormalcellularprionprotein(PrPc)intotheinfectiveprionform(PrPsc).Completeburningofmaterialattemperatureabove1000ºCisgenerallyeffectiveforcompleteinactivation.

However,whenmoistureisaddedtheeffectivenessofheatinactivationimproves.IthasbeendemonstratedthatsmallamountsofTSEagentcanbe inactivated inbatchrenderingsystemswhenexposedto134ºCandhighmoisturecontentfor14-18min-utes (Kimberlim et al., 1983). However, further studies with larger samples showedthattheinactivationmightnotbecomplete.IthasbeensuggestedthatlargersamplesmorerealisticallyrepresenttheactualvolumeofpotentiallyTSE-infectedtissuethatisdisposedofbyslaughterhouses(aswellasbyhumanorveterinaryhealthcaresystemsandotheragriculturalsystems)andthatsubsequentlyrequiresinactivation.Also,par-tialdryingofsmallamountsofinfectedtissueontoglassormetalsurfaceswithintheautoclavingorrenderingsystemshouldbetakenintoaccountwhendefiningeffectivestandards for inactivation of TSE agents by heat, as these materials might harbouradditionalinfectivity.

Otherexperimentshaveinvestigatedtheinactivationofdifferentscrapiestrains,dif-ferentamountsofinfectivity,anddifferentexposuredurationsattemperaturesbetween134and138ºC(TaylorandWoodgate,2003).Thesedatasuggestthatthethermostabilityofsomescrapieagentsvarieswiththeheatingprocedure,andinactivationisdependentonboth temperatureandholding time.Therefore,simply increasing the temperatureandkeepingtheholdingtimeconstantwillnotnecessarilylinearlyimprovetheinactiva-tion.Consequently,bothparametersshouldbeanalysedtogether.

In summary, most experimental evidence confirms that application of the conven-tionalrenderingparametersof133ºCat3barsofpressurefor20minutesreducestheinfectivityofaTSEagent in renderedmaterialbyanaverageof three logs.However,otheraspectsoftherenderingprocessareimportanttooptimizetheinactivation.Parti-clesizeshouldbenogreaterthan50mm(OIE,2005)andabatchratherthancontinuousprocessshouldbeused.Finally,complementarymeasures (e.g.anSRMban)shouldbeinplacetoexcludehighconcentrationsofTSEinfectivityfrominitiallyenteringthesystem(HeimandKihm,2003).

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2.2. Chemical inactivationExperimentsinvestigatingtheinactivationofvariousTSEagentsusingchemicalshavealsobeenpublished. Inonestudy, twoyearsofexposureof theBSEagent to formolsalinehadlittleeffectonreducinginfectivity(Fraseretal.,1992).TSEagentsalsoresistinactivationbyformalinandotheraldehydes,althoughBSEinfectivitywasinactivatedby30minutesofexposuretoasolutionofsodiumhypochlorite(NaOCl)containing16500ppmofavailablechlorine(Tayloretal.,1994).

StudieswithBSE-infectedbovinebrainandscrapie-infectedrodentbrainshowedthattreatmentwith1or2Msodiumhydroxide(NaOH)foruptotwohoursdidnotcompletelyinactivatetheseagents,andpermittedthepersistenceofuptofourlogsof infectivity(Tayloretal.,1994).Thedetectionofresidualscrapieinfectivityaftertreatmentwith1MNaOHforonehourandthesurvivalofCJDinfectivityafterexposureto1or2MNaOHhavealsobeenreported(ErnstandRace,1993).

EffectiveinactivationofTSEagentscanalsobeachievedbycombiningtheautoclavingprocedureandtheexposuretoNaOH.Ithasbeenshownthatthe22Astrainofscrapieisinactivatedbyautoclavingat121ºCfor30mininthepresenceof2MNaOH(Tayloretal., 1997).Therearepracticalproblemswith thisprocedure,suchas thepotentialexposureofoperatorstosplashingwithNaOH,andthepotentialdeleteriouseffectontheautoclaveandthematerialswithin(e.g.surgicalinstruments).

Although these chemical methods are not practical for inactivation of TSE agentsin large volumesofanimalby-products, theycouldbeapplied todecontamination inlaboratorysituationsorwhensurgical instrumentsmustbesterilizedprior to reuse.This is of considerable importance, since major concerns exist in human medicineabout inactivation of TSE agents in instruments used in general surgery, as well asneurosurgery.

3. FUTURE DEvELOpmENT OF INACTIvATION IN RENDERING It is widely accepted that the conventional techniques used for rendering animal by-productsconsiderablyreduce infectivity,butdonotcompletely inactivateTSEagents.Therefore,itwillbemostimportantinthefuturetodefinetheparametersforhandling,storageanduseofrenderedmaterial.Tooptimizeinactivation,high-riskmaterialmustbeexcludedfromanyrenderingprocesswheretheproductscouldbeincludedinanimalfeed.

Asdescribedabove for inactivationgenerally, thespecific inactivationeffectduringrenderingisdefinedbymultiplefactorssuchastemperature,moisturecontent,particlesize,TSEstrain,chemicalagents,bindingsurfacesandtime.Resultsunderlaboratoryconditionshavetobeadaptedtorenderingonalargescale.Becausethereisnogener-allyaccepted inactivationcurve forall typesof inactivation, it isat leastquestionableto apply results from one rendering system to another without further investigation.Theseissuesareexploredfurtherinthe“Renderingofanimalby-products”chapterinthiscoursemanual.

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4. REFERENCESAgrimi U, Cardone F, pocchiari m, Caramelli m. 1999. Epidemic of transmissible spongiform

encephalopathyinsheepandgoatsinItaly.Lancet353,560-561

Bernoulli C, Siegrief J, Baumgartner G, Regli F, Rabinowicz T, Gajdusek DC, Gibbs CJ Jr.1977.

Dangerofaccidentalperson toperson transmissionofCreutzfeldt-Jakobdiseasebysurgery.

Lancet1(8009)478-479Brown p, Rau EH, Johnson Bk, Bacote AE, Gibbs CJ Jr, Gajdusek DC.2000.Newstudiesonthe

heat resistance of hamster-adapted scrapie agent; threshold survival after ashing at 600C

suggestsaninorganictemplateofreplication.PNAS97,3418-3421

Ernst DR, Race RE. 1993. Comparative analysis of scrapie agent inactivation. J Virol. Methods41,193-202

EU (European Union). 2002.Regulation (EC)No1774/2002 layingdownhealthrulesconcerning

animalby-productsnotintendedforhumanconsumption.http://europa.eu.int/eur-lex/pri/en/oj/

dat/2002/l_273/l_27320021010en00010095.pdf

Fraser H, Bruce mE, Chree A, mcConnel I, wells GA. 1992.Transmissionofbovinespongiform

encephalopathyandscrapietomice.JGenVirol173,1891-1897

Heim D, kihm U. 2003. Risk Management of transmissible spongiform encephalopathies in

Europe.RevscitechOffIntEpiz22(1),179-199

kimberlin RH, walker CA, millson GC, Taylor Dm, Robertson pA, Tomlinson AH, Dickinson AG. 1983. Disinfection studies with two strains of mouse-passaged scrapie agent. Guidelines for

Creutzfeldt-Jakobandrelatedagents.JNeurolsci59,355-369

OIE (world Organization for Animal Health). 2005.Procedures for the reductionof infectivityof

transmissible spongiform encephalopathy agents. Terrestrial Animal Health Code, Appendix3.6.3.http://www.oie.int/eng/normes/MCode/en_chapitre_3.6.3.htm

Taylor Dm, Fraser H, mcConnell I, Brown DA, Brown kL, Lamza kA, Smith GR. 1994.

Decontamination studies with the agents of bovine spongiform encepholopathy and scrapie.

ArchVirol139,313-326

Taylor Dm, mcConnell I, Fernie k.1996.TheeffectofdryheatonME7strainofscrapieagent.JGenVirol.77,3161-3164

Taylor Dm et al. 1997. Inactivation of the 22A strain of scrapie agent by autoclaving in sodium

hydroxide.VetMicrobiol58,87-91

Taylor m, woodgate SL.2003.Renderingpracticesand inactivationof transmissiblespongiform

encephalopathyagents.RevscitechOffIntEpiz22(1),297-310

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rendering of animal by-Products

1. GENERAL CONCEpTSWhenconsideringthemeatindustry,itisoftenforgottenthatasubstantialproportionofeachslaughteredanimaldoesnotenterthehumanfoodchain.Duringthenormalslaughterandprocessingofanimals,33-43%oftheliveanimalweightisremovedanddiscardedas inediblewaste (by-products). Theactualpercentagedependsmostlyonthespecies,andishighestforruminants,moderateforswine,andlowestforpoultry.Moreover,italsodependsonthecountry,withindustrializedcountriesusingthelow-est percentage of each animal for human consumption. These discarded animal by-products(e.g.fattrim,meattrim,viscera,bone,blood,feathersinpoultry)mustbesafe-lydisposedof,astheymayrepresentariskforhumanandanimalhealth.Inaddition,someanimalsdieonthefarm,havetobeeuthanizedforvariousreasons,orarejudgedunfitforhumanconsumption.Thesafedisposaloftheseanimals(generallycalledfallenstockordowneranimals)isanimportantissuewithregardtoTSEcontrol.

Inmanycountries,animalby-productsarecollectedandthenprocessedbytheren-deringindustryintohigh-qualityfats(tallow)andproteins(meatandbonemeal/MBMandotherproteinmeals).Historically,MBMhasbeenanexcellentsourceofsupplemen-taryproteinduetoitswell-balancedaminoacidprofile,asdescribedinthe“Proteinuseinlivestockfeeding”chapterinthiscoursemanual.Inthepast,renderersintheformer15countriesof theEUprocessedabout16million tonnesofanimalby-productsperyear,whilethoseinNorthAmericaprocessednearly25milliontonnesperyear.Argen-tina,Australia,BrazilandNewZealandcollectivelyprocessedanother10milliontonnesperyearandthe increasingproduction inAsiarepresentsbetween10and14milliontonnesperyear.Fromaneconomicpointofview,therenderingindustryhastradition-allybeenquiteprofitable,astherenderedproductsweresoldforusebytheanimalfeedandoleochemicalindustriesaroundtheworld.Thetotalvalueofthefinishedrenderedproductsworldwide,beforetheimplementationofthecurrentTSE-relatedfeedbans,wasestimatedtobebetweenUS$6andUS$8billionperyear(Hamilton,2002).

2. THE RENDERING pROCESS Theterm“renderingofanimalby-products” isusedtodescribemanydifferentproc-esses applied to raw animal by-products. In this course manual, rendering refers tothepressureheatingofanimalby-productstomakeproductsforfurtheruse,includinguse inanimalfeeding.Renderingcantakeplaceaspartof theactivitiesofaspecificslaughterhouseorataseparateplantwhereanimalby-productsfrommultiplesourcesarecollected.

After arrival and collection at the rendering plant, animal by-products are movedontoaconveyerbelt,passedthroughametaldetector,andtransportedtoacrusher.There,therawmaterialiscrushedtoreduceparticlesize.Thenthematerialispressuresterilizedinthesterilizer.Aftersterilizationaviscousmassremains,whichispassedthroughafiltertoseparateliquidsandsolids.Inanenergy-intensiveprocessstep,thesolidparticlesarethendriedandground,yieldingacoarse-grainedpowderwithahigh

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animalproteincontent(animalmeal).Theliquidphasecontainsthefatfraction.Usingcentrifugalforcesorpresses,thefatsareseparatedfromtheotherliquidproductsandcanbefurtherprocessed.

Inthisprocess,temperature,pressure,andtimeareallimportant.Theheatingandpressuremustbeapplied in thesterilizer for theentire time, i.e. thetime it takestoreachthecorrecttemperatureandpressureshouldnotbeincludedintheprocessingduration. Also, the system used for the flow of raw material being processed in thesterilizer is important.Systemswherethematerialsareprocessed inbatches (batchsystems) are optimal for achieving the appropriate conditions, whereas continuous(i.e.flow-through)systemsmaynotbe.Inaddition,themaximalsizeoftheparticleisimportant,aspenetrationandthereforeinactivationimproveswithsmallerparticlesize.Therefore,mostcountriesrequireareductionoftheparticlesizebeforeheattreatmenttolessthan50millimetres(OIE,2005).

Therenderingparameterscanvaryaccordingtolegislativerequirements.InEurope,therenderingparametersformostanimalby-products(includingallBSEriskmaterial)requireaminimumheatingattheOIE-recommendedparametersof133°Cat3barsofpressurefor20minutes(OIE,2005).Lessstringentparametersonlycanbeappliedtocertaincategoriesofmaterialsthatrepresentminorrisktohumanandanimalhealth(EU,2002).

Worldwide,theminimumparametersfortheprocessingofanimalby-productsvarysubstantially,andaregenerallysubstantiallylowerthanrecommendedbytheOIE.Heatrequirementsmaybebelow100°Candpressuremayonlyberequiredincertainsitua-tions.Often,particlesizeisnotcontrolled,andcontinuoussystemsareused.

3. GOALS OF THE RENDERING pROCESS Irrespectiveoftheultimateusemadeoftherenderedproducts,twogoalsofrenderingareto:

• reduce the volume of animal by-products through the separation of the waterfractionfromtheremainingmaterial;

• minimizetheanimalandpublichealthriskfrompossiblepathogensthroughthepressuresterilizationprocess.

Unprocessed animal by-products contain approximately 60-65% water, as deter-minedby therelativeamountofmeat (higherwatercontent)andbones (lowerwatercontent).Theheatusedintherenderingprocessremovesmostofthemoisture,therebyreducingthevolume,whichisimportantwhenconsideringdisposal.Theindividualper-centagesofthefinalanimalmealandfatfractionsvaryaccordingtotheproportionofmeatandboneintherawanimalby-products,butthecombinedfinalweightisnormallyapproximately35%oftherawanimalby-productweight.Thefinalvolumeoftheanimalmealfractionisapproximately23%andthefatfractionapproximately12%oftherawanimal by-product volume. Globally, the rendering process reduces the total animalby-productvolumefrom60milliontonnesofrawmaterialtoabout8milliontonnesofanimalproteinsand8.2milliontonnesofrenderedfats(Hamilton,2002).

Theheatoftherenderingprocessalsosterilizestheby-products,astheprocessingtemperaturesareusuallymorethansufficienttokillbacteria,virusesandmanyothermicroorganisms.Arecentstudyshowedthatrenderingat133°Cat3barsofpressurefor 20 minutes eliminated Clostridium Spp., Listeria Spp., Campylobacter Spp.andSalmonellaSpp.inrawanimaltissues(Troutetal.,2001).Suchhightemperaturesare

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alsoeffectiveinkillingtheanthraxbacterium(Clostridiumanthracii)anddestroyingthefootandmouthdiseasevirus.However,renderingdoesnotcompletelydestroytheprioncausingBSE(seethe“InactivationofTSEagents”chapterinthiscoursemanual),whichhasledtothevariousbansonincludingrenderedanimalproteininlivestockfeedsinEuropeandinmanyothercountries(asdiscussedthroughoutthiscoursemanual).

4. OTHER OpTIONS FOR ANImAL By-pRODUCT DISpOSALWith implementation of the MBM bans in livestock feed, the disposal of animal by-products,eitherassuchorasrenderedmeals,becomesanextremelylargeproblemforallcountries.Whatultimatelyhappenstothesematerialsandproductswilldependonwhatrawmaterialwasusedaswellastheregulationsofthecountry.

Some alternatives currently being applied or considered are incineration, co-incineration(e.g.inthecementindustry,inwasteincineration,orinfertilizerprocess-ing),burial,disposal in landfills,use inbiogasproductionorcomposting.MostEuro-pean countries are using some form of incineration. However, incineration requiresinitialrendering(primarilytoreducethevolume)andstorageoftherenderedmaterialbeforeincineration.Directincinerationofrawmaterialispossible,butcannotbeusedon a large scale. Recent estimates by the European Fat Processors and RenderersAssociationgivetheannualincinerationcapacityintheEUas2.5milliontonnes,whilethequantitytobeincineratedisputat3.6milliontonnes(EU,2001).

Abeletal.(2002)alsonotetheproductionofgreenhouseandnoxiousgasesproducedby incineration. They calculate that combustion of one kilogram (kg) of MBM causesreleaseofabout1.4kgofcombinedcarbondioxide(CO2),carbonmonoxide(CO),andsome further trace gases including nitrous oxide (N2O) and sulphur dioxide (SO2). Ofthese, N2O is the most dangerous because its global warming potential has beenestimatedat310timesthatofCO2andbecauseofitsozonedepletingpotentialinthestratosphere.

Composting and other biological methods of raw material disposal do not achievethehightemperaturesnecessarytomakethematerialmicrobiologicallysafewithoutpriorheating.Inaddition,burial,disposalinlandfills,andstorageofdrymaterialposeunacceptableenvironmental risksas theyaresubject to incursionofbirdsandotheranimals,whichmaythenspreaddiseaseagentsoutintotheenvironment.

Regardlessofmethod,thecostsofdisposalmaybeveryhigh.Theyarecertainlyhigh-erthanbeforeTSE-relatedfeedbanswereimposed,whentherenderingindustrygen-erallypaidtopurchasetherawanimalby-productsfromfarmersandslaughterhousesandstillproducedproductsataprofit.ThedataofAbeletal.(2002)showthatthetotalcostsofthealternativeuseordisposalof3.6milliontonnesofMBMvariesfrom€1.0-1.8billion.Onaverage,everykgofMBMnotusedinlivestockfeedincursacostofabout€0.32,ornearlytwicethe1999supplypriceofMBM.Expresseddifferently,foreverykgofMBMnotusedinlivestockfeed,thereisanoveralleconomiclossofabout€0.14.

�. ANImAL By-pRODUCT LEGISLATION IN THE EUROpEAN UNIONAregulationlayingdownrulesconcerninganimalby-productsnotintendedforhumanconsumptionwasadoptedbytheEUinOctober2002,andappliedon1May2003(EU,2002).Inparticular,theregulation(referredtohereasRegulation1774/2002)introducesstringent conditions throughout the food and feed chains including safe collection,transport,storage,handling,processing,useanddisposalofanimalby-products.

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Asageneralprinciple,Regulation1774/2002describesarisk-basedcategorizationsystemforanimalby-products,andtheirpossibleuses.Threecategoriesaredefined.

• Category 1 Regulation1774/2002requires thecompletedisposal,by incinerationor landfill

afterappropriateheattreatment(133°C/3bars/20minutes),ofCategory1mate-rials.TherawmaterialofCategory1isdefinedasanimalby-productspresentingthe highest risk for diseases such as BSE or other TSEs (e.g. scrapie). It alsoincludesfallenstockfromruminantsandfromanimalsnotintendedforhumanconsumption(e.g.companionanimals,researchanimals).

• Category 2 Category 2 material can be used in the same way as animal by-products of

Category 1. In addition, it may be recycled for technical uses after proper heattreatment (e.g.biogas,composting,oleochemicalproducts).Theuseforanimalfeedingisprohibited.TherawmaterialofCategory2includesanimalby-productsthathavebeenrejectedbyante/postmortem inspection in theslaughterhouse.TheyalsopresentariskofcontaminationwithanimaldiseasesotherthanBSE.

• Category 3 Regulation 1774/2002 states that only Category 3 materials may be used in the

productionofanimalfeeds(includingpetfoods)followingappropriatetreatmentinapprovedprocessingplants.TherawmaterialofCategory3isdefinedasanimalby-products derived from healthy animals slaughtered for human consumption.

Thus, under Regulation 1774/2002, only materials derived from animals declaredfitforhumanconsumptionfollowingveterinaryinspectionmaypotentiallybeusedforthe production of livestock feeds. The regulationalso requires the exclusion of deadanimalsandothercondemnedmaterialsfromthefeedchain,thecompleteseparationduring collection, transport, storage, handling and processing of animal by-productsnotintendedforanimalfeedorhumanfood,andthecompleteseparationofrenderingplantsdedicatedtofeedproductionfromrenderingplantsprocessinganimalby-prod-uctsdestinedfordestruction(i.e.bycategoryofrawmaterialprocessed).

Italsosetsoutclearrulesonwhatcanandmustbedonewiththeexcludedanimalmaterials,includingimposingastrictidentificationandtraceabilitysystemandrequir-ingcertainproductssuchasMBMandfatsdestinedfordestructiontobepermanentlymarkedtoavoidpossiblefraudandriskofdiversionofunauthorizedproductsintofoodand feed.ThecontrolofmovementsofSRMbyarecord-keepingsystemandaccom-panyingdocumentsorhealthcertificates isalso required.Regulation1774/2002alsoprohibits any intra-species recycling of processed proteins (feeding material derivedfromaspeciesbacktothesamespecies).

However, Regulation 1��4/2002 does not in any way change or affect the current EU total ban on the feeding of mBm to farmed animals, which is a separate issue and remains in force without any termination date set.Regulation1774/2002onlyestab-lishesclearsafetyrulesfortheproductionofMBMincaseit iseverreauthorizedforinclusioninfeedforcertainnon-ruminantspecies,e.g.poultryorpigs.

WiththeadoptionofRegulation1774/2002,theenvironmentalandeconomicreper-cussionsof thefeedbancanpotentiallybereduced inthefuture,asonly twomilliontonnes of material derived from animals unfit for human consumption (compared tothe16million tonnesofanimalby-products incaseofa totalban)wouldneed tobedisposedof.

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�. THE FUTURE USE OF mEAT AND BONE mEALItispossiblethat,inthefuture,MBMcouldagainbeusedinfeedforfarmedanimalsin countries where it is presently banned (including countries in Europe) if appropri-atelegislationandcontrolsareimplementedandenforced.However,itsusewillmostprobablyalwaysberestrictedtonon-ruminantanimals.IfSRMisremoved,fallenstockareexcluded,andtheprocessensuresheattreatmentat133°Cat3barpressurefor20minutesitisassumedthattheriskofinfectivityofaTSEagentthatmightbepresentismarkedlyreduced.Inaddition,betterclassificationandseparationofdifferentmate-rials would further reduce the risk from the rendered products. However, caution isrequiredasthisstepmustonlybetakenifthesemeasurescouldbeeffectivelyimple-mented.

Irrespectiveofanyscientificjustifications,however,theBSEoutbreakhasseriouslyaffectedthepublicperception,atleastinEurope,regardingtherenderingindustry,thefeedingofanimalproteinstonaturallyherbivorousanimals,andthefeedingofproteinsderivedfromonespeciesbacktothesamespecies(whichmaybeseenascannibal-ism).TheseperceptionswillundoubtedlyinfluencetheacceptanceoftheuseofMBMoranimal-derivedproductsinanimalfeedsinthefuture.

�. SUmmARy OF TSE-RELEvANT CONCEpTS• Renderingprocessesandparametersvarysubstantiallyamongcountriesthrough-

outtheworld.• AppropriaterenderingcanreduceTSEinfectivityinanimalby-products,although

infectivityisnotentirelyinactivated.• Incinerationbysomemethodiscurrentlythemosteffectivemethodofdisposalof

TSEriskmaterial(rawandprocessedanimalby-products).• Although there is limitedcapacity foralternatedisposalof the largeamountof

rendered material that is now prohibited in feed, it must be assured that thismaterial isproperlydisposedofsothatitdoesnotillegallyre-enterthefoodorfeedchain.

• Separationofby-productsbyriskcategorycouldeventuallyallowtheuseofsomeanimalproductsinlivestockfeeds.

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�. REFERENCESAbel HJ, Rodehutscord m, Friedt w, wenk C, Flachowsky G, Ahlgrimm H-J, Johnke B, kühl

R Breves G. 2002. The ban of by-products from terrestrial animals in livestock feeding:

consequences for feeding, plant production, and alternative disposal ways. Proc Soc NutrPhysiol11,201-229

EC (European Commission). 2001.Commissionservicespaperon theprocessing,disposaland

usesofanimalby-productsinMemberStates.http://europa.eu.int/rapid/pressReleasesAction.

do?reference=MEMO/01/378&format=HTML&aged=0&language=EN&guiLanguage=en - file.

tmp_Foot_5

EU (European Union).2002.Regulation (EC)No1774/2002 layingdownhealthrulesconcerning

animal by-products not intended for human consumption. http://europa.eu.int/eur-lex/pri/en/

oj/dat/2002/l_273/l_27320021010en00010095.pdf

Hamilton CR.2002.Realandperceivedissuesinvolvinganimalproteins.Proceedingsofanexpert

consultationonalternativeproteinsourcesfortheanimalfeedindustry.FAO,Rome.

OIE (world Organization for Animal Health). 2005.Procedures for the reductionof infectivityof

transmissible spongiform encephalopathy agents. Terrestrial Animal Health Code, Appendix3.6.3.http://www.oie.int/eng/normes/MCode/en_chapitre_3.6.3.htm

Trout HF, Schaeffer D, kakoma I, pearl, G. 2001. Directors Digest No. 312. Fats and Proteins

ResearchFoundation.

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mANUFACTURING OF COmpOUND FEEDS FOR LIvESTOCk1

1. GENERAL CONCEpTSAlthoughproductionofcompoundfeedsforlivestockhaslevelledofforisdeclininginmanypartsofEuropeandNorthAmerica(Figures1aandb),itstillmaintainsanimpor-tanteconomicposition.ForexampleinEurope,compoundfeedproductionranksthirdaftermeatanddairyproduction,accountingfor7%ofthetotalsalesofCHF750billioninthissector.Feedmanufacturingwilllikelymaintainthisroleintheforeseeablefuture,althoughgrowthmayshiftgeographically.

Compoundfeedsaremanufacturedprimarilyfromorganiccompoundsofvegetableoranimalorigin.Thesmallinorganicpercentageisprimarilyofmineralorigin.Becauseofthehistoricalimportanceofincludingingredientsofanimalorigin,manufacturingofcompound feeds throughout theworldhasbeenaffectedby theappearanceofTSEs.Inmanycountries,feedproductshavehadtoundergoreformulationtocompensateforprohibited materials, and stricter controls of contamination and cross contaminationhavebeenimplementedinfeed-producingplants.

Inthischapter,amodernfeedmanufacturingprocess,usingthemosttechnologicallyadvancedequipmentpossible,isdescribed.ThischapterdoesnotcontainasummaryofTSE-relevantconcepts.Otheraspectsoffeedproductionarepresentedinotherchap-tersofthiscoursemanual.Forexample,aspectsofqualityassurancefortheprocessingstepsdescribedherearepresentedinthe“Qualityassuranceinfeed-producingplants”chapter.

2. STRUCTURE OF A FEED pRODUCTION pLANTA feedproductionplantcangenerallybedivided into themainprocessingareasandsecondaryprocessingareas,andservicesand infrastructure.Theservicesand infra-structurewillnotbedescribedhere,astheydonotdirectlyrelatetothequalityorsafetyofthefeedsproduced.

Mainprocessingareas:• Reception(intake)andcleaning• Proportioningandweighing• Grinding• Mixingandhomogenizing• Pelleting• Finishedproducts

1 ThemajorityofinformationwithinthischapterisextracteddirectlyoradaptedfrommaterialscopyrightedbytheSwissInstituteofFeedTechnology(SFT),underabilateralagreementwithSAFOSO(Nef,2002).TheSFTreserves all rights to this material and the objects described herein. This information must not be furtherreproducedorduplicated,eitherwhollyor inpart,norbemadeaccessible,eitherwhollyor inpart, to thirdpartiesinanyformwhatever,norbeusedforanypurposeotherthanthatforwhichithasbeengiventotherecipient.

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Secondaryprocessingareas:• Crushingofgrain• Hullingofgrain• Flaking• Extrusion• Expansion• Heattreatment

Servicesandinfrastructure• Exhaustsystems• Compressedairsupply• Steamsupply• Watersupply• Electricinstallationandcontrolsystem

FigUre 1a

world feed production by feed type, 1��4

Source:adaptedfromNef(2002).

Compound feeds:530 million tons

Home mixing: 350 million tons

Single ingredients:220 million tons

FigUre 1b

percent of world feed production by region, 1��4


North America24%

Latin America11%

Asia & Oceania26%

Eastern Europe11%

Western Europe24%

Middle East & Africa

4%

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3. FEED pRODUCTION pROCESSES 3.1. Intake of raw ingredientsTherawingredientstobeprocessedmayarriveatthefeedplantviaship,rail,orroad.Weight checks are usually performed at weighing bridges in the case of rail or roadvehicles,and/orbyintakescalesinthevariousin-plantconveyingsystems.

Grainisnormallysuppliedinbulk,andmealsormeal-typeingredients maybesup-pliedinbulkorinbags.Feedplantswithalowcapacitycanusethesamelineformealreceptionas forgrainreception.Largecapacity feedplants,ontheotherhand,musthaveseparatereceivingsectionsandconveyinglinestoaccommodatethelargevolumeofgrainarrivingperday.

Mineralsaswellaspremixesmaybesuppliedinplasticorpaperbags,tincans,ordrums, or they may be supplied by bulk trucks (tankers) with attached blowers. Forthistypeofsupply,apneumaticreceivinglinemustbeprovided.Premixesmayalsobeproducedin-house.

Bothfatandmolassesarenormallysuppliedinaheatedandliquidform.Theyaredischargedfromthebulktrucksintothestoragetanksdirectlybypumps.

The following machines and installations are used for receiving and conveying therawingredients:

• Shipunloadingsystems• Chainconveyors• Screwconveyors• Beltconveyors• Bucketelevators• Pneumaticconveyingsystems• Liquidspumps

3.2. Cleaning of raw ingredientsDependingontheiroriginandpreviousprocessing,rawingredientsmaybeheavilycon-taminatedandcontainforeignmatterthatmustberemoved.Asaresult,thecleaningsysteminafeedplanthastwofunctions:

• toseparateundesirableimpuritiessuchasstones,piecesofwood,strings,paper,straws,sand,andmetalparts;

• toprotectexpensive feedplantequipmentsuchasdischargers,hammermills,mixers,pelletmillsandothersagainstdamage.

Thefollowingequipmentmaybeusedforcleaningtherawingredients:• Drumsieves• Centrifugalsieves• Oscillatingsieves• Separators• De-stoners• Spoutmagnets• Cascademagnets• Drumtypemagnets

Dependingontheparticularmachine,theoutputfromthecleaningprocessincludestheacceptablematerial,aswellascourseimpurities,fineimpurities,anddust.

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3.3. Discharge and weighing of raw ingredientsBecauseoftheimportanceofofferingabalancedrationforaparticularlivestockspe-ciesorclass,compoundfeedproductsareusually formulatedandcontinuouslyopti-mizedbymeansofmoderncomputerprograms.Mostoftherawingredientsarestoredinbins.Theindividualpercentagesoftherawingredientsaredischargedfromthebinsusinga typeofdischargerappropriate to theparticularmaterial. Themostcommontypesareslidegatedischargers,rotarybindischargers,andscrewdischargers.

Afterdischarge,rawmaterialsarefedtotheallocatedscales.Inordertoguaranteethemostpreciseinputweighingpossible,themachineryiscapableofproportioningthematerialbyfastanddribbleflow.

Todeterminethenumberofbinsandthescalesize(s)needed,aproductformulalistisestablishedshowingtherequiredquantitiesoftheindividualingredients.Thescalesizeandthenumberofscalesareobtainedfromthelowestallowableingredientweightandthetotalweightperscaletobeweighedatonetime.Thelowestingredientweightthatcanbeweighedbyabatchscalemustbeatleast4%ofthescalecapacity.

3.4. Grinding Togetherwithmixingandpelleting,grindingtoreducetheparticlesizeofrawingredi-entsisakeyprocessincompoundfeedmanufacturing.About80%ofallrawingredi-entsusedfortheproductionofcompoundfeedrequiresizereduction.Sizereductionrankssecondinfeedplantenergyconsumption(afterpelleting),whichunderscorestheimportanceofcorrectsizingandoptimizedoperationofgrindingsystems.

Thepurposeofgrindingis:• toachievetherequiredmaterialfineness(texture)matchedtotheanimal'snutri-

tionalrequirementsanddigestivesystem;• toachieveuniformparticlesizeinordertoobtainahomogeneousproductduring

thesubsequentmixingoperation;• toachievethenecessaryfinenessinordertoobtainanacceptablepelletqualityif

thematerialissubsequentlypelleted.Abasicdistinction ismadebetweenpre-grindingandpost-grinding,andbothsys-

temsmayalsobedesignedforcirculationormulti-stagegrinding.Inpre-grindingsystems,alltheingredientsarefirstindividuallyground.Theadvan-

tagesofpre-grindingarethatgrindingisindependentofmixingandcanthereforebeefficientlyapplied,night-timegrindingatlowpowerratesispossible,andtheparticlesizedistributionof the individualmaterialscanbe varied.Thedisadvantagesare thehighcapitalcostofgrindingbinsandconveyorsforseparateingredients,thefactthatwithdifferentparticlesizedistributions there isdangerofsegregation (separationofrawingredients)inthefinishedfeedandthatmaterialscontainingchaffaredifficulttogrind.

Inpost-grindingsystems,alltheingredientsofamixarefirstproportioned,weighed,addedtogether,andthenground.Ifpossible,thefinesshouldbesiftedoutbeforegrind-ing.Theadvantagesofpost-grindingarethattheendparticlesizedistributioncanbecontrolledandtheproducttextureisuniform,hardtogrindmaterialsareeasiertogrindwhenmixedwithother ingredientsandbuildingcostsarelowerbecausenoseparategrindingbinsareneeded.Thedisadvantagesarethatindividualingredientscannotbeselectivelyreducedtoadesiredparticlesizeandthemixingsystemisdirectlydepend-entuponthegrindingcapacity.

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Dependingontherequiredcapacity,theparticlesizedistributionrequirements,andotherdevelopmentsinthemarketplace,differentgrindingmachinesmaybeused.

A tootheddiskmill canbeused forbreakingofgrainaheadof flaking, forpoultryfeed production and for detaching and grinding of minerals. Its advantages are easeofoperationandlowpercentageoffines,anditsdisadvantagesarethe lowthroughput(approximately4000kg/hr)andalackofabilitytovarytheparticlesizedistribution.

Arollermillisusedifaparticlesizedistributionofmaximumuniformityisrequired.Itsadvantagesarealowpowerrequirement,sizereductionisaccomplishedgentlyandwithoutalotofheatgenerationandthereisanarrowparticlesizedistribution.Itsdisad-vantagesareahighcapitalinvestment,itsunsuitabilityforfibregrinding,itsexpensivedesignanditslimitedinputparticlesize.

A conventional hammer mill is considered the universal grinding machine in feedmanufacturingand itallowssizereductionofalldry feed ingredients. Itsadvantagesareitsuniversalapplicability,highpossiblethroughputs,easyvariationofparticlesizedistribution,simpledesignandeasyoperation. Itsdisadvantagesareitswideparticlesizedistributionandahighpowerrequirement.

Thedevelopmentoftheverticalrotor (hammer)millhasopenednewpossibilities inthegrindingprocess.Comparedtoconventionalhammermills,itsadvantagesarethatnoexhaustsystemisrequired,thereisalowerburdenontheenvironment,thereisnolossofmoisture,ithasalowpowerrequirement,ahigherthroughputandalowernoiselevel.

3.�. Conveying Pneumaticsuctionsystems,pneumaticpressuresystems,ormechanicaltransportsys-temscanbeusedforconveyingmaterialsaftergrinding.Becauseoftheirhighoperat-ingcosts,pneumaticconveyingisgenerallyappliedforlow-capacityplantsonly.

3.�. mixing, addition of liquids, and homogenizationMixers are the main machines in feed plants. Their function is to uniformly mix theindividualrawingredients,whoseparticlesizesandbulkdensitymayvaryconsiderably.Micro-ingredientsmaybegravimetricallyaddedinthemixerusingspecialdispensingunitsorbyhand.

In the feed manufacturing industry, the mixers almost exclusively used are of thebatchtype,inwhichentireunits(normally500–5000kg,dependingonthemixersize)arepre-weighed,groundandthenmixed.Thistypeofmixingsystemensuresahomo-geneousproduct.

Themixersize,type(verticalorhorizontal)andmixingtimedeterminethecapacityofabatchmixingsystem.Dependingonthetypeofmixerused,themixingtimeswillvaryconsiderably.Forexampleusingaverticalmixerwithscrew,themixingtimewillbeapproximately10-30minutes,andifusingahorizontalmixerwithribbonflightorpad-dles,themixingtimewillbeapproximatelyonetofourminutes.Generally,horizontalmixerswithcountercurrentmixingactionononeshaftwillachievetherequiredmixingqualitywithintheshortesttime.Allmixersshouldmeetthefollowingstandards:

• Themixingaccuracyshouldbeguaranteedatadilutionof1:100000.• Homogeneityshouldbeachievedwithintheshortesttimepossible.• Thematerialtobemixedshouldbehandledgentlyaspossible.• Whenthemixerisemptied,residuesshouldbeatanabsoluteminimum.• Themixershouldbeadaptableforadditionofliquids.

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Inhorizontalmixers,thedryingredientsarefedbatchbybatchintothemixerwhiletherotorisrunning,andarehomogeneouslymixedinthemixingchamber.Themixingtimeisgenerallytwotofourminutes.Horizontalbatchmixersmaybeequippedwithapaddlerotororaribbonflightrotor.

Withribbonflightrotors,loadingispossiblealongtheentirelengthofthemixer.How-ever,partialbatchesmustbeloadedataminimumof50%capacityandribbonflightchangesarelabour-intensive.Theexpectedresidueisabout0.2%.Withpaddlerotors,loadingisonlypossibleinthecentrebutpartialbatchesdownto20%arepossible.Thepaddlesareadjustable,andthematerialsaremoregentlytreated.Theexpectedresidueis<0.2%.

The use of horizontal speed mixers can contribute to the plant flexibility and toreductionofcontamination.Comparedtoconventionalhorizontalmixers,speedmixershave:

• shortermixingtimes(1.5minutes);• athroughputofupto20batches/hour;• smallermixer,scalesandhoppers;• fastandcompletedischarge;• aresiduelevelofonly0.05%• atroughshape(length:depthratio=1:1);• norequirementforanairreplacementduct;• norestrictionregardingfilling;• easiermaintenance.

Theadditionofliquidingredientstofeedsisbecomingincreasinglyimportant.Liquidsmaybeaddedinordertobeabletouselessexpensiveby-productsfromotherproductionprocesses,toenrichenergy,tocontroltaste,smellandcolour,toreducedustgenerationandsegregation, to increasemoisturecontentand to improvepreservation.Commonliquidsincludewater,fats/oils,molasses,propionicacidandflavouringagents.Becauseoftheirviscosity,fats,oilsandmolassesmustbeheatedtoacertaintemperaturebeforetheycanbeaddedtofeeds.Thepointoftheprocessatwhichtheliquidisaddedandtherateofadditiondependsonthetypeandquantityofliquidtobeused.

Abatchmixer isgenerallynotsuitable for theadditionof liquids to the feed,how-everitmaybepossibleiftheadditionrateislowerthan5%.Otherwise,problemsmayincludelumpformation,contaminationofrotorandtrough, increasedpowerrequire-mentandincreasedamountofresidue.

Inthefeedindustry,homogenizationistheincorporationofliquidsintodrysolidsinacontinuousprocess.Homogenizersoperateatfairlyhighrotaryspeedsandensurethor-oughintermixingoftheliquidwiththesolids.Homogenizersmaybeusedaheadoforafterthebatchmixer,andcanhandlethesimultaneousadditionofuptothreeliquids.

3.�. pelletingThe purpose of pelleting is to transform a loose, mealy bulk material into normallycylindricalpelletsbycompactionandshaping.Pelletedfeedoffersanumberofadvan-tagesoverfineandcoarsemeal-typefeeds.

• Benefitstothefeedproducer:- lessstoragespaceandsmallerconveyersrequired;- costreduction(lowercostrawmaterialscanbeused);- lowerriskofsegregationandcontamination.

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• Benefitsinstorage/handling:- simplerdischargefrombins;- nosegregationduringbulkhandling;- bridging(feedflowblockageduringdischarge)inbinsisreduced;- lessdustisgenerated.

• Benefitstotheanimal:- higherdegreeofnutrientassimilation;- reductionofbacterialandfunguscountsinfeeds;- allconstituentsofthemixareavailableinuniformproportions.

Thepelletmillconsistsofthreemajorcomponents:(1)thescrewfeederwhichallowsavolumetricdischargeof themashfromthepelletmillsurgehopper, (2) themixingandconditioningsectionwhichallowsconditioningofthemashwithadditionofsteamand liquids (usuallymolasses),and (3) thepelletmillwhichcompacts themashandshapesitintopellets.Withinthepelletmill,themainpelletingcomponentsarethedieand the rolls. After the mash has been distributed between the rolls and across thewidthofthedie,theactualpelletingprocessstartsatthemomentthelayerofmashtouchestheroll.

Asaresultoftheever-increasingqualityandsanitationrequirementsthatmustbemet,andbecauseofthegreateruseof inexpensiverawmaterialswithpoorpelletingcharacteristics,itisoftennotpossibleusingtheconventionaldirectpelletingprocesstoachievethenecessarybindingforcesformakinghighqualitypellets(Figure2).There-fore, a double pelleting system was developed that considerably improves the pelletqualityandsimultaneouslyallowsahigherthroughput.

FigUre 2

Factors having a fundamental influence on the pelleting process and the final product


Raw product/mashParticle sizeParticle formProduct densityProduct moisturePelleting aids

Machine componentsDieRollDie speedRoll gap

Processing systemConditioningThroughputFines returnLiquid addition

FACTORS

Pelletability

QualityStabilityHardnessAbrasionEnergy

ASPECTS OF THE RESULTING PELLET

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3.�. Heat treatment and coolingThe demand for safe and hygienically produced feeds is increasing, not only in thedomesticandinternationalmarketsbutalsofromconsumers.EndproductsmustbeasfreeaspossiblefromSalmonellaSpp.andotherharmfulbacteria.

Heattreatmentisthemosteffectiveandeconomicalmethodofdestroyingbacteriaandotherpathogensinlivestockfeedsandimprovingthequalityoffeeds.Heattreat-ment, through theprocessof expansion,alsoenhances thequalityof energy, as thestarchinthefeedbecomesmoreavailable(especiallytonon-ruminants).Thetwomostcommonheattreatmentmethodsarepelletingwithheatshieldandtheapplicationofexpanders.

Byequipping thepelletingmillwithadoubleconditionerheatshield, theretentiontimeinthemixer-conditionersectionincreases.Theoptimaltemperatureismaintainedbymeansofelectricalsurfaceheatingandadditionofhotair.

Expandersmaybeappliedasanindependentprocessstageorincombinationwithapelletmill.Typicalapplicationsofexpandersinclude:

• salmonellacontrolforbroilerandlayinghenfeeds;• productionofcrumblesforslurryfeedingofpigs;• starchgelatinizationforyounganimals,especiallypiglets;• productionoflowabrasionpellets;• productionofcattlefeedwithhighliquidadditionrates.

Pelletsaredischargedfromthepelletmillatatemperatureofapproximately80°C.Inaddition,theyarestillmoistandsoftandthereforecannotbepackedorstoredbeforetheyhavecooledtoatemperaturenormally5to10°Cabovetheambienttemperatureandhavehardened.Themostcommoncoolertypesarehorizontal (belt type)coolersandcountercurrentcoolers.

Horizontalcoolerscanbeusedforalltypesandsizesofproducts,althoughtheyhaveahighspecificairrequirementandarelativelylargespacerequirement.Countercur-rentcoolers canonlybeused for free flowingmaterialsandpelletswithasizeofupto10mmbuthavealowspecificairrequirementandarelativelysmallspacerequire-ment.

4. REFERENCESNef E. 2002. Manufacturing of compound feed. Swiss Institute of Feed Technology, Uzwil,

Switzerland.http://www.sft-uzwil.ch/en/home/home_en.asp.

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LIvESTOCk FEED REGULATIONS AND INDUSTRy GUIDELINES

1. GENERAL CONCEpTSThe appearance of TSEs has presented new challenges to countries throughout theworld.Inordertoprotectbothdomesticpublicandanimalhealthandmaintaintradeinanimalsandanimalproducts,manycountrieshaveimplementedsomemeasurestocontrolandpreventTSEs,andBSE inparticular.Thesemeasuresvarywidelyamongcountries,butgenerallyincludesomeformoffeedbaninordertopreventruminantsfromingestingmaterialderivedfromruminants,asdescribedinthe“Overview:Imple-mentationofTSEmeasures”chapterinthiscoursemanual.

Internationalrecommendationsandregulationshavebeendevelopedtoimprovepub-licandanimalhealthandfacilitatefairtradethroughthestandardizationofBSE-relatedmeasuresacrosscountriesandregions.Nationalregulations,practiceguidelinesandcodes of practice have been developed to help countries and individual agriculturaloperationseffectively implement themeasures inplace.Manyorganizationsatmanylevelsparticipateindevelopingthesedocuments.InFigure1,theinternational,nationaland industry framework that contributes to the overall safety of animal feed in the

FigUre 1

The network of players contributing to the goal of international food and feed safety

OIE:WorldOrganisationforAnimalHealthIppC:InternationalPlantProtectionConventionwHO:WorldHealthOrganizationFAO:FoodandAgricultureOrganizationEU:EuropeanUnion

FEFAC:EuropeanFeedManufacturers’FederationGAFTA:GrainandFeedTradeAssociationAFIA:AmericanFeedIndustryAssociationIFIF:TheInternationalFeedIndustryFederationwRO:WorldRenderers’Organization

International Food andFeed Safety

IPPC OIE CodexAlimentarius WHO FAO

EU 171 Member Countries of the Codex Alimentarius

MemberStates

FEFAC GAFTA AFIA IFIF WRO

International

National

Industry

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world,aswellaswithrespecttoBSE, isshown. It isclearthatcountriesoutsidetheCodexAlimentariusalsocontributetoandparticipateinthisprocess.

2. INTERNATIONAL STANDARDS AND NATIONAL/REGIONAL REGULATIONS WTOconsidersthestandardssetandrecommendationsmadebytwointernationalbod-ies,theCodexAlimentariusCommissionforfeedandfoodissuesandtheOIEforanimalhealthissues,tobetheinternationalstandards.Inaddition,countriesandregionsadoptand implement legislation that should be in line with these international standards.LegislationoftheEUandtheUSAaregivenhereasexamples.

2.1. The Codex Alimentarius In 1963 the Codex Alimentarius Commission was created by the WHO and FAO todevelop food standards, guidelines and related texts such as codes of practice. Themainpurposesaretoprotectthehealthofconsumers,toensurefairtradepracticesinthefoodindustry,andtopromotecoordinationofallfoodstandardsworkundertakenbyinternationalgovernmentalandnon-governmentalorganizations.TheoutputfromtheCodexCommissioniscalledtheCodexAlimentarius,whichcomprehensivelydescribesbasicprinciplesoffoodhygiene,andisavailableathttp://www.codexalimentarius.net.

Atthe23rdSessionoftheJointCodexAlimentariusCommissionin1999,anAdHocIntergovernmentalCodexTaskForceonAnimalFeeding(hostedbytheDanishGovern-ment)wasestablishedtodevelopadraftcodeofpracticeonanimalfeeding.Thiscodeof practice was presented and approved by the Codex Commission in July 2004, andappliesinadditiontothebasicprinciplesalreadyestablishedintheCodexAlimentarius(CodexAlimentarius,2004).Itaimstoestablishafeedsafetysystemforfood-producinganimals,andcomprehensivelycoversthefoodandfeedchainstakingintoaccountrel-evantaspectsofanimalhealthandtheenvironmentinordertominimizepublichealthrisks.Thefullcodeofpracticecovers:

• generalprinciplesandrequirementswithrespecttofeedingredients;• labelling;• traceability/producttracingandrecord-keepingoffeedandfeedingredients;• inspectionandcontrolprocedures;• healthhazardsassociatedwithanimalfeed;• feedadditivesandveterinarydrugsusedinmedicatedfeed;• feedandfeedingredients;• undesirablesubstances;• production,processing,storage,transportanddistributionoffeedandfeed ingredients;• receiving,storageandtransportation;• personneltraining;• sanitationandpestcontrol;• equipmentperformanceandmaintenance;• manufacturingcontrols;• recalls;• on-farmproductionanduseoffeed;• goodanimalfeedingpractice;• methodsofsamplingandanalysis.

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Althoughthecodeofpracticedoesnotspecificallyrefertotheuseofanimalproteinsin feed, it does cover regulation and control of animal feed manufacturing includinglabelling,traceability,inspection,production,processing,storage,transport,samplingand analysis, and training. These aspects ultimately contribute to assuring effectiveenforcement of BSE measures in place, including feed bans and prevention of crosscontamination. The code of practice not only covers production at feed-producingplants,butalsocoverson-farmmanufactureoffeed.ThisisimportanttoBSEcontrol,asrawmaterialsprohibitedforuseincertainlivestockspeciesmaybeusedinappro-priatelyunderlooserprivatecontrol.

Furtherinformationonrelevantaspectsofcontrolandsafetythatarenotcoveredinthecodeofpracticemaybe found inotherCodexstandards (e.g.GeneralPrinciples,FoodLabelling,MethodsofSamplingandAnalysis).

2.2. Terrestrial Animal Health Code of the world Organization for Animal Health The OIE (http://www.oie.int/) is an intergovernmental organization representing 167membercountries.TheOIEcollects,analyses,andmakesavailablethelatestscientificinformation on animal diseases and disease control throughout the world. Scientificstandardsarethendevelopedbasedonthis information.Thestandardsarepreparedby elected specialist commissions and working groups comprising internationally-renownedscientists,mostofwhomareexpertswithinthenetworkof156OIEcollabo-ratingcentresandreferencelaboratories.Afteradoption,thestandardsaremadeavail-ableastheTerrestrialAnimalHealthCode(OIE,2005a)andtheManualofDiagnosticTestsandVaccinesforTerrestrialAnimals(OIE,2005b).Similarstandardsareavailableforaquaticspecies.

BecausetheOIEsetsstandardsforanimalhealthissues,itdoesnotprovidespecificguidanceonfeedproductionorfeeding.However,itdoesprovidespecificinformationonBSE(OIE,2005c),aswellasrecommendationsonwhatproductsaresafetotradeunderwhat conditions (OIE, 2005a). The OIE code recommends thatRuminant-derived meatandbonemealorgreaves,oranycommoditiescontainingsuchproducts,whichorigi-natefromacountry,zone,orcompartment(withnon-negligibleBSErisk)shouldnotbetradedbetweencountries(OIE,2005d,Article2.3.13.12),whichclearlymeansthattheseruminant-derivedproductsfrommostcountriesshouldnotbetraded.

Inaddition,recommendationsforTSEinactivationintheproductionofmeatandbonemeal(MBM)aregiven(OIE,2005d).Otherrecommendationsaremadefortradeinotherproducts,accordingtoacountry’sBSEstatus.TheOIErecommendationsforsurveil-lanceanddiagnosisofBSEaredescribedmorefully inthe“IntroductiontoTSEsandBSE”chapterinthiscoursemanual.

2.3. Regulations of the European Union TheEUcomprisesof25Europeanstates(countries)andwasestablishedbytheTreatyonEuropeanUnionin1992(althoughmanyelementsoftheUnionhaveexistedsincethe1950s).TheEUunitesitsstatesinmanyaspects,includingacommonsinglemarketconsistingofacustomsunionandasinglecurrency(adoptedby12outof25memberstates),aswellasasingleagriculturalpolicy.

GiventhatBSEwasfirstidentifiedintheUKandthatinitialspreadwasmostevidentwithin the EU, comprehensive regulations have been put in place to provide for the

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controlandeventualeradicationofBSE.AsadditionalcountrieslooktowardsbeginningtheEUaccessionprocess,orwishtoexpandtheiropportunitiesfortrade,theEUregu-lationsmustbeconsidered.Thus,manyothercountriesthroughouttheworldarebas-ingtheirneworrevisedregulationsonthoseoftheEU.Consequently,bansandothermeasures implementedbytheEUcontinueto influencetheworldmarket inanimalsandanimalproducts.

ThechronologyofadoptionofthemainEUregulationsisgiveninTable1,andspe-cificregulationscanbefoundontheEUWebsite(EU,2005).Theseregulationsaffectnotonlythemembercountries,butalsoothercountriesintheiractionsandtradewiththeEU.IndividualEUstatesmayhavetheirownrulesforimplementationbutallmustultimatelycomplywiththeEUregulations.

In 1��4,allproteinderivedfrommammalswasformallyprohibitedforuseinrumi-nantfeedintheEU(EU,1994),althoughsomememberstateshadimplementedsuchabanbeforethatdate.However,therewasnoprohibitionagainstexportofthesemateri-alsatthattime.

In 1�� and 1��,theEUformallyprohibitedexportofmammalianMBM(andrelatedproducts)fromtheUKandPortugal(respectivelyintheseyears)totherestoftheEUandthirdcountries(EU,1996and1998).

In 2001, theEUadopteda regulation layingdown rules for theprevention, controlanderadicationofcertainTSEs(“theTSERegulation”;EU,2001),whichprohibitsthefeeding of mammalian protein (except gelatine from non-ruminants, milk and milkproducts,andeggsandeggproducts)toanyfarmedanimal.Thisbanisoftenreferredtoasthe“totalfeedban”.TheregulationalsosetsoutmorerestrictiveregulationsformemberstatesorregionsintheGeographicBSERiskAssessment(GBR)categoryIV(i.e.currentlyUKandPortugal;adescriptionoftheGBRisgiveninsection6.2ofthe“IntroductiontoTSEsandBSE”chapterinthiscoursemanual).

CurrentlyintheEU,exportofprocessedanimalproteinsderivedfromruminants(andproductscontainingsuchproteins)intendedforfeedinglivestockisprohibitedfromtheentireEUtothirdcountries.However,fishmealandsomebloodproducts(butnotbloodmeal)canstillbeusedinfeedintendedfornon-ruminants.

TheEUregulationsarecontinuallybeingupdatedanditcanbedifficulttoextractthemostcurrentandrelevantinformation.Manyspecificdecisionsarenolongerinforce,andtherelevantregulationshavebeenincorporatedintoothercurrentlegislation.How-ever,updatedsummariesofnewinformationonallBSEtopicscanbefoundontheEUWebsite(EU,2006).Currently,thefollowingtworegulationsdirectlyapplytothefeedingoflivestockinthefaceofBSE.

Regulation1774/2002.MostoftheEUanimalby-productslegislationhasbeencon-solidated into the text of Regulation 1774/2002 (EU, 2002), which categorizes animalby-products(animalcarcases,partsofanimalcarcasesandproductsofanimaloriginwhicharenot intended forhumanconsumption)according to riskandcontrols theiruse and disposal. Regulation 1774/2002 also includes a fairly general prohibition onthefeedingofaspecieswithmaterialderivedfromthesamespecies.Thisregulationisdiscussedindetailinthe“Renderingofanimalby-products”chapterinthiscoursemanual.

Regulation882/2004.In2004,theEUadoptedanewregulationlayingdownrequire-mentsforfeedhygiene(EU,2004),whichdetails:

• compulsoryregistrationofallfeedbusinessoperatorsbythecompetentauthority;

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TABLE 1. principle legislation on TSE regarding animal feed in the European Union, including legislation number, date, and title

year Livestock Feeds/TSE-relevant legislation number, date and title (or topic)

1989 D89/469/EECof28July1989.RestrictionsonthedispatchofcertainlivecattlefromtheUK1994 D94/381/ECof27June1994.Banontheuseofproteinsderivedfrommammaliantissues forfeedingruminants D94/382/ECof27June1994.RenderingsystemsforprocessingruminantwasteintoMBM (inactivationofBSEagents) D94/474/ECof27July1994.RestrictionsonthedispatchfromtheUKoflivecattleandcertain ruminantproducts-Destructionofspecifiedbovineoffal(RepealsD89/469/ECand90/200/EC)1995 D95/29/ECof13February1995.AmendmentofD94/382/EC-Batchrenderingsystems D95/60/ECof6March1995.AmendmentofD94/381/EC-Derogationtothefeedban1996 D96/449/ECof18July1996.PressurecookingsystemforprocessingmammalianwasteintoMBM (inactivationofTSEagents)1997 D97/534/ECof30July1997.ProhibitionoftheuseofSRM(mainlybrain,eyesandspinalcord) D97/735/ECof21October1997.RestrictionsontradeinMBM1999 D1999/129/ECof29January1999.AmendmentofD94/381/EC-Hydrolysedproteins D1999/534/ECof19July1999.ConditionsfortheproductionofMBMandtallow(RepealsD96/449/EC) D1999/881/ECof14December1999.Postponementto30June2000ofthedateofapplicationof D97/534/EC(SRM)2000 D2000/418/ECof29June2000.ProhibitionoftheuseofSRM(RepealsD97/534/EC) D2000/766/ECof4December2000.TemporarybanonuseofMBM2001 D2001/2/ECof27December2000.AmendmentofD2000/418/EC–ExtensionofthelistofSRM (bovineintestines) D2001/9/ECof29December2000.Conditionsforfeedingcertainanimalproteins D2001/25/ECof27December2000.Prohibitionoftheuseofdeadanimalsintheproductionof animalfeed D2001/165/ECof27February2001.AmendmentofD2001/9/EC–Hydrolysedproteins D2001/233/ECof14March2001.AmendmentofD2000/418/EC–ExtensionofthelistofSRM (vertebralcolumn) D2001/270/ECof29March2001.AmendmentofD2000/418/EC–Importsfromthirdcountries R2001/999/ECof22May2001.Rulesfortheprevention,controlanderadicationofcertain transmissiblespongiformencephalopathies2002 R270/2002of14February2002.AmendmentofR999/2001–SRM,surveillance,animalfeedingand placingonthemarketofovineandcaprineanimalsandproductsthereof R2002/248/ECof27March2002.AmendingCouncilD2000/766/ECandCommissionD2001/9/ECwith regardtothefeedingofanimalproteins R2002/1774/EC.Layingdownhealthrulesconcerninganimalby-productsnotintendedfor humanconsumption2003 R1234/2003of10July2003.AmendmentofR999/2001–introducingthecurrentprovisionsofthefeed banintoRegulation(EC)No999/2001withoutafixedtimeschedule,thusendingthetransitional natureofthefeedban2004 D2004/653/ECof16September2004.AmendmentofCommissionDecision2001/376/ECasregards thedispatchofmeat-and-bonemealofmammalianoriginandrelatedproductsfromPortugal2005 R1292/2005of5August2005.AmendmentofR999/2001asregardsanimalnutrition.0

Note:R:Regulation,D:Decision.Source:Derivedfrom:http://ec.europa.eu/food/food/biosafety/bse/chronological_list_en.pdfaccessed,UpdateofFebruary2006.Updatesavailablethroughhttp://ec.europa.eu/food/food/biosafety/bse/legisl_en.htm.

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• maintenance of the approval system for feed businesses dealing with sensitivesubstances;

• operationofallfeedbusinessesinaccordancewithharmonizedhygienerequire-ments;

• applicationofgoodhygienepracticeatalllevelsofagricultureproductionanduseoffeed;

• introductionofHazardAnalysisCriticalControlPoint(HACCP)principlesforfeedbusinessoperatorsotherthanatthelevelofprimaryproduction;

• compulsoryrequirementsforfeedproductionatfarmlevel;• anEUframeworkforguidestogoodpracticeinfeedproduction;• provisionthatfeedbusinessoperatorsareonlypermittedtoimportfeed,including

singlefeedmaterials,fromcountriesoutsidetheEUiftheexportingcountryandtheestablishmentcomplywithspecificrequirementsandappearonalist.FeedfromsuchestablishmentswillneedtocomplywiththerequirementsoftheFeedHygieneRegulation;

• an endorsement of the principle that feed business operators must provide afinancialguaranteeinordertocovertherisksrelatedtotheirbusinesses.

2.4. Rules of the Food and Drug Administration, United States of AmericaIn1997,theFoodandDrugAdministration(FDA)oftheUSApublishedarule(herein-afterreferredtoasRule21;FDA,1997)describingthatmammalianproteinforuseinruminantfeedisconsideredafoodadditive.Thus,intheUSA,theuseofanymaterialthatcontainsmammalianproteinisprohibitedinruminantfeed,thoughinsomecasespureporcineorpureequinematerialsfromsingle-speciesslaughterfacilitiesmaybefedtoruminants.

According to the rule, renderers, protein blenders, feed manufacturers, and dis-tributors that manufacture, blend, process, and distribute products that contain (ormay contain) mammalian protein and that are intended for use in animal feed mustproperlylabelthematerialswiththewords‘‘Donotfeedtocattleorotherruminants’’andmustmaintain(andmakeavailabletothecompetentauthority)recordssufficienttotrackthematerialsthroughouttheirreceipt,processinganddistribution.Moreover,rendererswhoobtainruminantornon-pureporcineorequinematerialsmust imple-mentsufficientmeasuresinordertopreventcrosscontaminationofproductsthatmaybeusedforruminants.Theymustalsomaintainwrittenproceduresspecifyinginthesemeasurestheproceduresforseparatingproductsfromthetimeofreceiptuntilthetimeofshipment.

In addition, establishments and individuals that are responsible for the feeding ofruminantanimalsmustmaintaincopiesofpurchaseinvoicesandlabellingforallfeedsreceivedthatcontainanimalproteinproducts.

Following thereportingofaclinicalcaseofBSE in theUSA inDecember2003,aninternationalreviewteamwasinvitedtoconsidertheresponsetothisfinding. InJuly2004, subsequent to this review, the FDA described potential measures related toanimalfeed(USFDA,2004a).Thesemeasures,intendedtoreducetherisksthrough-out feed manufacturing and distribution and on the farm (due to misfeeding) and todecreaserecyclingof theagent (includinganSRMbanfor feed),wereproposedasaruleinOctoberof2005(USFDA,2005).

Inaddition,FDA(USFDA,2004b)measuresprohibittheuseofbovinematerialsthat

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could carry the BSE agent in cosmetics and human foods, including certain meat-based products and dietary supplements. These high-risk bovine materials includeSRM(includingbrain,skull,eyes,andspinalcordofcattle30monthsofageorolder,andsmallintestineandtonsilsfromallcattle),materialfromnon-ambulatorydisabledcattle, material from cattle not inspected and passed for human consumption, andmechanicallyseparatedbeef.

MuchasintheEU,individualstatesintheUSAmayhavetheirownrulesforimple-mentation,butallstatesmustultimatelycomplywiththeFDA(andotherfederal)rules.AlsoaswiththeEU(andmostcountries),officialrulesandlegislationarecontinuallybeingupdatedasnewinformationbecomesavailable.Themostrecentlegislationmustalwaysbecompliedwith.

3. ImpLEmENTATION OF INTERNATIONAL AND NATIONAL STANDARDS AND REGULATIONS: INDUSTRy GUIDELINESThevariousinternational,regionalandnationalrecommendationsandregulationsallincludethebanningofruminantand/orallmammalianproteininanimalfeedandtheidentification,labellingandtraceabilityofsuchmaterialsthroughthefeedchain.Theyalsoattempttoensurethatthereisnocrosscontaminationoffeedingredientsallalongthefeedchaininordertopreventevenextremelysmallquantitiesofinfectivematerialfrombeingfed.Figure2showstheanimalfeedchainandthevariousstepsandstake-holdersthatneedtocomplywiththeseregulations.

Theanimalfeedindustryandvariousstakeholdersinthefeedchainhavethereforedevelopedcodesandguidelinestofacilitatecompliancewiththerecommendationsandregulations.Someofthemajorcodesandguidelinesaredescribedbelow.

3.1. Grain and Feed Trade Association The Grain and Feed Trade Association (GAFTA: http://www.gafta.com/) is an interna-tionaltradeassociationforgrainsandotherfeeds,with930membersin80countries.It provides standard forms for contracts, training and professional development, adisputeresolutionservice,arbitrationandmediation,schemesforsuperintendentsandanalysts,aswellasinformationresources,notablytheGAFTATraders’Manual(GAFTA,2004),whichprovidesstandardsofbestpracticeforalltradeoperations.

TheGAFTAstandardfortheinternationalgrainandfeedtradeisanall-encompass-ingsystemtoprovidesafefoodandfeedmaterialsworldwide.UsingaHACCP1-basedapproach,itlinksthe“bestpractices”fortransport,storage,loading,discharge,super-visionandanalysisfromthefarmonwardsforallcombinablecropsanddry,moistandliquidanimalfeedmaterials.Therearesevenmajorsections:

• Storage-describingthestorageofcombinablecrops,anddry,moistandliquidanimalfeedsfromfarmonwards.

• Loading,discharge,supervisionandhandling-describingeachoftheselogisticaloperationswithreferencetotheGAFTAweighingrulesandtheGAFTASuperin-tendentsscheme.

1HazardAnalysisandCriticalControlPoints(HACCP)isdescribedinthe“Qualitycontrolconcepts,hygiene,andHACCPinthemeatindustry”chapterintheCapacityBuildingforSurveillanceandPreventionofBSEandOtherZoonoticDiseasesprojectcoursemanualManagementoftransmissiblespongiformencephalopathiesinmeatproduction(FAO,2007).

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• Analysis-describinganalysisthroughoutthesupplychain,withreferencetoalltheGAFTAmethodsofanalysisandtheGAFTAanalystsscheme.

• Transport - describing all transport operations from farm onwards, includingroad,rail,waterwayandsea.

• Pestcontrolandfumigation-describingminimizationoflossesanddamageandanintegratedpestprogramme.

• IntroductiontoHACCP-describinghowtheHACCPapproachistakentominimizelosses,damageandcontaminantrisks.ThebasicsofapplyingHACCPtothesup-plychainareexplained.

• Audit/verification–becausecertainimportmarketsrequiretraderstohavetheirsupply operations independently audited/verified, this section describes how togainGAFTAverification.

Toensureconformity,GAFTArequiresverificationofeachtrader’sofficeannuallyforthefirstthreeyears,thenonceeverytwoyearsthereafter.VerifiersmustbeindependentandaregovernedbytheirownGAFTACodeofPracticetoensuretheiroperationscon-stantlycomplywiththecriteriaandtheymustinformGAFTAofallverificationresults.

FigUre 2

Schematic of the livestock feed production chain and the areas to be considered in developing codes of

practice.

Crop producers

Raw materials

Feed mill

Farmer

Abattoir

Consumer

Export

Processor

Import

Transport

Transport

Transport

Transport

Transport

The Feed Chain

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3.2. International Feed Industry FederationThe International Feed Industry Federation (IFIF; http://www.ifif.org/) is an organiza-tionthatrepresentsnationalandregional feedassociationsandfederationsandoth-ersinvolvedintheproductionofcompoundanimalfeeds.MembersofIFIFaremainlynational associations, corporate/commercial members (suppliers to the feed trade),andotherfeed-relatedorganizations.TheIFIFhasobserverstatusintheCodexAlimen-tariusandisworkingcloselywithFAOinthepracticalimplementationoftheCodexcodeofpracticeonanimalfeeding,describedinsection2.1ofthischapter.

3.3. American Feed Industry Association TheAmericanFeedIndustryAssociation(AFIA;http://www.afia.org/)isthefeedindustryassociationfortheUSA.Itincludes690membercompanies,representingnearly75%of the commercial feed and pet food sold annually in the USA. The AFIA’s membersinclude manufacturers, ingredient suppliers, animal health companies, equipmentmanufacturers, large integrated livestockandpoultryproducers, and firmsprovidingothergoodsandservicestothecommercialanimalfoodindustry.Inaddition,AFIAalsoincludesmorethan35state,regional,nationaland internationalassociationsamongitsmembership.

The AFIA publishes the Feed Manufacturing Technology manual, which is revisedannually. Thechapteronqualityassurancedescribescontrolsaimed topromote theproductionofproductsthatconsistentlymeetpredeterminedqualitystandards.Itcom-prehensivelydescribesanin-plantqualitycommitmentprogrammeincludingpolicies,procedures,sampling,andtestingrelevanttofeedproductionintheUSA.

TheAFIAalsopublishesaguidetohelpfeedmanufacturerscomplywiththeFDARule21prohibitingmammalianproteininruminantfeed(AFIA,2001).Thespecificrequire-mentsinthethreeprincipalareas(labelling,record-keeping,andequipmentcleaning)aredetailed.Thisguideisdesignedforplantsthatmanufacturefeedformorethanonespecies,andthatuseMBMorothermammalianproteins.Itemphasizesthatspecificwrittenproceduresmustbedevelopedandusedforeachindividualfacility.

Itshouldbenotedthat,althoughmeetingtheseguidelineswillallowcompliancewiththeFDArulesandBSEmeasuresintheUSA,thesemeasureswillnotoptimallypreventcrosscontaminationwithBSEinfectivity,asdescribedinthe“Overview:ImplementationofTSEmeasuresforlivestockfeeds”chapterinthiscoursemanual.

3.4. European Feed manufacturers’ Federation TheEuropeanFeedManufacturers’Federation(FEFAC;http://www.fefac.org/)consistsofnationalassociationsfromEUmemberstatesasfullmembers,andmanyobservermembersfromnon-EUcountries.Asanindependentorganization,FEFACrepresentstheEuropeanfeedindustryinEUlegislativenegotiations,andholdsobserverstatusintheCodexAlimentarius.

Moreover, FEFAC develops professional rules and good manufacturing practicesfor improving the quality and safety of compound feed. It has published the FEFACguidelinesfortheimplementationofacodeofpracticeforthemanufactureofanimalfeedingstuffs(FEFAC,2001)covering:

• qualitymanagementandqualitycontrol;• riskanalysis;• undesirablesubstancesandproducts,includingbacteria;

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• additivesandmedicaments;• facilitiesandequipment;• personnel;• productconceptionandfeedformulation;• productsafety;• production (purchase,delivery,and intake,weighing,grindingandparticlesize,

mixing,pelleting/heattreatment,cooling,storage);• transportandstorage;• documentsandrecords;• registrationofcompoundfeedstuffs;• complaintsandproductrecall.

Inanattempt tomakealloperationsalong the feedchain fullyresponsible for theproductstheydeliver,thisdocumentincludestheimplementationofHACCPprinciplesatallstagesofproduction.Thus,itisstricterthanthecurrentEUlegislation.

In addition, FEFAC lists codes of practice from associations recognized by FEFAC.These include codes of practice developed (or in development) for trade, and for theproductionofanimal fatsandmeals, fishoilsandmealsandotherproductsandby-productsforuseinfeeds.

FEFACalsolistsNationalCodesofPracticedevelopedbyFEFACmembers,including• Códigodeboaspráticasparaofabricodeprémisturasedealimentosparaani-

mais(IACA-Portugal)• GMP-regelingdiervoedersector(ProductschapDiervoeder–TheNetherlands)• CodeGMPgeneralpour lesecteurdel’alimentationanimale (BEMEFA/APFACA

–Belgium)• Codicedibuonepraticheperlaproduzioneelacommercializzazionedialimenti

compostiperanimalidereddito(ASSALZOO–Italy)• Codedebonnespratiquespourlafabricationd’alimentsmédicamenteux–Guide

de mise à niveau pour l’agrément des établissements fabricants des alimentspouranimaux(SNIA–France)

• LeitfadenfüreineGuteHerstellungspraxisvonFuttermitteln(DVT–Germany)• UKASTAFeedAssuranceScheme(UFAS)-CodeofPracticefortheManufacture

ofSafeCompoundAnimalFeedingstuffs(UKASTA-UK)• Code of practice and general operating standard for poultry feed processing

(DAKOFO-Denmark)• Leitfadenfüreine“GuteHerstellungspraxisvonFuttermitteln”,GHF(VSF-Swit-

zerland).

4. SUmmARy OF TSE-RELEvANT CONCEpTS• Mostcountries implementingBSEmeasuresalreadyhavesomesortofbanon

feedinglivestockwithproteinderivedfromanimalby-products.CurrentlyunderdiscussioninthesecountriesisanadditionalbanonSRMinallanimalfeeds,fol-lowingtheexampleoftheEU.

• Internationally-recognizedstandardsforcontrolandpreventionofBSEareavail-ableforgeneralaspectsofrendering,livestockfeedmanufacturingandlivestockfeedinginordertoprotectdomesticpublicandanimalhealthandmaintaintradeinanimalsandanimalproducts.

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• TheregulationsoftheEUregardingimplementationofinternationalrecommen-dations regarding BSEs are currently being adopted or otherwise incorporatedintothelegislationofmanyothercountries.

• Otherinformation,includingseveraldifferentcodesofpractice,isalsoavailablefromgovernmentalandprivatesourcestoprovideadditionaldetailsforeffectivelyandconsistentlyimplementingtheregulations.

�. REFERENCESAFIA (American Feed Industry Association).2001.Guide for feedmanufacturers tocomplywith

the FDA final rule prohibiting mammalian protein in ruminant feed. http://www.afia.org/img/

assets/1209/GUIDE6-2.pdf?GUIDE6-2.pdf

Codex Alimentarius. 2004. Code of practice on good animal feeding, Codex Alimentarius,

Document CAC/RCP 54-2004. http://www.codexalimentarius.net/download/standards/10080/

CXC_054_2004e.pdf

EU (European Union). 1994. Commission Decision 94/381/EC concerning certain protection

measures with regard to bovine spongiform encephalopathy and the feeding of mammalian

derivedprotein(no longer in force).http://europa.eu.int/smartapi/cgi/sga_doc?smartapi!celexa

pi!prod!CELEXnumdoc&lg=EN&numdoc=31994D0381&model=guichett

EU. 1996. Commission Decision 96/239/EC on emergency measures to protect against bovine

spongiformencephalopathy(no longer in force).http://europa.eu.int/smartapi/cgi/sga_doc?sm

artapi!celexapi!prod!CELEXnumdoc&lg=EN&numdoc=31996D0239&model=guichett

EU.1998.CommissionDecision98/653/ECconcerningemergencymeasuresmadenecessaryby

theoccurrenceofbovinespongiformencephalopathy inPortugal.http://europa.eu.int/eur-lex/

pri/en/oj/dat/1998/l_311/l_31119981120en00230031.pdf

EU.2001.ECRegulationNo.999/2001layingdownrulesfortheprevention,controlanderadication

of certain transmissible spongiform encephalopathies. http://europa.eu.int/eur-lex/pri/en/oj/

dat/2001/l_147/l_14720010531en00010040.pdf

EU.2002.ECRegulationNo.1774/2002layingdownhealthrulesconcerninganimalby-products

not intended for human consumption. http://europa.eu.int/eur-lex/pri/en/oj/dat/2002/l_273/

l_27320021010en00010095.pdf

EU. 2004. EC Regulation No. 882/2004 on official controls performed to ensure the verification

oncompliancewithfeedandfoodlaw,animalhealth,andanimalwelfarerules.http://europa.

eu.int/eur-lex/pri/en/oj/dat/2004/l_165/l_16520040430en00010141.pdf

EU. 2005. Eur-Lex legislation search engine. http://europa.eu.int/eur-lex/en/search/search_lif.

html

EU.2006.Europa.Specificthemes(BSE)http://europa.eu/scadplus/leg/en/s89500.htm

FAO. 2007. Management of transmissible spongiform encephalopathies in meat production.Course manual. Project Capacity Building for Surveillance and Prevention of BSE and OtherZoonoticDiseases.Rome

FEFAC (European Feed manufacturers’ Federation).2001.Guidelinesfortheimplementationofa

codeofpracticeforthemanufactureofanimalfeedingstuffs.http://www.fefac.org/

GAFTA (Grain and Feed Trade Association).2004.GAFTAtradersmanual.http://www.gafta.com/

OIE (world Organization for Animal Health).2005a.Bovinespongiformencephalopathy.TerrestrialAnimalHealthCode,Chapter2.3.13.http://www.oie.int/eng/normes/MCode/en_chapitre_2.3.13.

htm

OIE. 2005b. Bovine spongiform encephalopathy. Manual of Standards for Diagnostic Tests andVaccines,Chapter2.3.13.http://www.oie.int/eng/normes/mmanual/A_00064.htm

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OIE. 2004c. Bovine spongiform encephalopathy disease card. http://www.oie.int/eng/maladies/

fiches/a_B115.htm

OIE.2005d.Proceduresforthereductionofinfectivityoftransmissiblespongiformencephalopathy

agents.TerrestrialAnimalHealthCode,Appendix3.6.3.http://www.oie.int/eng/normes/mcode/

en_chapitre_3.6.3.htm

US FDA (Food and drug administration).1997.Rule21substancesprohibitedfromuseinanimal

foodorfeed.USFederalRegisterCFRPart589,Vol.62,No.108,June5,1997.

US FDA. 2004a. Federal measures to mitigate BSE risks: considerations for further action.

APHIS:USDAandFDA:HHS.July8,2004.http://www.fda.gov/OHRMS/DOCKETS/98fr/04n-0264-

nap0001.pdf

US FDA. 2004b. Use of materials derived from cattle in human food and cosmetics, Federal

Register:July14,2004(Volume69,Number134)http://www.fda.gov/OHRMS/DOCKETS/98fr/04-

15881.htm

US FDA.2005. Substancesprohibitedfromuseinanimalfoodorfeed;proposedrule.APHIS:USDA

andFDA:HHS.Oct.6,2005.http://www.fda.gov/OHRMS/DOCKETS/98fr/05-20196.htm

spongiform encephalopathies · 2007-08-02 · elizabeth mumford ernst nef lukas perler andrew...

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