218 short communication original articles · 219 rev colomb cienc pecu 2016; 29:218-225 peripolli v...

Rev Colomb Cienc Pecu 2016; 29:218-225

218

Revista Colombiana de Ciencias Pecuarias

Original articles

Partial replacement of corn with glycerin: digestibility and ruminal fermentation kinetics by in vitro gas production¤

Sustitución parcial de maíz con glicerina: digestibilidad y cinética de la fermentación ruminal mediante producción de gas in vitro

Substituição parcial do milho pela glicerina: digestibilidade e cinética da fermentação ruminal através da produção de gases in vitro

Vanessa Peripolli1*, AS, MSc, PhD; Ênio R Prates2, AG, MSc, PhD; Júlio OJ Barcellos2, MV, MSc, PhD; João Batista G Costa Jr1, AS, MSc, PhD; Rúbia B Lopes1, AG, MSc; Claudia M Camargo3, AG.

1Programa de Pós-Graduação em Zootecnia, Universidade Federal do Rio Grande do Sul. NESPRO/UFRGS, Brazil.

2Faculdade de Agronomia, Departamento de Zootecnia, Universidade Federal do Rio Grande do Sul, Brazil.

3Curso de graduação em Agronomia, Universidade Federal do Rio Grande do Sul, Brazil.

(Received: August 4, 2015; accepted: March 6, 2016)

doi: 10.17533/udea.rccp.v29n3a07

¤ Tocitethisarticle:PeripolliV,PratesÊR,BarcellosJOJ,CostaJBG,LopesRB,CamargoCM.Partialreplacementofcornwithglycerin:digestibilityandruminalfermentationkineticsby in vitrogasproduction.RevColombCiencPecu2016;29:218-225.

* Correspondingauthor:VanessaPeripolli.ProgramadePósGraduaçãoemZootecnia,UniversidadeFederaldoRioGrandedoSul,Av.BentoGonçalves,7712.ZipCode:91540-000,PortoAlegre,RioGrandedoSul,Brazil.Tel:+55.051.3308.6039.E-mail:[email protected]

Summary

Background:glycerin,aco-productofbiodieselproduction,couldbeincludedinanimalfeeds.Objective: toevaluatetheeffectsofpartialreplacementofcornwithglycerinondigestibilityandruminalfermentationkinetics,estimatedbythein vitro gas production technique. Methods:dietarytreatmentsconsistedofcornsubstitutionwithcrudeglycerin (0,4,8, and12%onadrymatterbasis). In vitro digestibilityofneutraldetergentfiberandorganicmatterwerecalculatedasthedifferencebetweentheamountofincubatedandundigestedsubstrate.Cumulativegaspressurewasmeasuredin vitro using automatic equipment. Gas production kineticswasanalyzedusingadual-poollogisticmodel.Results:increasinglevelsofcrudeglycerintoreplacecorndidnotaffect in vitrodigestibilityofneutraldetergentfiber,organicmatter,ammonianitrogencontent,ordegradationrates.Anegativelineareffectonthepartitioningfactorandalinearincreaseintherapidlydegradablefractionwereobservedwiththeinclusionofcrudeglycerin.Conclusions:dietaryinclusionofupto12%crudeglycerin(drymatterbasis)replacingcorndidnotaffectdietdigestibility.Agreatervolumeofgaswasobservedwiththehighestinclusionlevelofglycerin,indicatingthatalfalfahay,cornandcrudeglycerincombinationcouldaffectfermentation,suggestingtheoccurrenceofassociativeeffects.

Short Communication

219


Peripolli V et al. Glycerin in ruminant diets

Keywords: bicompartimental logistic model, biodiesel by-product, energy, neutral detergent fiber, partitioning factor.

Resumen

Antecedentes: unaalternativaalusodelaglicerina,generadacomoresiduodelaproduccióndebiodiesel,essuutilizaciónenlaalimentaciónanimal.Objetivo:evaluarlosefectosdelasustituciónparcialdemaízconglicerinasobreladigestibilidaddeladietaylacinéticadelafermentaciónruminal,usandolatécnicadeproduccióndegasin vitro. Métodos: lostratamientosconsistieronenlasubstitucióndemaízporglicerinacruda(0,4,8y12%enbaseseca).Ladigestibilidadin vitrodelafibradetergenteneutraylamateriaorgánicafuecalculadaporladiferenciaentrelacantidaddelsustratoincubadoyelnodigerido.Lapresiónacumulativade gas in vitro fuemedidapor un equipo automático.La cinéticade la produccióndegas fue analizadaempleandounmodelologísticobicompartimental.Resultados:lainclusióndenivelescrecientesdeglicerinaensubstitucióndelmaíznoafectóladigestibilidadin vitrodelafibradetergenteneutra,lamateriaorgánica,latasadenitrógenoamoniacalolastasasdedegradación.Seobservóunefectolinealnegativoenelfactordeparticiónyunaumentolinealenlafracciónderápidadegradaciónporlainclusióndeglicerina.Conclusión: la inclusióndietariadehasta12%deglicerina(baseseca)parareemplazaralmaíznoafectóladigestibilidaddelamisma.Seobservóunamayorproducciondegasconelmayorniveldeinclusióndeglicerina,loqueindicaquelacombinacióndehenodealfalfa,maízyglicerinapodríaalterarlafermentación,loquesugierelaexistenciadeefectosasociativos.

Palabras clave: co-producto del biodiesel, energía, factor de partición, fibra detergente neutra, modelo logístico bicompartimental.

Resumo

Antecedentes: umusoalternativodaglicerinageradocomoumcoprodutodaproduçãodebiodieselpodeserasuainclusãonaalimentaçãoanimal. Objetivo:avaliaroefeitodasubstituiçãoparcialdomilhopelaglicerinasobreadigestibilidadedadietaeacinéticadefermentaçãoatravésdatécnicain vitrodeproduçãodegás.Métodos:ostratamentosconsistiramnasubstituiçãodomilhoporglicerinabruta(0,4,8e12%)combasenamatériaseca.Adigestibilidadedafibraemdetergenteneutroedamatériaorgânicafoicalculadacomoadiferençaentreaquantidadedesubstratoincubadoeonãodigerido.Apressãoacumulativadegásfoimensuradain vitroutilizandoumequipamentoautomáticodemediçãodegás.Acinéticasdaproduçãodegásfoianalisadautilizandoomodelologísticobicompartimental.Resultados:oaumentodosníveisdeinclusãodaglicerinabrutaparasubstituiromilhonadietanãoafetouadigestibilidadein vitrodafibraemdetergenteneutro, a digestibilidade in vitrodamatériaorgânica,teordenitrogênioamoniacaleataxadedegradação.Foramobservadosefeitolinearnegativonofatordepartiçãoeaumentolinearnafraçãorapidmentedegradávelcom a inclusão da glicerina bruta na dieta. Conclusão: ainclusãodietéticadeaté12%daglicerinabruta(namatériaseca)parasubstituiromilhonãoafetouadigestibilidadedadieta.Omaiorvolumedegásproduzidofoiobservadoparaomaiorníveldeinclusãodeglicerinaindicandoqueacombinaçãodefenodealfafa,milhoeglicerinabrutapoderiaalterarafermentação,sugerindoaocorrênciadeefeitosassociativos.

Palavras chave: coproduto do biodiesel, energia, fator de partição, fibra em detergente neutro, modelo logístico bicompartimental.

Introduction

Biodiesel production has increasedworldwide,aswell as the volume of co-products generated,particularly crudeglycerin.Brazilianproductionofbiodieselwas approximately3.4billionL in2014,whichgeneratedabout311millionLofcrudeglycerin(ANP,2014).ThereisnofeasiblealternativetoabsorbthisvolumeofcrudeglycerinintheexistingBrazilianNationalPolicyfortheProductionandUseofBiodiesel.

Utilizingglycerinasafeedingredientinruminantdiets could potentially inhibit fat degradation bybacteriaandmaypromoteruminalpassageof totallipidcontent, therebyprovidinghigherproportionsof beneficial unsaturated fat for incorporation intobeef products (Krueger et al., 2010). Glycerinretentionwithintherumenisdirectlyassociatedwithitsabsorption.Itcanbeabsorbedfromtherumeninsignificantamounts(Krueger et al., 2010;Omazicet al.,2015).Omazicet al.(2015)reportedthatglycerin

220



alsodisappearedviamicrobialdigestionandoutflowfromtherumenthroughtheomasalorifice.Absorbedglycerinismetabolizedintheliverandrequiresglycerinkinase(Hagopianet al.,2008),anenzymeresponsibleforchannelingglycerinintothetriosephosphatestepofglycolysis/gluconeogenesis.

Grossenergyofglycerinrangesfrom3to6Mcal/Kg,dependinguponitscomposition(Mendozaet al., 2010, Meurer et al.,2012;Françozoet al.,2013;Eiraset al., 2014).Sinceglycerinhashigh-energycontent—similartocornstarch(Yanget al.,2012)—itcouldpotentiallybeusedforanimalfeed.Therefore, it isnecessarytoevaluatecrudeglycerinasanalternativeenergyfeedstuffto replace corn grain in ruminant diets.

Theobjectiveof this studywas to evaluate theeffectofincreasinglevelsofcrudeglycerinreplacingcorn in corn-alfalfa hay diets on digestibility,cumulativegasproductionandruminalfermentationkineticsusing in vitrotechniquesfortruedigestibilityand cumulative gas production.

Materials and methods

Ethical considerations

Animal care procedures throughout the studyfollowedprotocolsapprovedbytheEthicsCommittee

forAnimalUse (CEUA) at theUniversity ofRioGrandedoSul,Brazil(number18442/2010).

Experimental design

Thedietarytreatmentsconsistedintheinclusionof0,4,8,and12%ofcrudeglycerinreplacinggroundcorn(drymatterbasis;DMbasis).Theexperimentaldietswere composedof 60%alfalfa hay and40%concentrate (DMbasis).Onegram (drymatter) ofcompositesamplewasaddedto250mLfermentationbottles.Fourreplicateswereusedpertreatment.Fourblankfermentationbottleswerealsoincubated(i.e.nosubstrate),totalingtwentybottlesfortheexperiment.Bottleswerekeptinanovenat39ºC.OnehundredmLofamixturecontainingculturemedium(GoeringandVanSoest,1970),alsomaintainedat39ºC,andsaturatedwithCO2were added to thebottles.ThebottlesweresaturatedwithCO2,closedandkeptintheincubatoruntil25mLofinoculumwasaddedtoeachbottle.Thebottleswerethenplacedinanincubatorat39 ºC for48hours.Thenutritionalcompositionof ingredients and the chemical composition ofexperimentaldietsaredescribedinTables1and2,respectively.

Samplesoftheincubatedfeedstuffs(alfalfahayandgroundcorn)wereanalyzedfordrymatter(DM;AOAC, 1990;method934.1 and 930.15), organic

Table 1. Nutritional composition of ingredients.

Ingredients DM OM CP NDF ADF ADL Energy Glycerin(fresh material) % DM (MJ/Kg) (g/Kg)

Alfalfa hay 88.5 88.3 19.2 54.4 30.6 9.7 18.6 -Ground corn 88.8 99.1 8.5 16.1 3.3 0.3 18.7 -Crude glycerin* 81.4 - 0.1 - - - 14.5 80.0

*Methanol content lower than 45 mg/L. Dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), gross energy (GE), acid detergent lignin (ADL) and glycerin contents.

Table 2. Chemical composition of the experimental diets.

Chemical fraction Corn substitution with crude glycerin (% DM)0 4 8 12

DM (fresh material) 88.5 88.3 88.2 88.4OM (% DM) 92.4 92.2 92.0 91.7CP (%DM) 16.5 16.3 16.2 16.0NDF (% DM) 33.8 33.5 32.9 32.6EE (%DM) 3.1 3.0 2.9 2.8Energy (MJ/Kg) 18.6 18.5 18.3 18.0

Dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), ether extract (EE), gross energy (GE) contents.

221



matter(OM,AOAC,1975;method7.010),andcrudeprotein(CP,AOAC,1990;method988.05).Neutraldetergent fiber (NDF), acid detergent fiber (ADF)and acid detergent lignin (ADL)were determinedaccording to Van Soest et al. (1991).Aspecializedlaboratoryevaluated thenutritionalcompositionofcrude glycerin (B.E.T.Laboratories doBrasil S/CLtda).Allanalyseswereperformedintriplicates.

TwoTexel sheep (60 ± 1.2Kg average bodyweight) fittedwith a rumen fistulawere used asinoculum donors. Two hours after the animalsreceived themorningmeal, ruminalmaterialwascollected (1 part of liquid to 1 part of solid).OnehundredmLofbuffersolutionplus25mLofrumenfluidwereincubated.

In vitrocumulativegaspressurewasautomaticallymeasuredevery10minutes for48hours,usinganautomaticgas-measuringequipment(ANKOM® Gas ProductionSystem,Macedon,NY,USA),equippedwithapressuretransducerattachedtoeachbottlethattransmitsbyradiofrequencythecumulativegaspressurevaluestoacomputer.Thebottleswereautomaticallyventedevery10minutes.Fourrunswerecarriedoutwithtworeplicatespertreatment.Gasproductionvalueswerecorrectedfortheblanks.Gasproductiondatawere fitted to the dual-pool logisticmodel(Schofieldet al.,1994).Themodelparameters(A,B,C,D,E,andF)wereestimatedby the iterativemethodofMarquardtusingtheNLINprocedureofSAS® (SAS Institute,Cary,NC,USA;2002).Thepartitioning factor (PF)was determined accordingtoMakkar(2004),where:PF=mgofTDOM(trulydegradedorganicmatter)/mLgasproduced.

After48hoursofincubation,fermentationwasstoppedbyputtingthebottlesinice.Thebottleswerethencentrifuged,thesupernatantwasremoved,and50mLofneutraldetergentsolution(GoeringandVanSoest,1970)wasaddedtothebottles,whichweremaintainedat90ºCinanovenduring16hourstoextracttheneutraldetergentsolublefraction(ChaiandUdén,1998).Theresiduewasfilteredinsinteredglasscrucibleswithcoarseporediameter(100to160microns)andplacedinanovenat105ºCfor12hours,weighed,andburntinamuffleat450ºCfor5hours.

The in vitro organicmatter true digestibility(IVOMTD) and in vitro neutral detergent fiberdigestibility (IVNDFD) were calculated as thedifferencebetween the incubatedOMorNDFandthenon-digestedOMorNDFresidueremaininginthecrucibles(GoeringandVanSoest,1970).

Afterremovingfromtheincubatorandcentrifugingthebottles, andbefore adding theneutraldetergentsolution,20mLofthesupernatantwasremovedandacidified for ammonia nitrogen (NH3-N) analysis.NH3-Nconcentrationwasdeterminedbydistillationwithmagnesiumoxide(AOAC,1990;method990.03).

Statistical analysis

Maximum gas production from the rapidlyand slowly degradable fractions of organicmatter(Schofieldet al.,1994),theirrespectivedegradationrates and lag timewere estimated by theNLINprocedure.Theeffectsofincreasingcrudeglycerininclusion levels in the diet on the estimated parameter, in vitro digestibilitywith 48 hours of incubation,ammonia nitrogen and partitioning factor wereanalyzed using theGLMprocedure.MeanswerecomparedbytheREGprocedure.In vitro cumulative gas production was evaluated using the GLMprocedure as repeated measures. All statistical procedureswereperformedusingtheSASpackage(StatisticalAnalysis System, version 9.3, SASInstitute,Cary,NC,USA;2002).

Results

Astherewasnosignificanteffect(p>0.05)ontheparametersevaluated,onlythesignificanteffectsofglycerinlevels(p<0.05)willbeshown.Increasingcrudeglycerinlevelstoreplacecorndidnotinfluencein vitroneutraldetergentfiberdigestibility(IVNDFD)nor in vitro trueorganicmatterdigestibility(IVTOMD)after48hoursof incubation.Meanvalues for thoseparameterswere57.8and80.4%,respectively(Table3).

Totalcumulativegasproductionrangedbetween82.1(0%glycerininthediet)and123.1(12%glycerininthediet)mL/gofincubatedOM(Figure1).Therewas no effect of glycerin inclusion on cumulative

222



Table 3. Effects of four inclusion levels of crude glycerin on the mean values of several parameters.

Parameters Crude glycerin inclusion levels (%) Mean P-values0 4 8 12 Linear Quadratic Cubic

IVNDFD (%) 57.4 57.1 58.7 58.1 57.8 0.4133 0.8596 0.3879

IVTOMD (%) 80.2 80.3 80.8 80.5 80.4 0.5227 0.6568 0.5134

A (mL)1 46.9 71.1 95.2 111.5 81.2 0.00201 0.7381 0.8828

B (%/h) 0.028 0.016 0.012 0.010 0.016 0.0574 0.4058 0.8095

C (h) 6.7 23.4 20.0 14.4 16.1 0.5591 0.1576 0.5980

D (mL) 37.5 38.4 24.9 14.9 28.9 0.33262 0.4648 0.5980

E (%/h) 0.022 0.011 0.008 0.019 0.015 0.5955 0.0592 0.7848

F (h)2 40.1 54.9 76.3 84.7 64.0 0.01463 0.0542 0.2867

PF (mg/mL)3 9.7 8.8 7.5 7.2 8.3 <0.00014 0.2161 0.2314

NH3-N( mg/dL) 16.6 15.6 14.8 15.6 15.6 0.5379 0.5303 0.79771Ŷ = 48.53 + 5.44x; 2Ŷ = 41.13 – 2.03x; 3Ŷ = 40.75 + 3.87x; 4Ŷ = 9.66 – 0.22x. In vitro neutral detergent fiber digestibility (IVNDFD, %), in vitro true organic matter digestibility (IVTOMD, %), maximum gas production of the rapidly (A, mL) and slowly (D, mL) degradable fractions of organic matter and their respective degradation rates (B and E, %/hours), lag times (C and F, hours), partitioning factor (PF - mg TDOM/mL gas, 24 hours of incubation), and ammonia nitrogen values (NH3-N, mg/dL).

gasproductionduringthefirsthoursofincubation.However, after 14 h of incubation, the inclusionof 12% glycerin yielded higher cumulative gasproduction(79.9mL/gOM)thanthetreatmentwithnoglycerin (54.8mL/gOM;p=0.0613),and thispatternwasobserveduntil 30hoursof incubation.After30hoursofincubation,the12and8%crudeglycerin levels producedmore gas (118.2 and107.7mL/gOM, respectively) comparedwith theno-glycerintreatment(79.3mL/gOM;p<0.01),andthistrendwasmaintaineduntiltheendof48hoursofincubation.Thestandarddeviationsofgasproductionvalues at 16, 30, and48hours of incubationwere15.03,18.83,and19.65,respectively.

The partitioning factor, which integratestotal cumulative gas production with substratedisappearance, is an indicator of fermentativeefficiency.The crude glycerin levels used in thepresentstudysignificantlydecreasedthePF(Table3).

Maximumgasproductionoftherapidly(A)andslowly (D) degradable fractions of organicmatterwereaffectedbyincreasinglevelsofcrudeglycerininreplacementofcorn(Table3).

Meandegradationratesoftherapidly(B)andslowly(E)degradable fractionswere0.016and0.015%/h,respectively,andwerenotaffectedbycrudeglycerininclusionlevels.ThemeanNH3-Nresultobtainedinthepresentstudywas15.6mg/dL(Table3).

Figure 1. Effect of crude glycerin inclusion level to replace the corn in the diet on the mean values of cumulative gas production (mL/g of OM incubated) during 48 hours of incubation.

Discussion

The digestibility results are consistent withpreviousstudies,whichshowedthatfeedingglycerinlevelsupto12%ofthetotalrationdoesnothaveaneffectonnutrientdigestibilityoranimalperformance(Kruegeret al., 2010; Meral et al.,2015).Ontheotherhand,AboEl-Noret al.(2010)observedthatglycerindecreased the in vitroorganicmatterdigestibilityandin vitroneutraldetergentfiberdigestibilityindiets.These results suggest that glycerin canmodulatedigestion in a dose-dependentmanner.Drouillard(2012) describes that the deleterious effects ofglycerinonfiberdigestionareevidentbecause the

1

Figure 1. Effectofcrudeglycerin inclusion level to replace the corn in the diet on the mean 2

valuesofcumulativegasproduction(mL/gofOMincubated)during48hoursofincubation. 3

0102030405060708090

100110120130

0 2 4 7 9 12 14 16 19 21 24 26 28 31 33 36 38 40 43 45 48

Cum

ulat

ive

gas p

rodu

ctio

n (m

L/g

OM

)

Incubation time (h)

0%glycerin

4%glycerin

8%glycerin

12%glycerin

54.8b

68.8ab

79.9a

79.3b

103.2ab

107.7a

118.2a

82.1b

103.1ab

115.4a

123.1a

223



inhibitoryeffectsofhighercrudeglycerinlevelsoncellulolytic bacteria and fungi activity are clearlyevidentandmayprovideaplausibleexplanationforreducedfiberdigestion.Inthisstudy,IVOMTDandIVNDFDwere not affected by crude glycerin duetoitslowlevelinthediet,allowingoptimumrumenfermentation, as growth, adhesion and cellulolyticactivitywereinhibitedwhenglycerinwasincludedat high concentrationbut not at lowconcentration(Benedetiet al.,2016).

Totalcumulativegasproductionvaluesarelow,butaccording to Lee et al.(2011),addingglycerintoalfalfaor corn tended to decrease the in vitro gas production comparedtoalfalfaorcornsubstrateswhentheywereincubatedwithoutglycerin.Kruegeret al.(2010)alsoreported a linear increase in gas productionwhenglycerinwasaddedtoalfalfahayat10,20and40%ofthe DM in vitro.Thedifferencesinthegasproductionprofileswere not expected as corn and glycerinproduce thesameamountofgas (Leeet al.,2011),andthereplacementofcornforglycerinshouldnotcausemodification.However,wecanhypothesizethatalfalfahay,cornandglycerincombinationcouldaffectfermentation,suggestingtheoccurrenceofassociativeeffects.Corngrainhasahydrophobicproteinmatrix,whichinterferesnegativelyonitsruminaldegradationrate (LarsonandHoffman,2008).However, alfalfahayhasahigherpercentageof soluble fractionandlowerNDF, thusmore nonstructural carbohydratecontent.These carbohydrates are associatedwithglycerin,whichisrapidlymetabolized(between4and6h),providinggreatersynchronismwiththesourcesof nitrogenof rapiddegradation, and consequentlyproducing more gas.

Partitioningfactorsindicatefermentativeefficiency,and therefore, higher PF values mean greaterincorporationofdegradedorganicmattertothemicrobialmass, thereby increasing theefficiencyofmicrobialproteinsynthesis.AccordingtoMakkar(2004),optimalPFvaluesrangebetween2.74and4.41mgTDOM/mLgasproduced.ThehighPFvaluesobtainedinthepresentstudyindicatethatfermentationconditionsweregood,stimulatingproductionofmicrobialproteinandresultingin high partitioning values.

Thehighergasproductionoftherapidlydegradablefractionrelativetotheslowlydegradableone(81.2vs

28.9mL/gOM)indicatesthatglycerinincreasedthesolublefractionofthediet.Thisresultisconsistentwith the findings byGetachew et al. (2004) andKruegeret al.(2010),whoreportedthatmaximumgasproductionoftherapidlydegradablefraction(A)increased linearlyas theamountofglycerin in thediet increased.

TheBandEdegradationratesmaybeconsideredas intrinsic characteristics of the feed, anddependon the chemical compositionof the roughage, thematuration stage of the plant, and the cell wallstructure.The degradation rate can influence theefficiencyofmicrobial synthesis, therebyaffectinggasproductionofeachfractionoftheincubatedfeed.AccordingtoCatonandDhuyvetter(1997),thereareusuallynoeffectsofdietaryenergysupplementationon substrate degradation rate, as observed in the resultsobtainedinthepresentstudy,probablyduetoefficiencyofenergyuse.

Tobedegradedintherumen,thesubstratemustundergo an attachment process by rumenbacteria,knownascolonizationtimeorlagtime,whichallowsenzymestoreachthesubstrate.Inthepresentstudy,the inclusion of increasing glycerin levels did notaffectthecolonizationtimeofbacteriatotherapidlydegradable fraction (C, h) of feed.However, thecolonizationtimetotheslowlydegradablefraction(F, h) of feedwas showingdirectionof the effect,probably due to a direct relationship between thepresence of highly fermentable glycerin and thecolonizationtime.

In this study, thekineticsofgasproduction fromglycerinfermentationweresimilartoresultsreportedbyLee et al.(2011)andKruegeret al.(2010)whoreportedlongcolonization times.This indicates thatkineticsof in vitro fermentationofglycerin seem todependon thecolonizationof rumenmicrobes. Inaddition,fermentationofglycerinmaybealteredbythepresenceofotherfeedingredients(Leeet al.,2011).

Fermentation kinetics of feedstuffs can bedeterminedbythegasproductionandbybufferingof volatile short-chain fatty acids (SCFAs) anddependsontherelativeratioofsoluble,insolublebutdegradable,andnon-degradableparticlesofthefeed.In in vitromedia,NH3-Nconcentrationisanindicator

224



ofproteindegradabilitybecausethereisnonitrogenabsorptionor recycling,comparedwith the in vivo rumenmedia(NRC,1985).

ThemeanNH3-N results obtained in the present studywere above 5mL/dl, which is, accordingtoSatter andSlyter (1974), the concentration thatmaximizesmicrobialproteinsynthesis.Theseresultsare consistentwith previousworks showing thatfeeding glycerin in substitution for corn or barleygraindoesnotaffectNH3-Nconcentration(AboEl-Noret al.,2010; Avila et al.,2011).

In conclusion, inclusion of up to 12% crudeglycerin(ondrymatterbasis)inreplacementofcorndidnotaffectdietdigestibility.Thegreatervolumeofgasproducedwasobservedatthehighestinclusionlevelofglycerin,indicatingthatalfalfahay,cornandglycerin combination could change fermentation,suggestingtheoccurrenceofassociativeeffects.

ReferencesAbo El-Nor S,AbughazalehAA, Potua RB, Hastings D,KhattabMSA.Effectsofdifferinglevelsofglycerol on rumen fermentationandbacteria.AnimFeedSciTech2010;162:99-105.

ANP.AgênciaNacionaldoPetróleo2013.Availablefrom:http://www.anp.gov.br

AOAC.OfficialMethodsofAnalysis.12thed.,AssociationofOfficialAnalyticalChemists,Washington,DC;1975.

AOAC.OfficialMethodsofAnalysis.15thed.,AssociationofOfficialAnalyticalChemists,Washington,D.C;1990.

Avila JS,ChavesAV,Hernandes-CalvaM,BeaucheminKA,McGinnSM,WangY,HarstadOM,McAllisterTA.Effectsofreplacingbarleygraininfeedlotdietswithincreasinglevelsofglycerolonin vitrofermentationandmethaneproduction.AnimFeedSciTech2011;166-167:265-268.

BenedetiPDB,PaulinoPVR,MarcondesMI,MacielIFS,SilvaMC,FaciolaAP.Partialreplacementofgroundcornwithglycerolinbeefcattlediets:intake,digestibility,performance,andcarcasscharacteristics.PLOS.One2016;28:1-16.

CatonJS,DhuyvetterDV.Influenceofenergysupplementationongrazingruminants:requirementsandresponses.J.Anim.Sci.1997;75:533-542.

ChaiW,UdénP.An alternative ovenmethod combinedwithdifferentdetergentstrengthsintheanalysisofneutraldetergentfiber.AnimFeedSciTech1998;74:281-288.

DrouillardJS.Utilizationofcrudeglycerineinbeefcattle.In:MAKKAR,H. P. S.Biofuel co-products as livestock feed –opportunities and challenges. Rome:FAO;2012.p.155-162.

Eiras CE, Barbosa LP,Marques JA,Araújo FL, LimaBS,ZawadzkiF,PerottoD,PradoIN.Glycerinelevelsinthedietsof crossbred bulls finished in feedlot:Apparent digestibility,feedintakeandanimalperformance.AnimFeedSciTech2014;197:222-226.

FrançozoMC,Prado IN,CecatoU,ValeroMV,Zawadzki F,Ribeiro OL, Prado RM, Visentainer JV. Growthperformance,carcass characteristics andmeat quality offinishingbulls fedcrude glycerin-supplemented diets.BrazArchBiolTechnol2013;56:327-336.

GetachewG,RobinsonPH,DepetersEJ,TaylorSJ.Relationshipsbetweenchemical composition,drymatterdegradationand in vitrogasproductionofseveralruminantfeeds.AnimFeedSciTech2004;111:57-71.

GoeringHK,VanSoest PJ. Foragefiber analyses (apparatus,regents,procedures,andsomeaplications).AgricultureHandbook379.U.S.GovernmentPrintingOffice,Washington(DC);1970.

HagopianK,RamseyJJ,Weindruch,R.Enzymesofglyceroland glyceraldehydemetabolism inmouse liver: effects ofcaloricrestrictionandageonactivities.BioscienceRep2008;28:107-115.

KruegerNA,AndersonRC,TedeschiLO,CallawayTL,EdringtonTS,NisbetDJ.Evaluationoffeedingglycerolonfree-fattyacidproductionandfermentationkineticsofmixedruminalmicrobesin vitro.Bioresour.Technol2010;101:8469-8472.

Larson J,HoffmanPC.Technical note:Amethod to quantifyprolaminproteins in corn that arenegatively related to starchdigestibilityinruminants.JDairySci2008;91:4834-4839.

Lee SY, Lee SM, ChoYB, KamDK, Lee SC, Kim CY,SeoS.Glycerol as feed supplement for ruminants: In vitro fermentation characteristics andmethane production.AnimFeedSciTech2011;166-167:269-274.

MakkarHPS.Recent advances in the in vitro gasmethod forevaluationofnutritionalqualityoffeedresources.In:AssessingQualityandSafetyoftheAnimalFeeds.FAOAnimalProductionandHealthSeries160.FAO:Roma;2004.p.55-88.

MendozaO,EllisM,McKeithF,GainesA.Metabolizableenergycontentofrefinedglycerinanditseffectsongrowthperformanceandcarcassandporkqualitycharacteristicsoffinishingpigs.J.Anim.Sci.2010;88:3887-3895.

MeralY,KaraÇ,BiricikH.Influenceofglycerolsupplementationtodairy and feedlot cattle diets onperformance andhealth: areview.JBiolEnvironSci2015;9:109-117.

Meurer F, FranzenA, Piovesan P,RossatoKA, SantosLD.Apparent energy digestibility of glycerol from biodieselproduction forNile tilapia (Oreochromis niloticus, Linnaeus 1758).AquacRes2012;43:1734-1737.

225



NRC.RuminantNitrogenUsage.Washington (DC):NationalAcademicPress;1985.

OmazicAW,KronqvistC,ZhongyanL,MartensH,Holtenius,K.Thefateofglycerolenteringtherumenofdairycowsandsheep.JAnimPhysiolaAnimNutr2015;99:258-264.

SAS, 2002. SAS/STATpackage.Version 9.3. SAS Inst. Inc.,Cary,NC,USA.

SatterLD,SlyterLL.Effectofammoniaconcentrationonrumenmicrobial protein production in vitro.BrJNutr1974;32:199-208.

SchofieldP,PittRE,PellAN.Kineticsoffiberdigestionfromin vitrogasproduction.J.Anim.Sci.1994;72:2980-2991.

VanSoestPJ,RobertsonJB,LewisBA.Methodsfordietaryfiber,neutraldetergentfiberandnon-starchpolysaccharidesinrelationtoanimalnutrition.JDairySci1991;74:3583-3597.

YangF,HannaMA,SunR.Value-addedusesforcrudeglycerol–abyproductofbiodieselproduction.BiotechnolBiofuels2012;5:1-10.

218 short communication original articles · 219 rev colomb cienc pecu 2016; 29:218-225 peripolli v...

Documents