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RESEARCHOpenAccessPhysiologicalindicatorsofstressandmeatandcarcasscharacteristicsintailbittenslaughterpigsAnnaValros1*,CamillaMunsterhjelm1,EeroPuolanne2,MaritaRuusunen2,MariHeinonen3,OlliATPeltoniemi3andAReetaPs4AbstractBackground:Tailbitingisacommonwelfareprobleminpigproductionandinadditiontobeingasignofunderlyingwelfareproblems,tailbitingreduceswelfareinitself.
Theaimofthisstudywastoevaluatetheeffectsoftailbitingondifferentpreandpostmortemindicatorsofstressinslaughterpigsandoncarcassandmeatcharacteristics.
Atotalof12tailbitten(TB)and13control(C)pigsfromafarmwithalong-termtailbitingproblemwereselectedforsalivarycortisolanalysesbeforeandaftertransporttotheslaughterhouse.
Afterstunning,samplesweretakenfortheanalysisofserumcortisol,bloodlactate,intestinalheatshockprotein70(HSP70),andmeatqualitycharacteristics.
Inaddition,bodytemperatureimmediatelyafterandmuscletemperature35minafterstunningweremeasured,aswellasleanmeatpercentageandcarcassweight.
Results:TBpigsshowedalowercortisolresponsetothetransport-inducedstressthanCpigsandalsohadalowerserumcortisolconcentrationafterstunning.
HSP70contentinthesmallintestinewashigherintheTBpigsthaninCpigs.
TBpigshadaconsiderablylowercarcassweightthereforeproducedalowertotalamountofleanmeatpercarcassthanCpigs.
Conclusions:Thisstudysuggeststhatprolongedorrepeatedstressintheformoftailbitingcausesabluntedstressresponse,possiblyasignofhypocortisolism.
Inaddition,itunderlinestheimportanceofreducingtailbiting,bothfromananimalwelfareandaneconomicpoint-of-view.
Keywords:Tailbiting,Pig,Cortisol,HSP70,Meatquality,CarcasscharacteristicsBackgroundTailbitingisacommonandseriouswelfareprobleminpigproduction.
Incountrieswheretaildockingisprohib-ited,theprevalenceoftaildamageinslaughterpigshasbeenreportedtobeashighas6-11.
7%[1,2]andaround3%incountrieswheretaildockingisallowed[3].
Inadditiontobeingasignofunderlyingwelfareprob-lems,tailbitingassuchreduceswelfare.
Tailbittenpigsaremorepronetogetinfections,suchasabscessesandarthritis[1,4].
Taildamageduetobitingmayalsohaveadverseeffectsoncarcasscharacteristics,asitmayre-ducegrowth[4,5]andcauseanincreaseincondemna-tionsatslaughter[1,5].
Reducedwelfare,atleastintheformofabarrenenvironment,increasestheriskfortailbiting[6,7]andcanalsohavenegativeconsequencesonmeatquality[8].
Eventhoughtherearemanyreasonstosupposethattailbitingislinkedtounderlyingstress[9,10]andthatbeingavictimisstressful[11],thereisstillscarceinformationavailableontheconsequencesoftailbitingtothevictim.
Theevaluationofprolongedorrepeated,i.
e.
chronic,psychologicalstressischallenging,andtogetareliablepictureseveralmeasuresshouldbeused[12].
Cortisolisatraditionalmeasureofstressinpigs,beingelevatedbyacutestress[13].
Theeffectsofchronicstressoncortisolconcentrations,however,arelessstraightforward.
Studiesonhumansandlaboratoryanimalsshowthatchronicstressorpainappearstoultimatelycauseareductionindailyoverallcortisolsecretion,aswellasincortisolre-activitytostressors(forareview,see[14]).
Similarresultshavebeenreportedinpigshousedinbarrenenvironmentsorunderrepeatednoisestress[15-17].
*Correspondence:anna.
valros@helsinki.
fi1ResearchCentreforAnimalWelfare,DepartmentofProductionAnimalMedicine,FacultyofVeterinaryMedicine,UniversityofHelsinki,P.
O.
Box57,00014Helsinki,FinlandFulllistofauthorinformationisavailableattheendofthearticle2013Valrosetal.
;licenseeBioMedCentralLtd.
ThisisanopenaccessarticledistributedunderthetermsoftheCreativeCommonsAttributionLicense(http://creativecommons.
org/licenses/by/2.
0),whichpermitsunrestricteduse,distribution,andreproductioninanymedium,providedtheoriginalworkisproperlycited.
Valrosetal.
ActaVeterinariaScandinavica2013,55:75http://www.
actavetscand.
com/content/55/1/75PremortemstressaffectsmusclepHpostmortem.
TheformationofDFD(Dark,Firm,Drymeat)isassociatedwithlong-lastingpre-slaughterstress,e.
g.
duringhandling,transportandslaughterhouselairageaswellasalongfast-ingtime[18-20].
IntheDFDcase,theglycogenreservoirsarediminishedalreadybeforeslaughter,duetothestress-induceddegradationofmuscleglycogen.
Therefore,theultimatelacticacidislowerthannormallyresultinginapHvaluehigherthan6.
0.
InthePSE(Pale,Soft,Exudativemeat)case,thosepigsthatstillhaveanormalglycogenlevelatslaughterandthathaveexperiencedpsychologicaland/orphysicalstressjustbeforeslaughter,haveafastenedmuscleglycogenbreakdownperimortem.
Lacticacidaccu-mulatesinthemusclewhenthemuscletemperatureisstillhigh,andthiscombinationcausesapartialdenaturationofmeatproteinsandthusalightcolourandsoftnessaswellasadecreaseofwater-holdingcapacity.
Heatshockproteins(HSPs)areapotentialmeasureofchronicstress.
CellsreacttostressbysynthesizingHSPs,whichhelpthemtomaintainintracellularproteinhomeo-stasis.
HSP-inductioniscausedbyseveraldifferentcell-levelstressors[21].
Amongthestress-inducibleHSPs,theresponseofHSP70hasbeenstudiedmostextensively.
Itssynthesispeaks8-10hoursafterstress,andtheconcentra-tionstayshighforseveraldays[21].
Therefore,shorttointermediatetransportandpre-slaughterhandlingmaynotlastlongenoughtohaveaneffectontheamountofHSP70andithasbeenspeculatedtoreflectstressorsthepigshaveencounteredonthefarm[22].
Theaimofthisstudywastoevaluatetheeffectsoftaildamageduetotailbitingondifferentpreandpostmortemindicatorsofstressinslaughterpigsandoncarcassandmeatcharacteristicsbycomparingpigswithtaildamagetocontrolpigswithclinicallyhealthytails.
Wehypothe-sisedthattaildamagecausesstresstothevictim,whichwillbereflectedinachangeincortisolsecretionduringastressfulsituation,i.
e.
transport,inanincreaseinHSP70andinreducedmeatquality,duetochangesinmusclemetabolismduringthepre-slaughterhandling.
Wereportseveralsignsofincreasedchronicstressintailbittenpigs.
MethodsAnimalsandgeneralhousingconditionsAltogether25pigsfromafarmthathadhadfrequentproblemswithtailbitingwereselectedonthefarmbeforetransporttotheslaughterhouseinthemorning.
Asthiswas,toourknowledge,thefirststudyofthistype,thenumberofpigswasdecidedmainlyfromapracticalpoint-of-view.
Itwasestimatedthatthiswasthemaximumnumberofpigswecouldsampleduringoneslaughteringsession.
Thefarmusedallin–alloutmanagementbyroomandhoused8-9pigsinsimilarstandard-sizedpens.
Onefourthofthepenfloorconsistedofconcreteslatsandtherestwassolidconcrete.
Thefarmergavethepigsaverysmallamountofsawdustasenrichment.
Thepigswerefedliquidfeedfromalongthrough,fromwhichallpigswereabletoeatatthesametime.
Waterwasdeliv-eredforthepigsfreelyfromonewaternippleineachpen.
Twoveterinariansselected12casepigswithclearlyvisibletailwounds(TB)and13controlpigsfrompenswherenotailbitingoccurred(C).
Theyinspectedthepigsandeartaggedthemindividually.
TheTBpigshadbittentails;otherwisetheTBandCanimalswereclinic-allyfreefromsignsofdisease.
Allpigscamefromoneroomofabout800finishingpigsatapproximately100-115kgliveweight.
PigsfortheTBandCgroupswereselectedevenlywithintheroomandbothgroupsin-cluded8castrates,therestoftheanimalsbeinggilts.
Withineachpenoneortwopigshadvisibletailwounds.
SelectionofCpigsoccurredinpenswithnotailbitingandaimedatasimilargenderdistributionasinTBpigs.
Consequently,thepigscamefromatotalof22differentpens(11penswithtailbiting,11controlpens),withoneortwopigsfromeachpen.
Allpigshadarrivedatthefinishingfarmatthesametime(ataround25kgliveweight)andwerethusofapproximatelythesameage.
Transporttotheslaughterhousestartedat07:00h,afteranapproximately30-minloadingperiod,andlastedonehour.
Beforetransport,thepigshadbeenfastedsincethepreviousafternoon.
TBandCpigswerekeptinseparatepensduringtransport.
Attheslaughterhousethepigswererandomlydi-videdintotwostunninggroupsandTBandCpigsweremixed.
StunningofGroup1beganat09:00h(6TBand6Cpigs)andstunningofGroup2at12:00h(6TBand7Cpigs).
Pigswerestunnedwithcarbondioxideingroupsof3anddrivingtostunningwasmainlyautomatic.
AnethicalapprovalforthestudywasobtainedfromtheEthicsBoardofViikkiCampusoftheUniversityofHelsinki.
SalivaandbloodsamplingandassaysTwosalivacortisolsamplesperpigwerecollected:onebasalsampleinthehomepenspriortoclinicalinspection(between06:00and07:00h),beforethenormalfeedingtimeofthepigs,andapost-transportsalivasampleafterarrivalandmixingattheslaughterhouse(between08:00and09:00).
SalivasamplesweretakenusingSalivettetubes(SarstedtAG&Co,Germany),allowingeachanimaltochewonacottonswabforapproximatelyoneminute.
Theswabwasthenreplacedinthetube,transportedoniceinacoolboxtothelaboratorywithin10hours,andcentrifugedat3000rpmfor10minutes.
Thesalivawasfrozenat18°Cuntilanalysis.
Thesalivarycortisolconcen-trationwasanalysedbyradioimmunoassay(Coat-A-CountCortisol,OrionDiagnostica,Turku,Finland)withmodifi-cationsforusewithpigsaliva[23].
Themethodhasbeenvalidatedforusewithpigsaliva[24].
Valrosetal.
ActaVeterinariaScandinavica2013,55:75Page2of8http://www.
actavetscand.
com/content/55/1/75Bloodsampleswerecollectedduringbleedingdirectlyafterstunningforassessmentofcortisolandlactate.
Forlactateanalysisbloodwascollectedintubesthatcon-tainedsodiumfluoride,andforcortisolinserumtubes.
Tubeswerekeptoniceduringtransporttothelabora-tory.
Thesampleswereanalysedonthefollowingdayusinganautomaticlactateanalyzer(YSI2300STAT,YellowSpringsInstrumentCo.
,YellowSprings,OH,USA).
Forcortisolanalysesserumwasseparatedbycen-trifugationinthelaboratoryandkeptfrozen(70°C)untilanalysed.
Serumcortisolconcentrationsweremeasuredbyradioimmunoassay(Coat-A-CountCortisol,DiagnosticProductsCorporation,LosAngeles,CA,USA).
Heatshockprotein70FortheanalysisofHSP70tissuesamplesweretakenfromthestomach,smallintestine(approximately1mfromthepylorus),largeintestine(proximalcolon)andthesemimem-branosusmuscle(M.
semimembranosus)within1.
5hoursafterstunning.
Samplestakenfromthegastrointestinaltractwererinsedfreeofluminalcontentsinphysiologicalsaline,cutintopiecesandfrozeninliquidnitrogen.
Themusclesampleswereblotteddryandfrozeninliquidnitrogen.
Allthesampleswerekeptat70°Cuntilanalysis.
TheinducibleHSP70wasanalyzedusingaHSP70EIAkit(EKS-700,StressGenBiotechnologiesCorp,Victoria,Canada)whichhasbeentestedbytheproducerandfoundtorecognizeporcineHSP70.
TissueswerehomogenizedwithFastPrephomogenizer(FP120,Bio101,ThermoSavant,SavantIn-struments,Holbrook,NY,USA)inthebufferprovidedinthekitforproteinextractionandsupplementedwithprote-aseinhibitorcocktail(P8340,Sigma,St.
Louis,MO,USA).
Atissuepieceof250mgwashomogenizedin500μLofbufferwiththreetimes40shomogenization.
CarcassandmeatcharacteristicsTheslaughterhouseprovidedthedataaboutcarcassweightandleanmeatpercentage.
Thelatterwasmea-suredwithaHennessyGradingprobe(HennessyGrad-ingProbeGP4,HennessyGradingSystems,Auckland,NewZealand).
Bodytemperaturewasmeasuredfromrectum1-2minutesafterstunning(Trectum,°C)andmuscletemperatureat5cmdepthfromthesemimem-branosusmuscle35minafterstunning(T35min,°C).
ThepHvaluewasmeasuredfromthesemimembranosusmuscle35minutespostmortem(pH35min)byhomogen-izingonegramofmusclesamplein10mlof5mMNa-iodoacetate+150mMKCl,andbymeasuringthepHofthehomogenateatroomtemperature.
TheultimatepHwasmeasureddirectlyfromthesemimembranosusmuscle(pH24h)24hpostmortem.
Acombinedglasselectrodewasused(KnickPortamess752pH-meterwithMettlerToledoInlab427electrode).
Muscleglycogen,lactateandglycolyticpotentialGlycogenconcentrationwasdeterminedfromthesemi-membranosusmuscleaccordingto[25].
Tenμlofhom-ogenatewashydrolyzedin200μlof1MHClat100°Cfor2h,afterwhichpHwasadjustedto6.
5-7.
5andglu-cosewasdeterminedviaNADP+reductionwithlinkedassayinvolvinghexokinaseandglucose-6-phosphatedehydrogenase(Glucose(HK)16-50,SigmaDiagnostics).
LactateconcentrationwasdeterminedfromthehomogenateviaNAD+reductionwithalinkedassayinvolvinglactatedehydrogenaseandglutamatepyruvatetransaminase(Boehringer-Mannheimno.
139084).
Glyco-lyticpotentialwascalculatedasfollows[26]:GP(mmollactate/kg)=[2*(Glycogen+Glucose+G-6-P)+(Lactate)].
MeatcolouranddriplossMeatcolourwasmeasuredfromthesemimembranosusmuscle24hourspostmortemwithaMinoltaChroma-meterCR-200,(MinoltaCameraCo.
Japan)setatD65illu-minantafterbloomingfor5min.
Samplesweretakenfromthemiddleofthemuscle.
Thelightness(L*)andred-ness(a*)valueswererecordedfromtheaverageofthreereadingsacrosseachmusclesurface.
Driplosswasdeter-mined[27]byweighingmusclesamplesof100gthatwerethenputinaplasticbag,storedfortwodaysat4°Candreweighed.
Thedripwastheweightdifference,expressedaspercentage.
Tworeplicatesamplesweredeterminedoneachmusclesample.
StatisticalanalysesThechangeincortisolduetostressduringloading,trans-portandmixingattheslaughterhousewasestimatedasthedifferencebetweenthehomepenandthepost-transportcortisolconcentration.
Duetotechnicalandpracticalproblems,oneofthepre-transport(Cpig)andfour(oneCpigand3TBpigs)ofthepost-transportsalivasamplesweremissingfromthedata.
Allmeasuresrelatedtochronicstress(salivaandserumcortisol,bloodlactate,HSP70andbodytemperature)andcarcass(carcassweight,leanmeatpercentage)andmeatquality(glycogenandlactatecontentandglycolyticpoten-tialofthesemimembranosusmuscle,meatcolour,driploss)werenormallydistributed.
Therefore,theeffectoftaildamageonthedifferentmeasureswastestedusingANOVA.
Inadditiontothetestvariable(TBvsC)whichwasaddedasafixedfactor,alsostunninggroupwasforcedintothemodelsasafixedfactor.
Inaddition,theANOVAmodelforleanmeatpercentageincludedcarcassweightasacovariate.
Preliminaryanalysesshowedthatgenderdidnotinfluenceanyofthemeasures,andgenderwasthusnotincludedinthemodels.
Interactiontermsfortestvariable*stunninggrouponlycontributedsignifi-cantly(P0.
1).
NopigsinthisstudyhadmusclepH24h–valuesabove6.
0orpH35minbelow5.
8indicatingnocasesofDFDorPSEmeat.
DiscussionWefoundevidencethattaildamageisassociatedwithchangesinthestressphysiologyandcarcasscharacteristicsofslaughterpigs.
Eventhoughthisisbasedonalimitednumberofanimalsfromonlyonefarm,thefindingisrea-sonableasitcanbeassumedthattailbitingisassociated-5515257,47,031,821,724,43545556575HomepensampleLairagesampleLairagelevel-homepenlevelCortisol,nmol/lControlTailbitten*********ns14,4Figure1Mean(SE)cortisollevelsinsalivafromtailbitten(N=12)andcontrolpigs(N=13),sampledinthehomepenandinslaughterhouse,andthedifferencebetweenthesetwovalues(PairedSamplet-test,***P0.
1).
Onehomepensample(Cpig)andfourslaughterhousesamplesaremissing(oneCpig,threeTBpigs).
Meansaregivenasdatalabels.
Valrosetal.
ActaVeterinariaScandinavica2013,55:75Page4of8http://www.
actavetscand.
com/content/55/1/75withstressinthepigs.
Inconjunctionwiththecurrentstudywealsofoundthattaildamagecausedsevereinfec-tions,possiblycausinglong-lastingpain[28].
Painisawell-knowncauseofstress.
Inadditiontocausingpain,beingatailbitingvictimcanbestressfulinotherways,e.
g.
asvic-timsareoftenchasedandmightavoidfeedingatthetroughinfearofexposingthetail(forareview,see[10]).
Ourfindingthattailbittenpigshadasignificantlylowerconcentrationofsalivacortisolaftertransportthannon-bittencontrolpigsmayseemcontradictorytoearlierre-sults[29],showingelevatedcortisollevelsintailbittenpigs,measuredfromsinglesalivasamplestakeninthehomepen.
Thismightbeduetothefactthatmostofthetailbittenanimalsintheearlierstudy[29]hadsignsofmildfreshbiting,whilemostofthepigsinourstudyhadbeenbittenseverelyandchronically,asevidentfromourearlierpublishedresults[28].
Humanandrodentstudieshaveshownthattraumaticeventsandlong-lastingorre-peatedstresscancauseabluntedday-rhythmincortisol.
Thisphenomenoniscalledhypocortisolism[14]andcanalsobeseenasareducedincreaseincortisolsecretionwhenfacedwithacutestressors[14]orintheACTHtest[30].
Inourstudy,thelowercortisolpost-transportinbothsalivaandserumintailbittenpigsascomparedtocontrolpigswasprobablyduetoadecreasedcortisolsecretionduringtransport,ratherthantoabluntedday-rhythm,astherewasnodifferencebetweenbittenandcontrolpigsinthecortisolsamplestakenintheirhomepenbeforetrans-portation.
Eventhoughserumandsalivacortisolcannotbedirectlycompared,thefactthatcortisol,asmeasuredfromboththesemedia,wasincreasedintailbittenpigscomparedtocontrolpigsstrengthensourresults.
Thedifferenceincortisol,whencomparingsalivaandserumisatanexpectedlevelandtheresponsesshouldbe050100150200250300350400450Control208,6TailbittenCortisolnmol/l**99,0Figure2Mean(SE)cortisollevelsinbloodfromtailbitten(N=12)andcontrol(N=13)pigs,sampledatbleedingdirectlyafterstunning(PairedSamplet-test,**P<0.
01).
Meansaregivenasdatalabels.
Table1HSP70valuesincontrol(N=13)andtailbitten(N=12)pigsHSP70ControlTailbittenSignificanceLargeintestine,ng/gtissue1446±2811554±2920.
79Smallintestine,ng/gtissue2151±2632949±2730.
047Stomach,ng/gtissue421±76370±790.
64Semimembraneosusmuscle,ng/gtissue183±41253±430.
26Resultsaregivenasestimatedmarginalmeansandstandarderror.
Valrosetal.
ActaVeterinariaScandinavica2013,55:75Page5of8http://www.
actavetscand.
com/content/55/1/75comparable,asthereisahighcorrelationbetweensalivaandserumlevels,andthetimingoftheresponsepeakisverysimilar[31].
Histopathologicalanalysesfromthesamepigs,pub-lishedelsewhere,revealedsignsofinflammationandanincreasedacutephaseproteinresponse[28].
Therewasalsoahigherlevelofcarcasscondemnationsintailbittenpigs,especiallyduetoabscesses,whichsuggeststhatthetaildamagewasalreadychronic.
Thishasimplicationsfortheresultsofthecurrentstudy,astailbittenpigsmighthavesufferedfrominfections,causingchangesintheircortisolsecretion.
Theinteractionbetweentheimmunesystemandstressiscomplicatedandstudiesofcortisolduringdiseasechallengeshaveshownbothanincreaseandadecreaseincortisolresponsefollowingdiseasechal-lenge[32-34].
Thestress-inducedincreaseintheamountofHSP70isaresultfromgeneactivationfollowedbysynthesisofmRNAandtheprotein[35].
Thiscascadetakestime;inporcineintestinetheincreasesattheproteinlevelareseenapproximately6hoursaftertheinsult[35].
ThetimecourseofHSP70inductiontogetherwiththepresentfind-ingofelevatedHSP70concentrationsinthetailbittenpigssupporttheviewthatthetailbittenpigshadexperiencedanincreasedlevelofstressalreadypriortotransportation.
Astheexacttimingforthestress-inducedriseinHSPisnotknown,weincludedstunninggroupinthestatisticalmodelevaluatingtheeffectoftaildamageonpigHSP.
Thepigsslaughteredinthelaterstunninggrouphadexpe-riencedapproximately5hoursofantemortemhandling,whichisclosetothe6hourestimationmentionedabove.
However,inthecurrentstudytheHSPvalueswereactu-allynumericallylower(datanotshown)inpigsinthesec-ondstunninggroup,indicatingthatthiswasnotthecase.
Whilethecurrentstudydesigndoesnotallowforaconclusiononcauseandeffectregardingtaildamageandbodyweight,thedifferencebetweentailbittenandcontrolpigsincarcassweightssupportspreviousresultsonanegativeeffectofbeingtailbittenongrowth[5,36].
InTBpigsmeatpercentagewashigherbutduetothelargedifferenceincarcassweighttheamountofleanmeatwasconsiderablysmallerthaninCpigs(41.
2vs46.
3kg).
Eventhoughwedonothaveinformationontheexactdatewhentaildamagefirstoccurred,previ-ouslypublishedresultsfromthesamepigsusedhere[28]suggestthatthetaildamagewaschronic,whichmighthelpexplainthelargedifferenceincarcassweight.
Chronicpainordiscomforthasbeensuggestedtoretardgrowthintail-bittenpigs[4],possiblypartlyduetore-ducedfeedintake.
Chronicallybittenpigshavebeenre-portedtobereluctanttospendtimeatatroughfeeder,asthisexposesthetail[10].
Inaddition,stress,inthiscasecausedbypainorbybeingbittenassuch,mayhaveanegativeeffectonthefoodconversionefficiency[37].
Itcannotbeexcluded,thattherewasacommonunder-lyingillnesscausingboththevictimisationandatleastpartlythereducedgrowth.
Recentstudieshaveshownatwo-wayconnectionbetweenillnessandtailbiting.
Pigswithe.
g.
legproblemshaveahigherriskofbecomingtailbitten[38].
Theanimalsinourstudydidnotshowclinicalsignsofillness,butthatdoesnotexcludethepossibilityofsubclinicalsymptoms,oranearlierperiodofpoorhealth.
Onlyminordifferencesinmeatcharacteristicswerefoundinthecurrentstudy.
Stressincreasesbodytemperature[39]andhighmuscletemperatureimmedi-atelypostmortemweakensmeatqualityasseenasincreas-ingdripandinlightermeatcolour[39].
Thetemperatureinthesemimembranosusmusclewasnotsignificantlyhigherintailbittenthanincontrolpigs35minutespostmorteminthecurrentstudy.
However,themeatwaslighter,andthebodytemperaturemeasuredfromrectumafterstunningwashigherintailbittenthanincontrolpigs,furthersupportingthefindingthattailbittenpigshadexperiencedahigherlevelofstress.
ConclusionsTailbittenpigsshowedalowercortisolincreaseaftertransportandante-mortemhandlingthannon-bittencon-trolpigs.
ThisindicatesalessreactiveHPA-axis,possiblyduetoprolongedorrepeatedstressintheirhomepen,duetopainandtothebitingassuch.
ResultsfromHSP70supporttheseresults.
ThisstudyalsoindicatesthatHSP70isapromisingmeasureforchronicstress,whiletheTable2Comparisonofcarcassandmeatcharacteristicsbetweencontrol(N=13)andtailbitten(N=12)pigsControlTailbittenSignificanceCarcassweight,kg82.
4±2.
067.
7±2.
1<0.
001Meat-%a56.
2±0.
6060.
8±0.
480.
003Trectum,°Cb38.
9±0.
1239.
2±0.
130.
09T35min,°Cc39.
8±0.
1640.
2±0.
160.
13pH35mind6.
73±0.
036.
75±0.
030.
57pH24e5.
56±0.
035.
57±0.
030.
81Glycogen(mmol/kg)58.
2±4.
062.
8±4.
20.
44Lactate(mmol/kg)46.
1±3.
043.
7±3.
10.
59Glycolyticpotential(mmol/kg)f162.
5±6.
8169.
2±7.
10.
50Driploss,%6.
30±0.
566.
79±0.
580.
56L*(lightness)46.
0±0.
5748.
9±0.
590.
002a*(redness)8.
49±0.
308.
00±0.
310.
26Resultsaregivenasestimatedmarginalmeansandstandarderror.
aMeat-%:LeanmeatpercentagemeasuredwithHennessydevice;bTrectum,°C:bodytemperaturemeasuredfromrectumafterstunning;cT35min,°C:temperaturemeasuredfromthesemimembraneosusmuscle35minafterstun-ning;dpH35min:pHvaluemeasuredfromthesemimembraneosusmuscle35minafterstunning;epH24h:pHvaluemeasuredfromthesemimembraneo-susmuscle24hoursafterstunning;fGlycolyticpotential(mmollactate/kg):[2*(Glycogen+Glucose+G-6-P)]+(Lactate)].
Valrosetal.
ActaVeterinariaScandinavica2013,55:75Page6of8http://www.
actavetscand.
com/content/55/1/75cortisolresponseduringacutestressisnotanunambigu-ousreflectionofpreviouslyexperiencedstresslevel.
Thestudyshowedsupportforthefactthattailbittenpigsmightproducelessleanmeatpercarcass.
CompetinginterestsTheauthorsdeclarethattheyhavenocompetinginterests.
Authors'contributionsAllauthorswereincludedintheplanningofthestudydesignandsamplingprocedures,aswellasindatacollectionandpreparingthemanuscript,whichwasdraftedbyAV.
Inaddition,EPandMRwereinchargeofthemeasuresandanalysesofmeatcharacteristics,MHandOPoftheclinicalinspectionandselectionofthestudyanimalson-farmandAVandCMofthesamplingandanalysingofsalivacortisol.
RPwasinchargeofsamplingandanalysingtheHSP70aswellasserumcortisolandbloodlactate.
Allauthorsreadandapprovedthefinalmanuscript.
AcknowledgementsThisstudywasfinancedbytheFinnishMinistryofAgricultureandForestry,(Grant4934/501/2003).
TheauthorsthankMerjaAhonen(KoivistoSlaughterhouse,Mellill,HKFoodFinland)forarrangingtheexperiment,andthestaffattheslaughterhousefortheirassistanceinsampling.
WealsothankLauraHnninenattheUniversityofHelsinkiforvaluablecommentsonanearlyversionofthemanuscript.
Authordetails1ResearchCentreforAnimalWelfare,DepartmentofProductionAnimalMedicine,FacultyofVeterinaryMedicine,UniversityofHelsinki,P.
O.
Box57,00014Helsinki,Finland.
2DepartmentofFoodandEnvironmentalSciences,FacultyofAgricultureandForestry,UniversityofHelsinki,P.
O.
Box66,00014Helsinki,Finland.
3SaariUnit,DepartmentofProductionAnimalMedicine,FacultyofVeterinaryMedicine,UniversityofHelsinki,Pohjoinenpikatie800,04920Saarentaus,Finland.
4ReetaPs,DepartmentofVeterinaryBiosciences,UniversityofHelsinki,P.
O.
Box66,00014Helsinki,Finland.
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