the life of a typical meat chicken · 2020-02-27 · the life of a typical meat chicken 7 executive...

THE LIFE OF A TYPICAL MEAT CHICKEN

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THE LIFE OF A TYPICAL MEAT CHICKEN

Hubbard Flex at 34 days of age.

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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

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JA757 perching at 34 days of age.

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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.


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.


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.


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.


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 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


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


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 (%

)


Breed

a

bb

a


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 (%

)


Breed

a

b

b

a


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


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


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


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


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 (%

)


Breed

a

b

c c

40

50

60

70

80Pr

opor

tion

of t

ime

(%)

Bird age (days)2 9 16 23 30 37


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


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)


Breed

a

b

ab

0

500

1,000

1,500

2,000

2,500

Wei

ght

(g)


Breed

aa

b a


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

)


Breed

a

b b b


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


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


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.


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.


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.


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KittelsenKE,GranquistEG,KolbjørnsenØ,NafstadOandMoeRO.(2015)Acomparisonofpost-mortemfindingsinbroilersdead-on-farmandbroilersdead-on-arrivalattheabattoir.Poultry Science94(11):2622–2629.

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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.


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*.

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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

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