Type of grinding of the main cereal of the diet affects production of brown egg-laying hens

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ContentslistsavailableatScienceDirect

Animal

Feed

Science

and

Technology

journalhomepage:www.elsevier.com/locate/anifeedsci

Type

of

grinding

of

the

main

cereal

of

the

diet

affects

production

of

brown

egg-laying

hens

A. Pérez-Bonilla

a

_,

_M.

_Frikha

b

_,

_R.P.

_Lázaro

b

_,

_G.G.

_Mateos

b,∗

a_Camar_{Agroalimentaria}_S.L,_Cedillo_del_Condado,_Toledo_45214,_Spain

b_Departamento_de_Producción_Animal,_Universidad_Politécnica_de_Madrid,₂₈₀₄₀_Madrid,_Spain

a

r

t

i

c

l

e

i

n

f

o

Articlehistory:

Received26March2014

Receivedinrevisedform19May2014 Accepted22May2014

Keywords:

Barley Hammermill Layinghenperformance Maize

Rollermill Wheat

a

b

s

t

r

a

c

t

Theinﬂuenceofmethodofgrindingofthecerealofthedietonproductionandeggquality wasstudiedin420Hy-linebrownegg-layinghens.Thedesignwascompletelyrandomized withsixtreatmentsarrangedasa3×2factorialwiththreecereals(barley,dentedmaize andsoftwheat)andtwogrindingprocedures(hammermillvs.rollermill).Eachtreatment wasreplicatedseventimesandtheexperimentalunitwasanenrichedcagewithtenhens. Productionwasrecordedeveryfourweeksfrom24to59weeksofageandeggqualitywas measuredat40and56weeksofage.Fortheentireexperiment,feedintakewashigherin hensfedwheatormaizethaninhensfedbarley(110.8and110.7vs.109.7g/d;P=0.014) butmostofthedifferenceswereobservedwhenthecerealwasrollermilled(P=0.009for theinteraction).Also,eggproductionwassimilarforthethreedietswhenthecerealwas hammermilledbuttendedtobelowerforthebarleythanforthewheatormaizedietswhen thecerealwasrollermilled(P=0.09fortheinteraction).Noneoftheotherproductiveor eggqualitytraitswasaffectedbydietarytreatment.Weconcludethatrollermillsareuseful togrindlowﬁbercereals,suchasmaizeorwheat.However,theuseoftherollermillmight notbeadequatewhenbarleyisthemaincerealindietsforegg-layinghens.

1. Introduction

Maize(ZeamaysL.)andsoftwheat(TriticumaestivumL.)arethemaincerealsusedinpoultrydietsworldwide,although barley(HordeumvulgareL.)isalsoofcommonuse(Graciaetal.,2003;JacobandPescatore,2012).Maizeisgenerallypreferred totheothercerealsbecauseithasamoreuniformnutritivevalueandprovidesabetterstructureofthefeed,whichmight favourfeedintake(FI)inpoultry(Frikhaetal.,2009a).Wheatandbarleyarelesseasilydigestedbecauseofthepresence ofvariableamountsofnon-starchpolysaccharides(NSP)(Lázaroetal.,2003;Garcíaetal.,2008;Mirzaieetal.,2012).Also, linoleicacid(LNL)contentishigherinmaizethaninwheatorbarleywhichfavoursitsuseinlayinghendiets.However, Safaaetal.(2009)andPérez-Bonillaetal.(2011)reportedsimilarproductionandeggqualityofbrownegg-layinghensfed isonutritivedietsbasedonmaize,wheatorbarley.

Abbreviations:AMEn,Nitrogencorrectedapparentmetabolizableenergy;BW,bodyweight;DM,drymatter;FI,feedintake;FCR,feedconversionratio; GMD,geometricmeandiameter;GSD,geometricstandarddeviation;HM,hammermill;LNL,linoleicacid;NDF,neutrodetergentﬁber;NSP,non-starch polysaccharides;RM,rollermill.

∗ Correspondingauthor.Tel.:+34914524851;fax:+34915499763.

E-mailaddress:[email protected](G.G.Mateos).

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Theinterestontheeffectsofparticlesizeofthedietonproductionofpoultryhasincreasedinrecentyears,astheindustry continuestosearchfornewpracticestooptimizefeedefficiency(Frikhaetal.,2009b;Safaaetal.,2009;Svihus,2010b). ParticlesizeaffectsthedevelopmentofthegastrointestinaltractandvoluntaryFIinmostavianspecies(Amerahetal.,2007; Jiménez-Morenoetal.,2010;Mateosetal.,2012).Infact,ISABrown(2012)andLohmann(2012)recommendedthatatleast 75–80%offeedparticlesshouldbewithintherangeof500and3200␮mtooptimizeFIandperformanceoflayinghens.Two millsavailabletoreducetheparticlesizeofthegrainsinpoultrydietsarethehammermill(HM)andtherollermill(RM).One ofthemainadvantagesoftheRMascomparedwiththeHMistheimprovementinparticlesizeuniformitywhichreduces dustgenerationandmightbenefitFI(Niretal.,1990;Svihusetal.,2004).However,HMequipmentsarecheaper,easierto handleandhavelowermaintenancecostthanRMequipments,whichfavoursitsusebythefeedcompoundindustry(Audet, 1995;Koch,1996;Amerahetal.,2007).Totheauthorknowledge,noinformationisavailableintheliteraturequantifying thepotentialinteractionbetweencerealtypeandmethodofgrindingofthecerealonproductionofbrownegg-layinghens. Thehypothesisofthisresearchwasthatbarley,maizeandwheatcouldbeusedindistinctlyasthemaincerealindiets forlayinghenswithoutanynegativeeffectonperformanceoreggqualityandthatbecauseofbetterfeeduniformity,the useofarollermillcouldimprovehenperformanceascomparedwiththeuseofahammermill.Theobjectivesofthestudy weretodeterminetheinfluenceofthemaincerealofthediet(barley,maizeorwheat)andgrindingmethod(hammermill vs.rollermill)andtheirpotentialinteractionsonproductionandeggqualityofbrownegg-layinghensfrom24to59weeks ofage.

2. Materialsandmethods

2.1. Husbandry,dietsandexperimentaldesign

AllexperimentalprocedureswereapprovedbytheanimalEthicsCommitteeoftheUniversidadPolitécnicadeMadrid andwereincompliancewiththeSpanishguidelinesforthecareanduseofanimalsinresearch(BoletínOﬁcialdelEstado, 2007).

Intotal,420Hy-LineBrownegg-layinghenswerehousedat22weeksofageinatotallyenvironmentalcontrolledbarn andfedfortwoweeksacommonpre-experimentaldietbasedonmaizeandsoybeanmealthatcontained11.5MJ,175g crudeproteinand3.9gdigestiblemethionineperkg.At24weeksofage,thehenswereweighedindividually(1733±48g BW)andsortedatrandomingroupsof10in42enrichedcages(635mm×1200mm;FaccoS.A.,Padova,Italy)providedwith anopentroughfeederandtwonippledrinkers.Barntemperaturewasrecordeddailythroughouttheexperiment,witha minimumaveragevalueof19±3◦CinJanuary(startoftheexperiment)andamaximumof25±3◦CinJuly(7thperiodof theexperiment).Thelightprogramwasconstantthroughouttheexperimentandconsistedof16hoflightperday.

Twobatchespereachofthethreecerealswereobtainedfromthesamecommercialsourcesandusedduringthe exper-iment.Thefirstbatchwasusedforthefirstfourexperimentalperiodsandthesecondbatchforthelastfiveperiods.Each batchofcerealwasdividedin2portionsandgroundusingeitheraHM(Model-DFZC,BühlerAG,Uzwil,Switzerland)ora doublecylinderRM(Model-MDDP,BühlerAG,Uzwil,Switzerland).TheHMhadtwoscreensandwasdrivenbya115kW electricmotorwitharotationalspeedof1500rpm.Thediameteroftheroundholesofthescreenwasof6.0mmformaizeand 5.0mmforwheatandbarley.TherollsoftheRMhadadiameterof300mmandalengthof1800mm.Thedistancebetween thegrooveswasofthreeandtwomm,fortheupperandlowerpairofrolls,respectively.Thetworollsweredrivenbya 40kWengineataspeedof1040rpm.Theseparationselectedforthefirstpairofrollswasof2.0mmforwheatandbarleyand 1.0mmformaize.Forthesecondpairofrollsthedistancechosenwas0.7mmforwheatandmaizeand0.6mmforbarley. Theconditionsduringthefeedmanufacturingprocesseswerecontrolledbyspecializedpersonnel(Catesa,Trujillo,Spain) andtheobjectivewastoachievesimilargeometricmeandiameter(GMD)foralltheexperimentalfeeds.Aftergrinding,the cerealwasmixedinadequateproportionswiththeotheringredientstomanufacturethecorrespondingexperimentaldiets. Alldietsmetorexceededthenutrientrequirementsforbrownegg-layinghensasrecommendedbyFundaciónEspa ñola DesarrolloNutriciónAnimal,2008.Theingredientcompositionofthefeedswasadjustedtoinsurethatalldietshad sim-ilarAMEnanddigestibleindispensableaminoacids(Lys,Met,Thr,Met+CysandTrp)contents,accordingtoFundación Espa ñolaDesarrolloNutriciónAnimal,2010.However,noattemptwasmadetoequalizetheLNLcontentofthedietsthat was14.1g,11.1gand8.2g/kg,forthemaize,barleyandwheatdiets,respectively.Alldietsincludedafixedamountofa commercialenzymecomplexthatincluded␤-glucanaseandxylanaseactivity(Endofeed,GNCBiofermInc.,Saskatoon,SK, Canada)andacommercialpigmentbasedoncanthaxantinandtheesterof␤-apo-8-carotenoic(Miavityellow/red,MIAVIT NutriciónAnimalS.L.,Tarragona,Spain).Theingredientcompositionandthecalculatedanddeterminednutritivevalueof theexperimentaldietsarepresentedinTable1.

Theexperimentwasconductedasacompletelyrandomizeddesignwithsixdietsorganizedinafactorialarrangement withtwogrindingmethods(hammervs.rollermill)andthreemaincereals(barley,maizeandsoftwheat).Theexperimental unitwasacagewithtenbirdsforalltraitsstudied.

2.2. Laboratoryanalysis

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Table1

Ingredientcompositionandchemicalanalysesoftheexperimentaldiets(g/kgas-fedbasis,unlessotherwiseindicated).

Barley Maize Wheat

Item Hammermill Rollermill Hammermill Rollermill Hammermill Rollermill

Ingredient

Barley 549.0 549.0 – – 98.0 98.0

Maize 51.0 51.0 549.0 549.0 – –

Wheat – – 51.0 51.0 549.0 549.0

Soybeanmeal(470gCP/kg) 245.0 245.0 269.0 269.0 225.0 225.0

Lard 45.0 45.0 19.0 19.0 18.3 18.3

Dicalciumphosphate 12.2 12.2 16.2 16.2 12.0 12.0

Limestonea _88.0 _88.0 _86.0 _86.0 _88.0 _88.0

Sodiumchloride 3.0 3.0 3.0 3.0 3.0 3.0

DL-methionine(990g/kg) 1.8 1.8 1.8 1.8 1.7 1.7

Vitaminandmineralpremixb _5.0 _5.0 _5.0 _5.0 _5.0 _5.0

Calculatedanalysisc

AMEn(MJ/kg) 11.5 11.5 11.5 11.5 11.5 11.5

Crudeﬁber 37.0 37.0 25.0 25.0 29.2 29.2

DigestibleLys 8.8 8.8 8.7 8.7 8.5 8.5

DigestibleMet 4.1 4.1 4.2 4.2 4.0 4.0

DigestibleMet+Cys 7.1 7.1 7.2 7.2 7.0 7.0

DigestibleThr 6.1 6.1 6.1 6.1 6.1 6.1

DigestibleTrp 1.7 1.7 1.7 1.7 1.7 1.7

Calcium 38.0 38.0 38.0 38.0 38.0 38.0

Totalphosphorous 7.0 7.0 7.0 7.0 7.0 7.0

Availablephosphorous 4.6 4.6 4.6 4.6 4.6 4.6

Determinedanalysisd

Drymatter 911 910 887 893 905 898

Grossenergy(MJ/kg) 15.35 15.37 15.37 15.36 15.36 15.37

Neutraldetergentﬁber 125 127 73 73 98 98

Etherextract 40.0 40.2 43.0 43.4 43.9 44.1

Crudeprotein 173 169 173 174 171 172

Linoleicacid 11.0 11.4 13.8 13.6 9.1 9.0

Ash 127 130 120 128 127 128

a_44.0_g_of_the_calcium_carbonate_per_kilogram_of_all_diets_was_supplied_coarsely_ground_(3-mm_screen).

b_Supplied_the_following_(per_kilogram_of_diet):_vitamin_A_{(trans-retinyl}_acetate),_10,000_IU;_vitamin_D3_{(cholecalciferol),}_2,000_IU;_vitamin_E_(dl-_␣ -tocopherylacetate),10mg;vitaminB1,1mg;vitaminB2,4mg;vitaminB6,1mg;vitaminB12(cyanocobalamin),15␮g;vitaminK3,2.5mg;choline (cholinechloride),150mg;nicotinicacid,25mg;pantothenicacid(d-calciumpantothenate),7.5mg;folicacid,0.10mg;manganese(MnO),70mg;zinc (ZnO),50mg;iron(FeSO4H2O),30mg;copper(CuSO45H2O),5mg;iodine(Ca(IO3)2),0.5mg;selenium(Na2SeO3),0.3mg;canthaxantin;2.4g;esterof␤ -apo-8-carotenoic,1.7g(Lucanmixyellow/red,Basf,Tarragona,Spain),[Endo-1.3(4)-␤-glucanase(EC3.2.1.6),150IU/g];[Endo-1.4-␤-xylanase(EC3.2.1.8), 105IU/g(Endofeed,GNCBioferm,Saskatchewan,SK,Canada)],Natuphos5000[300FTU/kgof6-phytase(EC3.1.3.26),BasfEspa ˜nola,S.A.,Tarragona,Spain].

c_According_to_Fundación_{Espa ˜}_nola_Desarrollo_Nutrición_Animal₍₂₀₁₀₎_.

d_Chemical_analyses_were_similar_for_the₂_batches_of_feed_used₍₂₄_to₄₀_weeks_and₄₀_to₅₉_weeks).

andnitrogenbycombustion(method990.03)usingaLECOanalyzer(ModelFP-528,LECO,St.Joseph,MI)asdescribedby AOACInternational(2000).NeutraldetergentﬁberwasdeterminedsequentiallyasdescribedbyVanSoestetal.(1991),ether extractbySoxhletanalysisafter3NHClacidhydrolysis(BoletínOﬁcialdelEstado,1995)andgrossenergywithanisoperibol bombcalorimeter(Model356,ParrInstrumentCompany,Moline,IL).TheLNLcontentofthedietswasdeterminedby gas-liquidchromatography(GC-14B,Shimazy,Kyoto,Japan)asindicatedbyGrobasetal.(1999b).Theparticlesizedistribution andtheGMDofthedietsweredeterminedintriplicatein100gsamplesusingaRetschshaker(Retsch,Stuttgart,Germany) providedwith8sievesranginginmeshfrom5000to40␮maccordingtothemethodologyoutlinedbyASAE(1995).The chemicalcompositionandGMDofthetwobatchesofdietsusedinthisexperimentweresimilar,andtheaveragevaluesare showninTable1.

2.3. Productionperformanceandeggquality

Feedintakeandeggproductionwererecordedperreplicatebyperiodandfortheentireexperiment.Mortalitywas weighedandrecordedasproduced.Eggweightwasmeasuredinalleggslaidduringthelastthreedaysofeachofthenine four-weekperiods.Fromthesedata,eggproduction,eggweight,eggmass,averagedailyFIandfeedconversionratio(FCR) perkgandperdozenofeggswerecalculatedbyperiodandcumulatively.Inaddition,allhenswereweighedperreplicate atthebeginningandattheendoftheexperiment,andBWgainwasdeterminedperreplicate.

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Table2

Particlesizedistributiona_and_geometric_mean_diameter_of_the_experimental_diets.

Sievediameter(␮m) GMDb_±_GSDc₍_␮_m)

Cereal Milltype 2,500 1,250 630 315 160 80

Barley Hammer 12.9 32.3 33.3 17.8 3.6 0.1 1,117±2.03

Roller 7.6 40.8 33.2 14.5 3.9 – 1,116±1.92

Maize Hammer 13.9 33.6 34.1 14.4 3.6 0.4 1,162±2.13

Roller 6.6 35.9 28.9 19.2 9.2 0.2 955±2.02

Wheat Hammer 12.8 36.0 30.8 16.0 4.2 0.2 1,141±2.05

Roller 4.0 42.5 31.9 14.9 6.6 0.1 1,033±1.96

a_Analyzed_in_triplicate_according_to_ASAE₍₁₉₉₅₎_._The_proportion_of_particles_smaller_than₈₀_␮_m_and_bigger_than₂₅₀₀_␮_m_was_negligible_for_all_diets. b _Geometric_mean_diameter._Data_correspond_to_the_average_of_the_diets_supplied_from₂₄_to₄₀_weeks_and_from₄₀_to₅₉_weeks_of_age.

c _Geometric_standard_deviation._(Log_normal_SD).

UK)wasused(Pérez-Bonillaetal.,2011).Inaddition,theproportionofshell,albumenandyolk,andtheyolktoalbumen ratioweredeterminedperreplicateintheeggsusedforqualitymeasurementsasindicatedbyPérez-Bonillaetal.(2012). Brieﬂy,freshraweggswerebrokenandtheyolkwascarefullyseparatedfromthealbumen.Theyolkwasrolledonpaper tissuetoremoveanyadheredalbumenandthechalazaepriortoweighing.Theshellwascarefullywashed,driedatroom temperaturefor48handweighed.Albumenweightwascalculatedbydifferencebetweeneggweightandtheweightsof theyolkandtheshell.

2.4. Statisticalanalysis

ProductiondataandeggqualitytraitswereanalyzedasacompletelyrandomizeddesignusingtheMIXEDprocedureof SASforrepeatedmeasureswiththemaincerealandgrindingmethodasfixedeffects,andperiod(fourweeksforproduction andsixteenweeksfor eggqualitytraits)astherepeatedterm(Littelletal.,1996).Severalcovariancestructureswere testedandthefinalstructurewasselectedaccordingtotheAkaike’informationcriterion.Resultsintablesarepresented asmeans,anddifferenceswereconsideredsignificantatP<0.05.MortalitydatawereanalyzedbytheGENMODprocedure ofSASInstitute(1990)usingabinomialdistribution.Thelinkfunctionwaslogit-transformation[ln(␮/1−␮)].Valuesare representedinbiologicalsenseusinglogitfunctionastransformation.

3. Results

3.1. Particlesizedistributionandgeometricmeandiameter

TheGMDofthedietsrangedfrom955␮mfortheRMmaizeto1141␮mfortheHMwheat(Table2).Ascomparedwith theHM,rollingreducedtheGMDofthemaize(1162vs.955␮m)andwheat(1141vs.1033␮m)dietsbutdidnotaffectthat ofthebarleydiets(1117vs.1116␮m).Thegeometricstandarddeviation(GSD)ofthedietswaslowerwhenthecerealwas RMthanwhenthecerealwasHM(1.96vs.2.07␮m,respectively).Theproportionoffeedparticlesthatpassedthroughthe 160␮mscreenwasincreasedwhentheRMratherthantheHMwasusedtogrindthemaize(4.0vs.9.4%)andthewheat(4.4 vs.6.7%)butnodifferenceswereobservedforthebarley(3.7vs.3.9%)(Table2).Ontheotherhand,theproportionoffeed particlescoarserthan2500␮mwasreducedwhenthecerealwasrollermilled(a59,47and31%reductionforthebarley, maizeandwheatdiets,respectively)(Table2).

3.2. Productionperformance

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Table3

Inﬂuenceofthemaincerealandtypeofmillusedtogrindthecerealonproductiveperformancefrom24to59weeksofagea_.

Cereal Milltype Egg productionb

Feed intake (g/d)

Egg weight(g)

Eggmassc _FCRd (kg/kg)

FCR (kg/dozen eggs)

BWgain (g)

Mortalitye (%)

Barley Hammer 0.906 110.9a _62.4 _56.5 _1.96 _1.46 ₂₃₈ _2.2

Roller 0.879 108.4b _62.2 _54.7 _1.99 _1.48 ₂₂₆ _0.0

Maize Hammer 0.903 110.8a _62.2 _56.2 _1.98 _1.47 ₂₄₁ _4.4

Roller 0.905 110.6a _62.3 _56.3 _1.97 _1.48 ₂₅₄ _2.2

Wheat Hammer 0.906 110.9a _62.0 _56.2 _1.98 _1.47 ₂₃₆ _0.0

Roller 0.904 110.6a _61.8 _55.9 _1.98 _1.48 ₂₀₉ _1.1

S.E.Mf _0.007 _0.40 _0.23 _0.51 _0.020 _0.015 _22.7

Cereal

Barley 0.893 109.7b _62.3 _55.6 _1.98 _1.47 ₂₃₂ _1.1

Maize 0.904 110.7a _62.2 _56.3 _1.97 _1.47 ₂₄₇ _3.3

Wheat 0.905 110.8a _61.9 _56.0 _1.98 _1.48 ₂₂₃ _0.6

S.E.Mg _0.005 _0.28 _0.16 _0.36 _0.014 _0.011 _16.1

Milltype

Hammer 0.905 110.9a _62.2 _56.3 _1.97 _1.47 ₂₃₈ _2.2

Roller 0.896 109.9b _62.1 _55.6 _1.98 _1.48 ₂₃₀ _1.1

S.E.Mh _0.004 _0.23 _0.13 _0.29 _0.011 _0.009 _13.1

Effect

Cereal 0.14 0.014 0.23 0.45 0.89 0.98 0.55 0.10

Grinding 0.11 0.004 0.57 0.12 0.71 0.19 0.64 0.31

Cereal*milltype 0.09 0.009 0.80 0.14 0.73 0.96 0.69 0.36

(a–b)_Means_within_a_column_and_main_effects_not_sharing_a_common_superscript_are_different₍_P_<_0.05). a_Data_presented_correspond_to_the_means_of₈_periods_of₂₈_days_each.

b_Eggs/hen_per_day. c_Grams_of_eggs/hen_per_day d_FCR₌_feed_conversion_ratio. e_Analyzed_by_GENMOD_procedure.

f_Standard_error_of_the_mean:₍_n₌₇_replicates_of₁₀_hens). g_Standard_error_of_the_mean:₍_n₌₁₄_replicates_of₁₀_hens). h_Standard_error_of_the_mean:₍_n₌₂₁_replicates_of₁₀_hens).

Fig.1.Effectofgrindingmethodofthecerealonfeedintake(A),eggproduction(B),eggweight(C)andfeedconversionratio(D)from24to59weeksof age.

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Fig.2.Effectofthemaincerealofthedietonfeedintake(A),eggproduction(B),eggweight(C)andfeedconversionratio(D)from24to59weeksofage. **P≤0.01;***P≤0.001.They-axisvaluedoesnotstartintheorigin.

3.3. Eggquality

Nointeractionsbetweencerealandgrindingmethodofthecerealweredetectedforanyoftheeggqualitytraitsstudied andtherefore,onlymaineffectsarepresented.Percentageofdirty,brokenandshell-lesseggs,Haughunitsandtheproportion ofshell,yolk,albumen,andtheyolktoalbumenratio,werenotaffectedbydietarytreatment(Table4).However,yolkcolour washigher(P<0.001)inhensfedmaizethaninhensfedbarleyorthewheat(9.6vs.8.8and8.8,respectively).

4. Discussion

4.1. Particlesizedistributionandgeometricmeandiameter

TheGMDofthebarleydietwasnotaffectedbytypeofmillusedbutthatofthemaizeandwheatdietwerelowerwith theRMthanwiththeHM,reflectingprobablydifferencesinNDFcontentamongcereals.Irrespectiveofthecerealused, theGSDofthedietswasreducedwhentheRMwasused,resultsthatagreewithdataofKoch(1996)whoindicatedthat particlesizeuniformityofthedietwashigherwiththeRMthanwiththeHM.Theproportionofparticlesfinerthan160␮m ofthemaizeandwheatdietswashigherwiththeHMthanwiththeRM,butnodifferenceswereobservedforthebarley diet.Theauthorshavenotfoundanypublishedresearchontheeffectsofmethodofgrindingofthethreecerealsonparticle sizedistributionandGSDofthediets.Niretal.(1990)compareddietsforbroilersfrom1to14dofagebasedonsorghum thatwasgroundfine,mediumorcoarse,usingaHMoraRM.ThescreensizeoftheHMusedwas2-,4-or8mmandthe gapbetweenrollersoftheRMwas0.45-,0.65-and1.0mm.Theauthorsreported6%lowerGMDfortheRMthanforthe HMdiets,inagreementwiththeresultsofthecurrentstudyforcornandwheat.Douglasetal.(1990)groundmaizeand sorghumusingaHMprovidedwitha4.8mmoraRMwith0.625mmgapbetweenrollsandreportedlowerGSD.Thus,the uniformitywashigherwiththeRMthanwithHMforbothcereals,inagreementwiththeresultsofthecurrentresearch.The datafromalltheseresearchesusingdifferentcerealsgroundwithaHMorwithaRMmustbetakenwithcautionbecause oftentheeffectsofmillingtypeandGMDofthedietsareconfounded.

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Table4

Inﬂuenceofthemaincerealandtypeofmillusedtogrindthecerealoneggqualityvariablesa_.

Cereal Milltype Dirty eggs(%)

Broken eggs(%)

Shell-less eggs(%)

Haugh units

Yolk colourb

Weightofeggcomponents(% oftheegg)

Yolkto albumenratio

Shell Yolk Albumen

Barley Hammer 6.7 1.4 0.03 84.7 8.9 10.2 24.6 65.1 0.38

Roller 5.2 1.4 0.13 85.1 8.6 10.2 24.3 65.5 0.37

Maize Hammer 6.5 1.3 0.06 84.4 9.8 10.2 24.5 65.3 0.38

Roller 6.7 0.9 0.07 85.0 9.4 10.3 24.8 65.0 0.38

Wheat Hammer 5.6 1.2 0.07 85.0 8.9 10.3 24.8 64.9 0.38

Roller 6.9 1.7 0.09 84.3 8.7 10.0 24.7 65.3 0.38

S.E.Mc _0.64 _0.28 _0.038 _1.85 _0.29 _0.11 _0.30 _0.39 _0.008

Cereal

Barley 6.0 1.4 0.08 84.9 8.8b _10.1 _24.5 _65.3 _0.38

Maize 6.6 1.1 0.07 84.7 9.6a _10.2 _24.6 _65.2 _0.38

Wheat 6.3 1.4 0.08 84.8 8.8b _10.1 _24.7 _65.3 _0.38

S.E.Md _0.45 _0.20 _0.030 _1.35 _0.20 _0.08 _0.21 _0.28 _0.006

Milltype

Hammer 6.3 1.3 0.06 84.7 9.2 10.2 24.6 65.1 0.38

Roller 6.3 1.3 0.09 84.8 8.9 10.2 24.6 65.2 0.38

S.E.Me _0.37 _0.16 _0.022 _0.10 _0.15 _0.07 _0.18 _0.23 _0.005

Effect

Cereal 0.62 0.46 0.87 0.94 0.001 0.52 0.94 0.96 0.57

Grinding 0.99 0.90 0.15 0.45 0.12 0.73 0.97 0.89 0.29

Cereal*mill type

0.11 0.32 0.25 0.82 0.86 0.68 0.57 0.57 0.99

(a–b)_Means_within_a_column_and_main_effects_not_sharing_a_common_superscript_are_different₍_P_<_0.05).

a_Dirty,_broken_and_shell-less_eggs_data_correspond_to_the_mean_of₈_periods_of₂₈_days_each._Haugh_units,_yolk_colour,_weight_components_of_the_egg andyolktoalbumenratiodatacorrespondtotheaveragevalueofthemeasurementsof10eggschosenatrandomat40and56weeksofage.

b_Measured_using_the_DSM_colour_fan.

c_Standard_error_of_the_mean:₍_n₌₇_replicates_of₁₀_hens). d_Standard_error_of_the_mean:₍_n₌₁₄_replicates_of₁₀_hens). e_Standard_error_of_the_mean:₍_n₌₂₁_replicates_of₁₀_hens).

andsoftwheathavedifferentphysico-chemicalcharacteristics,withahigherproportionofcleavedstarchgranulesforthe hardthanforthesoftwheat,whichmightaffecttheﬁnalstructureandparticlesizeofthecereal.

4.2. Productionperformance

4.2.1. Cereal

Whenthegrainswerehammermilled,eggproduction,eggweightandFCRwerenotaffectedbythemaincerealofthe diet,consistentwithdataofPérez-Bonillaetal.(2011)andLázaroetal.(2003)comparingdietsbasedonthethreecereals. Incontrast,Coonetal.(1988)reportedhigherFI,lowereggsizeandreducedfeedefﬁciencyandBWgaininhensfedabarley dietthaninhensfedamaizedietbutinthisresearch,thefeedswerenotsupplementedwithenzymes.Wheatandbarley areoftenproducedinnon-irrigatedﬁelds,whichresultsinamorevariablenutritivevaluethanmaizewhichisproducedin irrigatedlands.Inbroilers,Cowiesonetal.(2010)reportedthattheresponsetoenzymesupplementationwashigherwhen feddietsbasedonlowqualitywheatthanwhenfeddietsbasedonhighqualitywheat.Consequently,dependingonthe physico-chemicalcharacteristicsofthegrains,poultrymightresponddifferentlytodietsbasedonbarley,maizeorwheat. Moreover,thepotentialdifferencesinnutritivevalueamongcerealsmightdisappear,whenthedietsaresupplemented withanadequatecombinationofenzymes(Graciaetal.,2003;Mirzaieetal.,2012).

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4.2.2. Millingofthecereal

Theinformationavailableontheeffectsofgrindingmethodofthecerealonproductionoflayinghensisveryscarce. Deatonetal.(1989)comparedinthreeexperimentstheinﬂuenceofgrindingmethod(HMandRM)ofmaizeonperformance ofwhitehens.ThescreensizeoftheHMwasof4.8mmandthegapbetweenrollsoftheRMwas0.635mm.Thegrinding methoddidnotaffectanyoftheperformancevariablesstudiedinanyofthethreeexperiments,consistentwiththeresults reportedhereinforthecorndiet.IntheresearchofDeatonetal.(1989)theGMDofthedietswashigherwiththeRM thanwiththeHM(rangingfrom1343to1501␮mandfrom814to873␮macrossthethreeexperiments,respectively). Consequently,theeffectsofgrindingmethodandparticlesizeofthedietwereconfoundedandtherefore,noconclusionon theeffectsofmilltypeonhenperformancecanbereached.

Inthecurrentresearch,hensfeddietsbasedonRMcerealsatelessfeedthanhensfeddietsbasedonHMcerealsbutmost ofthedifferencedetectedwascausedbythelowerFIdetectedinhensfedtheRMbarleydiets.Infact,nodifferencesinFI wereobservedwhenthecerealswereHM.Also,hensfedtheRMbarleydietstendedtoproducelesseggsthanhensfedthe RMmaizeorwheatdiets,afindingthatwasconsistentwiththereductioninFIobserved.Niretal.(1990)comparedinyoung broilersdietsbasedonfine,mediumorcoarsegroundsorghumusingeitheraHMprovidedwitha2-,4and8mmscreen (GMDofthedietsrangingfrom629_␮mto829_␮m)oraRMwithagapbetweenrollersof0.45-,0.65and1.0mm(GMDofthe dietsrangingfrom558␮mto748␮m).Theauthorsfailedtodetectanysignificanteffectofmilltypeonbirdperformance butFIandBWgainincreasedastheparticlesizeofthedietincreased.Inlayinghens,Safaaetal.(2009)comparedmaize anddurumwheatgroundwithaHMprovidedwitha6-,8-or10-mmscreenandreportedalsoasignificantincreaseinFI, astheparticlesizeofthedietincreased.However,eggproduction,eggmassandFCRwerenotaffectedbytheGMDofthe diet,inagreementwiththeresultsofthecurrentresearch.

FeedintakeofthehenswasreducedwhenfedtheRMbarleydietascomparedwhenfedtheHMbarley.However,no differencesweredetectedinhensfedthemaizeorwheatdiets.ThereasonforthedecreaseinFIobservedinhensfedthe RMbarleydietisnotknownbutmightberelated,atleastinpart,withchangesinthephysicalcharacteristicsofthecereals, includingparticlesizedistribution.Theproportionofparticlesthatpassedthroughthe1,250␮mscreenwas11.0%and4.7% lowerwiththeHMthanwiththeRMforthemaizeandwheatdiets,respectivelybut7.0%higherfortheRMbarleydiet thanfortheHMbarleydiet.Hetlandetal.(2002)andSvihus(2010a)reportedthatcoarseparticlesremainforlongerinthe gizzardthanfineparticles.Consequently,thehigherproportionofcoarseparticlesoftheRMbarleydietwillaccumulatein thegizzard,resultinginsatiationandinadecreaseinFI(González-Alvaradoetal.,2007,2008;Jiménez-Morenoetal.,2009). Inaddition,theNDFfractionofthecereal,whichishigherforthebarleythanforthewheatandmaizediets,concentrates inthecoarserportionofthefeed.Moreover,theNDFofbarleyhasahighcontentininsolubleNSP,afractionwithahigh capacitytoretainlargeamountsofwater(BachKnudsen,1997).Mateosetal.(2012)suggestedthatthecombinationofhigh proportionofcoarseparticlesandhighinsolubleNSPcontentofbarleymightaccentuatetheretentionofthedigestainthe gizzardandreducevoluntaryFI.Also,thestructureofthedietsbasedonRMbarley,asperdirectobservation,waspoorer andlessuniformthanthatoftheotherdiets,whichmighthavepenalizedvoluntaryFIofthehens.Thedatareportedherein indicatethathensresponddifferentlytocerealinclusioninthedietdependingonthemillused,afindingthathastobe takenintoaccountinfeedmanufacturing.Itseems,however,thattheabilityofthegizzardoflayinghenstogrindlowfiber cereals,suchasmaizeandwheat,ishighandthatundermostpracticalconditions,areductioninparticlesizeofthesetwo cerealswillnotaffecthenperformance.

4.3. Eggquality

Typeofcerealdidnotaffectanyoftheeggqualitytraitsstudiedexceptforeggyolkcolourthatwasincreasedwhen maizewasused.Theinformationavailableontheeffectsofthemaincerealofthedietoneggqualitytraitsisscarce.Mirzaie etal.(2012)reportedsimilaralbumenandshellqualityinwhitehensfeddietsbasedonwheatormaize.Lázaroetal.(2003) indicatedinwhitehens,thatthemaincerealofthediet(barley,maizeandwheat)didnotaffectanyofthequalitytraits studied(shellweight,percentageofshell-less,andHaughunits).Lázaroetal.(2003)reportedalsosimilarincidenceofdirty eggsinhensfedbarleythaninhensfedwheatormaizebutwhenthedietsweresupplementedwithenzymes.Thebeneﬁcial effectofmaizefeedingonyolkcolourwasexpectedbecausealldiets,independentofthecerealused,weresupplemented withthesameamountofanexogenouspigmentsource.

Asexpected,typeofmilldidnotaffectanyofthequalitytraitsoftheeggsstudied.Theauthorshavenotfoundany reportontheeffectsofgrindingmethodoneggqualitytraitsexceptthatofDeatonetal.(1989)whoreportedthateggshell breakingstrengthoftheeggswasnotaffectedbythetypeofmillused.

5. Conclusions

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Conﬂictsofinterest

Theauthorsconﬁrmthattherearenotconﬂictsofinterestinthisresearch

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