View
4
Download
0
Category
Preview:
Citation preview
THE LIFE OF A TYPICAL MEAT CHICKEN
w
THE LIFE OF A TYPICAL MEAT CHICKEN
Hubbard Flex at 34 days of age.
w
THE LIFE OF A TYPICAL MEAT CHICKEN 3
Report conclusions 5
Executive summary 7
Overview of the broiler genetics industry 9
Welfare implications of intense genetic selection for performance 11
Health 11l Heartandcirculatoryhealth 11l Walkingability 12l Hockburnandfootburn 12
Behaviour 12l Foraging 13l Dustbathing 13l Perching 13
The trial: meat chicken welfare assessment 15
Methodology 15
Results 15l Productionparameters 16 l Growthrate 16 l Feedconversionratio 16 l Woodshavingsusage 17
l Health 17 l Mortalityandculls 17 l Walkingability 19 l Hockburn 20 l Footburn 21 l Breastfeathercleanliness 21 l Sectionsummary 22
l Behaviour 22 l Feeding 22 l Walking 23 l Standing 23 l Sitting 23 l Foraging 24 l Dustbathing 24 l Perching 25 l Sectionsummary 25
l Meatyield 26 l Carcassweight 26 l Breastweight 26 l Legweight 26 l Sectionsummary 27
l Meatquality 27 l Whitestriping 27 l Woodenbreast 28 l Sectionsummary 28
Conclusion 29
Is conventional chicken production falling fowl of the law? 31
Acknowledgements 31
References 32
Endnotes 34
Appendix 1 35
w
JA757 perching at 34 days of age.
w
THE LIFE OF A TYPICAL MEAT CHICKEN 5
Report conclusionsl There are three meat chicken (broiler) breeds that account
for the majority of chicken meat produced globally.
l Each breed is the breed used most extensively worldwide from each of the world’s three largest broiler breeding companies.
l An RSPCA commissioned trial revealed that, in general, compared to a commercially viable slower growing breed, these three conventional breeds had significantly higher mortality (including culls), poorer leg, hock and plummage health, and more birds affected by breast muscle disease (wooden breast and white striping)*. Further, they were less active – spending less time walking and standing, and more time feeding and sitting – and spent less time engaged in enrichment type behaviours: foraging, perching and dustbathing.
l The genetics of these three conventional breeds fail to adequately safeguard their welfare* to such an extent that many birds of these breeds could be considered as having a life not worth living.
l It is clear that conventional meat chicken breeding programmes have serious inherent flaws and lead to poor health and welfare*.
l There are significant inefficiencies in producing meat from these conventional meat chicken breeds and, if taken into account, the cost of producing meat from such breeds would likely represent a false economy and result in higher production costs compared to rearing higher welfare breeds.
l The production of chicken meat using conventional meat chicken breeds is a wasteful business*, which brings into question the sustainability of this enterprise.
l As the market has failed to safeguard chicken welfare, legislation must be implemented to address this issue.
l There are commercially-viable breeds available that have improved welfare outcomes and these higher welfare breeds should replace the use of conventional breeds.
* Refer to Appendix 1.
Ross 308 birds at 34 days of age.
THE LIFE OF A TYPICAL MEAT CHICKEN 7
Executive summaryMeat chickens, also referred to as ‘broilers’, are by far the most numerously produced farm animals reared for meat, with more than a billion 1 being slaughtered each year in the UK, 7.4 billion across the EU and more than 66 billion worldwide.
Meatchickenshavebeengeneticallyselectedtogrowveryquickly.Today’sbroilerscanreachanaverageUKslaughterweightof2.2kginjust35days.Threebroilerbreedingcompaniesdominatetheworldwidesupplyofbroilers,andachievingthegreatestmeatyieldintheshortesttimecontinuestobetheirprimaryfocus.Thisselectionforperformancehasbeenreportedtoberesponsibleforcontributingtonotonlythemost,butalsothemostsevere,welfareproblemsseeninbroilerstoday,suchaschroniclegdisordersandheartandcirculatoryproblems.Theseverityofthewelfareproblems,thehugenumberofanimalsinvolvedglobally,andthefactthatthesewelfareconcernshavenotbeenadequatelyaddressedtodate,meansthislong-standingissuerequiresurgentattention.
In2018,theRSPCAcommissionedatrial*toassesstheproductionandwelfarecharacteristicsofthebreedusedmostextensivelyworldwidefromeachofthethreegloballydominantmeatchickenbreedingcompanies.Thesethreebreedsarereferredtothroughoutthereportasthe‘conventional’breeds.Toprovidesomecontexttotheresults,anothercommercially-viablebreed,lessheavilygeneticallyselectedforperformancecharacteristics,wasalsoassessed.Thisbreedisreferredtoasthe‘slowergrowingbreed’.Thetrialrevealedthat,comparedtotheslowergrowingbreed,theconventionalbreedshadsignificantlypoorerhealth–highermortality(includingculls);poorerleg,hockandplumagehealth–andmorebirdsaffectedbybreastmuscledisease(woodenbreastandwhitestriping).Theconventionalbreedswerealsolessactive–spendinglesstimewalkingandstanding,andmoretimefeedingandsitting–andspentlesstimeengagedinenrichmenttypebehaviours:foraging,perchinganddustbathing.Theresultsdemonstratethatthegeneticsofthemostextensivelyusedconventionalbroilerbreedsfailtoensuremanyofthesechickenshavealifeworthliving.
Theconventionalbreeds,however,weremoreefficientatconvertingfeedintobodyweightand,duetobeingslaughteredatayoungerage,moreflocks(andthereforebirds)canberearedperyearwithinacommercialchickenhouse.Bothfactorshavesignificanteconomicbenefits.However,therearesignificantinefficienciesassociatedwithproducingmeatfromtheconventionalbreedsthat,iftakenintoaccount,wouldhaveaconsiderableimpactonthecostofproductionandcouldresultinhigherproductioncostscomparedtotherearingofhigherwelfarebreeds.Moreover,itisapparentthattheproductionofchickenmeatusingconventionalbreedsisawastefulandethicallyquestionablebusiness(e.g.highermortality,higherculls,andpoorermeatquality),bringingintoquestionthesustainabilityofthisenterprise.
Conventionalmeatchickenbreedingprogrammeshaveseriousinherentflawsandleadtopoorhealthandwelfare.Ifthecurrentlevelandscaleofsufferingandwasteistobeavoided,geneticbreedingprogrammesmustplaceamuchgreateremphasisonhealthandwelfaretraits.Whiletherearelegalprovisionsinplacethatshouldbeabletoaddressthesegenetic-relatedwelfareissues,newlegislationmayberequiredtoenforceameaningfulchangeinbroilergenetics.Suchlegislationisurgentlyrequiredtoensurebreedingcompaniesaremandatedtoprioritisebirdhealthandwelfareoverperformanceparameters,suchasgrowthrate.Intheinterim,whilethemainwelfareissuesmaynothavebeencompletelyeliminatedinbreedsthathavebeenlessheavilyselectedforperformance,thesebreedshaveasignificantlybetterqualityoflifeandshouldreplacetheuseofconventionalbreeds.
*ToaccompanythisreportthetrialwillalsobepublishedasascientificpaperbytheresearcherwhoundertookthetrialatScotland’sRuralCollege.
Figure 1: Top: Cobb 500 (male); Middle: Ross 308 (female); Bottom: Hubbard Flex (male) all at 40 days of age.
THE LIFE OF A TYPICAL MEAT CHICKEN 9
Overview of the broiler genetics industryIn 2017, approximately 1.1 billion meat chickens were slaughtered in the UK2. To provide a sense of scale, averaged over one year, this is equivalent to 35 birds being slaughtered every second, every day. Alternatively, if all the chickens were lined up head-to-toe they would circle the world nearly 11 times. In 2017, 7.4 billion2 chickens were slaughtered in the EU and 66 billion worldwide2.
Threebroilerbreedingcompanies–Cobb,AviagenandHubbard(whichisnowasubsidiaryofAviagen)–dominatetheglobalsupplyofmeatchickens.Whereveryouareintheworld,whetheryouarebuying,cookingoreatingchickenmeat,oneofthesethreecompanieswilllikelyhavebeenresponsiblefordeterminingthegeneticcharacteristicsofthatbird.
WithintheUK,mostmeatchickensarerearedtoaslaughterweightof2.2kg–roughlythesameweightasatwo-litre(fourpint)bottleofmilk–whichtakesaround35days3.Whileeachgeneticcompanyproducesanumberofdifferentchickenbreeds,thefastgrowingbreedsfromeachcompanyarethemostpopularanddominatenotonlyUK,butglobalproduction.
IntheUK,70–80percentofthemeatchickensrearedareproducedbyAviagen,whereasCobbaccountforbetween20–30percent4,andHubbardaccountforlessthanfivepercent.Whilethemarketshareofacompanyvariessignificantlyfromcountrytocountry,itwillbethefastgrowingbreedfromeachcompanythatisusedmostextensivelyworldwide–theEuropeanRoss308(fromAviagen),Cobb500andHubbardFlex.Thesebreedslookalmostidenticalandhaveverysimilarperformancecharacteristics(Figure1andTable1).TheRoss308isthemostwidelyusedbreedintheUKfollowedbytheCobb500.TheHubbardFlexisnottypicallyrearedintheUK.
TABLE 1: The most globally dominant broiler breed from each of the world’s three largest broiler breeding companies*.
Numberofdaystoachieveabodyweightof2.2kg
Averagedailyweightgain**(g/day)
Amountoffeed(kg)toachieve1kgofbodyweight**
Cobb5005 35 64 1.50
HubbardFlex6 35 62 1.54
Ross3083 35 63 1.47
* Thefiguresrepresenttheaverageforbothmaleandfemalebirds:maleswilltypicallygrowfasterthanfemalesandthereforebeofaheavierweightatthesameage,butthedataaveragestheperformanceofbothsexes.
** Basedonabodyweightofc.2.2kg.
Geneticselectionprogrammesfocusonthosetraitsthathavethegreatesteconomicvalue:growthrate,feedconversionratio(FCR)andbreastmeatyield(breastmeatistypicallythepremiumpartofthecarcass).FCRistheefficiencywithwhichchickensconvertfeedintobodyweight–principallymuscle(meat).Theprimarygoalforbreedingcompaniesistoproduceabirdthatreachesslaughterweightinasshortatimeaspossiblewhileutilisingtheleastamountoffeed.Reducingtheamountoftimeittakestoreachslaughterweightenablesproducerstorearmoreflocksofchickensperyearinthesamehouse,whilereducingfeedconsumptionclearlyreducesfeedcosts,whichisoneofthemostexpensiveresourcesinvolvedinchickenproduction.
Numberofdaystoachieveabodyweightof2.2kg Averagedailyweightgain**(g/day) Amountoffeed(kg)toachieve1kgofbodyweight**
Ross308335 63 1.47
Cobb5005 35 64 1.50
HubbardFlex6 35 62 1.54
*Thefiguresrepresenttheaverageforbothmaleandfemalebirds:maleswilltypicallygrowfasterthanfemalesandthereforebeofaheavierweightatthesameage,butthedataaveragestheperformanceofbothsexes.
**Basedonabodyweightofc.2.2kg.
Cobb 500 birds feeding at six weeks of age.
THE LIFE OF A TYPICAL MEAT CHICKEN 11
Welfare implications of intense genetic selection for performanceMeat chickens have been selected to grow quickly, producing the maximum amount of meat in the minimum amount of time7. Since the late 1950s, genetics companies have approximately halved the amount of time it takes for a meat chicken to achieve the same slaughter weight – at the rate of about one day shorter per year8. Further, as a result of improving the conversion of feed into muscle, the amount of feed required to achieve this weight has reduced by around a kilo since the early 1970s9.
Thecontinued,intensegeneticselectionforperformancetraitshasbeenreportedtoberesponsiblefor
contributingtonotonlythemost,butalsothemostsevere,welfareproblemsseenintoday’sbroiler10.
Whilechangestothebirds’environmentcanleadtoimprovementsinwelfare,afailuretoconsiderthe
birds’geneticsmeansthatanysuchimprovementinwelfarewillbe,atbest,modest.Takingintoaccount
theseverityofthewelfareissuesandthenumberofanimalsinvolved,broilerwelfareisoneofthemost
significantanimalwelfareconcernsintheworldtoday.
Health
Heart and circulatory health
Asaresultofgeneticselectionforfastgrowth,energyisdivertedprimarilyintomusclegrowth11.Thisprocess
candepriveotherpartsofthebodyofenergyandoxygen,andputpressureonthebird’sorgans,especially
theheartandlungs11.Assuch,fastgrowthcanincreasetheriskoftwotypesofheartconditions:ascitesand
suddendeathsyndrome11.
Suddendeathsyndromeisacuteheartfailure,i.e.heartattack,whichcanbetriggeredbystress;either
environmentalstress,suchasheatstress,orastressfulevent,forexamplecatchingandtransportation.
Itisdifficulttodeterminethetrueprevalenceofdeathfromheartfailure,butithasbeenestimatedthat
thisconditionaccountsforjustoverathirdofallmortalitiesonfarm12.Inaddition,althoughbirdsthatarrive
deadattheslaughterhousearenottypicallyexaminedforcauseofdeath,astudyrevealedthatthemajority
ofthesebirdsarelikelytohavediedfromsuddendeathsyndrome12.Researchhasshownthatbirdsthat
diefromthisconditionhavehistoriesofcardiac(heart)rhythmdisturbances,withanirregularheartbeat
detectableinbirdsasyoungassevendaysofage13.Infastgrowingbreeds,irregularheartrhythmshave
beenfoundtoaffectupto27percentoftheflock13indicatingthat,whilenotalwaysfatal,thiscondition
canbewidespread.
Inaworldwidesurvey,theincidenceofasciteswasestimatedtobe4.7percent,whichmakesitoneofthe
majorcausesofdeathinbroilers14.Ascitesoccursasaresultoftheincreasedmetabolicdemandsoffast
growth,whichcausesanincreasedneedforoxygeninthebloodstream.This,inturn,createsstressonthe
heartandlungs,resultinginenlargementoftheheart.Asaconsequenceofthis,fluidleaksfromtheliver
andgathersintheabdomenofthebird.Aswellasthisconditioncausingmortalityonfarm,carcassesare
increasinglybeingcondemnedattheabattoirduetothisdisease,withanaverageof2.4millionchickens
beingrejectedfromthefoodchainasaresultofthisconditioneachyearbetween2011and201315.In
additiontotheeconomicimpact,ascitesalsohasamajorimpactonbirdwelfare–itdevelopsgradually,
causingthebirdstosufferforanextendedperiodbeforetheydie16.
THE LIFE OF A TYPICAL MEAT CHICKEN12
Walking ability
Fastgrowthcancauselegdevelopmentaldisorders,suchastibialdyschondroplasia(TD)–aconditionwherethecartilageinthelegandhipdevelopsabnormallyandaffectsthebird’sabilitytowalk.Typically,itcausesfiveto25percentofthelamenessobservedinchickens17.
Fastgrowthcanalsocausethelegbonestobecomedeformedasthebodygainsweighttooquicklyforskeletaldevelopmenttokeeppace.Thepressurethisfastgrowthputsontheimmatureskeletonofthebirdcanalsocausemicrofracturesinthecartilageandbone.Thesefracturescanbecolonisedbybacterialeadingtopainfulinfectionsandlameness,resultinginaconditioncalledbacterialchondronecrosiswithosteomyelitis(BCO)whichaffectsaroundonepercentofbirdsinconventionalflocks18.Inactivity,withlongperiodsofsittingdown,canalsostuntboneandcartilagedevelopment,increasingtheriskofBCO18.
Gaitscoringisamethodusedtoassessthewalkingabilityofabird.Thescoresrangefrom0(normalwalkingability)to5(incapableofsustainedwalking).Inthemiddleoftherangeisscore3,whichdescribesabirdwalkingwithanidentifiableabnormality,i.e.abirdthatisobservablylame.Researchhasdemonstratedthatbirdswithascore3areinpainanddiscomfort19,andithasbeensuggestedalsothatbirdswithascore1or2mightalsobeexperiencingsomepain,astheywillchoosetoselfmedicatewithananalgesic(painkiller)ifavailable20.Theproportionofbirdswithinaflockwithascore3hasbeenreportedtorangefromaround26percent21to57percent22.IntheUK,asurveyrevealedthatinmorethan50percentofflocks,98percentofbirdshadanobservablegait(leg)defectbythetimetheyreachedtheendofproduction,with28percentofbirdshavingascore3orhigher23.
Althoughgeneticscompanieshavefocusedonimprovingleghealth,meaningfuladvanceshavebeenlimitedduetoitsnegativerelationshipwithgrowthrate24,i.e.selectingforgrowthrateimpactsnegativelyonleghealth.
Hock burn and foot burn
Ithasbeenreportedthatfastgrowingbreedsmayspend76percentoftheirtimesittingbythetimetheyreachslaughterweight,withlamebirdsspending86percentoftheirtimesitting25.Prolongedperiodsofinactivitycancontributetothedevelopmentofulcersandlesionsonthoseareasofthebirdthatareincontactwiththefloor:typicallythefeet(footburn)andhocks(hockburn)26.Ulcersandlesionscanbepainfulandthoseaffectingthelegsandfeetcancontributetolameness27.In2007,astudyexaminedtheprevalenceoftheseconditionsacross206UKflocks26.Footburnwasthemostcommoncondition,withanaverageof11percentofallbirds,andupto72percentofasingleflock,affected.Anaverageof1.3percentofallbirdshadhockburn,withupto33percentofasingleflockbeingaffectedbythiscondition.Amorerecentstudyof53UKflocksfoundsimilarlyhighlevelsoffootburn,buthigherlevelsofhockburn:anaverageprevalenceof51.6percentand20.5percent,respectively,acrossallflocks28.
Thereappearstobeaviciouscyclebetweeninactivityandleghealth;thelessactiveabirdisthenthemorelikelyitwillbetohavepoorleghealthand,theworseitsleghealthis,themorelikelyitistobeinactive.Further,ifthefloorcoveringofthehouse,e.g.woodshavings,isnotmaintainedingoodconditionthenthiscancontributetothedevelopmentandseverityofbothhockandfootburn.
Behaviour
Selectivebreedingforincreasedperformancehasresultedinareductionintheactivitiesthebirdscancarryout10.Healthychickensaremotivatedtoperformawiderangeofbehaviours,includingforaging,dustbathingandperching.Itiswidelyacceptedthatforananimaltohave‘goodwelfare’,inadditiontoanabsenceofnegativepsychologicalstates,suchasfear,theyshouldbeabletoexperiencepositivepsychologicalstates,suchaspleasure29.Ifthehealthofachicken,forwhateverreason,meansitcannotexpressafullrepertoireofnaturalbehaviour,itmayexperiencefrustration,helplessnessorboredomandmaynothavetheopportunitytoexperiencepleasureorotherpositivestates.
THE LIFE OF A TYPICAL MEAT CHICKEN 13
Foraging
Birdscanbemotivatedtoperformcertainbehaviours,evenwhentheymayappeartobeunnecessary.Forexample,inonestudy,whenredjunglefowl(theancestorofthechicken)werepresentedwithaneasilyavailablefoodsourcetheystillchosetospendaround30percentoftheirtimeforagingforfood30.Bycontrast,fastgrowingmeatchickensspentverylittletimeengagedinforagingbehaviour–aroundfivepercent–with95percentoftheirtimeeatingtheeasilyavailablefoodprovided.
Dust bathing
Dustbathingisacomfortbehaviour(anactivitythathelpsmaintainthefeathersandincreasesthephysicalcomfortofthebird)andinvolvesthebirdrakinguploose,dryground,e.g.soil,withtheirfeetandthenlyingdowntowing-shake,kickdustintotheirfeathers,andthenrubthemselvesagainsttheground31.Sostrongisthemotivationtocarryoutthisbehaviourthatlayinghenshavebeenshowntoattemptdustbathingonwireflooringintheabsenceofasuitablematerial32,andwillspendadditionaltimeengagedinthisbehaviourfollowingaperiodofrestriction31.
Astudyofdustbathinginmeatchickensdemonstratedtheydustbathedeverydayand,likelayinghens,willincreasetheirtimedustbathingafteraperiodofrestriction33.Itislikely,therefore,thatmeatchickensarehighlymotivatedtodustbathe,butinadequateconditionsandpoorleghealthcanlimitbirdsdustbathingincommercialsettings.Beingunabletosatisfyamotivation,andrestrictinganimportantbehaviour,cancausefrustrationandstress34.Further,inthecaseofdustbathing,limitingthisbehaviourcouldhaveanimpactonfeatherconditionandhealth.
Perching
Astrongmotivationtoperchhasbeendemonstratedinlayinghens35,wherebyhenswillperchtorestandpreen,forexample36.Althoughmoreresearchhasbeenconductedtoexamineperchprovisionforhensthanmeatchickens,whenprovidedwiththecorrecttypeofperch,healthyandcapablebroilerswillusethem37
–especiallytoroostduringtheeveningperiod38–indicatingtheytooaremotivatedtoperformthisbehaviour.
JA757 birds perching at four weeks of age.
JA757 perching at 34 days of age.
THE LIFE OF A TYPICAL MEAT CHICKEN 15
The trial: meat chicken welfare assessmentThe RSPCA commissioned a trial to assess the production and welfare characteristics of the meat chicken breed used most extensively worldwide from each of the three globally dominant meat chicken breeding companies. As these three conventional breeds – the Cobb 500, the Hubbard Flex and the Ross 308 (from Aviagen) – dominate the global production of chicken meat, the results have widespread significance. To provide context to the results, a commercially-viable breed that has undergone less intensive genetic selection for performance traits was also assessed: the Hubbard JA757.
Methodology
ThetrialwascarriedoutaccordingtotheRSPCABroilerBreedWelfareAssessmentProtocol*39.Thisprotocolwasinitiallydevelopedin2013toassessthewelfareofmeatchickenbreedsanddeterminetheiracceptabilityforuseundertheRSPCAWelfareStandardsforChickens.Theprotocoldescribeshowbirdsaretoberearedtohelppromotefullexpressionoftheirgeneticpotential,i.e.byprovidinganon-limitingdietandenvironment,anddetailstheassessmentmethodologyforanumberofkeywelfareparameters,includingwalkingability,hockburn,footburnandmortality.
Intotal,400dayoldchicksfromeachbreed,sourcedfromcommercialhatcheries,werereared.Thebirdswererearedindoorsinpenswithapproximately80percentmorespaceperbirdcomparedtotypicalUKcommercialconditions(stockingdensityof21kg/m2).Eachpenheld50birdsofthesamebreed.Thefloorofeachpenwascoveredinlitter(woodshavings),whichwasmaintainedinadryandfriableconditionatalltimes.Birdshadconstantaccesstofeedandwater,anda130cmlongperch.Startingfromsixdaysofage,thebirdshadasix-hourcontinuousnightperiod(lightsoff)per24hours.
ThebirdswereassessedforanumberofkeywelfareparameterswhentheyachievedtheaverageUKslaughterweightof2.2kg.Theywerealsoassessedat2.5kgtogatherdatarelevanttowhenthesebirdsarerearedtothisheavierweight.Theresultspresentedbelowrepresenttheaverageacrossbothassessments,exceptwherestatedotherwise.Formostparameters,therewasnosignificantdifferencebetweentheresultswhenthebirdswere2.2kgcomparedto2.5kg.However,wherethedegreeofdifferencebetweenthebreedschangedconsiderablybetweenthetwoassessments,thishasbeenreported.Thebirdsfromallfourbreedswereslaughteredatasimilaraverageweightofapproximately3kg.
Allpenswerefilmedfora24-hourperiodeachweeksothebirds’behaviourcouldbeexamined.Thebehavioursrecordedduringhourlyscansamplingwere:feeding,walking,standing,sitting,foraging,perchinganddustbathing.Birdsfromallfourbreedsspentthemajorityofthenightperiodsitting/resting,soonlybehavioursperformedduringthedayhavebeenpresented.Behaviourwascomparedacrossallbreedsforbirdsatthesameage.Inaddition,becausetheslowergrowingbreedwaslighterthantheconventionalbreedsatthesameage,i.e.duetoitbeingslowergrowing,behaviourwasalsocomparedacrossbreedswhentheyweresimilarweights.However,comparisonaccordingtoweightdidnotprovideanymoremeaningfulinsights,andwereverysimilartothecomparisonsdonebyage,andthereforeitwasnotconsiderednecessarytopresenttheresultshere.Thisindicatesthattherateofweightgaincausesmoreofachangeinbehaviourthanweightitself.
Results
Resultsthatrelatespecificallytoeachconventionalbreedhavenotbeenrevealed,asitisnottheintentionofthisreporttosingleoutanyofthesebreedsinparticular.Therefore,theconventionalbreedsarereferredtoaseitherBreedA,BorC,andarecollectivelyreferredtoasthe‘conventionalbreeds’.TheHubbardJA757isreferredtoastheslowergrowingbreed.
*Exceptfortheassessmentmethodologyforhockburnandfootburn,forwhichscoringsystemsdevelopedforusebytheindustrywereused.Inthecaseoffootburn,theagreedDefra/FSA/industryScorecardwasused.
0
500
1,000
1,500
2,000
2,500
Age (days)
Bird
wei
ght
(g)
0 14 28 35 42 49
THE LIFE OF A TYPICAL MEAT CHICKEN16
TheageofthebirdsatthetwoassessmentsisshowninTable2.Duetotheslowergrowingnatureoftheslowergrowingbreeditwasolderthantheconventionalbreedsateachassessment.
TABLE 2: Average age of all four breeds when assessed at 2.2kg and 2.5kg.
Breed Slowergrowingbreed
BreedA BreedB BreedC
Age(days)atthefirstassessment(birdsweighed2.2kg)
48 35 35 35
Age(days)atthesecondassessment(birdsweighed2.5kg)
54 37 38 38
Throughoutthissection,wheretheterms‘significant’and‘significantly’havebeenused,thisreferstoastatisticalsignificance,i.e.wherestatisticalanalysisofthedatahasconfirmedthatthereisatleasta95percentlikelihoodofthedifferencebetweenthebreedsbeingreal.
Production parameters
Growthrate
Theconventionalbreedsallgrewatasimilarratetoeachotherandhadanaveragedailyweightgainofapproximately63gat2.2kg.Theslowergrowingbreedgrewapproximately26percentslowerthantheconventionalbreeds–averaging46gperdayat2.2kg.Thegrowthcurvesforeachbreedoverthedurationofthetrialtoachieveanaverageweightof2.2kgareshowninFigure2.
FIGURE 2: Growth curves for each breed to 2.2kg.
Feedconversionratio
Feedconversionratio(FCR)isexpressedastheamountoffeed(kg)ittakestogainonekilogramofbodyweight.Thelessfeedrequiredtoachieveeachkiloofbodyweightthenthemoreefficientthebirdisinconvertingfoodintomeat,andthelowertheFCRvalue.
TheconventionalbreedshadsignificantlylowerFCRscomparedtotheslowergrowingbreed:1.46,1.43and1.35forbreedsA,BandC,respectively,comparedwith1.76.
Slowergrowingbreed
BreedA
BreedB
BreedC
0
5
10
15
20
25
Woo
d sh
avin
gs w
eigh
t (k
g)
Slower growing breed Breed A Breed B Breed C
Breed
a
bb b
THE LIFE OF A TYPICAL MEAT CHICKEN 17
Woodshavingsusage
Woodshavingswereusedtocoverthefloor.Overthecourseofthetrial,theconventionalbreedsrequiredsignificantlymorewoodshavingstomaintaintheflooringingoodcondition,i.e.keepthewoodshavingsdryandfriable,comparedtotheslowergrowingbreed:23.7–24.8kgv14.5kgperbreed,respectively(NB.thiswasinadditiontotheinitialallocationofwoodshavings)(Figure3).
FIGURE 3: Amount (kg) of wood shavings added during the trial per breed. Differentlettersindicateasignificantdifferencebetweenthosebreeds.
Health
Mortalityandculls
ThespecificcausesofmortalityandreasonsforcullingthataffectedallfourbreedsduringthetrialarepresentedinFigure4.
FIGURE 4: Causes of mortality and reasons for culling (data combined for all four breeds).
Yolksacinfection40%
Heartattack8%
Runt5%
Unknowncause11%
Unresponsive7%
Injured5%
Lame24%
0
2
4
6
8
10
12
Mor
talit
y (%
)
Slower growing breed Breed A Breed B Breed C
Breed
a
bb
a
THE LIFE OF A TYPICAL MEAT CHICKEN18
Whenthecausesofmortalityandreasonsforcullingwereexaminedindividually,therewasnosignificantdifferencebetweenthebreedsfordeathfromyolksacinfection(abacterialinfectionthatprimarilyaffectsyoungchickswithintheirfirstweekoflife)orbirdsbeingculledforbeingunresponsive(birdsthatappearedunwell,e.g.hunchedandlistless,anddidnotrespondtofoodandwaterorwereconsideredunlikelytomakearecovery).Therewasinsufficientdatatodetermineanystatisticaldifferencesbetweenthebreedsfortheothercausesofmortalityandreasonsforculling,exceptlameness.However,thenumberofbirdsforeachbreedaffectedbyeachcauseisshowninTable3.See‘Walkingability’sectiononpage19fordatarelatingtolameness.
TABLE 3: Number of birds culled or found dead by cause for each breed.
Reasonformortalityandculls(numberofbirds)
Breed Heartattack
Runt Injured Lame,i.e.severeinabilitytowalk/unable
towalk*
Yolksac
Un-responsive
Unknowncause
Total
Slowergrowing
1 1 0 4 10 2 4 22
BreedA 4 0 5 17 12 2 5 45
BreedB 4 4 1 12 15 4 6 46
BreedC 3 2 1 1 18 2 1 28
* Birdswithagaitscoreof4or5(See‘Walkingability’sectiononpage19forfurtherdetails).
Whenallthecausesofmortalityandreasonsforcullingwerecombinedforeachbreed,therewasnosignificantdifferencebetweentheslowergrowingbreedandBreedC:5.2percentv6.8percent,respectively(Figure5).However,comparedtotheslowergrowingbreed,theaveragemortality,includingculls,forBreedsAandBweresignificantlyhigher:10.7percentand11.2percent,respectively(Figure5).
FIGURE 5: The average (%) mortality, including culls, for each breed. Differentlettersindicateasignificantdifferencebetweenthosebreeds.
0
10
20
30
40
50
60
70
543210 (normal)
Prop
orti
on o
f bird
s (%
)
Gait score
0
0.5
1
1.5
2
2.5
3
3.5
4
Prop
orti
on o
f bird
s (%
)
Slower growing breed Breed A Breed B Breed C
Breed
a
b
b
a
THE LIFE OF A TYPICAL MEAT CHICKEN 19
Walkingability
Gaitscoring(GS)isamethodusedtoassessabird’swalkingability.Thescorerangesfrom0(normalwalking
ability)to5(incapableofsustainedwalking).Inthemiddleoftherangeisscore3,whichdescribeswalking
withanidentifiableabnormality,i.e.abirdthatisobservablylame.
Duringthetrial,birdswithagaitscoreof4and5wereimmediatelyculledandrecordedaslame(Table3).
Therewasnosignificantdifferencebetweenthenumberofbirdsculledwiththesescoresfortheslower
growingbreedandBreedC(Figure6).However,theslowergrowingbreedhadsignificantlyfewerbirdsculled
withlamenessscoresof4and5(onepercent)comparedtoBreedsAandB(4.0percentand2.8percent
respectively)(Figure6).
FIGURE 6: The proportion of birds for each breed culled throughout the trial with a gait score of 4 or 5. Differentlettersindicateasignificantdifferencebetweenthosebreeds.
Atthetimeofthewelfareassessments,theslowergrowingbreedhadsignificantlybetterleghealth
(lowergaitscores)thanallthreeconventionalbreeds(Figure7).Further,itwastheonlybreedwherea
proportionofthebirds(13percent)hadascore0.Thevastmajorityoftheslowergrowingbreedbirdshad
gaitscoresof2orlower(89.4percent),withmostbirdshavingascoreof1.Incontrast,thevastmajority
ofallthreeconventionalbreedshadascoreof2orhigher(92.1percent,89.6percentand88.1percent,
forBreedsA,BandC,respectively),withmostbirdshavingascoreof2(Figure7).Duetobirdswithascore
of4and5beingculledthroughoutthetrial,veryfewbirdswiththesescoreswereobservedatthetime
ofthesewelfareassessments.
FIGURE 7: Gait scores for all breeds (NB. combined results for 2.2 and 2.5kg assessments).
Slowergrowingbreed
BreedA
BreedB
BreedC
THE LIFE OF A TYPICAL MEAT CHICKEN20
Overall,acrossallbreeds,gaitscoresdeterioratedsignificantlybetweenthefirstandsecondwelfareassessment,i.e.asthebirdsaged(Table4)However,whilethewalkingabilityoftheslowergrowingbreedalsodeterioratedwithtime,therewerefewermoderatelytoseverelylamebirds(gaitscores3–5)comparedtotheconventionalbreeds.
TABLE 4: Average percentage of birds within each gait score range (0, 1, 2 combined and 3, 4, 5 combined) for all breeds at the first and second welfare assessment.
Assessment Gaitscorerange
Slowergrowingbreed
BreedA BreedB BreedC
Firstassessment:birdsweighing2.2kg
0–2 96.0 72.5 81.3 84.0
3–5 4.0 27.3 18.7 16.0
Secondassessment:birdsweighing2.5kg
0–2 82.8 51.4 62.0 64.4
3–5 17.2 48.6 38.0 35.6
Whenexaminingtheaverageresultsacrossbothassessments,26–38percentoftheconventionalbirdshadagaitscoreof3andabove,whileonly11percentoftheslowergrowingbirdshadthesescores(Figure7).
Hockburn
Hockburnwasscoredonafour-pointscale,asfollows:
l Score0:healthy,i.e.nodiscolorationorlesions.
l Score0P:nodiscolorationorlesions,butpink and/orswollen.
l Score1:substantialdiscolourationofskin,visible lesionsbutnoulcerations.
l Score2:largeareasofaffectedskin,deepulcerations orlesions,orlargescabsandseverelyswollen.
Theconventionalbreedshadsignificantlypoorerhockhealththantheslowergrowingbreed:23.5to40.7percentoftheconventionalbreedbirdshadhealthyhocks(score0)comparedwith81.2percentfortheslowergrowingbreed(Figure8).
Themajorityofthebirdsforallthreeconventionalbreedshadpinkand/orswollenhocks(score0P)(68percent,59.2percentand50.4percent,forBreedA,BandC,respectively),andasmallproportionscored1(8.5percent,10.4percentand8.5percent,forBreedsA,BandC,respectively)(Figure8).AverysmallproportionoftheBreedBandCbirdshadascore2.Only16.1percentand2.5percentoftheslowergrowingbreedbirdsscored0Pand1,respectively,withnobirdshavingascore2.
Ross 308 resting at 34 days of age.
0
20
40
60
80
100
21OP0 (Healthy)
Prop
orti
on o
f bird
s (%
)
Hock burn score
0
20
40
60
80
100
21OP0 (Healthy)
Prop
orti
on o
f bird
s (%
)
Foot burn score
THE LIFE OF A TYPICAL MEAT CHICKEN 21
FIGURE 8: Hock burn scores for all breeds.
Footburn
Footburnwasscoredonafour-pointscale,asfollows:
l Score0:healthy,i.e.nodiscolorationorlesions.
l Score0P:nolesionsbutpinkand/orswollenand/orhealedscarring/verysmallsuperficiallesions, slightdiscolouration,mildthickeningoftheskin.
l Score1:substantialdiscolourationofskin,visiblelesions,butnoulcerations.
l Score2:largeareasofaffectedskin,deepulcerationsorlesionsandswollen.
Therewerenosignificantdifferencesinfootburnscoresbetweenallfourbreeds,withthevastmajority(morethan95percent)ofbirdsforallbreedsscoring0(Figure9).
FIGURE 9: Foot burn scores for all breeds.
Breastfeathercleanliness
Birdsusetheirfeatherstokeepwarmandprotectthemselvesfrommoisture,dirtandskininfections.Healthybirdswillspendtimekeepingtheirfeathersingoodcondition.Iffeathersbecomewetordirtythentheycanlosetheirprotectiveproperties.Therefore,feathersthatareinpoorconditioncanhavesignificanteffectsonbirdwelfare.
Breastcleanlinesswasscoredonathree-pointscale,asfollows:
l Score0:clean.
l Score1:slightlydirty.
l Score2:largepatchesofdirtyfeathersonbreast,orbreastiscompletelycoveredindirtyfeathers.
Slowergrowingbreed
BreedA
BreedB
BreedC
Slowergrowingbreed
BreedA
BreedB
BreedC
0
20
40
60
80
100
210 (clean)
Prop
orti
on o
f bird
s (%
)
Breast cleanliness score
1
2
3
4
5
6
7
8
Prop
orti
on o
f tim
e (%
)
Bird age (days) 2 9 16 23 30 37
THE LIFE OF A TYPICAL MEAT CHICKEN22
Theconventionalbreedshadsignificantlypoorerbreastcleanlinessscoresthantheslowergrowingbreed.Theslowergrowingbreedwastheonlybreedtohavebirdswithcompletelycleanbreastfeathers(score0)(Figure10).
Mostoftheslowergrowingbreedbirdshadascoreof1(40.5percent),whereasthevastmajorityofthethreeconventionalbreedsscored2:80.1,82.1and81.5percentforBreedsA,BandC,respectively(Figure10).Noneoftheconventionalbreedshadcompletelycleanbreastfeathers(score0).
FIGURE 10: Breast feather cleanliness scores for all breeds.
SECTION SUMMARY
l Ingeneral,comparedtotheslowergrowingbreed,theconventionalbreeds–takenasagroup–had significantlypoorerleghealth,hockhealthandbreastfeathercleanlinessscoresandsignificantlyhigher mortality(includingculls).
l Foothealthforallfourbreedswasgoodwithnosignificantdifferenceinscoresbetweenthebreeds.
Behaviour
Feeding
Throughoutthetrial,theconventionalbreedsspentsignificantlymoretimefeedingthantheslowergrowingbreed(Figure11).
FIGURE 11: The average proportion of time each breed spent feeding throughout the trial.
Slowergrowingbreed
BreedA
BreedB
BreedC
Slowergrowingbreed
BreedA
BreedB
BreedC
1
2
3
4
5
Prop
orti
on o
f tim
e (%
)
Bird age (days) 2 9 16 23 30 37
0
5
10
15
20
Prop
orti
on o
f tim
e (%
)
Bird age (days)2 9 16 23 30 37
THE LIFE OF A TYPICAL MEAT CHICKEN 23
Walking
Overthecourseofthetrial,allthreeconventionalbreedsspentsignificantlylesstimewalkingcomparedtotheslowergrowingbreed(Figure12).
Forallfourbreeds,theamountoftimespentwalkinggraduallydeclinedfromninedaysofage.However,thisdecreasedatasignificantlygreaterratefortheconventionalbreedscomparedtotheslowergrowingbreed(Figure12).
FIGURE 12: The average proportion of time each breed spent walking throughout the trial.
Standing
Overthecourseofthetrial,theconventionalbreedsspentsignificantlylesstimestandingcomparedtotheslowergrowingbreed(Figure13).Thisdifferenceprimarilyoccurredafter16daysofage.
FIGURE 13: The average proportion of time each breed spent standing throughout the trial.
Sitting
Overthecourseofthetrial,theconventionalbreedsspentsignificantlymoretimesittingthantheslowergrowingbreed(Figure14).From16daysofage,thetimespentsittingincreasedforallbreedsasthebirdsgainedweight,butthisincreasewassignificantlylessfortheslowergrowingbreed(Figure14).Towardstheendofthetrial,whenthebirdswere37daysofage,theslowergrowingbreedspent51percentofthetimesittingcomparedto71–74percentfortheconventionalbreeds.
Slowergrowingbreed
BreedA
BreedB
BreedC
Slowergrowingbreed
BreedA
BreedB
BreedC
0
3
6
9
12
15
Prop
orti
on o
f tim
e (%
)
Slower growing breed Breed A Breed B Breed C
Breed
a
b
c c
40
50
60
70
80Pr
opor
tion
of t
ime
(%)
Bird age (days)2 9 16 23 30 37
THE LIFE OF A TYPICAL MEAT CHICKEN24
FIGURE 14: The average proportion of time each breed spent sitting throughout the trial.
Foraging
Overthecourseofthetrial,theconventionalbreedsspentsignificantlylesstimeperformingforagingbehaviour(scratchingordigginginasubstratewiththebeakorfeet)comparedtotheslowergrowingbreed(7.9–10.3percentv12.9percent)(Figure15).
FIGURE 15: The average proportion of time spent foraging for all four breeds. Differentlettersindicateasignificantdifferencebetweenthosebreeds.
Dustbathing
Overthecourseofthetrial,theconventionalbreedsspentsignificantlylesstimedustbathingthantheslowergrowingbreed(Figure16).Forallfourbreeds,thetimespentdustbathingincreaseduptoday16andthenremainedapproximatelyconstantuntilaroundday30whenthisincreasedagainfortheslowergrowingbreedbutdecreasedfortheconventionalbreeds(Figure16).
JA757 birds displaying dust bathing behaviour at 34 days of age.
Slowergrowingbreed
BreedA
BreedB
BreedC
0.0
0.2
0.4
0.6
0.8
1.0
1.2Pr
opor
tion
of t
ime
(%)
Bird age (days)2 9 16 23 30 37
0
3
6
9
12
15
Prop
orti
on o
f tim
e (%
)
Bird age (days)2 9 16 23 30 37
THE LIFE OF A TYPICAL MEAT CHICKEN 25
FIGURE 16: The average proportion of time spent dust bathing for all four breeds.
Perching
Overthecourseofthetrial,theconventionalbreedsspentsignificantlylesstimeperchingthantheslowergrowingbreed–spendingverylittletimeperformingthisbehaviour(dailyaverage:0.5–1.2percentv8.0percent,respectively)(Figure17).Fromapproximatelynineto30daysofage,thetimespentperchingfortheslowergrowingbreedincreasedsharply(Figure17).Incontrast,fortheconventionalbreeds,thetimespentperchingincreasedmarginallyupuntilday16,beforedecreasingtotheendofthetrialwhenthebirdswererarelyobservedperformingthisbehaviour(Figure17).
FIGURE 17: The average proportion of time spent perching for all four breeds.
Note:allpenshada130cmperchspaceper50birds.Fromapproximately14daysofage,theslowergrowingbreedbirdswereobservedtoalmostalwaysoccupythefulllengthoftheperch.Therefore,ifmoreperchspacehadbeenprovided,itislikelymorebirdswouldhaveperformedthisbehaviour.Theconventionalbreedswerefrequentlyobservedtryingtoperch,butonlyveryfewindividualsweresuccessful.Anecdotally,manyofthosethatattemptedtoperchappearedtohavetroublebalancingandwouldhavetostepdowntoavoidfallingoff.Itthereforeappearstheconventionalbreedsweremotivatedtoperch,butwerephysicallyincapableofdoingso.
SECTION SUMMARY
l Overthecourseofthetrial,theconventionalbreedsspentsignificantlylesstimewalking,standing,foraging, dustbathingandperching,andmoretimefeedingandsitting,comparedtotheslowergrowingbreed.
Slowergrowingbreed
BreedA
BreedB
BreedC
Slowergrowingbreed
BreedA
BreedB
BreedC
0
100
200
300
400
500
600
700
800
Wei
ght
(g)
Slower growing breed Breed A Breed B Breed C
Breed
a
b
ab
0
500
1,000
1,500
2,000
2,500
Wei
ght
(g)
Slower growing breed Breed A Breed B Breed C
Breed
aa
b a
THE LIFE OF A TYPICAL MEAT CHICKEN26
Meat yield
Carcassweight
Thebirdsfromallfourbreedswereslaughteredatasimilaraverageliveweightofapproximately3kg.
Carcassweightistheweightofadeadbirdonceitsinnards,headandlowerlegs(feetuptothehock)havebeenremoved.Therewasnosignificantdifferencebetweentheslowergrowingbreedandtheconventionalbreedsforaveragecarcassweight,exceptBreedBwhichhadasignificantlylighteraveragecarcassweightcomparedtoalltheotherbreeds(Figure18).
FIGURE 18: Average carcass weight at slaughter for the four breeds. Differentlettersindicateasignificantdifferencebetweenthosebreeds.
Breastweight
TherewasnosignificantdifferenceinaveragebreastweightbetweentheslowergrowingbreedandBreedB,bothofwhichhadsignificantlylighterbreastweightscomparedtoBreedsAandC(Figure19).
FIGURE 19: Average breast weight per bird for the four breeds. Differentlettersindicateasignificantdifferencebetweenthosebreeds.
Legweight
Theaveragebirdlegweightfortheslowergrowingbreedwassignificantlyheavierthanthoseoftheconventionalbreeds(Figure20).
0
100
200
300
400
500
600
700
800W
eigh
t (g
)
Slower growing breed Breed A Breed B Breed C
Breed
a
b b b
THE LIFE OF A TYPICAL MEAT CHICKEN 27
FIGURE 20: Average leg weight per bird for the four breeds. Differentlettersindicateasignificantdifferencebetweenthosebreeds.
SECTION SUMMARY
l Thecarcassweightsoftheconventionalbreedswereequivalentto,orsignificantlylighterthan, theslowergrowingbreed.
l Thebreastweightofoneoftheconventionalbreedswasequivalenttotheslowergrowingbreed.
l Allconventionalbreedshadlighterlegweightsthantheslowergrowingbreed.
l Therefore,althoughtheslowergrowingbreedtookapproximately14dayslongertoreachthesame weightastheconventionalbreedsforslaughter,ithadanatleastequivalentmeatyieldcomparedto oneormoreofthesebreedsacrossalltheparametersassessed.
Meat quality
Whitestriping
Whitestripingisadiseaseofthebreastmuscleandiscausedbyfatdepositinginthebreastmuscleduringthebird’sgrowthanddevelopment.Thediseaseaffectsthefunctioningofthemusclefibresandresultsinmuscularweakness.Thisparameterwasscoredasfollows:
l Score0:nostriping.
l Score1:moderatestriping.
l Score2:severestriping.
Mostoftheconventionalbreedbirdshadamoderatedegreeofstriping(57.1–63.9percent),and6.3–14.8percenthadseverestriping(Figure21).Conversely,theslowergrowingbreedhadsignificantlyfewerbirdsaffectedbywhitestripingcomparedtotheconventionalbreeds,withthevastmajorityofthebirds(90.4percent)notaffectedbythiscondition,andonly8.7percentwithamoderatedegreeofstriping(Figure21).
Breast meat with white striping.
0
20
40
60
80
100
210 (no striping)
Prop
orti
on o
f bird
s (%
)
White striping score
0
20
40
60
80
100
10
Prop
orti
on o
f bird
s (%
)
Wooden breast score
THE LIFE OF A TYPICAL MEAT CHICKEN28
FIGURE 21: Average proportion of birds from each of the four breeds affected by white striping.
Woodenbreast
Woodenbreastisadiseaseofthebreastmuscleandiscausedbyfastmusclegrowthwherethemusclecellsbecomeenlargedandthespacebetweenthefibresreduces.Thisconditionrestrictsblood,andthereforeoxygen,supplytothemuscles,whichresultsincelldeathandmuscularweakness.Theaffectedmuscletissueconsequentlyhardens,i.e.becomes‘woody’.Thisparameterwasscoredasfollows:
l Score0:absenceofwoodenbreast.
l Score1:presenceofwoodenbreast.
WoodenbreastwasnotobservedinthevastmajorityoftheslowergrowingbreedandBreedBbirds(99.1and96.3percent,respectively)(Figure22).BreedsAandChadasignificantlygreaterproportionofbirdswithwoodenbreast(23.4and14.3percent,respectively),comparedtotheslowergrowingbreedandBreedB.
FIGURE 22: Average proportion of birds from each of the four breeds with wooden breasts.
SECTION SUMMARY
l Withtheexceptionofwoodenbreastforoneoftheconventionalbreeds,meatqualitywassignificantlyworsefortheconventionalbreedscomparedtotheslowergrowingbreed.
Note:whitestripingandwoodenbreastarediseasesofthemuscleandresultindowngradedcarcasses4041.Whileresearchconcerningtheseconditionshasprimarilyfocussedonmeatqualityandconsumeracceptance,thediscomfortandpainassociatedwiththesediseasescannotbeexcluded42.Bothdiseasesresultinprogressivedeteriorationandlossoffunctioninthetissues,whichcausessomedegreeofnecrosis(death)ofthemusclefibresandmuscleweakness43.Researchhasshownthatinflammationcanaccompanythisdegenerativeprocess44,particularlyinrelationtowoodenbreast,whichmayalsobepainful.Further,necrosisitselfcanbepainful.
Slowergrowingbreed
BreedA
BreedB
BreedC
Slowergrowingbreed
BreedA
BreedB
BreedC
THE LIFE OF A TYPICAL MEAT CHICKEN 29
ConclusionThe trial revealed that, in general, compared to the slower growing breed, the conventional breeds had significantly poorer health: higher mortality (including culls), poorer leg, hock and plumage health, and more birds affected by breast muscle disease (white striping and wooden breast) (Appendix 1, page 35). The conventional breeds were also less active, spending less time walking and standing, and more time feeding and sitting, and spent less time engaged in enrichment type behaviours: foraging, perching and dust bathing.
Thewelfareimpactofpoorhealthonananimalisclearand,dependingontheissueanditsseverity,poorhealthcanresultinpersistentandsignificantpainandsuffering.However,thewelfareimpactofreducedbehaviouralexpressionislessclear,butshouldnotbeunderestimated,asitcanhaveasignificantpsychologicalimpact.Chickensshouldbeabletobehavelikechickens,withtheabilitytoexhibitbehavioursnaturaltothespecies.Whentheyarehinderedfromperformingcertainbehaviours,suchasperching,thisisnotnecessarilybecausetheyarenotmotivatedtoperformthem,butbecausetheyarephysicallyincapableofdoingso,e.g.duetotheirlargersizeandpoorerhealth(e.g.lameness).Thethwartingofsuchbehaviourscanbeasignificantsourceoffrustration10.
Overall,therewasnosignificantdifferenceinmeatyieldbetweentheslowergrowingbreedandtheconventionalbreedsbut,asaconsequenceoflivinglonger,theslowergrowingbreedconsumedmorefeedtoachievethesameslaughterweight,whichresultedinitbeinglessefficientatconvertingfeedintobodyweight.Assuch,itconsumedapproximately21percentmorefeedthanBreedAtoachieveaweightof2.2kg,i.e.anextrac.660goffeedperbird.Further,asaconsequenceoflivinglonger,thiswouldmeanfewerflocks(andthereforebirds)couldberearedperyearinacommercialhouse,whichwouldhaveadditionalcostimplications.However,theseinefficienciesarelikelytobesignificantly,ifnotentirely,offsetifotherfactorsaffectingtheconventionalbreedsaretakenintoaccount.Forexample,the mortality (including culls) of two of the conventional breeds was more than double that of the slower growing breed: 10.7 percent and 11.2 percent for Breeds A and B, respectively, versus 5.2 percent for the slower growing breed. Further, these figures do not include the lame birds (gait scores 3–5) identified at assessment that should be culled if the birds were being reared commercially under higher welfare standards. Such birds represented between 26–38 percent of the flock for the conventional breeds compared to 11 percent for the slower growing breed, an increase of 136–245 percent.Inadditiontoalossofincomefrombeingunabletosellsuchbirds(becausetheyhadbeenculled)thereareadditionalcostsinvolvedinthedisposalofthesebirdsthatneedtobefactoredin,aswellasthecostofrearingthesebirdstothepointofculling.
Inaddition,overthecourseofthetrial,the conventional breeds required approximately 67 percent more wood shavingstomaintainthefloorcoveringingoodcondition(15kgvc.25kgperbreed).Thecauseofthegreaterdeteriorationinlitterqualityfortheconventionalbreedsisunknown,butcouldpossiblybearesultofgreaterfaecaloutput(asthebirdswereconsumingmorefeedperunitoftimeandthereforedefecatingmore)and/orpoorerfaecalquality.Itcouldalsobearesultofthebirdsbeinglessactiveandthereforenot‘working’thelitterasmuch.Whateverthecause,thisincreasedlitterrequirement(ifprovidedincommercialpractice)wouldamounttoaconsiderableadditionalexpense.
Further,meatqualitywassignificantlypoorerfortheconventionalbreeds.Wooden breast affected 3.1–23.4 percent of the conventional breeds versus 0.9 percent for the slower growing breed,anincreaseof244–2,500percent.Whereaswhite striping (moderate and severe) affected 63.4–78.1 percent of the conventional breeds versus 9.6 percent for the slower growing breed,anincreaseof560–713percent.Whileweunderstandthatsuch meat is often downgraded and removed at the processing plant,someislikelytobesoldtotheconsumer,especiallyinthecaseofwholebirdcarcasseswhereitmaygoundetectedattheprocessingplant.Woodenbreasthasahard,chewytexturewhencookedandthereforeisregardedasa
Cobb 500 bird sitting at 34 days of age.
THE LIFE OF A TYPICAL MEAT CHICKEN30
productqualityissuethatconsumersshouldnotbeunwittinglypayingfor.Whitestripingiscausedbyfatdeposits,meaningthatthemeatislessleanandtender45and,arguably,lessdesirableforconsumerswhochosechickenbreastmeatforitshealthier,lowerfatcredentials.
Insummary,theconventionalbreedshadsignificantlypoorerwelfareoutcomes,butweremoreefficientatconvertingfeedintobodyweightand,duetobeingslaughteredatayoungerage,moreflockscanberearedinabuildingperyear.However,there are significant inefficiencies in producing meat from these conventional breeds: mortality (including culls) (11.2%); lame birds requiring culling (26–38% of the flock); birds affected by meat quality issues resulting in downgrading/removal and disposal of affected meat (white striping (63–78% of flock) and wooden breast (3–23% of the flock)), and increased use of wood shavings. If all of these parameters were accounted for then this would considerably impact the cost of production. Currently, it appears that the cost of ‘standard’ chicken meat is being kept artificially low due to some of these issues not being addressed. If they were addressed, the rearing of conventional breeds would likely represent a false economy. Further, it’s highly probable that if we were to truly consider the welfare of chickens and do what is morally right – not simply what is legal – then the cost of chicken meat from conventional breeds would be greater than that from higher welfare breeds. But, even despite these economic and welfare elements, it is clear that the production of chicken meat using conventional breeds is a wasteful and ethically questionable business, bringing into question the sustainability of this enterprise.
Althoughthewelfareoftheslowergrowingbreedwassignificantlybetterthantheconventionalbreeds,thereisroomforimprovement.It is clear that genetic breeding programmes, even those with a less prominent focus on performance, need to place a much greater emphasis on health traits.Currentbreedingprogrammeshavefailurein-built–knowinglyacceptingacompromiseonbirdhealth.Asthemarkethasfailedtosafeguardchickenwelfare,legislation needs to be developed to address this issue.
THE LIFE OF A TYPICAL MEAT CHICKEN 31
Is conventional chicken production falling fowl of the law?Currently, legislation states: “Animals may only be kept for farming purposes if it can reasonably be expected, on the basis of their genotype or phenotype, that they can be kept without any detrimental effect on their health or welfare.”46 Further, the Defra code of practice for the welfare of meat chickens47 states: “Welfare and health considerations, in addition to productivity, should be taken into account when choosing a strain for a particular purpose or production system. In line with this, meat chickens should stem from broad breeding programmes, which promote and protect health, welfare and productivity.”
However,despitetheselegalprovisionsandcodes,legalproceedingsin200448resultedinobiterdicta(ajudge’sexpressionofopinion,butnotlegallybindingasaprecedent)fromtheCourtofAppealthatnewlegislationwouldberequiredtobringaboutachangeinthegeneticsofmeatchickenstoaddressthewelfareissueswehavehighlightedinthisreport.Thecourtsaidthatrequiringproducerstoselectcertaingenotypes(breeds)tomeetthelegislationwentbeyondthescopeofcurrentlegislation.Thecourtexpressedtheopinionthatwithoutnewregulationthentheuseofexistingconventionalgenotypeswasunavoidableandunlikelytobesuccessfullylegallychallenged.
Thetrialdemonstratesthat,atpresent,themostcommonlyusedgeneticsdonotadequatelysafeguardchickenwelfareandarenotconsistentwithensuringthevastmajorityofchickensliveagoodlifeorevenhavealifeworthliving.Whilebreedsthathavebeenlessheavilyselectedforperformancemaynotcompletelyeliminateallwelfareissues,theyofferasignificantimprovement.These‘higherwelfare’breeds,whichhavebeenshowntobecommercially-viableinpractice,shouldbeadoptedinstead,andbreedingcompaniesmandatedtoprioritisehealthandwelfaretraitsoverperformance.
Althoughcurrentgeneticselectionprogrammesmaybejustifiedbysomeonthebasistheyresultinananimalthatprovidesacheapandefficientsourceofmeatandprotein,thereisnoacceptablejustificationwhensuchprogrammeshaveseriousinherentflawsandareassociatedwithpoorhealthandwelfare.Ifgeneticscompaniesweremanufacturersof,say,mechanicalproducts,thentheseproductswouldbeverycheaptobuybutalsoveryunreliable–productsthatcouldonlybeusedwithgreatcare,underverycontrolledconditionsandforashortperiodbeforemechanicalfailurewouldoccur.Suchproductswouldbeconsideredunacceptable.However,chickensaren’tinanimateobjects,theyaresentientanimals,soitisfarmoreimportanttoensurethe‘product’–andthewayinwhichitisproduced–isashighinqualityaspossible.
Acknowledgements
ThetrialwasmadepossiblebyagenerousgrantfromtheFarmAnimalWelfareForum.ThankstoScotland’sRuralCollegeforconductingthetrialanddataanalysis.ThanksalsotothetechniciansandstockworkersattheAvianScienceResearchCentrefortheirhelpinthehousingandmanagementofthebirds.
THE LIFE OF A TYPICAL MEAT CHICKEN32
ReferencesAfolayanM,AbekeFandAtandaA.(2016)Ascitesversussuddendeathsyndrome(SDS)inbroilerchickens:areview.Journal of Animal Production Research28:76–78.
ApplebyMC,SmithSFandHughesBO.(1992)Individualperchingbehaviouroflayinghensanditseffectsincages.British Poultry Science33:227–238.
Aviagen(2019)Ross308BroilerPerformanceObjectives.http://en.aviagen.com/brands/ross/products/ross-308
BailieCLandO’ConnellNE.(2015)Theinfluenceofprovidingperchesandstringonactivitylevels,fearfulnessandleghealthincommercialbroilerchickens.Animal9(4):660–668.
BesseiW.(2006)Welfareofbroilers:areview.World’s Poultry Science Journal62:455–466.
BoissyA,ManteufeelG,JensenMB,MoeRO,SpruijtB,KeelingLJ,WincklerC,ForkmanB,DimitrovI,LangbeinJ,BakkenM,VeissierIandAubertA.(2007)Assessmentofpositiveemotionsinanimalstoimprovetheirwelfare.Physiology and Behaviour92:375–397.
Cobb(2018)Cobb500BroilerPerformanceAndNutritionSupplement.www.cobb-vantress.com/en_US/products/cobb500/
CompetitionandMarketsAuthority.(2018)Anticipated acquisition by Aviagen Group Holding Inc. of Hubbard Holding SAS.GreatBritain.
CooperMDandWrathallJHM.(2010)Assuranceschemesasatooltotacklegeneticwelfareproblemsinfarmanimals:broilers.Animal Welfare19(S):51–56.
DanburyTC,WeeksCA,ChambersJP,Waterman-PearsonAEandKestinSC.(2000)Self-selectionoftheanalgesicdrugCarprofenbylamebroilerchickens.Veterinary Record146:307–311.
DaviesJ.(2013)Onegiantleapforchicken-kind.Poultry WorldJanuary2013pp28–29.
DawkinsMS,RobertsSJ,CainRJ,NicksonTandDonnellyCA.(2017)Earlywarningoffootpaddermatitisandhockburninbroilerchickenflocksusingopticalflow,bodyweightandwaterconsumption.Veterinary Record180(20):499–499.
deJongI,PerezMoyaT,GunninkH,vandenHeuvelH,HindleVA,MulMandvanReenenK.(2011)SimplifyingtheWelfareQualityassessmentprotocolforbroilers.Wageningen UR Livestock Research,p14.
deJongI,BergC,ButterworthAandEstevézI.(2012)ScientificreportupdatingtheEFSAopinionsonthewelfareofbroilersandbroilerbreeders.SupportingPublications2012:EN-295.[116pp].Availableonline:www.efsa.europa.eu/publications
Defra(2018)Codeofpracticeforthewelfareofmeatchickensandmeatbreedingchickens.Defra.
EFSAAHAWPanel(EFSAPanelonAnimalHealthandAnimalWelfare)(2015)ScientificOpiniononwelfareaspectsoftheuseofperchesforlayinghens.EFSA Journal2015;13(6):4131,70pp.doi:10.2903/j.efsa.2015.4131.
FAO(2017)www.fao.org/faostat/en/#data/QL
HaslamSM,KnowlesTG,BrownSN,WilkinsLJ,KestinSC,WarrissPDandNicolCJ.(2007)Factorsaffectingtheprevalenceoffootpaddermatitis,hockburnandbreastburninbroilerchicken.British Poultry Science48(3):264–275.
HooijetJ.(2005)Newbroilersetsthestandard.Poultry WorldJunep16.
Hubbard(2015)PerformanceSummary(broiler)HubbardFlexwww.hubbardbreeders.com/media/psbrflexfrenes__049193900_1532_26062017.pdf
THE LIFE OF A TYPICAL MEAT CHICKEN 33
JulianRJ.2004.Chapter4:EvaluatingtheImpactofMetabolicDisordersontheWelfareofBroilers.EditedbyWeeksCAandButterworthA.2004.Measuring and Auditing Broiler Welfare.CABIPublishing.
KestinSC,KnowlesTG,TinchAEandGregoryNG.(1992)Prevalenceoflegweaknessinbroilerchickensanditsrelationshipwithgenotype.Veterinary Record131:190–194.
KittelsenKE,GranquistEG,KolbjørnsenØ,NafstadOandMoeRO.(2015)Acomparisonofpost-mortemfindingsinbroilersdead-on-farmandbroilersdead-on-arrivalattheabattoir.Poultry Science94(11):2622–2629.
KnowlesTG,KestinSC,HaslamSM,BrownSN,GreenLE,ButterworthAandNicolCJ.(2008)Legdisordersinbroilerchickens:prevalence,riskfactorsandprevention.PLOS ONE3(2):e1545.https://doi.org/10.1371/journal.pone.0001545
KuttapanVA,HargisBMandOwensCM.(2016)Whitestripingandwoodybreastmyopathiesinthemodernpoultryindustry:areview.Poultry Science95:2724–2733.
LeVanNF,EstevezIandStricklinWR.(2000)Useofhorizontalandangledperchesbybroilerchickens.Applied Animal Behaviour Science65:349–365.
LindbergACandNicolCJ.(1997)Dustbathinginmodifiedbatterycages:Isshamdustbathinganadequatesubstitute?Applied Animal Behaviour Science55:113–128.
MasonGJandBurnCC.(2011)Chapter7:BehaviouralrestrictionInApplebyMC,MenchJA,OlssonAandHughesBO.(Ed.),Animal Welfare(2nded.):CABIPublishing.pp98–119.
MaxwellMHandRobertsonGW.(1997)WorldBroilerAscietessurvey1996.Poultry International36,4:16–30.
McGeownD,DanburyTC,Waterman-PearsonAEandKestinSC.(1999)EffectofCarprofenonlamenessinbroilerchickens.Veterinary Record144:668–671.
MichelV,PrampartE,MirabitoL,AllainV,ArnouldC,HuonnicD,LeBouquinSandAlbaricO.(2012)Histologically-validatedfootpaddermatitisscoringsystemforuseinchickenprocessingplants.British Poultry Science53:275–281.
OlkowskiAAandClassenHL.(1998)Highincidenceofcardiacarrhythmiasinbroilerchickens.Journal of Veterinary Medicine45:83–91.
PartCE,EdwardsP,HajatSandCollinsLM.(2016)PrevalenceratesofhealthandwelfareconditionsinbroilerchickenschangewithweatherinatemperateclimateRoyal Society Open Science3.10.1098/rsos.160197.
PetracciM,MudalalS,BabiniEandCavaniC.(2014)EffectofWhiteStripingonChemicalCompositionandNutritionalValueofChickenBreastMeat.Italian Journal of Animal Science13(1):3138,doi:10.4081/ijas.2014.3138.
ReginaontheapplicationofCIWFLtdvtheSecretaryofStatefortheEnvironment,FoodandRuralAffairs[2004]EWCACiv1009.
RSPCABroilerBreedWelfareAssessmentProtocoltodeterminethewelfareofbroilerbreeds.Version:May2017.
SchützKEandJensenP.(2001).Effectsofresourceallocationonbehaviouralstrategies:acomparisonofredjunglefowl(Gallus gallus)andtwodomesticatedbreedsofpoultry.Ethology107(8):753–765.
ScientificCommitteeonAnimalHealthandAnimalWelfare(SCAHAW)(2000).Thewelfareofchickenskeptformeatproduction(broilers)(SCAHAWReportNo.SANCO.B3/AH/R15/2000).Brussels:EuropeanCommission.http://europa.eu.int/comm/food/fs/sc/scah/out39_en.pdf
SihvoH-K,ImmonenKandPuolanneE.(2014)MyodegenerationWithFibrosisandRegenerationinthePectoralisMajorMuscleofBroilers.Veterinary Pathology51(3):619–623.
SihvoH-K,LindenJ,AirasN,ImmonenK,ValajaJandPuolanneE.(2017)WoodenBreastMyodegenerationofPectoralisMajorMuscleOvertheGrowthPeriodinBroilers.Veterinary Pathology54(1):119–128.
THE LIFE OF A TYPICAL MEAT CHICKEN34
SogliaF,MudalalS,BabiniE,DiNunzioM,MazzoniM,SirriF,CavaniCandPetracciM.(2016)Histology,composition,andqualitytraitsofchickenPectoralismajormuscleaffectedbywoodenbreastabnormality.Poultry Science95:651–659.
TrocinoA,PiccirilloA,BiroloM,RadaelliG,BertottoD,FiliouE,PetracciMandXiccatoG.(2016)Effectofgenotype,genderandfeedrestrictionongrowth,meatqualityandtheoccurrenceofwhitestripingandwoodenbreastinbroilerchickens.Poultry Science94:2996–3004.
vanLiereDW.(1991)Functionandorganizationofdustbathinginlayinghens.PhDthesis.DepartmentofAnimalHusbandry,AgriculturalUniversity,Wageningen,TheNetherlands.
VestergaardKS,andSanotraGS.(1999)Relationshipsbetweenlegdisordersandchangesinthebehaviourofbroilerchickens.The Veterinary Record144(8):205–209.
WeeksCA,DanburyTD,DaviesHC,HuntPandKestinSC.(2000)Thebehaviourofbroilerchickensanditsmodificationbylameness.Applied Animal Behaviour Science67:111–125.
WelfareofFarmedAnimals(England)Regulations(2007),paragraph29ofSchedule1.
WidemanRFJr(2015).Bacterialchondronecrosiswithosteomyelitisandlamenessinbroilers:areview.Poultry Science95(2):325–344.
Endnotes
1 Forthepurposesofthis report,onebillion=one thousandmillion.2 FAO,2017.3 Aviagen,2019.4 CompetitionandMarkets Authority,2018.5 Cobb,2018.6 Hubbard,2015.7 Hooijet,2005.8 CooperandWrathall,2010.9 Davies,2013.10 deJongetal.,2012.11 SCAHAW,2000.12 Kittelsenetal.,2015.13 OlkowskiandClassen,1998.14 MaxwellandRobertson,1997.15 Partetal.,2016.16 Afolayanetal.,2016.
17 Julian,2004.18 Wideman,2015.19 McGeownetal.,1999.20 Danburyetal.2000.21 Kestinetal.1992.22 deJong,etal.,2011.23 Knowlesetal.,2008.24 Bessei,2006.25 Weeksetal.,2000.26 Haslametal.,2007.27 Micheletal.,2012.28 Dawkinsetal.,2017.29 Boissyetal.,2007.30 SchützandJensen,2001.31 vanLiere,1991.32 LindbergandNicol,1997.33 VestergaardandSanotra,1999.34 MasonandBurn,2011.
35 EFSA,2015.36 Applebyetal.,1992.37 BailieandO’Connell,2015.w38 LeVanetal.,2000.39 RSPCA,2017.40 Trocinoetal.,2016.41 Shivoetal.,2014.42 Shivoetal.,2017.43 Kuttappanetal.,2016.44 Sogliaetal.,2016.45 Petraccietal.,2014.46 WelfareofFarmedAnimals (England)Regulations(2007).47 Defra,2018.48 Reginaontheapplicationof CIWFLtdvtheSecretaryof StatefortheEnvironment,Food andRuralAffairs[2004]EWCA Civ1009.
THE LIFE OF A TYPICAL MEAT CHICKEN 35
APP
END
IX 1:
Key
pro
duct
ion,
hea
lth
and
mea
t qu
alit
y re
sult
s fr
om t
he R
SPC
A c
omm
issi
oned
tria
l to
asse
ss t
he p
rodu
ctio
n an
d w
elfa
re c
hara
cter
isti
cs o
f the
lead
ing
mea
t ch
icke
n br
eed
from
ea
ch o
f the
thr
ee g
loba
lly d
omin
ant
mea
t ch
icke
n br
eedi
ng c
ompa
nies
(Con
vent
iona
l bre
eds)
and
a c
omm
erci
ally
via
ble
slow
er g
row
ing
bree
d*.
Slow
er
grow
ing
bree
d
Conv
enti
onal
bre
eds
Com
pare
d to
the
slo
wer
gro
win
g br
eed,
th
e co
nven
tion
al b
reed
s…Co
mpa
red
to t
he s
low
er g
row
ing
bree
d,
the
Conv
enti
onal
bre
eds
wer
e…
Bree
d A
Bree
d B
Bree
d C
Gro
wth
rate
(g/d
ay)*
*46
6363
63…g
rew
1.4
times
fast
er(a
nin
crea
seo
f37
%)
—
Feed
con
vers
ion
rati
o (K
g)**
1.76
1.46
1.43
1.35
…con
sum
ed17
–23%
less
feed
.(N
Bth
esl
ower
gr
owin
gbr
eed
cons
umed
21–
30%
mor
efe
ed).
—
Mor
talit
y
(incl
udin
g cu
lls) (
%)
511
117
…had
1.4–
2.2
times
hig
herm
orta
lity
(an
incr
ease
of4
0–12
0%)
…up
toa
roun
dtw
ice
asli
kely
to
die/
bec
ulle
d.
Lam
e bi
rds
(mod
erat
e to
sev
ere)
(%)*
**11
3828
26…h
ad2
.4–3
.5t
imes
mor
ela
me
bird
s(a
nin
crea
seo
f136
–245
%).
…up
to3
.5t
imes
mor
elik
ely
tob
em
oder
atel
y
tos
ever
ely
lam
ean
dre
quire
cul
ling.
Hoc
k bu
rn (%
)***
*19
7770
59…h
ad3
.1–4.
1tim
esm
ore
bird
sw
ithh
ock
burn
(a
nin
crea
seo
f211–
305%
)…u
pto
4.1
times
mor
elik
ely
tos
uffe
rfr
omh
ock
burn
.
Dir
ty fe
athe
rs (%
)70
100
100
100
…had
1.4
times
mor
ebi
rds
with
dirt
yfe
athe
rs
(an
incr
ease
of
43%
)—
Whi
te s
trip
ing
of
brea
st m
uscl
e (%
)10
7878
63…h
ad6
.3–7
.8t
imes
mor
ebi
rds
with
whi
tes
trip
ing
oft
heb
reas
tm
uscl
e(a
nin
crea
seo
f56
0–71
3%).
…up
to7
.8t
imes
mor
elik
ely
tos
uffe
rfr
omw
hite
str
ipin
gof
the
bre
ast
mus
cle.
Woo
den
brea
st
mus
cle
(%)
123
314
…had
3–2
3tim
esm
ore
bird
sw
ithw
oode
n
brea
st(a
nin
crea
seo
f24
4–2,
500%
).…u
pto
23
times
mor
elik
ely
tos
uffe
rfr
omw
oode
nbr
east
.
*Fi
gure
sha
veb
een
roun
ded
fore
ase
ofp
rese
ntat
ion
(exc
eptF
eed
conv
ersio
nra
tio).
Cal
cula
tions
are
bas
edo
nac
tual
(not
roun
ded)
figu
res.
**A
ta
body
wei
ght
of2
.2kg
.**
*G
ait
scor
e3,
4a
nd5
(see
pag
e19
).**
**Sc
ore
0P–2
(see
pag
e20
).
Royal Society for the Prevention of Cruelty to AnimalsWilberforce Way, Southwater, Horsham, West Sussex RH13 9RS 0300 1234 999 rspca.org.uk
facebook.com/RSPCA twitter.com/RSPCA_official www.instagram.com/official_rspca
The RSPCA helps animals in England and Wales. Registered charity no. 219099. The RSPCA only exists with the support of public donations. ©RSPCA 2020. All rights reserved. This material must not be reproduced or used in any manner whatsoever without the express written permission of the RSPCA.
Photos: RSPCA, World Animal Protection, CIWF.
Recommended