McDonald cap10001 livro sobre silagem em ingles

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\1 I 1/1' (,111 dition ISBN 0948617012
ISBN O 94861712 8I 11 I I-LlJf..NT
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I" I N D I1 -A LTH ISBN0948617160
ISBN O 94861700 4
ISBN 094861721 7)111 I /WJI EREALS
)II~II" / ( R ~'IILK ANDMEAT
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I IINArJ (
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I 1I JlIN(i
ISBN 0948617071
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':' EVALUATIONAND UTILlSATION ISBN 0948617/87
- RUMINANTS: Principlesand Practice ISBN O94861709 8
I I' ( ()MI'OSITION: UK Tables of Feed Composition
I' 'lJlllllllvf V iluc for Rurninants ISBN 0948617055
, It ",.., Ruw Materiais for Animal Feed
1"'j'"1I1I1I1 r II1(J arrners Second
.Edition
ISBN 0948617 152
Adr iana Guim
I·Prof" AdjuntaNutnção Animal. . Mat 1310722~ -. .,~~, .
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liochemistry
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S"i.'··:·~I· - r::Ia~e w . 'i2J-;UV... ,... ~pl5. O -
Second Edition
P: McDONALD A.R. 'HENDERS,0f'J S.J.E. HERON-
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Second Edition
,: The Biochemistry
of
Silage
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Peter McDonald
Formerly Reader in Agricultura/ Biochemistrv,
University of Edinburgh
and
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Head of lhe Department of Agricultura! Biochemi,'ilry,
Edillburgh School of Agriculture.
Nancy Henderson
Senior Si/age Spedalisi'jorihé Scottish Agricultural Coltege,
Bush Estate, Penicuik,
ShirIey Heron
Research Microbiologist, ICl Bia/ogical Products, Bi/lingham, Cleveland.
cff.driana (}uim
Zootecnista CRMV 777/Z
Ji' J:-rr l~'I:~ CHALCOMBE PUBLICATIONS
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Contents
19
\48 ;
J.,,--'"
Page
Preface ' _ _ , ,'. 7
~8J .
l .._" -~
1152
, t"._"
Ü6"L_~__
184
~uthOí lndex .. , . , . , , . , , , . , .. , .. , , . ' ,' . , , .. , . . . 306
2..';0
, , ,
Chapter :~, \ Lesses during ensílage .,..... .. ,.", .. ",',.,.:"., .. " ..
Chapter 9 Nutritive value of silages , , . ' , , , . , . ' , . ' .. .-, , . , .. : , ,
Chapter 1 lntroductíon ", . , , ' , ' ,.. , ',' , , , .. ' , , , , .. , , .. ' ,
Chapter 2 Crops for silage , , , " .. , .
..~ r;"-'" .
Chaptez 3 \ Plant enzymes .... , .... , .. , ... , .. , . , , , , . ' .. , , . , , , , . : . , . ,
I
Chapter!4 : Microorganisms . , , , , , ' .. , , .. , , . '. , , . ' " ..
"--1
Chapterê ] Oxygen , , , .. ',',. , , ,
-.' ;
I r t dition published by J. Wiley and-Sons ltd. Chapterjé : Water ,., ,'" .. , .. , .. : , , , , , , . " '" .
Chapteri7! ~dditi",es, ,., ,.:, , , , , , , . , . , , . , , , , .. , .. ,
I N O 9.48617 22 5 ,/
SubjecQindex .... , ... , , .. , .... , , ' ... , , , , .' , ... , , . , .. , , . 321
-.-,
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I und edition published byChalcombei Publieatíons, ,1;l Highwoods
Ilr v . Marlow Bcttorn, Marlow, Bucks SL7 3PU' '
,t dltion 1981
,,""rI edition 1991
P. McDonald, AR, Henderson and S,:'.E. H~;Ó~~ 1991
11 IIlln/ll,\' reserved. No pan of rhfs publication ma)' be reproduced. stored in a
I I1 1111/ system, or transmitted in any form or , by any means electronic,
1/1 r/lIl/lf 'aI; photocopying, recording 01' otherwise, without lhe prior permis-
\ '1/1 ({'he .Copvrigh: owners.
1'1 IlIr'c1 ln reat Britain by Cambrian Printers Lrd: Aberystwyth
' ... ~;
'Preface
Sinee the first edition 01 this book was published in 1981. silage has beeome even
(: more importam as a winter f'eed .for ruminanl animais and in many countries
cnsilagc is JlOW lhe major mctbod oflorugc conscrvution. As a conscqucncc. thc
levelof research in this field during lhe past 10 years has increased considerably
~' ando in this new edition of lhe Biochernistryof Silage , we have atternpted to take
into account lhe main findings of these studies, In lhe second edition we have
followed a similar formal to that of lhe ürst , but have found it more convenient 10::
discuss lhe microbiology of süage in a single chapter ..
We "'ipuld like toexpress our thanks to the many individuais on whose help we
have diàwn. In particular we are grateful to Dr Anne McDonald for her
invaluable help and advice in the preparation'nnd editing of lhe rnanuscript. We .
are grateful to Dr Mike Wilkinson and Dr Barbara Stark for their helpful
suggestions, Our thanks are also due to lhe staff of lhe Nutrition Departrnent of
lhe Edinburgh School of Agrículture. r
We are grateful to those who gave perrnission to reproduce copyright data,
particularly Dr J.M. Wilkinson (Table 1.1 and Figure lU), Acadernic Press,
London (Figure 2.1). Carnbridge University Press(Table 2.8). Springer-Verlag
(Figure 3.7) .. Oxford University Press (Figure 3.10), Longman. London (Figure
3.9), Bioehemical Journal (Figure 3.15). The British Grassland Society (Tables
5.4 andR.3. Figure 8.]), Blackvell Scientifie Publications (Tables 5.1 and 9.28)
~, . and the Controller of Her Majesty's Stationery Office (Figures 6;2 and 6.4).
. '
P. McDonald
A.R. Hendcrson
S.J.E. I Ieron
October 1l}90
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Chapter 1
lntroduction
The main objective in the conservation of any crop is to preserve it at lhe
optirnum stage of growth for use during those .seasons when the crop is
unavailabíe. ln countries such as lhe United Kingdom, where there is a restricted
.growing season, conserved forage has forrnany-centuries played a major role in
helpiog to rneet lhe nutritional needs of ruminants for survival during lhe winter
period.
Haymaking has long been lhe traditional technique of preserving forage, but
the need to delay harvesting until a mature stage of growth of relatively high dry
.matter (DM) content was reached meant that lhe crop was of low digestibility
before it was dried. This fact coupled with the vagaries of the weather, which
frequentíy resulted in high lesses during lhe drying processo led to a product of
variable composition, and often.of low nutritional value. Early interest by farmers
in conserving crops by natural fermentation as silage stemmed frorn lhe
-realisaton that this process was less deperdent on both the weather and lhe need
to harvest crops at an advanced stage of growth.
Taday, although haymaking methods have been improved considerably by lhe'
introduction of .:new drying techniques, many farmers find these to be toa
specialised and time-consuming and prefer to preserve their crops instead as
silage. ln Western Europe , and in many other regions of lhe world, the quantity
'of forage preserved as silage now exceeds that preserved as hay!:' (Table 1.1).
Table Ll , Estimaled production of sila~e and .hay .in,.Weslern Europe, 1975 and 1?85
(million tonnes UM)I .
1975 19!!5
Silage Hay Tolal . Siluge Hay. Total
European Cornmunity 12 44.6 51U 102.9 70.9 45.8 116.i'
. ·Austria + Switzerland 1.7 5.!! 7.5 3.2 4.7 7.9
Scandinavia l.O 7.3 11.3 1.9 7.6 9..1
Tplal 47.3 . 71.4 IIIU . 76.U 58.1 IJ4.l
.. ' HISTOR'ICAL DEVELOPMENT OF SILAGE
Silage is lhe material produced by lhe controlled Iermentation of a crop of high
moisture contento Ensilage is the narne giyen to lhe process and the container, if
used, is called lhe silo, The storage of material in silos. either ~I$ grain or as a
green crop, has been common ,practice·for mariy centuries.:'
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scuxon of lhe ye;'t'f'~~;í,jJ,"\Ve hnvc lhe mosi Icisure 10 111<1"e il, il;ltlwhen it b ririg-
lhe bcst price in lhe i'l',., .....: our bcc v l·s can bc kcpt gro\\'ing lhe year roun d , ill1,(;
more of thcm to lhe aCh'''' )'D ever be íore . and for a Icss pricc.'
Nol surprisingly. ensilagc \tl"'~~t:/husiaSlicall\'ild()plt:d in thc USA und Fr ancx ,
bUI it ,\"'s some lime bcfore it w~i<.,".ke}llJp in lhe UK. and it was not unt il IX:L
lhal rhe subjccrrcccived general int erest J.!l11>ng,Hrilish Iarrners. AI lhe Readif!.t!
Show "I lhe KIl\',11 Auriculturul Socict v .Wicomtc ue' Chczellcs, OI1l: or lhe mo~H
urdem stlpro;tc~s of e~lsilage in Frilnce· • g ave ail~!JI1P~essive account of hi~ <yst enr
which includcd lhe filling of thc 'Iargcst siln in ',~c WIlI'I(f of I.()()(l ionncs
capacity." In I HiG it wus reported thut not more rhan I'. "r a dozen silos were in
existc ncc in t hc UK, hut within thc n e xt few )'eaiS intcrest ill·Li<·;,;'/.:tIdramut ical lv.
Sll Ihal hv the veur IXK(l thcre cxis tc d 1.<íIJ:' silos in thc clJuni"."
111the l:rK. i;I(~rL'st hiu! conccntrtu c d nn the l!S~'nfgrass ruthcr thun 111i1IZ<.." ,l
silagc crop. hut il wns rculised that the procedur es o~ullined hy Goffart. sue] a,
rapid lillinl! fo"ll<lwctl hy seuling of lhe mass 11)'Il,Wke it airtight , upplicd cqu ully to
lhe grass crop as to maize. Unfor tun arely the principies outlined by Golf art
rece ive d iI sct-buck in this country o n the publicauon, in IHK5. of lhe bouk ,<'jh'H'1
ClIsilagr bv Fry." The sweet ensilage procex-, dcpcnded upon lhe dcvc lopn rc nt i"
lhe hcrhug« 01' a tcmpcrurure of at le ast :íO"c. bll,l frcqucntly it rnse to iI híglter
lcvc l. To achicvc Ihi~ u-mperuturc it was nCl"~\;li!· io :tllo\\' uir to pc nct rnt c lhe
mass und it \VilSusual to cut thc crup lute anil to witt bclorc lillillg the silo. Sé;llin~;
\VilS thercforc delaycd until thc herbagc rc achcd !h.: dcsire d lelJ1pt.Til tu re .
Alt11l1U~h sil;lge pruduccd by this mcthod was lIsuaily wc!l prcservcd . hecuu se 01
loss<:s arising lrum oxid.uion andhc a ti ng lhe prl wllll'1wus .11lél111"p()or I1UIr it iona]
valuc and of littlc better than rnuintc n ance 41l~lil~:!"This rncthod 01' :1110\\ ing t hc
crop to heal up in the silll prior tu sealing persí51~'U as a Icchllique in the l' K unlil
the miu~1e 01' lhe pn:senl century. anu 1l1ily \\'.::11hil'.'t.:hecl1 iI rilCIDr in dei;" ing lhe
ad\'ílncc 01' silagc lI1aking in Ihis cuuntry. II
.-\parl 1'1'0111~h(lrt perinds during lhe 1\\'(1 \\'0 rid war". gcneral intereSl in ~nsilag.r'
wa~ nOI revi\'ed ulltiJ the 195(Js' as iJ. resul.!.. of ilTlrnl\:ements il1 mechanis;tti, 111a nd
the lIecessity for more intensive ill1imal'producti!1n. coupled wíth' lhe hig,h cost oi
collcentlates. Toua)' it is generally acccpted that. prcwided cerlain basic pri ncipk5
nf silagelllaking are followed. the proc!uclion ora high 4Uillily fced rur ruminanl5
is assund. . .
Thc wonl ~ihl'is de;i"L'd Irorn lhe Grcck siros. Il1cilllin!,\ iI ril or hole sunk in the
groulld fur st oring corn.:' Pliny. in hi-. Naturu! Historv. meutions lhe prcservation of
corn in trenches. whi1h 'were called siri, in Cappndocia und Thrace. 111Spain and
África speciul cure '\\Ias taken 10 select a dry xite illltlló\preadichaff or stubble on top
of lhe soil, Among lhe Greeks. who reter .tn silos are;: Euripidcv. Thcophrastus.'
Hcsychius and Stlitlils~" The Grcck word siromastcs rderr~d 10 ;'1tvpc of instrume m
with un jron P()jl11 \lr.J1nll1g. for probing the silosro.sce ir cont rubund \Ir orhcr
illlpn11'L'r )!()ous' wcrc ' sccrctcd in thcm. This inxtrumcn: wus abo uscd as a
scrviceuble wcapor: in time of war und is rcferrcd 10 in lhe GIlI Tcstument (2 Kinus,
xi, 10). where Jehoiada is rcprcscntcd as g.i~ing lhe centurions the sirornastue -of
Dil\'id:',Olú paiillings Iound in Egypt , dat ing frorn thc period ubout J(J(){)to 15rKJ
13,C.. Sll!!)!r:,l that thc uncicnt Egyptinns wcre Iumiliur. wiih ensilinu as a means (Ir
prcxcrviuj; crops:c Àccording to Kirstein.' silo~ wcre Iound in the ruil1~ of Carthauc.
which indicares thut Ioddcr was ensilcd thcre in about I2IHI B,C. , -
Fr(llJ' ilncient.·'wril;ings in the l\leditt:rranean rczion it secrns tllat air-tizht
sealing. of the foddcr wus considered to be an irnport« 11Icont.lilion for succesxful
conxcrvution..' The Rornun historiun Caro (ubout A·.D, 111(1)me ntioned that the
Tellllllls stor ed grccn Ioddcr in lhe ground ;IIlU therí covercd it with dung. ~ I n
11<11)',en,iling of wilterl gruss hus hcen practiscil.for at Icast 7iJD years." 10
l""rlh<:1'II l.u ropc. /;!rass has hccn cnsilcd in Swcden an,d,in !lIc Ruxsian Baltic
provinccs sincc lhe be ginning 01' thc cighrccnth centurv: while bect rops and
lcil\'t'S \\'LT~ 'cnsilcd in Northern Gcrrrum v at lhe hccinning 01' the ninctecnth
ccnturv." . . --
111SI;i te uf lhis'eilrl~ 'knl1wledge of ensibge as a C(lI;WRilt'illll'leehniljlle in man y
purrs "( the \\'orld. íl "'as nu! 1I11til lhe liltler p<trt \lI' th\:! nrneteenth ccntury thal
inlerest in this pnlce~~ hecame mOfe widespreatl, Thc earliest Iloted uescriptioll \l[
silage making \\'il~ that 01' Gries\\ald. who pubHs:hed .his techniquc ill the
Trc'lll.\'c/CI;OIl5(l/lhe 8(//ric ASSOt'ÍlIIioll forlfle .-Idl'unc<'l1/ctlf ofAgricl/llllre in lil42.;
(jric~\\'i\ld recolllmenueu lhat the pilS lIseu sh@l!1t~eli.lled with fresh grilsS as
rilridly <lSl'0ssib!e hy tramping. anu evcn hy ramming lhe g~,iss'lr;ló the~íI(), As
S\lun as l.he silp \vas filletl. the conlents sholllt.l bc scaled~()ff with a lan!r nf bnards
!li' iI \\'t'II·litting lid, nn which should he rlaced a 1:lyer .o( earlh abolll -t5cm in
heighl. ,111 I tló2. Rcihleu oí Stllttgarl puhlished ali acC'ount 01' his cnsiling
procedure in lhe Wumelllhcrg \V()('h(,llbl(/II.~ This was lr<lnslated int(l French and
publisht:d in lhe )oltrlwl d'Awicl/llllre Prmiquc in IR7().
The chid credit for what 'may he lermeu the pr'lctical.mouernising of cnsilage
lIndoubleuly bclongs to Goffart. ,I Frcnch farmer \\'ho. in 1~77, puhlished lhe firsl
hook 011 cnsilagc. which was based on hi~ own cxperiences 01' ensiling green
Illaj7.e.~ Ahoul a yeilr laIa, an English trarlsl,ltion (rf this hllok WilS puhlished in
lhe US;\ and Ihc 'nc\\" consen'illion techniquc\\'as quiddy taken up by
1\l11ericilll brmcrs, Ai lhe rifth Ensilage Cpngr\!ss helu ín Ncl\' York in J:lIIl1ar~'
1:-;1>0, Slllith 01' Verll1(1nt sUlllmarised the feeling of nUlII\' filrm~r~ thus:'
'li i, III11ILT~~~ar."I" d\\'dl \111lhe illh';lItlagc's "r iI wsleljl 01' L'lIril\!! rllddcr whidl
~"all lilkL' I'liI<:L'as illuepelldel1l uf the \\'L·all1er. or \\'hieh \ViII I:lwhk us to kecp
t\V() CI1\\'S in the rJacL' "f ane Ol! our farms. \Ve alI ad:nowlcug.e its practical "alue.
IIlId \\'1: kntJ\\' \\'L' han: fOlll!d it in en:;ilage, .. 0ow, thRn.ks 1(11l\1:(Jofrar!. til wht11ll
,\meric<ill farmcr, (1\\,1': a li"clier der! 01' gratilude ll1ilO 1(1any lother living mall,
Illld In lhal an1azing grass. our native Indian cofll.'ft1ur farms are capabl.: af
qllllLlrlll'ling their pl<ldllctions: the bcst ilnd s\\retesl plbuttcr can he maue in thc
The firsl L'sselllial objccti\'e in preserving: Cf<1pS by lIatural fermenlalilll! is lhe
aehievcllle.nt ()[ ill\:lL'fohic cl1nditi\lns. 111rraclin: all;lcrnhiosis Cilll hc ()1~lilínctl to\
\'ari(lu~ n1el11l.1us. .
Tlle 1II,"'t cflieielll \\'iI\' is tI' s[Ore lhe l1liliL'lial in iI I1cnllclicalh ,;cilkJ
CtllltilillL'l. illld II1Idcr Ih~SL' c\llldititll1' tllL' "\\~CII tral'l'L'l1 ill lhe 1ll"rb;l!!c i,;
rapidly rrnl\l\'cd by n:spirillor~ Cll/y/lle'S in the plilllt. 111111<,Ilpl'II·lyre ~il", 111.:
dliciency witlt \\'hich anaerobi(1~is ciln he ebl;iiJléd tlepcnds up\ln the degree llr
cnnsoliualipll ;1I1dlhe elkcti\'eness of thé final sealinQ. Th~ IJwil1 aim (lf se<t1illf is
10 pr.e\·ent re·enlry nntl circulalion of air during S(afage. \\'here OX\'!!éll is' ill
conlact with hernage for an!, period of time. an()l~i( micr~lniill aCli,il\'I;;curs ,ll1d
Ihl:' 1lI;IlCriill dCl'iI~'s 10 a usekss. incdiblé. ;rnd freljul'lIlly lnxic produ,,'!.
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PRLlliClPLES OF F.:'iSILA(;E
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The second main objective is to discourage the actrvmes of undesirable.
microorganisms such as clostridia and enterobacteria. Clostridia are usually
present on harvested forage in the form of spores,'! but start to multiply as soon
as condítions inthe silo become anaerobic. t:I The growth of these organisms is
undeslrable, as they produce butyric acid and degrade amino acids to <Ivariety of
products which are óf poor nutritional value. The enterobacteria are non-spore
forming. facultative anaerobes (able to grow in both the presence and absenee of
oxygen), which ferment sugars to acetic acid and other products and also have the
ability to degrade amino acids.!" The commonest way of inhibiting the growth of
these undesirable microorganisms is to promote lactic acid íermentation.P'!"
The lactic acid bactéria are also normally present on harvested erops ando like
lhe enterobacteria, are faculta tive anaerobes. These :organisrns ferment lhe
naturally occurring sugars (mainly glucose und fructose) in the crop .to a mixturc
of acids, but predominantly lactic. The lactic acid produced Tncreases the
hydrogen ion concentration to a leveI at whieh the undesirable ibacteria are-
inhibited.IJ.'7.'H This inhibition is caused notonly by lhe hydrogen ion
concentration but also by the undissociated acids thernselves. IJ lt is difficult to
state an exact critical pH value of the silage at which this inhibiting effect oecurs.
as the inhibition depends 110tonly on pH but also onthe moisture content and the
temperature. The wetter the material. the lower will be the critica! pH value.
With unwilted grass crops of DM content 01' about 2011 g kg"", it is normal!y
accepted that the achievernent of a pH value of about 4.0 will preserve the crop
satisíactorily. provided the silo remains airtight and is free from penetration by
rain.
An alternative rnethod of inhibiting thegrowth of úndesirable bacteria is to
reducc the moisture contcnt of the crop by wilting prior to ensiling. Lactic acid
bactéria have a relatively high tolerance to low moisture conditions and are able
to dominate lhe fermentation in high DM crops.!" Clostridiu are known to bc
purticularly sensitivo to watcr uvuilubility and thcy require vcry wet cunditions for
uctive dcvclopmcnt.'? With very we: crops.'i.e.ihosc with a DM concentrution of
,ibout ISO g kg-I. even the uchieveriient ora pl+value as low as ·LO rnuynot inhibit
lostridial growth."
The rate of lactic acid production is an important factor in inhibiting the growth
of undesirable bacteria and in reducing fermentation Iosses. and rhis depe~ds
upon lhe initial lactic acid bacterial population on lhe ensiled crop and upon the
ubstrate availability. This in turn is influenced by lhe degree of physical damage
(bruising, laceration, chopping and mincing). 21~2.1Modern precision-chop forage
harvesters are capable of chopping herbage into particle lengths <25mm. With
such material, plant sap is rapidly liberated and lactic acid bacterial growth is
timulated.é" Finely chopped silage of this type is more readily eaten by ruminant
mirnals than long or coarsely choppetl material.~~·2h
or clàmp wirhout retaining walls. iover.: surface-walled c\amp or bunker,
flexible-walíed. vacuum. plastic sausage and big bale.
Stack or clamp silo without retaining valls
Thetterm stack, often used synonymously with the term clarnp, is· taken to
comprise a heap of herbage built verticslly' 10 a height of about 2 to 3 rnetres on
grouadlevel, or on slightly excavated grourid.3..1.31 Originally the surfaces of stack
silos vere left exposed to the air anel thisresulted in very high oxidatiolllosses.3•n
Since' lhe 19505. when plastic sheeting was first introduced in to agriaIlture.
oxidàtion losses in stack silos have been. markedly reduced.V
ln thé modern technique, lhe stack is built on a sheet of plastic placed on the
ground and when sufficient herbage has been deposited on ~his. it !s coveH.d with
a second sheet of plastic which is sealed 10 lhe lower one usmg a sirnple strip-seal
or other suitable technique.:' In the Netherlands, small c1amps of herbage ol about
1.5 metres in height are covered with tW(J plastic sheets, weighted down at lhe lop
and sides with old rubber Iyres and held in place with sandbags positioned round
lhe periphery. .
Tower silo
Talltcylindrical towers, built of concrete. steel or wood, are probably the most
effective way of storing herbage as sjlage, since surface exposure to the air is
minirnal. Pressures obtained in this type of silo are greater than those in other
silos.and, 'ul1Jess the crop is pre-wilted in the field. the outward pressures exerted
. on the bottom walls orthe tower can cause a serious problcm of cffluent Ilowand
may even dumuge th~ structure 01 the silo." '
Surfare-walled clamp (Ir bunker si/o
This.silu generally consists of three solid walls some 2 to 3 metres in he ight ,and it
is often 'b'uilt beneath a Dutch bam to protect the silage frorn lhe weather.r'" ..11>
The crop is generally ensiledin a series of wedgés, which 'ure laid' onéupcn lhe
other. progressively along lhe silo. and the top is sealedwith plastic sheeting
<\I,lripgthe course of filling.-1.2~Finally. tbe surface is weighted with.some suitable
material, such as sandbags. tyres or bales of straw, to prevent re-en try of air. The
walls.ef buriker silos rnust be strong enough to withstand the thrust of tractors
used to consolidare the herbage, .and of lhe, silage itself.-'UH
SILOS'
FIr:xible-lI'alled silo
This type of silo was originally developed by theNational lnstitute of Agricultura!
Engineering. England." and resern bles a bunker silo but with walls which can .
move ourwards. With this arrangernent, ir is possible to fil! the silo to aheight of
a~~uQ rnetres without exerting excessive pressure on the side walls ..The silage
eventsally settles to a height of about 4 metres.
'ommercial silos.
The types of silo in which the farrner may choose to ferment his cropare very
vnri d and they huve beeri reviewed hy a number of workers'r':"' ..".11:.", For
(onvl!llience' commercial silos can bc classified inlo se.ven muin clllegories: stack
". . " .
VIlCL/um silo
In.thevacuum silo. the forage is placed on IOp of a sheet of plastic and builtup 10
th~ re,q",ired heighl. A similar sheel (lI' ~alerial is thcn plact;l1 (lver rhe foragc IInd. .
'. .. - ".:. -~..• . ',' .... ~ ::.: .; ...•..• :-. : : •.... : .., . " .-,"'.' .
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, I
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I
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I
lhe cdges o" lhe shccting are joincd togcthcr using ú strip-scal. Thc uir inside lhe
silo is thenrernoved using a vaeuum pump, whkr~'also hclps to consolidate the
Iorage. 'This method is only successful as long :15 lhe silo rernains scaled. If lhe
plastic is darnaged during storage and air e nters thecs(iú. lósses ean be as high as in
lhe unprotected stack silo:' .'
l~'
li_
Plustic 5(//r5t1~(· silo
I I
This type of silo was devised in Gerrnany. A speeial muchine Iills a tube ofplasric
. with chopped forage. which 11:Ispreviously passedjhrough a shaping Iunnel,
When Iilled. lhe sausaac has a diarnetcr 01' ahuut 2.4 metros hut eun bc 01' unv
lcngth upto about 3rJ rnetres, J i' • . -
)
'i
Big bale
)
)
)
In recent years the urnount of silage conserve d l~LS Iurge bales has increused
drumatically. und this system of making silage is .i1l;,'Vwidêly practised in lhe UK
and in other countríes.r"?" There are two basic tyPes of baling rnachines, the fíxed
chamher and the variable chamber, In the folMel'. the perirneter of lhe
bale-forrning mechanism rernains in a fixed po~iliori so that lhe crop is only
subjected 10 a rolling action and conscquent .cdmp~eS:~ion when it. tills lhe
chamber. The centre core ofthe bales is less densé than lhe ou ter lavers which
have becn rolled during formation.4U.4:! In lhe vari~ble cha~ber machi~e. lhe bale
furming mechanism engages lhe bale from lhe start and expands during bale
formation. The bale is thus subjected to contin,!lq:us~ rolling and consequently
tends 10 bé more densely uniform.?"
Bales vary in size but usually weigh frorn 0.5 10'0.75tohne. The bales may be
stacked on a ground sheet and covered with plastic sheeting which is sealed aI lhe
base ar. more commonly, placed into large plastic bags which are tied ut lhe neck. ,
These bales are then stacked in' pyramid formation and lhe whole pyramid is . , •
·covered-witb a weighted plastjc sheet ar net 10, protecr.it from daifiágê?r-ltr~Wn"A -- ....~"· ..;i 7
A recent innovation is the use of stretch lilm instead of plastic bags.' 1t is
claimed that lhe plastic film wrapping is cheaper than bags and makes the system
less labour intensive.2A9 In a compurison.of bags versuswrapping , Braithwaite,
and Jones'" found that, providing the bales werei well-scaled, thcre was no
difference in silage quality between bagged and wrapped big bules. However. the
risk of poor fermentation or complete loss of a bale due to aerohic deterioration
following damage during storage was greater wilh bagi;. Aerohic deterioral~(}n ill
wrapped bales tended to be confined to ~he site of damage. Wrapping of low DM
bales is not recommended because of possible problems wilh sealing and
effluent. ~I
"
),
)\ i
Experimental silos
LIII>Of(/wry silo
I :r ' ~
Barnen27 has reviewed lhe literature on earl)' lahoTUtor;y techniques and has
described a range of different types {lf silo including t\=st-(ubes. ~~milk botlles,~.l
glass jars.:>4 and glass cylinders. ~~Tht: most widdy u~ll type of I<lhoratory silo is
lhe tcsi-mbc , with él c.ipucity normully runging [rum 50 g to 250 g, 'lhe: tube is
litted with some. kind of scaling devicc which pcrmits thecscupe of gases but "r,. II
preve nts thc entrv of air. Suitable sealing devices are rubber stoppers carryng
either a ralve nf mercurv supported on a sintered glass di~c"< or. preferubly, a
simple glass ur plustic fermentation trap fillet.l with watcr." Virtanerr'" used
porcelain coniainers holding about 15 to 20 kg tlf ~resh crop which permifti~J DM
loss, curbon dioxide (COz) production , and cfllueut flow to be monitored. íir
Wieringa" lIsedglass preserving jars 01' I to ~. litres cupacity which could ~e
hcrrnetically seale d. whilc.Ohyumu and Musak i" used I litre gluss hottles wjh
I1ICreli rv "L'ais.
I,n the studies curried nut by Jones.?" thin guuge polycthylcne bugs (20 x 4{1em)
were Iilled with herbaue und sealcd at lhe neck. These bugs wcrc then place d ina
larger. thick-guugc polvcthylene bag (40 X 80 em) litted with a simple connector
for attaching 10 a sucrion pump. Polyethylene bugs. placed in srnall PVC
cvlinde r s, have. also be e n use d for consoticlarion tests an d fri crion ~,
n;easurem~nt;. 01
Wilson and Wilkins"~ cvaluutcd laborutorycnsiting techniques by comparing IR
arasses und eizht legumes in test-tube silos holding 100 g of fresh herbage with the
~amc crops e~,iled in PVC bags holding I tcnne of fresh material. Measurements
mude on silages frorn the test-tuhc silos were closcly corrclatcd with those fron
the PVC bags. Our own results at Edinburgh in general confirrn the above
findings. aithough in some instunces ferrnentations in laboratory silos may h/
atypical unless precautions are raken to ensure that the herbage.contains normal
levels of lactic acid bactéria or. alternativelj. herhage is inoculated with these
organisrns prior to ensiling.
1 t
Pilot-scalc silo
This type (lf silo is used in experiments when a sufficient quantity of silage is
needed for feeding trials with rurninants, or when detuiled measurements 01
nutrienl lesses are required. An early experimental silo of this type was that used
bv Watsan and Ferguson'" in 1937. which consisted of a scaled-down tower silo
made of woodor concrete, holding about I tonne of material. Golf and Gneist":'
used li similar silo made of steel. whieh had <Icapacity of 0.75 tonne , Burnett :Ind
f\lillel" used a scwuge pipe of height 1.8 metros anú internal diarncter 1.2 metres.
This pipe rested on :J solid concrete base through which passed an iron tube which
drained off lhe eff1uent. Nash'>(' used :;imilllr silos made of eonerete. each being
fittel.'l with a flIof. tllermocouples. and cfllucnt-colleeting appar:ltus. The
experiment:tl tOlver silos used at lhe USDA research cenlre aI Beltsvillefo1 in the
1950s were I1lade of enamelled steel and possessed s'lmpling ports. Each silo.
which had :J diameter of 1.2 metres and a heighl of ~A metres, was capable af
being transported for weighing purposes.
An expcrinlcntal silo uni I designcd speeifil.'llIy for mcasuring losses during
ensilage was Duilt hy McOonald and Attwood.(I< The unit eonsisled of fllur silos.
each éonstructed (lf steeland having a diameterof 1.2 metres anú a hei~ht 01' 1.8 t'
mctrcs. E<Jch siln had scven sampling ports :lI1d ten thermocouples. and wa.~
suspended from a weighing apparatu~ of lhe steelyard type. bolteu to él steel
beam. The wcighing lIpp<lratus was designed 1(1 counterbalance lhe whole 10m.!
and to measure the actual weight loss. The silo lIeld :Ibout I tonne of foragc and
the ·cquipmenl WilSsuflidcntly sensitive to n!cord a changc in \Vcight 010.1 kg.
.( r.
.-111
Dulphy .. LP. and Micllllcl. B.. (1975) Annales de Zll/JII·('frl/(llllgie.h4 .• 757-763.
Deswysen, A.G .. Vanbdlc. M·. ánd Focart, M. (1<J7X)Journal o(rl",n,.iii.f!r Grossland
Societv; 33. I07-Il<i., ,
Bam~tt, A1- G. (I 'l54) Si/age ·Pt.'rmelllaliO/I. Butterwarth. Lond~n,.·'
Murdoch. l.c (1961) N,(/kit/g and Feeding Si/age, Dairy Farmer (Bo6ks). Ipswích.
Raymond. W.F .. Shepperson, O. and Waltham. R. (I972) Forap,eConservation IlIId
Feeding; Farming Press, lpswich. "
Dulphy, l.P. (1984) Pusticulture, No. 63. 1-14.
Haigh. P.M. (1978) NeM' Zealand Iournal o/ Experimental Agriwlwr'e. 6.279-283.
Savoie, P .. Fertin, J.M. and: Wauthy. l.M. (1986) .Transactions Df lhe American
Society of Agticuiturol Engineers, 29. 1784-17X9.
Savoie, P, (1987) Apprlf!d Engineering ill Agriculturc; 3. 145-141.
Hastings. M. (I972) Agricultura! Developmcnt (//1(/ Advisory Service Quarterly
Review, No, S. 1-11, .
Ministry of Agriculture •Fisheries and Food (1977) Silag«, Bulletin 37. Her Majesty's
Stationerv Office , Loncon.
Johnsan:C'.. Clark, 1.1.. Machattie. K.L. and Watsou.. O.A.L. (19115)Silage Clamps:
Design and Crm.urilC'lÍ(}i. Scottish Farm Buildings lnvestigation Usit , Bucksburn.
Aberdeen.
Agricultural Development and Advisory Service (19RUj BIII/ker Silo Construction,
Leaflet 761. Ministry ti Agriculture -, Fisheries nnd Food [Publications]. Pinner,
Middlesex.
Agricultural De\'elopme~t and Advisory Service (I 'iR3) EII.I'ifilW Grass. :Leallet 482.
Ministry of Agriculture, Fisheries and Food (Publicarions), Alnwick. Northumber-
land. '
Hawkins. l.C and Messer, H.J.M. (19n) Ioumal 01 Agricultura! 'Engiueering
Researclt . 22. 259-27IJ. .
Agricultural Development üO(]:Advisory Service (I 982) Ri!!, Bel« Sitoge, Hooklet.
2408. Mínistry of Agricdture, Fisheries and Food (Publicationsl. Alnwick , North-
umberland.
Ciotti, A .. Delmastro. R.• Canale , A. and Valente. M.E. (198.-l1I'rorculings of the
CRPA COllferrllce. Bobgna, ts May 1984. 21l9,212,
Murshall. I.G. and Hove, S.D. (19H9) Procecdings ar ti Confernu« ''''. Di/< lia/(;
Si/age. SIOIreh'ÍX/I. Ilrili!h Grassland Society. 3.1·3.16 .
Guillard, F. (19H4) 1'/wlÍcufwrl'. No. 63 . .49-56.
Frilz. U, (19H4). i'lustitulture, No. 63. 4:1-4X.
Gaillard, F, and Zwaerepoeí. P. (19H7) BTMEA. No. 18: 37-l1í.
Howe, S.D, (19R7) 10 Drvelopmnus in Silugc 1987 (l.M, Wilkinsnn 1IrlU BA. Stark.
eds) Chalcombe Publicaions.. Marlow Bottorn. Bucks, 17-22,
Lingvall. P. and Linclhe.r~. H. (1989) Proceedings (~ra Confercnccos 8ig Bale Si/agi',
Stoneleigh . British Grussland Socierv. 5.1-5.10. '
Kennedy. S.J. (1'1H9) Ptoceedings o; a Confcrencr on Big IMI' Si/ag!'. SII)l/(·/('i~lr.
Brirísh Grassland Society. 4.1-4.13, , " .'
Cau, W.R. (198611n Destlopments 111Si/age IYH6 (H.A. Stark and J.fI.LWilkinsoll. eds)
Chalcombe Publicutions , Marlow Bottom. Bucks 1-11 .
B~ailhwaite. G.I). and Jones., L (19X7) ,l'mcl!(:tÚngs;'ll';(" IIlh Sliag« Ccilllemrce.
. Hurlev. 111. .
Evan~. D, (1%'1)) I'w('('('diIlRS ~/{1i ("ol!l('rell(,~ IIIr Ilig /lal" Siltl,~I·. S/O!wÚiglr. British
Grassland Socicty, 7,1-1.6. , . '
Allen. L.A .. Harrison, J •• Watscn. 5.1 .. and Fcrguson. ws. (1937) .lournal 01
Agricultura! Science • 27, 271-2~J. ' " :' .
Johnson. B.C .. Peterson, W,'~:.Hegsted ..D.M .• ind Bohste dt. G .. (I~41) Jôurnul o{
Agriclllwral RtsearcJ,. 62. 337-J4!!. '.. . .'
Oldland. T.E .. Cox:T,R and ~inith:'J ,B. (111-11)}mll'lw/;;r l!tl' "l/1/rricUlI Soci(,I\' of
Agroll(}I/I.~·. 33. 3114-.113, . , •
111 111/0 un rxncrjmental bunker siloof 40 tonne capacity W;IS huií.t at Edinburgh .
I' I Ilully I() measure gaseousand .eft1uent losses. This silo wasconstructed of
I I 111111 WUN rnounted on load cellswhich were supported on concrete pillars
111 \110 til ground.,q· ,
1'.,,11 Ibly lhe most sophisticated experimental silo unit W'dS that built aI
li, 1111 ~ hw Ig.'" which consisted of six sealed tower silos. each af2 to 3 tonnes
, 11111' Iy, The first two of these were constructed of glass-lined steel, while the
1 UIII 11 "11 fou were built of glass fibre reinforced polyester resin. Ali silos were
, 11' hl C/r being weighed and .were equipped with facilities for continuous
IUIWI\III rneasurement and analysis of gases.
MOI!' 1 ntly, silos mude af PVC have become available for pilot-scale studies,I" I 111 be rnanufactured to any size up to about 3 tonnes and are usually fttted
1111 1I1111n~e taps for eftluenl collection. (,2.71.72
25.
. 2h,
TI.
28.
29.
30.
31.
32.
33.
34.
35.
36.
37.
, 38.
39,
40.
41.
42.
., , ,.~~, ...,.,
43.
44.
45.
46.
47.
s .
41{,
49.
50.
51.
52.
'53.
54.
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• 111• O,R, and Henderson, A:R. (l9H5) Annual Report-oj the Edinburgh Scfr(JOI o]
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11'II/u:tI Bncle,;o!oKY, 24. (~I-'7~I..,' ','
x:.~':~';~:':"~~~!.~;':~~ft~~~~.~.
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