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Abstract

Background: starch is an important energy source for ruminants nutrition. This carbohydrate is often used to improve rumen fermentation, optimizing digestion of structural carbohydrates and increasing protein flow to the small intestine. Microbial and digestive enzymes are involved in starch digestion, generating products that can positively or negatively affect animal performance and health, depending on the starch contents of the diet. Objective: to describe the basic characteristics of starches, the factors affecting its nutritional availability, and its effects in ruminants. Conclusion: a number of factors affect starch digestibility, including granule size, amylose/amylopectin ratio, proportion of farinaceous and vitreous endosperm, presence of starch-lipid and starch-protein complexes, and physical-chemical processing of the feed. Ingestion of large amounts of starch can trigger ruminal acidosis. However, its rational use in the diet has positive effects on methane emissions, and in milk yield and composition.
Rev Colomb Cienc Pecu 2016; 29:77-90
Revista Colombiana de Ciencias Pecuarias
Original articles
77
Literature Review
Starch in ruminant diets: a review¤
Almidones en la alimentación de rumiantes: revisión de literatura
Amido na alimentação dos ruminantes: revisão de literatura
Luis M Gómez1,2,3*, MVZ, MSc, (c)Dr. Sc; Sandra L Posada2, Zoot, MSc, Dr. Sc; Martha Olivera3, MV, Dr. Sc.
1Departamento de Investigación y Desarrollo, Grupo Nutri-Solla, Solla S.A., AA 1272, Itagui, Colombia.
2GRICA Research Group, Facultad de Ciencias Agrarias, Universidad de Antioquia, AA 1226, Medellín, Colombia.
3BIOGENESIS Research Group, Facultad de Ciencias Agrarias, Universidad de Antioquia, AA 1226, Medellín, Colombia.
(Received: April 15, 2015; accepted: November 11, 2015)
doi: 10.17533/udea.rccp.v29n2a01
¤ Tocitethisarticle:GómezLM,PosadaSL,OliveraM.Starchinruminantdiets:areview.RevColombCiencPecu2016;29:77-90.
* Correspondingauthor: LuisM Gómez.Director ofResearch andDevelopment, SollaS.A. Company.Carrera42 No.33-80 Itagui,Colombia. Tel+574
4448411.E-mail:lmgomezo@solla.com
Summary
Background:starchisanimportantenergysourceforruminantsnutrition.Thiscarbohydrateisoftenused
toimproverumenfermentation,optimizingdigestionofstructuralcarbohydratesandincreasingproteinow
tothesmallintestine.Microbialanddigestiveenzymesareinvolvedinstarchdigestion,generatingproducts
thatcanpositivelyornegativelyaffectanimalperformanceandhealth,dependingonthestarchcontentsofthe
diet. Objective: todescribethebasiccharacteristicsofstarches,thefactorsaffectingitsnutritionalavailability,
anditseffectsinruminants.Conclusion:anumberoffactorsaffectstarchdigestibility,includinggranulesize,
amylose/amylopectinratio,proportionoffarinaceousandvitreous endosperm,presence ofstarch-lipidand
starch-proteincomplexes,andphysical-chemicalprocessingofthefeed.Ingestionoflargeamountsofstarch
cantriggerruminalacidosis.However,itsrationaluseinthediethaspositiveeffectsonmethaneemissions,
andinmilkyieldandcomposition.
Keywords: acidosis, amylopectin, amylose, digestibility, lactation, methanogenesis.
Resumen
Antecedentes: el almidónes unimportante recursoenergético parala alimentaciónde rumiantes.Este
carbohidratoesfrecuentementeempleadoparaelmejoramientodelosparámetrosdefermentaciónruminal,
loqueoptimiza elaprovechamiento de loscarbohidratos estructurales eincrementa elujode proteínaal
intestinodelgado.Ensudigestiónparticipanenzimasmicrobianasydigestivas,lascualesgenerandiferentes
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Gómez LM et al. Starch in ruminant diets: a review
productosqueimpactanpositivaonegativamenteeldesempeñoproductivoylasaluddelanimal,dependiendo
del nivel de almidón en la dieta. Objetivo: describirlascaracterísticasbásicasdelosalmidones,losfactores
queafectansudisponibilidadnutricionalylosefectosdesuutilizaciónenlaalimentacióndelosrumiantes.
Conclusión:existeunsinnúmerodefactoresqueafectanladigestibilidaddelalmidón,entreellos,eltamaño
delgránulo,la relaciónamilosa/amilopéctina,laproporcióndeendospermofarináceoyvítreo,lapresencia
decomplejosconlípidosyproteínas,ysuprocesamientofísico-químico.Laingestióndegrandescantidades
dealmidónpuededesencadenaracidosisruminal;noobstante,suempleoracionalenladietadelosrumiantes
tieneefectospositivossobrelaemisióndemetano,ylaproducciónycalidaddelaleche.
Palabras clave: acidosis, amilopectina, amilosa, digestibilidad, lactancia, metanogénesis.
Resumo
Antecedentes: oamidoéuma importantefonte deenergianaalimentaçãodos ruminantes.Este carboidrato
é geralmente utilizado para melhorar os parâmetros de fermentação no rúmen, o que otimiza a utilização dos
carboidratosestruturaiseaumentao uxodeproteínaparao intestinodelgadodoanimal.Nasuadigestãoestão
envolvidas enzimas digestivas e microbianas, as quais geram diferentes produtos que impactam positiva ou
negativamenteodesempenhoprodutivoe asaúdedoanimaldependendo doníveldeamidona dieta.Objetivo:
descreverascaracterísticasbásicasdoamido,factoresqueafectamasuadisponibilidadenutricionaleosefeitosdasua
utilizaçãonaalimentaçãoderuminantes.Conclusão: diversosfatoresafetamadigestibilidadedoamido,incluindo
otamanhodogrânulo,arelaçãoamilose/amilopectina,aproporçãodeendospermafarináceoevítreo,aformação
decomplexoscomlipídeoseproteínaseoseuprocessamentofísico-químico.Aingestãodegrandesquantidades
deamidopodeprovocaracidoseruminal,noentanto,asuautilizaçãoracionalnaalimentaçãoderuminantestem
efeitospositivossobreasemissõesdemetano,aproduçãodeleiteeasuaqualidadecomposicional.
Palavras chave:acidose, amilopectina, amilose, digestibilidade, lactação, metanogênese.
Introduction
Starch–thelargestreservoirofplantpolysaccharides-
playsanimportantroleingerminationandgrowth,
anditssynthesisissecondonlytothatofcellulose.
Starchisthemainenergycomponentusedinruminant
feeds due to its availability (Ortega and Mendoza,
2003). It is often included in the diet to improve
ruminal fermentation, allowing for a better use of
structuralcarbohydratesandtoincreaseproteinow
tothesmallintestine(Huntingtonet al.,2006).Starch
sourcesare expensive,sotheymustbeusedwisely
tobecost-effective.Itisimportanttounderstandthe
structural characteristics of starch, its ruminal and
post-ruminal digestion and the factors affecting its
digestibility in order to improve performance and
prot of livestock systems. This review describes
starch,thefactorsaffectingitsnutritionalavailability,
anditseffectsinruminantfeedingandnutrition.
Description of starch
Composition
Starches are mainly α-glucans composed of
two types of molecules: amylose and amylopectin
(SantanaandMeireles,2014;Table1).Amyloseisa
linearD-glucosepolymercontainingabout99%α-1,4
links(Parker andRing,2001).Amylopectin,which
has95%α-1,4linksand5%α-1,6links(Stevneboet
al.,2006),isthemostabundantcomponentofstarches
(Figure 1). On the other hand, amylose content in
starchusuallyuctuatesfrom200to300g/Kg.Some
starch-richfeedssuchaswaxycerealsusuallycontain
negligibleamountsofamylose,whilehigh-amylose
sourcesmaycontainupto700gamylose/Kg.Cereals
suchaswheat,maize,barley,andricecancontaina
waxygenederivedfromnaturalmutationsofgenes
encoding granule bound starch synthase, which is
requiredforamylosesynthesis(Svihuset al.,2005).
Structure
Starchgranulesareformedbyconcentricallygrowing
layersalternatingsemi-crystallineandamorphouslms
(Figure1).Thesemi-crystallineregionismoreabundant
in amylopectin and is more impervious to enzymatic
attackbecauseofits resistance to entryofwater.The
amorphous region is rich in amylose and has lower
densitythanthecrystallinearea,whichfacilitateswater
ow and enzyme attack; however, it is abundant in
hydrogenbonds(Perezet al., 2009).
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Table 1. Properties of starch components.
Characteristic Component
Amylose Amylopectin
General structure Linear Branched
Branch sites Nonea1 per 20 to 25 glucose units
Polymerization degreeb
Molecular weight
~1.000
1 x 105-1 x 106 g/mol
~10.000-100.000
1 x 107-1 x 109 g/mol
Stability in solution Low High
a There is a type of branched amylose with 1 or 2 α-1,6 links per molecule.
b Number of glucose residues per molecule.
Adapted from Parker and Ring, 2001.
Figure 1. (A) Structure of starch granules, represented by organized laminar forms. Amorphous rings (composed mainly of amylose)
separate layers in the semi-crystalline regions (composed primarily of amylopectin). Modied from Perez et al., 2009. (B) Amylopectin
structure according with the cluster model by Myers et al., 2000. Glucan chains are depicted by solid lines while intersections between
them indicate branch linkages. The dotted lines show the limit of amylopectin side chain clusters with unbranched chains associated in
tightly packed double helices. a) depicts the amorphous areas separating amylopectin side chain clusters.
A
B
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Structural alterations
Gelatinization. It is the permanent alteration
of the granule structure by breaking its hydrogen
bonds. Starch absorbs water during gelatinization,
theexpansionbreaks the hydrogenbondsreleasing
someoftheamylosebyleaching,thusbirefringence
is reduced and starch becomes more soluble
and exposed to enzyme activity (Rooney and
Pugfelder,1986).Inexcessofwater,moststarches
gelatinise at temperatures higher than 80 °C. The
gelatinisationtemperatureishigherforsmallstarch
granules. Amylose-rich cereals are more resistant
togelatinisationthancereals with normal andhigh
amylopectin levels (Svihus et al., 2005). Table 2
shows gelatinization values for several foods and
processing methods. The degree of gelatinization
is higher for extruded vs. pelleted food since the
temperatureusedintheprocessishigher(upto250°C
vs.60-95°C;Caballero,2010).
Table 2. Starch gelatinization under several processing methods
in various feeds.
Food Gelatinization (%)1Processing
Corn 17.06 Unprocessed
Sorghum 12.47 Unprocessed
Yucca 7.59 Unprocessed
Concentrate 1 32.49 Pelleting
Concentrate 2 32.55 Pelleting
Concentrate 3 31.92 Pelleting
Corn 79. 3 Extruded
1Assessed by an enzymatic method (Medel et al., 1999).
Retrogradation. It is dened as the reversible
returnofasolubilized,dispersedoramorphousstate
toacrystallineorinsolubleform,whichlimitsstarch
digestibility. Amylose is the main component that
facilitatesretrogradation(Biliaderis,2009).
Sources of starch
Cereal grains and roots
Cerealgrainsare a major source of starch used
inanimalfeeds.Cereals are composed ofpericarp,
endosperm and germ (Figure 2). The pericarp
comprises3to8%ofthekernelweight,althoughit
canbeupto 25% in oats(Everset al.,1999).It is
mostlycomposed(90%)ofhighlyligniedberand
thestarchcontentislessthan10%(Liet al.,2007),
thuspericarpdigestibilitydoesnotexceed40%(Van
Barneveld,1999).
Figure 2.Corn kernel composition.Adapted from Eckhoff
andWatson(2009).
Theendospermrepresentsbetween60and90%of
thegrain.Itisthemorphologicalstructurecontaining
the starch. It also contains proteins, phospholipids
andash,butlittleneutraldetergentber(NDF)and
phosphorus (P; Eckhoff and Watson, 2009). The
endospermlayers,fromtheoutsidein,arealeurone,
peripheralendosperm,horny(orvitreous)andoury.
Boththeperipheraland the horny endospermhave
starch granules surrounded by a matrix abundant
in hydrophobic proteins called prolamines and
non-starch polysaccharides (PNAs; β-glucans,
arabinoxylans, and pectins), which are relatively
impermeabletowaterandenzymaticactivity(Zeoula
andCaldasNeto,2001;Giubertiet al.,2014).Grains
exhibitinghighproportion of peripheral and horny
endospermarecalledvitreousorhorny,whilethose
abundantinoury endosperm arecalledopaqueor
soft(ZeoulaandCaldasNeto,2001).
Non-conventional sources
Starchrepresentsanimportant fraction in many
crops.Mostcereals(i.e.corn, wheat, rice, oat, and
barley) contain between 60 and 80% starch, while
legumes (chickpea, bean, pea) contain from 25 to
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50%, tubers (potato, cassava, cocoyam, arrowroot)
from 60 to 90%, and some green fruit (banana,
mango) contain as much as 70% (Santana and
Meireles,2014).Asincereals,thelargestproportion
ofstarchcorrespondstoamylopectinandthesmallest
to amylose (17-30%; Hu et al., 2010). Amylose
represents14to19%ofstarchincassava,between2
and22%inpotato,andapproximately37%inplantain
(Knowleset al.,2012).Amylopectininstarchfrom
potatoislessbranchedcomparedtocereals(Alvani
et al.,2011).Itisalsohighlyexpandable(Vasanthan
andBhatty,1996) and gelatinizes atrelatively low
temperature(between64.4 and 69.9 °C) compared
tootherstarches(Hernandez-Medinaet al.,2008).
Table3showsamyloseandamylopectinconcentration
indifferentstarchyfoodsandconcentratesfedtodairy
cattle.Differencesinamylose/amylopectinratioaffect
therateofruminalorintestinaldigestion.Digestionrate
ofamylopectinis usuallyhigherthanthat of amylose
(Knowleset al.,2012).
Tab le 3. Amylose and amylopectin content in various feeds.
Source Amylose (%) Amylopectin (%)
Corn 29.24 70.76
Sorghum 29.55 70.45
Yucca 19.84 80.16
Concentrate 1 (C1)* 21.17 78.83
Concentrate 2 (C2) 22.22 77.78
Concentrate 3 (C3) 20.25 79.75
Concentrate 4 (C4) 24.89 75.10
*Isoenergetic and isoproteic concentrates (C) for dairy cattle formulated
with four carbohydrate sources: corn (C1), sorghum (C2), yucca (C3), citrus
pulp (C4). Assessed using the method described by Gibson et al. (1997).
Ruminal and post-ruminal digestion of starch
Once it reaches the rumen, starch is degraded
mainly by amylolytic bacteria and by fungi and
protozoato alesserextent(Huntington,1997).The
α-1-4andα-1-6endoandexoamylasesproducedby
rumenmicroorganismshavetheabilitytohydrolyze
amylose and amylopectin glycosidic linkages,
releasingdifferentoligosaccharides(Table4).
The post-ruminal process of starch degradation
begins with pancreatic α-amylase secretion, which
hydrolyzes amylose and amylopectin into dextrins
andlinearoligosaccharideswithtwotothreeglucose
units. The process is completed by the action of
oligosaccharidases(maltaseandisomaltase)secretedin
theintestinalmembrane(OrtegaandMendoza,2003).
Inruminants,thesite of starchdigestionaffects
thesubstratesabsorbed.Ruminaldigestiongenerates
volatilefattyacids(VFA)forabsorptionandprovides
energyformicrobialproteinsynthesis(Huhtanenand
Sveinbjörnsson,2006). Decreasedrumendigestibility
ofstarchisdesirabletopreventfromacidosisandto
increasethesupplyofglycogenicsubstrates(Svihus
et al.,2005). Starchdigestioninthesmallintestine
implies greater energetic efciency compared with
ruminaldigestionduetoreducedmethaneproduction
and fermentation heat losses and higher efciency
of metabolisable energy utilisation (Huhtanen and
Sveinbjörnsson, 2006). Nevertheless, the increased
energyefciencyfromhigherstarchdigestioninthe
small intestine is offset by the increase in hindgut
fermentation,becauseonlyVFAareabsorbedfrom
thehindgutwhereasmicrobialmatterisexcretedin
feces.Adecrease inruminalstarchdigestion isnot
associated with an increase in its small intestinal
Table 4. Enzymes involved in starch hydrolysis.
Enzyme Link End product
Phosphorylase α -1-4 glycosyl Glucose 1 phosphate
Alpha-amylase α -1-4 glycosyl Linear and branched oligosaccharides
Beta-amylase α -1-4 glycosyl Maltose and limit dextrins
Amyloglucosidase α -1-4 glycosyl and α -1-6 glycosyl Glucose
Isoamylase α -1-6 glycosyl Lineal chains of α -1-4 glucans
Pullulanase α -1-6 glycosyl Lineal chains of α -1-4 glucans
Adapted from Tester et al., 2004.
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digestion,butitisassociatedwithhigherhindgutand
lowertotaltractdigestibility(Larsenet al.,2009).
Forthisreason,rumenisconsideredtheprimary
site of starch digestion. Ruminal digestion usually
accountsfor 75to80% oftheintake, andabout35
to60%ofthestarch entering the small intestine is
degraded.About35to50%ofthestarchthatescapes
digestion in the small intestine is degraded in the
hindgut(Harson,2009).Accordingtoameta-analysis
byMoharreryet al.(2014),ruminalstarchdigestibility
variesgreatly(from 224to942 g/Kg).Theauthors
alsonotedthatstarchconsumptionadverselyaffected
ruminalstarchdigestibility,obtaininganegativeslope
of1.4%perKgincreaseindailystarchintake.Table
5 presents the content and ruminal digestibility of
various starch sources used in livestock.
Table 5. Starch content and ruminal digestibility of several starch
sources commonly used as feed supplements in dairy cattle.
Grain Starch (%) Rumen digestibility (%)a
Corn1,2 76.0 72 - 89.9
Sorghum1,2 71.3 60 - 78.4
Wheat1,2 70.3 88.3 - 88.1
Barley1,2 64.3 80.7 - 84.6
Oats1,258.1 92.7 - 94.0
Yucca380.0 91.0
a Variability is explained by grain treatment (grinding, rolling, aking).
1 Herrera-Saldana et al., 1990. 2Huntington, 1997. 3Vearsilp and Mikled, 2001.
Factors affecting starch digestibility
Granule size
Thisisalimitingfactorinstarchdigestionbecause
therelationship betweenstarchvolumeandsurface
area,andthussubstrate-enzymecontact,decreasesas
granulesizeincreases(Sviluset al.,2005).Cereals
withsmallgranules,suchasoatsandrice,aremore
digestiblethancorn, wheat andpotato,whichhave
longgranules(Bednaret al.,2001;Sviluset al.,2005).
Amylose/amylopectin ratio
Several studies have shown that amylose/
amylopectinratioisnegativelycorrelatedwithstarch
digestion(Bednaret al.,2001).Amyloseisinserted
intoamylopectinmoleculesincreasingtheamountof
hydrogen bonds within the starch molecule, which
negatively impacts the ability of expansion and
enzymeactivity(Caldas-Netoet al., 2000).Likewise,
starchgranuleswithhighamylosecontentaremore
pronetoretrogradation(Sviluset al.,2005).
Floury versus vitreous endosperm
Severalresearchers(Correaet al.,2002;Ngonyamo-
Majeeet al.,2008)havereportedaninverserelationship
betweenstarch digestibilityandvitreousness.Allen
et al.(2008),studiedruminalandduodenal-stulated
cows using corn with vitreous endosperm content
varyingbetween25and66%.Theyfoundthatfeeding
cornwith66%ofvitreousendospermreducedruminal
digestionin19.1%andoveralldigestionin7.1%.
Starch-lipid complexes
Quantitatively,lipids are the major non-starch
compoundsinstarchgranulesandcanbefoundas
freefattyacids(mostly palmiticandlinoleicacid)
and lysophospholipids (Svihus et al., 2005). In
cereal grains, a portion of amylose has insoluble
starch-lipidcomplexes,whichformhelicalstructures
that provide greater adhesion between molecules,
dininish starch swelling (Vasanthan and Bhatty,
1996), decrease their solubility (Rooney and
Pugfelder,1986)andreducetherateofenzymatic
digestion(Croweet al., 2000).Cassavaandpotato
starch contain a smaller percentage of lipids
compared with cereal starch (Zeoula and Caldas
Neto,2001;Alvaniet al.,2011).
Starch-protein complexes
The proteinaceous matrix surrounding starch
granulesaffectsstarchdigestibility.Digestibilityis
negativelyassociatedwiththepresenceofprolamins.
Prolaminsarestorageproteinsthatreceiveadifferent
nameforeach cereal,namelyzein(corn), karins
(sorghum), gliadin (wheat), hordeins (barley),
secalins(rice),andavenines(oats).Usually,wheat,
oats, rice and barley have fewer prolamins than
cornand sorghum(Momanyet al.,2006; Giuberti
et al.,2014).
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Zeinsaccountfor50to60%oftheproteininthe
wholegrainand are locatedattheperiphery of the
cell.Flouryendospermislowinzeincomparedwith
vitreous endosperm (Giuberti et al., 2014). Zeins
arenotsolubleintherumenenvironment(Lawton,
2002).Starchdigestionrequiresthatrumenbacteria
degradezeinsrstviaproteolysis,beforestartingthe
amylolyticactivity(Cotta,1998).
Processing of cereal grains
Grain processing using temperature, humidity
andpressurefacilitatebinding of bacteria tostarch
granules,increasingits digestibility (Huntington et
al., 2006). Common processing includes grinding,
pelleting, dry rolling, steam rolling (addition of
water before rolling), and steam aking. All these
processes aim to break grain barriers such as the
pericarp and the protein-starch matrix, allowing
accessof microorganismstostarchgranules.These
processesalsoreducetheparticlesize,andincrease
surfaceareaandmicrobialcolonization(Giubertiet
al., 2014). The response to processing varies with
differentgrains,withsorghum>corn>oats=barley>
wheat(Huntingtonet al.,2006).
Gelatinizationofstarchmakesitmorewater-soluble
anddigestible.AccordingtoHuntington(1997),steam
akingofcornimprovesruminal,post-ruminalandtotal
tractdigestibilitycomparedwithdryrolling(85vs.70%,
92vs.69%,and99vs.90%,respectively).According
toSveinbjörnssonet al.(2007),heattreatmentincreases
starchdegradationduring8hofin vitro incubation,as
follows:0.155vs.0.870forpurepotatostarch,0.491vs.
0.815forpeas,0.686vs.0.913forbarley,and0.351
vs.0.498formaize.
Only a fraction of starch is gelatinazed during
steamconditioningand pelleting offeeds(from10
to200gstarch/Kg).Theexpanderprocessing,onthe
otherhand,addsupto80gwater/Kgwhilethediet
reachesahighpressureandtemperaturesabove100°C,
thusresultinginbetween220and 350 g starch/Kg
gelatinizedduringthisprocess.The extrusion adds
evenmorewater(upto180gwater/Kg)andthediet
issubjectedto evenhighertemperatures(>110°C)
underhighpressure,thusresultinginmorecomplete
gelatinisation and disintegration of starch granules
(Svihus et al.,2005).ThiswasevidencedbyOffner
et al.(2003),whoreported0.607,0.663,0.743,0.746,
0.819, 0.830, and 0.867 effective degradabilities
foruntreated, cracked, ground, pelleted, expanded,
steamakedandextrudedcorn,respectively(passage
rate0.04h-1).Graintypealsoinuencestheresults.
Steamakingofcorneliminatedtheadverseeffects
ofvitreousendospermandprotein-starchmatrix on
digestibilityincomparisonwithdryrolling.Thiswas
contrary to the results obtained for barley, a grain
withahighlydigestibleprotein-starchmatrix,where
nodifferencewasobservedbetweenbothtreatments
(Engstromet al.,1992).
Starch source
The highest effective degradability of starch
in cereal grains was obtained for oats, wheat and
barley,being lower for corn and sorghum. Corn
and especially sorghum have a high proportion
of peripheral and horny endosperm resulting in
increased resistance to microbial activity (Rooney
andPugfelder,1986),unlikewheatandoats,which
have higher proportion of floury endosperm. In
addition, corn and sorghum have a denser protein
matrix(Kotarskiet al.,1992).Thein vitro experiment
byLanzaset al.(2007)measuredfractionalgasrates,
as a measure of starch digestion (Huhtanen and
Sveinbjörnsson,2006),reporting0.26,0.24,0.15,and
0.06h-1 ratesforwheat,barley,corn andsorghum,
respectively(p<0.001).
Cassavahashighereffectivedegradabilitythan
cornandsorghumduetoitslackofpericarp,protein
matrix,hornyandperipheralendosperm;aswellas
lowproportionoflipids,lackofassociationsbetween
starchandprotein,lessamylose,moreamylopectin,
lesshydrogenbonding,andgreaterswelling when
subjected to chemical processes. Cassava starch
is composed exclusively of amylopectin in the
crystalline region and amylose in the amorphous
region, which prevents excessive formation of
hydrogenbondswithamylopectin,allowingamylose
to be readily leached. This is contrary to cereals,
whichhaveamyloseinthecrystallineregion(Zeoula
andCaldasNeto,2001).Effectivedegradabilityof
corn,sorghumandcassava,reported by Offner et
al.(2003),was 0.597,0.603y0.802, respectively
(passagerate0.06h-1).
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Physiological restrictions of the small intestine
Starch digestibility in the small intestine is
limited.Asdigestaowincreases,starchdigestibility
decreases (Huntington et al., 2006). Factors that
limitstarchdigestibilityincludecontrolledglucose
absorption,decientenzymeaccessibilitytostarch
granules,alterationsinruminalandintestinalpH,and
lackofsynchronybetween starch ow throughthe
intestineandamylasesecretion(Owenset al.,1986).
Starchdigestion efciencyinthesmallintestine
variesbetweensources.Tothiet al.(2003)reported
higher digestibility for barley starch in the small
intestine compared with cornstarch, resulting in
higher small intestine absorption in terms of g/Kg
starchingested.
Starch and ruminal acidosis
Starchfermentationincreasesvolatilefattyacids
(VFA) and lactate production, which can reduce
ruminal pH and kill cellulolytic microorganisms,
leadingtodecreasedberdigestibilityanddrymatter
(DM) intake. Additionally, it can cause metabolic
disorders such as acute and sub acute ruminal
acidosis, rumenitis, laminitis, liver abscesses and
polyencephalomalacia(Plaizieret al.,2009).
The risk of ruminal acidosis increases when
starchdigestionrate increases.Thisratevaries with
graintypeandprocessingandgenerallyoccursinthe
followingorder:wheat(32%h)>oat>barley(29%h)
>potato(5%h)>corn(2%h)andsorghum(Callison
et al.,2001;Mosaviet al.,2012).Krauseet al.(2002)
reportedlowerruminalpHinlactatingcowsfedhigh
moisture corn vs. dried corn. Gulmez and Turkmen
(2007) observed a decrease of ruminal pH (<6) in
lactatingcowswhencornwasreplacedbywheat.They
alsoobservedlowpH(<5.8)over13continuoushours
whenwheatwastheonlysourceofstarch.
Cassavaisused asareadily fermentableenergy
source for ruminants. It has a high rate and extent
of ruminal degradation, as evidenced by Khampa
andWanapat(2006)whocomparedcassavavs.corn
supplementation at 1 and 2% of live weight. They
found that 2% cassava supplementation lowered
ruminalpH(5.3vs.6.4)andcellulolyticbacteria(2.3
vs.5.9x107).
Starch and methanogenesis
Ruminal digestion of ber-rich diets increases
hydrogen and carbon dioxide production, which
are substrates for methanogenesis. Moreover,
starch-rich diets change the bacterial ecology by
favoring propionic-acid producing bacteria over
methanogens (Bannink et al., 2006; Ellis et al.,
2008).Propionicacidproductionfromdicarboxylic
acids(aspartate,malate,fumarate)viathesuccinate
pathway is thermodynamically more efficient
than methanogenesis (Offner and Sauvant, 2006).
Moreover,rapidly-fermentingdietsreducemethane
productionbydecreasingruminalpH,whichaffects
thegrowthofmethanogens,protozoa (Hook et al.,
2011)andcellulolyticbacteria(Sunget al.,2007),
andincreasespassagerate,whichreducesprotozoans
and,thereby,interspecieshydrogentransfer(Kumar
et al.,2013).
Agle et al. (2010) reported that diets with higher
proportionofnon-structuralcarbohydrates(52and72%)
resultedinnumerically lowermethaneemissions(1.5
vs.3.4g/hour,respectively),althoughresultsshowed
nodifferenceduetohighvariability.Arecentstudyin
grazingHolsteinFriesiancowsfoundthatconcentrate
level (2, 4, 6, and 8 Kg/cow/day) had no impact on
methane emissions (287, 273, 272, and 277 g/day,
respectively). However, when it was associated with
DMandenergyconsumption,methanedecreasedwith
increasinglevelsofconcentrate(gCH4/KgDM:20,19.3,
17.7,and18.1;CH4-E/grossenergyintake:0.059,0.057,
0.053,and0.054,respectively).Theydemonstratedthat
concentratesupplementationtograzingcowsincreased
milkproductionanddecreasedmethaneemissionsper
unitofmilkproduced(Jiaoet al.,2014).Aguerreet
al.(2011)foundthatchangingforage:supplement
ratio(F/S)from68:32to47:53reducedmethane
emissionsfrom648to538g/cow/day.Pirondiniet
al.(2015)evaluatedtheeffectofstarch(23.7and
27.7%DM)onmethaneemissionsindairycows,
ndingloweremissionsforstarch-richdiets(415
vs. 396 g/d, respectively). Finally,Hatew et al.
(2015) investigated the effect of starch (270 vs.
530g/Kg concentrateDM)andfermentationrate
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Gómez LM et al. Starch in ruminant diets: a review
(fastvs.slow)indairycows.Theyfoundnodifferences
inmethaneproducedperKgoffat-correctedmilkand
protein,orper KgDMconsumed, orasafraction of
thegrossenergyconsumed.However,thehighstarch
diet(46.9vs.43.1g/Kg)hadlessruminalmethane
per Kg of fermentable organic matter (42.6 vs. 47.4
g/Kg).Haleset al.(2012)evaluatedtheeffectofcorn
processing. They found that Jersey animals eating
steamedcornakesproducedlessmethanethanthose
eatingdryrolledcorn(58.77vs.74.31L/animal,11.65
vs. 14.06 L/KgDMintake,2.47 vs. 3.04% ofgross
energyconsumed,and3.30vs.4.18% of digestible
energ y consu med). The reduction was explained by
differences in ruminal fermentation, changi ng the
placeofdigestion(fromtherumentotheintestine),or
decreasedruminalpH.Scarceliteratureisavailableon
theeffectofstarchsourceandprocessingonmethane
emissions.InastudyreportedbytheCCRP(2012)a
reductionofmethaneemissionsincowsfedground
wheat(219gmethane/day,11.1gmethane/KgofDM
consumed)vs.groundcorn(424and19.5gmethane,
respectively).
The difference in methane production per starch
vs. cellulose unit does not depend on the chemical
composition,asboth carbohydratesarehydrolyzedto
glucosebeforefermentation.Conversely,hemicellulose
polymerincludessugarswith5to6carbons,whichcould
lead to changes in the fermentation prole (different
proportionsofVFA)andmethaneemissions.Ratherthan
thechemicalcomposition,thedifferences in methane
production from starch, cellulose and hemicellulose
appear to be a function of the microbial species that
degrade each substrate. Fermentation patterns and
methaneproductionvaryasmicrobialspeciesadaptto
changes in dietary substrates and ruminal conditions.
Additionally,associative effects between nutrients
inuence methane production, which means that this
gascanbeestimatedforthedietandnotforindividual
ingredients(Knappet al.,2014).
Relationship between starch and milk
composition and yield
Effect on milk yield and fat content
Milk yield response depends on the starch
source(Khorasaniet al.,2001) and its degradation
rate. Mosavi et al. (2012) compared milk yield in
Holstein cows consuming wheat, barley,maize or
potatoes. They found a reduced milk yield for the
diet added with potatoes, and attributed it to its
lower digestibility. Supplementation with rapidly
degradablestarchesinrumen-suchasbarley,wheat
or cassava- increases yield but reduces milk fat
(Sutton, 1989). Poore et al. (1993) found a milk
yieldincreaseof3.4Kg/dayand0.4%fatreduction
whenruminaldigestibilityincreasedfrom48to72%.
Milkfatreductionisassociatedwithchangesinthe
fermentationprole,causedbyarelativereductionin
lipogenicvs.glycogenicprecursors(Reynoldset al.,
1997).Rumenpropionateincreaseswhileacetateand
butyratedecreasewheningestionofrapidlydegradable
starchexceeds7Kg/day(Casperet al.,1990).Jurjanz
et al.(1998)evaluatedstarchsourceand level(wheat
orpotatopeels;<5,6,or>7.5Kg/d)onmilkyieldand
composition.Highstarchconsumptionfrom potato
peels(>7.5Kg/day)leadtoslowerruminaldegradation
andincreasedmilkfatcontent(+3.3g/Kg)compared
towheat.Fedinloweramounts,thestarchsourcedid
notaffectmilkfatsynthesis.Thelowerrateofstarch
degradationcouldhavereleasedmorefatprecursors.
Mosavi et al.(2012)alsoobservedslowerruminal
degradation for corn starch compared with wheat,
barley or potato, as well as increased acetate and
butyrateproductionalongwithhighermilkfat(3.43%
vs.3.12,3.09,and3.13%,respectively).Contraryto
thesendings,Chanjulaet al.(2004)didnotobserve
differences in milk production and compositional
qualitybyaddingcorn(lowdegradability)orcassava
(highdegradability)attwoinclusionlevels(55vs.
75%).
AccordingtoKennellyandGlimm(1998),milkfat
isreducedduetheinhibitoryeffectofmethylmalonyl
CoA(synthesizedfrompropionicacid)onfattyacid
synthesisinthemammarygland.MethylmalonylCoA
accumulation competitively inhibits malonyl CoA
(VanSoest,1994).
Reynoldset al.(1997)associatedmilkfatdecrease
withincreasedlevelsofplasmaglucoseandinsulin
in animals fed high amounts of the supplement.
Insulinlowerslipolysisandpromoteslipogenesisin
adiposetissue,reducingfattyacidsavailabilitytothe
mammarygland,thusdecreasingmilkfat.According
to Van Soest (1994), lipogenesis in adipose tissue
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Gómez LM et al. Starch in ruminant diets: a review
is insulin dependent, which is not the case for the
mammarygland.
Thereductioninmilkfatcanalsobeexplainedby
increasedtrans-unsaturatedfattyacidsintherumen
(Gaynoret al.,1995).Cerealgrainsarehighinlinoleic
and oleic acid. A ruminal pH decrease due to the
dietcandisturbbiohydrogenationofunsaturated18
carbonfatty acidsincreasingtransC18:1fattyacid
(transisomersresultfromincompletemicrobialbio-
hydrogenationoflinoleicacidintostearicacid).Itis
knownthatruminalandmilkincreaseintransC18:1
iscorrelatedwithlowmilkfatlevelsincowsfedhigh
graindiets(Griinariet al.,1998).Corncontainsahigh
concentration of linoleic (C18:2) and octadecanoic
acid (trans C18:1),whichinhibit biohydrogenation
andreducelipogenesisinthemammarygland.
AccordingwithMontoyaet al.(2004),theoptimal
content of nonstructural carbohydrates (NSC) for
maximizingmilkyieldisbetween30and38%ofthe
diet. Those researchers supplemented cows with 4
Kgofacommercialconcentrateand0,6,and12Kg
offreshpotatoes,thusNSCaccountedfor7.2,12.4,
and17.9%ofDMintake.Milkyieldwashigherfor
the potato treatments (17.2 vs. 15.8 liters/cow/day;
p=0.004).Nevertheless,nodifferencewasobserved
fortheinclusionof6vs.12Kgpotatoes,whichcould
beassociatedwithalimitedabilitytousepotatoNSC.
Theirstudyfoundnodifferencebetweentreatmentsfor
fatpercentageand production(p>0.05).Pimentel et
al.(2006)alsoevaluatedcassavasupplementationon
milkyieldandcomposition.Theyreplaced0,25,50,
and75%ofcornwithcassava,ndingalineardecrease
of30and1.15g/dayinmilkyield(correctedfor3.5%
fat)andfatproduction,respectively.Accordingtothe
authors,theviabilityandlevelofcornsubstitutionwith
cassavawilldependonalowcostofsubstitutionthat
compensatesfortheexpecteddecreaseinproduction.
Dann et al. (2014) evaluated three starch levels
(17.7, 21.0, and 24.6%) in Holstein cows using
increasing levels of ground corn. They found that
solids-corrected milk yield was not affected by the
diet, averaging 40.8 Kg/d. They concluded that
starch content did not affect rumen fermentation or
performance.Theirhigheststarchlevel(onaDMbasis)
was between 23 to 30%, which follows within the
recommendedrangeforlactatingcows(Grant,2005).
Delahoyet al.(2003)conductedtwoexperiments
assuming that supplements such as steam-flaked
corn(SFC)andnon-forageber(NFF)sourcesmay
provide benets over corn. In the rst experiment,
animalswereassignedtoacracked-corn(CC)orto
asteam-akedcorn(SFC)supplement.Inthesecond
experiment,animalswereofferedgroundcorn(GC)
ornoforagesourcesofber(NFF).No differences
wereobservedinmilkyield(24.3and27.5Kg/dfor
experiments1and2,respectively),explainedbyalack
ofdifferenceinnetenergyconsumptionforlactation,
which exceeded the requirements (Experiment 1).
Anotherfactorthatcouldexplaintheseresultsisthe
qualityofthepasture,whichdidnotreducethepH,a
targettoimprovebyNFFinclusioninExperiment2.
Effect on the protein content
Dietsrichinnonstructuralcarbohydratesincrease
ruminalammonianitrogenutilizationandmicrobial
protein synthesis (Svihus et al., 2005). Therefore,
whendietaryenergyincreases,metabolizableprotein
is also increased. Mosavi et al. (2012) evaluated
theeffectof four starch sourcesonmilkproteinin
Holstein cows. While protein levels of milk were
similar (3.03, 3.10, 3.14, and 3.04%) for wheat,
barley,corn and potato supplements, respectively,
milkproteindifferedin favor of wheat, barley and
corn,comparedtopotato(1.08,1.06,1.06,and0.98
Kg/d,respectively; p=0.02).GozhoandMutsvangwa
(2008)foundnodifferenceinmilkproteinforanimals
feddietsbasedonwheat,barleyorcorn,buthigher
milk protein was observed for diets based on corn
vs. oats. On the contrary, other studies comparing
slowversusfastruminaldegradingstarchesfoundno
differencesin milkprotein(Khorasaniet al., 2001;
Silveira et al.,2007;Cabritaet al.,2009).
It has been suggested by Huhtanen and
Sveinbjörnsson(2006)thatenhancedstarchdigestion
in the small intestine increases milk protein,
perhapsbysparingaminoacidsfrombeingusedfor
gluconeogenesisintheliver.Theyreportastudyin
whichmilkproteinyieldwasslightlybutsignicantly
higherformaizecomparedwithbarleysupplements.
Contrarytothisconcept,increasingstarchdigestion
intherumenisconsideredadvantageousintermsof
milkproteinyield,sinceitincreasestheenergysupply
formicrobialproteinsynthesisandthemetabolisable
87
Rev Colomb Cienc Pecu 2016; 29:77-90
Gómez LM et al. Starch in ruminant diets: a review
protein ow to the small intestine (Thair, 2012).
Finally, Reynolds (2006) reports a study in which
therewasnoevidencethatthesiteofstarchdigestion
increasedmilkproductionorchangeditscomposition.
Final thoughts
Rumenfermentationofstarch-althoughitreduces
energy efciency over the enzymatic digestion in
the intestine- determines its nutritional value for
ruminants. The rate and extent of ruminal starch
digestion alters pH, cellulolytic activity, microbial
proteinsynthesis,methaneemissionsand,eventually,
animalproduction.Thereisa considerablebodyof
researchon degradation potential of various cereal
grains, but little information on non-traditional
sourcesofstarchthatcouldreplacecerealgrainswhen
availabilityandcostsarecompetitive.Thestructural
traitsofstarch fromthesesources,their interaction
withothercomponents,andtheeffectofprocessing
should be examined. In vitro digestion techniques
constituteastartingpointforstudyingtheextentand
kineticsofstarchdegradationfromnon-conventional
sources.
Starch is the main energy component used in
ruminants feed to modulate ruminal fermentation
andpromote sync with the nitrogen sources. More
researchisrequiredtoevaluatetheeffectofusingone
ormoresources of starch —with different degrees
of degradability and processing— on protein use
efficiency, milk yield and compositional quality.
Studiesshouldfocusonadditionlevelsandnutrient
composition of the forage base according with the
stage of lactation and energy requirements of the
animal.
Acknowledgements
The Administrative Department of Science,
TechnologyandInnovation(Colciencias,Colombia,
call 569 of 2012. Code 1115+569-33874) and
the Sustainability Strategy 2014-2015 (CODI,
UniversidaddeAntioquia,Colombia)supportedthe
research project entitled “Evaluación in vitro e in
vivodediversasestrategiasnutricionalesparamitigar
las emisiones de metano y su impacto productivo,
reproductivo y económico en ganadería de leche
especializadaenelnortedeAntioquia”,whichmade
possiblethisliteraturereview.
Conict of interest
Theauthorsdeclaretheyhavenoconictsofinterest
withregardtotheworkpresentedinthisreport.
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... The presence of starch plays a critical role in energy production in cereal grains and potatoes. Nevertheless, the quantity of starch varies across these food sources (Gómez et al. 2016). Starch digestibility is influenced by a variety of factors, both intrinsic and extrinsic. ...
... Altering the levels of starch concentration and fermentability in the dietary intake can have a notable effect on the productivity of dairy cows (Gómez et al. 2016;Tian and Sun, 2020;Shipandeni et al. 2023). This phenomenon encompasses the influence of energy intake, partitioning, and protein absorption. ...
... A meta-analysis by Moharrery et al. (2014) illustrated how rumen starch digredability was affected by both the intake and source of starch. Conversely, the digestibility of starch in the small intestine was primarily influenced by the origin of starch, while the digestibility in the hindgut was solely dependent on the escape of pre-compartment starch (Mosavi et al. 2012;Gómez et al. 2016). Ruminal breakdown rates of different feed components, such as starch, are commonly assessed using the in situ technique, in which feed samples are placed in nylon bags and incubated in a ruminant with a cannula. ...
... It is known that in the corn, the starch is surrounded by the protein matrix which affects or retard their enzymatic hydrolysis (Bednar et al. 2001 andGómez et al. 2016), obstacle that the sweet potato did not has. It has been showed a reverse relation between the amylose-amylopectin proportion and starch degradability (Bednar et al. 2001 andBrewer et al. 2012), product of high amount of hydrogen bonds that the amylose make, situation which made it more compact with less surface per molecular area (Brewer et al. 2012) and more resistance to enzymatic action. ...
... and 22.1:77.9 %, respectively (Hernández et al. 2008, Gómez et al. 2016and Manzanillas 2018. However, there is not information of this proportion for the starch of the sweet potato silage, process that can increase it due to the starch loss, possibly as consequence of high enzymatic hydrolysis of the amylopectin. ...
... y 22.1:77.9 %, respectivamente (Hernández et al. 2008, Gómez et al. 2016y Manzanillas 2018. Sin embargo, no hay información de esta proporción para el almidón del camote ensilado, proceso que puede aumentarla debido a la pérdida de almidón, posiblemente como consecuencia de mayor hidrólisis enzimática de la amilopectina. ...
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In order to evaluate the substitution of ground granule corn by integral sweet potato silage in a diet for male cattle fattening, a completely randomized design with factorial arrangement 2x2 was used. A total of two substitution levels of the granule corn by integral sweet potato silage, dry basis were studied: 0.0 and 100.0 % and two evaluation periods (28 days each), with previous adaptation of 21 days. The diets were iso-energetic (10.88 MJ ME kg-1 DM) and iso-protein (12.0 % CP). The silage had good organoleptic characteristics. There was not effect of the silage (p > 0.05) on dry matter intake, crude protein and metabolizable energy (2.66 kg, 0.321 and 27.97 MJ 100 kg-1 LWday1). The daily weight gain (p > 0.05), the dry matter conversion and metabolizable energy (p > 0.05), with average of 1.84 kg animal-1 day-1, 6.86 kg and 72.00 MJ kg-1 weight gain , respectively was neither affected. The substitution of 0.0 % showed better crude protein conversion than those of the 100.0 % (0.796 y 0.849 kg kg-1of weight gain) (p < 0.01). The weight in hot carcass was not affected by the silage, with average of 269.4 kg animal-1 (p > 0.05).The feeding cost of the treatment with the silage was 21.4 % lower than those with the ground granule corn. It is concluded that the integral sweet potato silage have viability as competitive alternative for the substitution of the granule corn in fattening diets of male cattle.
... Wheat starch has a higher proportion of amylopectin compared to corn, resulting in it being easier for it to bind with amylase for hydrolysis. Wheat starch was slightly more digestible in the total tract [38]. It has been suggested that reducing the ratio of amylose to amylopectin in the diet can improve the ADG of Qinchuan cattle [39]. ...
... Similarly, in the current study, rumen protein AQP3 detected the 20 and 28-38 kDa bands and their expression patterns were similar. Therefore, we believe that the two distinct protein bands detected by our AQP3 antibody may represent N-glycosylated (28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38) and nonglycosylated (20 kDa) forms of the AQP3 protein [61]. This indicates that the long-term regulation of AQP3 proteins appears to be primarily influenced by dietary fermentable starch. ...
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Alfalfa silage due to its high protein can lead to easier feeding management, but its high proportion of rumen-degradable protein can reduce rumen nitrogen utilization. Nevertheless, increasing dietary energy can enhance ruminal microbial protein synthesis. Thirty-two Suffolk female sheep were used in this study, with a 2 × 2 factorial arrangement of treatment. The four treatments were a combination of two forage types (alfalfa hay; AH vs. alfalfa silage; AS) and two rumen-degradable starch levels (low RDS; LR vs. high RDS; HR) with a 15 d adaptation and 60 d experimental period. The rumen content and rumen epithelium samples were collected after slaughter. Feeding AS increased the rumen isobutyrate, valerate, ammonia-N (NH3-N) concentration, urase activity, and papillae height (p < 0.05) and reduced the feed to gain (F:G), rumen bacterial protein (BCP), rumen lactic acid concentration, and papillae width (p < 0.05) of sheep. Increased RDS in the diet improved the daily matter intake, average daily gain, and rumen weight, reduced the F:G, and enhanced the rumen nitrogen capture rate by decreasing total amino acids and the NH3-N concentration to increase BCP, aquaporins 3 gene, and protein expression. The rumen microbiota also changed as the HR diet reduced the Chao index (p < 0.05). The metabolomics analysis showed that feeding AS upregulated the rumen tryptophan metabolism and steroid hormone biosynthesis, while the purine metabolism, linoleic acid metabolism, and amino acid biosynthesis were downregulated. Furthermore, increased RDS in the diet upregulated rumen lysine degradation and sphingolipid metabolism, while aromatic amino acid biosynthesis was downregulated. Additionally, the correlation analysis results showed that ADG was positively correlated with 5-aminopentanoic acid, and three microorganisms (unclassified_f__Selenomonadaceae, Quinella, Christensenellaceae_R-7_group) were positively correlated with the rumen isobutyrate, valerate, NH3-N concentration, urase activity, tryptophan metabolism, and steroid hormone biosynthesis and negatively correlated with linoleic acid metabolism and amino acid biosynthesis in sheep. In summary, increased RDS in the diet improved the growth performance and rumen N utilization and reduced bacterial diversity in sheep. The alfalfa silage diet only increased feed efficiency; it did not affect growth performance. Additionally, it decreased rumen nitrogen utilization, linoleic acid, and amino acid biosynthesis. Nevertheless, there were limited interactions between forage and RDS; increased RDS in the AS diet enhanced the nitrogen capture rate of rumen microorganisms for alfalfa silage, with only slight improvements in the purine metabolism, linoleic acid, and amino acid synthesis.
... Cows offered the less-fermentable starch source also had higher milk production in the early postpartum period and after this period when all cows received a common diet [6]. Corn grain contains starch with moderate ruminal fermentability compared with the more rumenfermentable starch from wheat grain [22] and should allow for increased post-ruminal digestion of starch and differential supply of glucose and glucose precursors. The rate of starch fermentation in the rumen can modulate the production of volatile fatty acids, such as propionate, and the supply of these fuels to the cow. ...
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This experiment determined the effects of two different starch sources when offered twice a day to cows during the early postpartum period (1 to 23 d postpartum, treatment period) on dry matter intake (DMI), feeding behavior, and milk production. The subsequent effects on milk production in the carryover period (24 to 72 d) where cows received a common diet (grazed perennial ryegrass pasture plus concentrate supplements) were also measured. Thirty-two multiparous dairy cows were offered concentrate feed (8 kg DM/d) containing 5 kg DM of crushed wheat grain or ground corn grain (7 h in vitro starch digestibility of 65.8% and 58.8%, respectively). At each milking (morning and afternoon), cows were offered half of the concentrate feed, and upon return to their individual stalls, they were offered perennial ryegrass pasture silage (56.2% neutral detergent fiber (NDF), 39.8% acid detergent fiber (ADF), 16.6% crude protein (CP)) at 130% of their expected daily intake. Dry matter intake, milk yield, and body weight were recorded daily. Blood and milk sampling, body condition score, and feeding behavior measurements were performed weekly during the treatment period. During the carryover period, milk sampling and body condition score measurements were conducted on a weekly and fortnightly basis, respectively. In the treatment and carryover periods, there was no significant effect of starch source treatment on DMI, milk yield, milk composition, change in body weight, or body condition. Similarly, the starch source did not affect the concentrations of blood markers of energy status or inflammatory response. Despite differences in the in vitro starch fermentability between treatments, the starch source did not significantly affect production responses. It is possible that the elevated NDF and ADF concentrations of the forage offered during the treatment period, the limited difference in starch fermentability between treatments, and the temporal supply of fuels to the liver when starch sources were offered twice a day may have offset the effects of the type of starch source on DMI and production via physical signals associated with rumen fill and distention.
... The lignified fractions of WTB also reduced DM ruminal degradability. In contrast, the protein matrix surrounding starch granules was probably almost entirely degraded (Gómez et al., 2016), which explains the higher DM degradability found in silages containing higher proportion of maize grain and lower of WTB. The 45% WTB inclusion level significantly impaired ruminal degradation compared to the other WTB levels, due to the elevated undigestible fibre content observed in silages rehydrated with such a high amount of WTB (Ribeiro et al., 2020). ...
... These grain feeds contain higher starch levels than other feeds, but their starch content, structure, and ruminal degradability characteristics are different (Huntington et al., 1997;Philippeau et al., 1999;Swan et al., 2006). Wheat and corn have the highest starch content (76.0 %), followed by sorghum (71.3 %), barley (64.3 %), and oat (58.1 %) (Gomez et al., 2016). Although the degradability of starch in the rumen varies according to the grain type, the starch of wheat and barley is more degradable in the rumen than sorghum and corn (Van Barneveld, 1999). ...
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This study aimed to determine the effects of whole and steam-flaked corn supplementation on the feed intake, serum parameters, and reproductive performance of dairy ewes. A total of 48 ewes (at the end of their lactation period; 57 ± 1.3 kg body weight, BW; 2.69 ± 0.19 body condition score, BCS) were divided into three treatment groups (16 animals per group): the control group (C), which was fed with alfalfa hay and corn silage; the whole-corn group (WC), which was fed with alfalfa hay, corn silage, and whole corn; and the steam-flaked corn group (FC), which was fed with alfalfa hay, corn silage, and steam-flaked corn. The study was conducted for 15 d before ram introduction and for 30 d during the mating in the breeding season. The WC group had higher dry matter (DM), metabolizable energy (ME), and starch intake values than the FC group (P<0.0001). The BW and BCS values were increased in the groups supplemented with whole corn and steam-flaked corn (P≤0.05). The lambing rate was higher in ewes from the WC and FC groups (P≤0.05). Whole and steam-flaked corn supplementation did not affect the non-return ratio or litter size (P>0.05). The serum glucose concentration was similar among the groups, whereas the serum urea concentration increased with either whole or steam-flaked corn supplementation (P≤0.05). In conclusion, whole and steam-flaked corn supplementation increased the BW, BCS, and lambing rate values in dairy ewes.
... Bitter vetch (Vicia ervilia) and sorghum (Sorghum bicolor (L.) Moench) are underused crops in northern Morocco (Boukrouh et al., 2023b(Boukrouh et al., , 2024Hmimsa and Ater, 2008). Bitter vetch, an ancient legume native to the Mediterranean region, is cultivated as both fodder and grain. ...
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Bitter vetch and sorghum grains are alternative local feed resources that are underutilized in the southern Mediterranean area. This study aimed to assess the effects of incorporating these grains into the diet of local goat breeds on growth performance, carcass characteristics, and meat quality. Twenty-four goat kids were divided into three groups. The control group received a conventional diet consisting of oat hay, barley, and fava beans. In the first group, fava beans were replaced with bitter vetch, and in the second group, barley was replaced with sorghum. At the end of the trial, the animals were slaughtered and carcass characteristics and meat fatty acid profiles of the longissimus dorsi (LD) muscle were determined. Alternative grain incorporation had no significant effect on the growth parameters. Still, it significantly affected carcass characteristics, especially in the sorghum group compared to the control group, where mesenteric fat was lower (266 vs. 437 g). The back color was lighter (L * = 55.1 vs. 59.
... 88.1-88.3% and 80.7-84.6%, respectively, depending on the different feed processing techniques (Gomez et al., 2016) and feeding managements. ...
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In this study, it was aimed to determine the effects of different starch sources on ruminal fermentation and in situ digestibility characteristics and some blood parameters in cows. In the study, three different total mixed rations (TMR) with similar energy, protein and starch contents were prepared and these TMR’s formed the groups of the ex-periment. The main starch sources of the TMR’s were from the barley, wheat, and corn grains, respectively. The study was carried out as two consecutive trails using 3 non-lactating Holstein female cattle with rumen cannulate within a 3 × 3 Latin square trial design. These TMRs were fed at ad libitum and then nutrient intakes, ruminal fermentation (pH, acetic, propionic, butyric, and lactic acids), some serum (urea, glucose, total protein, albumin, triglyceride) and blood gas parameters (pH, pCO2, pO2, HCO3-, Na+, K+, Ca++, Cl-, anion gap, lactate) were determined. Also, in situ dry matter and starch degradability were carried out in these animals. Nutrient intakes of cows fed different TMRs were similar (P>0.05), except neutral detergent fiber (NDF) intake (P0.05). As a result, it was determined that there were no serious changes in the ruminal fluid, serum, and blood gas parameter values of the subjects due to the content difference of the trial TMR’s. On the other hand, it was determined that in situ dry matter (DM) and starch degradability of barley and wheat were significantly different among cereal grains, ruminal DM and starch degradability of corn followed a slower, stable, and gradual increase.
... The ruminal pH ranged from 6.70 to 6.78 in the current investigation, which falls within the established range of rumen ecology (pH 6.20 to 7.00) [30]. The decrease in pH at 4 h indicates that the dietary changes had an immediate impact on rumen pH. ...
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Simple Summary The increasing expenses of animal feed, which are affected by the prices of protein and carbohydrates, emphasize the need for alternate sources of protein. Thailand is now doing research on tropical legumes, with a special focus on winged beans. The tubers of winged beans, which are rich in carbohydrates and protein, provide a viable alternative to animal feed. The process of pelletizing winged bean tubers has many benefits, including enhanced durability and prolonged preservation. This makes it a feasible substitute for corn meal in animal feed. The research assesses the replacement of corn meal with winged bean tuber pellets in ruminant diets, examining its impact on ruminal fermentation, gas production, and in vitro degradability. Abstract The objective of this study is to evaluate the effects of replacing corn meal in ruminant diets with winged bean (Psophocarpus tetragonolobus) tubers (WBT) on ruminal fermentation, gas production parameters, and in vitro degradability. The study employed a completely random design (CRD) in its execution. The experimental design employed was a completely randomized design (CRD), featuring eleven levels of corn meal substitution with winged bean tubers pellet (WBTP) at 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%. The levels were grouped into four categories of replacement: control (0% in the diet), low levels (10%, 20%, and 30% in the diet), medium levels (40%, 50%, 60%, and 70% in the diet), and high levels (80%, 90%, and 100% in the diet). The experimental results indicated that substituting corn meal with WBTP at moderate and high levels in the diet could improve the performance of the fermentation process by increasing the gas production rate constant from the insoluble fraction (p < 0.01). The IVDMD exhibited a higher degree of in vitro degradation after 12 h (h), with the mean value being higher in the high group compared to the medium until the high group (p < 0.05). At the 4 h mark, the groups that substituted corn meal with WBTP exhibited a decrease in pH value (p < 0.05) in comparison to the control group. The substitution of corn meal with WBTP resulted in the lowest protozoal count after 8 h in the median group (p < 0.05). A significant difference in the effect of WBTP on total volatile fatty acid (TVFA) concentration was observed at 8 h after incubation (p < 0.05). The medium and high levels of WBTP replacement resulted in the lowest TVFA concentration at 8 h (p < 0.05). The mean proportion of acetic acid (C2) linearly declined and was lowest when a high level of WBTP replaced cornmeal (p < 0.05). The concentration of propionic acid (C3) at 8 h after incubation and average values were linearly significantly different when various levels of WBTP were utilized. Replacing corn meal with WBTP at a high level showed the highest concentration of C3. Moreover, substituting medium and high concentrations of WBTP for corn meal resulted in a significant reduction in both the C2:C3 ratio at 8 h and the mean value (p < 0.05). In conclusion, WBTP exhibits a nutritional composition that is advantageous and may be an energetic substitute for corn meal.
Article
The utilization of polyphenol‐modified starch in ruminants has not undergone extensive exploration. This study aimed to investigate the impact of the complex formed between starch and Melastoma candidum D. Don fruit extract on physicochemical properties, phenol release kinetics in various buffers simulating the gastrointestinal tract, methane production, and post‐rumen digestibility. The interaction between starch and M. candidum D. Don fruit extract significantly (p < 0.001) increased resistant starch and particle size diameter. The maximum phenolic release from complex between starch and M. candidum D. Don fruit extract, due to gastrointestinal tract‐simulated buffers, ranged from 22.96 to 34.60 mg/100 mg tannic acid equivalent. However, rumen and abomasum‐simulated buffers released more phenolic content, whereas the intestine‐simulated buffer showed higher antioxidant activity (ferric ion‐reducing antioxidant power). Furthermore, complex between starch and M. candidum D. Don fruit extract significantly decreased dry matter rumen digestibility (p < 0.001) and maximum methane gas production (p < 0.001).
Chapter
The ready availability of corn at low and steady prices, its storability from season to season, and its high starch content led to the development of commercial processes for the recovery of corn starch. Although grain sorghums are a major world crop, they are considered to be inferior to corn for food, feed, or industrial uses. They require less water than corn for growth; therefore, they are grown in the arid regions. The principles of steeping and milling corn for the separation of starch are universal because they are dictated by the nature of the corn kernel and the properties of its components. Feed products produced during grain sorghum starch production have names and protein contents similar to the com starch feed by-products. Milo (sorghum) steep liquor has been used as an ingredient in liquid feed supplements for beef cattle feeding. As grain sorghums are brown in color and contain condensed tannins, all the feed products are dark brown in color. Therefore, they are used almost exclusively in ruminant feeds.
Chapter
Corn has been the staple food for countless generations of natives of North and South America. Corn has reached its present state of development through continual mutations, hybridizations, segregations and selections by random, natural processes, and by conscious selection. A number of types have developed by this process, which differ primarily in the structure of the grain. Grain sorghum (Sorghum bicolor Moench) is a cereal grain also known in some localities as milo, milo maize, or kaffir corn. The sorghum plant resembles the corn plant, but the grains, about the size and shape of No. 5 shot, are borne on a terminal, bisexual rachis (head). Mature corn or sorghum kernels are unique, well-organized entities that exist for the purpose of reproducing the species. Descriptions of their structures and compositions are helpful in understanding the process of disruption that is achieved during the wet-milling process. Grain sorghums are considered to be inferior to corn for food, feed, or industrial uses. They require less water for growth than corn and, therefore, are grown in more arid regions. The wet-milling of grain sorghum is similar to that of corn, although novel methods of extracting starch from sorghum have recently been investigated. Wet milling, as a process to recover starch, is essentially a method of disrupting the corn or sorghum kernel in such a way that the component parts can be separated in an aqueous medium into relatively pure fractions.
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Small- and large granule starches were isolated from pin-milled and air classified fractions of waxy (SB 89528), regular (Condor), and high-amylose (Glacier) barleys, and their physicochemical properties were investigated. The isolations contained 95-97% starch, 0.1-0.3% protein, and 0.1-0.2% ash. Scanning electron microscopy showed that the starch granules were oval to round in shape with diameter ranges of 2-10 μm for small and 12-26 μm for large granules. The starches had A-type X-ray diffraction patterns, typical of cereal starches. The differences in the physicochemical properties such as X-ray diffraction relative intensities, swelling factor, amylose leaching. Brabender pasting, differential scanning calorimetry thermal characteristics, and resistance to acid and α-amylase hydrolysis were greater among the three genotypes than between the small and large-granule starches from the same genotype. The large granule barley starches may be substituted for corn starches because their physicochemical properties are generally similar.
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Matching production of milk components to demand improves the biological efficiency and ultimately enhances the overall profitability of the dairy industry. Consumer demand for the major components of milk has changed considerably over the past two decades. To align production with demand successfully, the dairy industry must be able to respond to changes in consumption patterns. A better understanding of the biological control of milk protein, fat and lactose synthesis is necessary before the dairy industry can fully exploit the potential to alter milk composition. The topic of this review is the current state of knowledge about using dietary intervention or genetic-based techniques to alter the composition of bovine milk. The usefulness of the two approaches is evaluated. The methods are also assessed in terms of both their present and anticipated abilities to exploit the biological potential to alter the composition of milk. The scope of the article covers the details of current approaches and relevant difficulties, as well as expected advances that should contribute to the development of more refined and therefore more effective methods for selectively altering milk composition. Progress in targeted modification of milk components depends upon an increased understanding of lactation biology, particularly the genetic basis of milk component synthesis. Bioactive and functional components of milk are discussed in terms of target compositions for milk and implications for human health. Advances in knowledge about ruminant nutrition and genetics will allow the dairy industry to modify milk composition and better match consumer demand, especially for components perceived as healthy.
Chapter
The functional properties of starch depend on a number of integrated factors, which include polymer composition, molecular structure, interchain organization, and minor constituents such as lipids, phosphate ester groups, and proteins. Chemical, enzymic, and physical modification of starch, with either preservation or destruction of the native granule, broaden the functionality-imparting properties of different starches. The greatest challenge is to relate physicochemical properties and functions of starch with information on various levels of structure. There is a diversity of structures depending on starch source, amylose-amylopectin ratios, lipid, moisture and plasticizer contents, and thermo-mechanical histories. In addition to difficulties in describing and quantifying the structural morphology of starch materials, the ultra structural level of starch also presents a great challenge. This chapter discusses some aspects of phase transition behavior and other material properties of starch, particularly as they pertain to the structural order and interactions of the starch polysaccharides with water, lipids, and other solutes. Understanding the thermally induced structural transitions of starch is helpful in controlling its physical properties and processing behaviors (e.g. plasticization, viscosity), as well as in designing products with improved properties (e.g. texture, stability). The description of the state and phase transition behavior of starch systems is focused on with an emphasis on their molecular organization and their response to various environments (temperature, solvent, other cosolutes). Selected material properties are also discussed in an effort to demonstrate structure-function relationships of this biopolymer mixture in pure systems and in real food products.