Copyright is owned by the Author of the thesis. Permission is given for
a copy to be downloaded by an individual for the purpose of research and
private study only. The thesis may not be reproduced elsewhere without
the permission of the Author.
MAIZE SILAGE
A s tudy of the nutritive value of ensiled ZEA MAYS L.
'
for growth in young cattle
A thesis
present ed in pertial fulfilment of the requirements
for the degree of
HJ\.STER OF .t\GlUCULTURAL SCIENCE
in
/\YIMAL SCIENCE
at
MASSEV UNIVERSITY
.i\LEXA.�DER LOCK1.JOOD S?1ITH
1973
ABSTRACT
tm exneri!:wnt is descrihed in �vl-tich the nutritive value of Nmv Zealand nroduced maize silare, harvested at the dent-p;laze star>,e of maturity, was investi?ated. Of central interest in the study was the adequacy of the protein content of the �aize sila�e for suoporting grmvth in youn� cattle.
Pollmvinp: a six-week stanrlardi_sati0n period, 15 Friesian steers, eil?,ht Months of age • r,rere each allocated to one of three treatments in
an exneriMent of randomised block, covariance .desia:n. T.Jhile Maize
silap;e either alone (HS) or sunnlemented '1.vi.th hiurct (MSB) , formed t�vo
of the treatments, it was considered necessary to include a ration of better knmvn nutritive value as a form of control. Hay and barley Meal (HB) was selected for this nuroose.
Durinw, R six-�veek corp-,arison TJeriod • rRtivn nhysical and chemical analyses were made; drv natter (�M) �nd co�nonent digestibilities
and intakes, nitroRen (N) utilisation, Rnd livewcight �ain by the steers
were measured. Identical recordin0s were mRde durin� the standardisation neriod for uss in covariance an�lyses. Throu?hout the study emrhasis wr>s placed on anirne.l ,,c�rformance ( live'•7Ci�>,l-tt fWin) c>_s the r)rime criterior:
of nutritive value, the oth·2r nHra:rteters measure� :;eing considered to char!lcterise thfl.t nutritive value ns co:nnonents of it.
'!can rates of live,veiRht r��in durincr the coM-r,arison neriod •vere
similar for all three >�rourys (0.44, 0.52 and D.Sl kr>/cay for the HB, :-!f-.
and HSTI treatments respectively). Liveveight �ains adiusted for �T!
intake, hmvever, significantly favoured the �1SJ3 treatment in comparison
with the HB ('P < 0 .OS) and �S (::> < 0 .10) treatments.
The possibility that this sunerior efficiency of the MSB treatment
\vas a result of unaccounted bias is discussed. Notwithstanding the reasonably convincing evidence presented in favour of the reliability of the finding, the possihility that it was merely an artifact could
not be unequivocally excluded.
The apparent equivalence of the MSB treatment to, if not
superiority over the HB treatment, -.;.;ras difficult to reconcile with the recorded DM digestibilities and digestihle enerP,y intakes (62, 14.7 mef;acals./day and o7, 18.1 megacals./day respectively, for the MS and
HB treatments). Enhanced efficiency of utilisation of metabolisable
ener�y mediated via increased post·-ruminal digestion is suggested as a possible explanation for this unusual finding.
Jf the efficiency advantaq,e of the "'1SB over the l'1S treatment
iii.
was truly � nutritional effect, it can only be ascriberl. to the presence of biuret in the fanner ration. Hhile evid.ence presented would suggest so�e utilisation of the su�nlernental biuret hy the rumen microbes, the extent is clearly indicated by the N retention Yesults to be limited.
It �·Tas fo1md that Ne,,7 7.ea.land flroduced Maize silage, harvested
at the cent-?,laze sta�e of maturity (33% D�) heci physical and chel:lical compositions closely apnroximatin� those of the .t�er:tcan nroduce�
material. Hhen fed as a sole ration to youn� grmving cattle, levels of D}1 intake (2.6-2.7% of liver,.n�ight) notentia.lly conducive to rapid rates of liv,;�.veii�ht rrlin ( i . e. ?rC<'lter than 0. 75 kg/day) May be expected. The present results t-muld holvever sw�gest that t}1e
di�estibility of the �ross enerev (61%) may imnose a ceiling of 0.75 kg/day on notential rates of gain. The possit-ility of bi<1s in the estd.mation of both intakes and dir,estibilities, resulting fro!Tl the use of t11e oven�dryin>!. techniqu2 in deter'Tlining; s ilage D:1 contents,
is discussed. It i•JOuld seen th,qt both th9 !Y! di�estibili ties and digestiole enerQy intakes recorded in the nrcsent study, may be consistently low.
It is c oncluded thP..t maize silage \vith ;:� 9-·10% crude T'!ratein
c ontent can su-pport growth rates in young cHttle of 0.5 kp:/de.y, at
le<1st in the short tcn'l.. 1,tfth the intake e..nr. digestibilit y data
recorded in the study nescribed betr..r- of a level sufftcient to support
greater rates of liveHeil!ht gain, it would seem reasonable to suggest, assuming no vitamin or mineral deficiencies, that protein availability to the steers fed maize silage �¥as liJTtitin� �rovrth rate. The nresent study does surmort a response to N supnlementation (hiuret) although
the fincl.in� is adopted t.vith caution. Th8 ev�_dence is inconclusive.
It fq therefore suggested that the need exists for a further more specific study of the adequacy of the protein content of maize aila�e for growth in young cattle. A longer nerion of maize silage feeding, and the inclusion of a treatrnent containing a natural proteiU supplement \Wuld be considered essential.
ACKNO\�LEDGH1ENTS
To the many peorle who so willingly assisted in this work I am
indebted and have pleasure in recording my gratitude. }1y deepest
resr.ect and sincere thanks are accorded my surervis0rs �- Mr. A.l-7. F. Davey for his cor:tinued understanding, encouragement and sound gu idance,
and Professor /LL . Rac for his astute an . .1 clear assistance on statistical problems encountered.
T!-le f ollmving persons are also extended my sincere thanks�
Tvir. R.D. Anderson (Sheep Husbandry -:Jeut.) �vho so generously gave of his time in discussion, and nrovtded invaluable guidance on statistical matters.
!:lr. D.D.S. nacKf.!nzie (Dairy Husbandry Dept.) for his cheerful
assistance Hith the maB!noth task of Proof readin�, and editortal guidance.
Nr. G.C. Haghorn (post-graduate student) Hho made availnLle unnublished information from his recent studies of �aize
sila:-;e.
�'lessrs. G.C . .Tukes, H./· . . HcLean nnd J .. \. T->.aven (Dairy Husbandry Dent.) for t�eir willin� and skillerl technical assistance
�vitl: the an;::�lytical r.vork.
Mr. N.D. Grace (D.S.I.�.) 1�10 carried out the snectroscopic mineral analyses.
Dr. �.W. Bailey (D.s.r.R.) for his �uidRnce and advi�e on
chenical analys:i.s '"'roce·lures.
Hr, n. }1orris for his conscientious technical assistance durinr the exueri1:1ent.
Mr. 1'. H. l.fnitehead (Sheen Farn Sunervisor) for making available both the land used for nroduction of the maize crop, and the
<lnimals used in the nutritive valu2 study.
Mr. B. Clarke (Blades Chemicals Ltd.) �lho, through his generous assistance and knowled�e, made the ensilinr a less formidable task.
Dr . . T.P. Kerr (D.S,I.R.) •-rho assisted �rith the samcling and physical analysis of the maize nlants Rt harvest.
Mr. G.O. Edmeades (fcrmerly o f the Agronomy Dept.) for h is
invaluable guidance with the nroduction of the maize crop.
Mr . C.J. Baker (Agronomy Dent.) for the use of cultivation
equipment.
Dr. K.J. T-1itchell (Director , Plant Phys iology Divis ion. D . S .I .R . ) f or his nersonal support and ass is tance in obtainin�
financial backin� for the work.
In the harves ting of the maiz e crop, a numb er of firms and inst itutions gave ready assis tance . Thanks are extended through Mr .
v.
C.H. Fisher to A .M. Bisley & Co. Ltd., for the use of a precision maize planter; through �1r. B. Scott to the then Daring Imnlement Sunplies Ltd., for the use of a forage trailer; to Messrs. I.P. McOueen and P.H.
�fuitehead. and the Massey University farm staff • for the suT>nly of tractors, forage boxes and personnel during harvesting; to Dr. K.J.
�1itchell and the staff of Plant Physiology Division, D.S.I.�., for the use of machinery and personnel; throu�h Mr. E. !"m.rke to the
Hinistry of Transport for their weiGhint:>; of the silav,e at harvest; and to Mr. M. Craw, who both supplied and drove the naize chonper used in harvesting the silage. The many friends \•7ho assisted \vith the ensiling of the maize have my sincere aopreciation.
Thanks are accorded Mrs. K. Morgan for her skilled typing of the final copy of this thesis.
To my friends and fomer colleagues on the ?•1assey University staff �o my sincere thanks for continued interest and helnful discussion throughout.
I extend my snecial appreciation to Dr. R. Buchanan and Ivon-1-Jatkins Dow Ltd. • �vi thout ,.;hose generous financial supnort this work \vould not have been possible.
PREFJ\CE
Progress in pasture management has resulted in rJOre efficient utilisation of available grass by the grazing animal and concomitantly, increased nroduction of milk, meat and wool. The point has no-v1 been reached, however, �vhere the amount of grass actually grown is limitin�
further increases in animal productivity. Possible means of liftinr.
this annual herbage production w ould include the use of nitrogen fertilizer, irrigation. or high yield forage crons.
1lliile the use of both nitrogen and i rrir�ation on pastures can
be clearly beneficial. their potential seems limited by the very
morphology and physiology of the nasture nlant. i.Jithout the limitations imnosed by the r;razinr, animal, the use of hiGh yielcl forage crops may have the greater nroductive potential.
Maize (Zea mays L,) is one of the T!!Ost nroductive forage crons known to ""1e�..r Zealand and when used as silage, provides an animal feed at quite lm.; cost, comnarable �vith grass silage. Its characterisation in Ne\v Zealand hmvever, is still in initial stacres.
�<Jhile extensive ivorl:: on r1aize silage has been reported in the United States. extrapolation of their findings to our vastly different conditions is difficult. Emergin� from their �·rork, hmvever, with
singular clarity, is the confused understanding of the protein adequacy of maize silage for growing animals.
The study described herein �.,as designed to investi»;ate the nutritive value of New Zealand produced maize silage as a sole ration for young growing cattle. \.,ith emnhasis on the adequacy of its protein content.
Abstract
Acknmvled9,cments Preface
List of Tables L:ts t of /'igures
List of Plates List of Appendices
TABLE OF CONTENTS
Chapter One Revie,,; of Literature
1.1 Characteristics of Maize Silage
1.1.1 Physical Composition
1.1.2 Chemical Composition FeedinF Value of Haize SilaR.e
1.2
1.3 "!"actors Aff'.:!cting the "Feedin� Value of Haize Silaw3
1.4
1.3.1 Fertilizer Rate.
1. 3.2 Plant Ponulation Density
1.3. 3 �1aize VHriety
1.3.4 Sta9,e of �1a turi ty and Dry :1atter Content at Harvest
1.3.5 Buffers and Other Additives Sunplementation of Maize Silage
1. 4.1 Protein CJr 1'Htrogcn c�n Sun::>lementation
1.4.1.1 Non-�rotein Nitrogen (NPN)
Utilisation by Ruminants
iv vi
1 2 2 2 5 8 8 9 10
11 15 17 18
19 1. 4 .1. 2 NPN Supplementation of Maize Silar,e 23
1.5
1.6
1.4.1.3 Choice of NPN Sup�lement 26 1.4.2 Enerp,y Sunplementation of Maize Silage
1.4.3 Vitamin Sunnlementation
1.4.4 Mineral Supplementation
Consideration of Experimental Design
1.5.1 Choice of Desi�n
1. 5. 2 Heasurement of M8.j or Response Parameters
1.5.2.1 Measurement of Liveweight Gain
1.5.2.2 Nitrogen (N) Balance Summary
28 28 32 34 34 37 37 38 40
Chapter THo Hethods and �faterials
2 . 1 Experimental Design
2 . 2
2 . 3 2.4
2 . 5
Exnerimental Feeds
2 . 2.1 Hay and Barley (HB) 2 . 2 . 2 Maize Sila:?,e (�iS)
2 . 2 . 3 Malz e S ilap,e plus Biuret (�fSB)
Experimental /.nimals GX�erimental ?rocedures
2.4.1 Physical L'.nalys is of Rations 2 . 4 . 2 Chemical Analysis of Feeds
2.4. 3 Digestibility of Rations
2.4.4 Voluntary Intake
2.4.5 Nitro�en on Balance 2.4.6 Li ve1:-Jeir>h t G:=dn Statisticel Procedures
2. 5.1 '.'l1ysical i\nalysis of n.ations 2.5.2 Chemical Analysis of Feeri.s
2.5.3 Di:restibility of Re.tions 2..5.4 Volunt3ry Intake
2..5.5 NitroQen (�) Balance
2 . 5 . 6 LiveHeight Gain
Chapter Three Result3
3 . 1 Physical r\nc>.lysis of Rations 3.2 Chemical Analysis of Feeds 3.3 9iges tib ili ty of Rations 3.4 Voluntary Intake
3 . 5 Nitroo;en (I-1) Balance
3.6 LivGwei�ht Gain Chapter Four
4 . 1 4 . 2
A Posteriori Consideration of the Experimental Design Interrrctation of Results
4.2 . 1 Physical Analysis o f Rations 4.2 . 2 Chemical Analysis o f "Reeds
4 . 2 . 3 Di�estibili ty of Rations 4 . 2 . 4 Voluntary Intake
4 . 2 . 5 Nitro�en (N) Balance
4 . 2 . 6 Li veveigh t Gain
42 43 43 44 44 46 46 47 47 48 49 49 51 54 55 55 55 55 56 58 59 61 62 62 65 67 73 73 76 77 80 80 81
84 87 9 2 9 4
Conclusions Chapter Five
Apuendices
Literature Cited
Page 99 101 132
LIST OF TABLES T.i\BLE
1.1 Physical analysis of maize �lants at ensiling
(30-35% DH content) 2
1.2 ProxiMate composition of maize silage made at the dent stage of maturity (a�nrox. 30% DM). The pasture analysis results of Davey (1964) are included for com�arison 4 1. 3 Further chemical analysis of maize sila(;e - crude
protein and ash fractions, and carotene content
(7. of total maize silage DM). The pasture mineral analyses of �.Jilson _et al (1969) are included for
comnaris on 5
L 4 Energy and nrotein adequflcy of maize silar;e for grm.;ring
cattle. 7
1.5 The effect of stage of maturity at harvest on the DM
diRestibility of maize silage 14
2 .1 Feeds used during the three major periods of the
experiment 43
2. 2 Tyne I anova for �1odel ( 2 ) Hi th exnected mean squares 57 3.1 Com�onent feed contents of the dry matter of the CP
rations 62
3.2 Physical composition of the maize silap.e 62 3.3 Proximate analysis of CP rations (DH basis) 63
3.4 �nalysis of the carbohydrate fractions of the CP rations by the acid-detergent fibre and neutral detergent fihre techniques (Van Soes t, 1963, 19 6 7) (�� of total DH) 64 3.5 Composition of the crude nrotein fraction of the CP
rations (% of total DH) 64
3 . 6 Calcium, ph0sphorus and sulphur contents of the C�
rations 65
3. 7 Anparent digestibilities of the DH, fibre and crude
protein fractions of the er rations 65 3.8 Statistical significance of the differences beb�een
treatment means for D�1, fibre and crude protein
digestibilities 66
3.9 DOH, DE and J.1E contents of the CP rations, including
the apparent digestibility of GE 66
3.10 Digestible crude protein contents of CP rations 66
3.11 Mean daily dry matter intakes of treatments during the
comparison period (kg/day) 67
3.12 Statistical si�nificance of differences beoveen the treatment mean daily dry matter intakes shown in
Table 3.11 67
TABLE
3.13 3.14
3.15
3.16
3.17
3.18 3.19 4.1
Mean daily DM. intakes of CP rations with period one
omitted 68
Hean daily DOH, DE and HE intakes of treatments, based on the DM intake data of Table 3.13 (i.e. period one
omitted) 72
Hean daily crude ;.rotein, dir�estib1e crude protein, true nrotein and non-protein nitrogen intakes of treatments, based on the DM intake data of Table 3.13 72 Mean daily N intake, urinary N output 9 faecal N outT'ut
and N balance for each treatment durin� the comparison
period 73
Statistical s i�nificance of differences between treatment mean daily N intake, faecal N output, urinary N output Rnd N balance durin� the comparj
period 73
Treatment mean daily liveweight R,ains during the
conparison �eriod 74
Hean liveweight gains of CP treatments adjusted hv
reqression on DM intake per 100 kR LW 75 Importance of the r.rain fraction in maize silage 81
LIST OF FIGURES FIGURE
1.1 Changes in physical com.-.os i tion of hybrid maize plants
(120 day maturity) �dth advancinp maturity (Based on
Hamvay, 19:':3) 3
1. 2 Changes in cheMical cor.mositio!1 of the maize nlant
r,,i th advancinr maturity (Adante-:1 froM Bopner 9 1925) f;
1.3 Effect of maturity on N distribution in maiz,� plants
and maize sila<>c (Ada�ted fron Johnson et al, 19A7) 13
3.1 �re�t::nent mea:-. rlaily DH int:�.kes avera);ec! over- each h'eek,
shmvin�; the tn::�tnent by period inter<tction 59 3. 2 Treatment r,w�n ctaily T)H intakes durinr, the comparison
period, plotted against blocks to indicate thr2 cause
of the treatment by rylock interaction 70
3.3 Co::!T1arison period nean daily D1·i intakes of blocks plotted P:;>:aL:1s t tine. s!"lmdnp, the absence of R T�eriod
by hlock inter�ction 71
3. 4 �Jeekly mean live�vcir>hts for each treat!':lent in both
th.::: standar':lisation and comT'arison periods 74 4.1 The relatio�shi;.' betueen N retention and live-v1eic:cht
gain of the HS ( 1::. ) and !'1SI3 ( • ) trent!':lents durin;:>;
t�e com�arison nerioc 95
IX. i '·7ithin tre�.tm'-!nt rer;ressions of CI' Di'>f c1ir-(cstibility on
S';"' m1 digest:i.bility 114
XVI. i Re:?,ression of CP livevrcight �ain durinf; each period
on D� intake per 100 kv, livewei�ht for that Period 126
P� .\TE 2.1
LIST OF PLATES
The maize sila�e at time of feeding� in the O!_)ened face of the stack
2.2 Steers harnessed for total collection of urine and 2.3
2.4
rl <:_
L..o.J
VI.i
faer::cs
Urine col.lecticn funnel mounted in place during a
collection period
Butyl rubber9 urine collection funnel r-artially dismantled
Urine collection funnel c.ompletely dismantled
Silage t:vas tage
45 50 52
52 53 110
LIST OF APPENDICES
APPENDIX
I Time Sequence of Events
II Sensitivity of the Experiment as Designed for Liveweight Gain Comnarisons
III Level of Barley Heal Feedin>>, IV Maize Silage Production Details V Haize Silage Yield Data
VI Maize Silage Storage
UII CelculatLJn of Biuret Requirements for HSB Treatme:1t VIII The Blocking of the Exnerimental Animals and their
RRndom Allocation to Treatment Groups
IX Analysis of DM Di�estibility Data
X An.<tlysis of DM Intake Data
XI Serial Lnalysis of DM Intake Data XII
XIII XIV XV XVI
Analysis of DM Intake as a Percentar;e of Livm>Teight .i'.,nalysis of N Retention Data
P�nalysis of Comparison Period Live�.;reip;ht Gain Data Serial Analysis of CP �criod One Intermediate LiveweiP:hts
Analysts of CP LiveHei<rht Gain Data Adjusted for DH Intake per 100 kg Liveweight
XVII Estimation of �Tarinnce Components for Live\,7eigh t G.�in Data
Page
102
103 105 107 108 109 111
112 113 116 118 119 120 121
122
124
127
XVIII XIX
Analysis of Oven DH Determination Data for Maize Silage 129
Analysis of Biuret Utilisation Data 131
