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.
AF.PL I CAT I ON Of' L I NJ�AR PF.CGI ."\.;.;;..!I NG TO Fi•J\M }1�'\!'L\.GE!vU:::NT )J.'\.\.L YS IS: INTENSIVE DEi�.F'
GHAZIN'G :.JYSTE;,;s
A thesis presented in partial fulfilment of the rectuircmcnts for the degree of Ma s t e r of Ag r i c u 1 tu r a l S c i c n c e i n .r a n.1
Management at Massey University.
Alan F. McRae September 1975.
TABLE U2 CONT2NTS LIST OF FIGURES ACKNU. iLI-=DGE�·;ENT S ABSTRACT
{ i i )
TABLE OF COI,'TENTS
CHAFT£1\. ONE: :t-,;OTIVATJON, OBJECT I VES A;'-JD Ol!TLINE
OF STuDY 1.1 Introduction
1.1.1 Intensive Grazing Systems 1.2 Motivation for This Study
1.2.1 The Systems Rese arch Concept 1.2.2 The Usefulness of J.,.:athematical
Systems }.!ode l s 1.3 Objectives of the Study 1.4 Thesis Outline
CJL\.FfEF<. TWO: THE B2EF Gi\..AZI.t\G SYSTE\l 2.1 Introduction
2.2 Components of the Grazing System
2. 2. 1 Interaction of the System ComFoncnts Over Time
2 . 2 • 2 U n c e r t a i n t y ·. ,· i t h i n t h c S y s t em 2.2.3 Summary of System Components
2.3 Research Nork on the Components of a Beef Grazing System
2.3.1 Pasture Product i on and Grazing
.lvlanagement
2.3.2 Animal Production and Feed.
Requirements
2.3.3 The Use of Research Data 1n This Study
2.4 SystewModelling St,Jdies on Beef Production
page,
1 1 Vi i ix
:X.
1 1 3 4
9 1.0 10
12 12
14 17 1 8
18 19 22 24
in New Zealand 25
2.4.1 The Profitability Studies of Lattimore
{1970) and Lowe {1971) 25
2.4.2 Thc_Simulation Study of Wright,
Vallanc� and Nicol (1973)
2.5 A Dairy Farming Systems Modelling Study
27
29
2.6
2.7 2.8
( i i i )
The Compari s or.. o f Linear Programming wi t h Simulation as a Technique for Studying Grazing Sys t ems
The ./\lode l Used Summary
30
31
32
CHAFf El\ THI.I.EE: PASTURE GRO".\'TH
3.1 Introduction
3.2 Factors Affe cting the Regrowth of Pasture 3.2.1 The Pasture Regrowth Curve
3.2.2 Changes in the Grov,·th Cur ves
33 33 33
Throughout the Year 34
p.2.3 The Effect of Managemen t on Pasture
/
Growth 343.2.4 The Effect of Grazing Anima l s on
Pasture Producti on 39
3.2.4,1 The Number of Anirr:als GrLl.zed 39 3.2.4.2 The Treading Effects of
An i mals
3.2.4.3 The Effect of Faeces
40 41
3.3 Pasture Produc t ion Da t a Used in This Study 42 3.3.1 Assumptions Involved in Defining
Pasture Regrow t h
3.4 The Pasture Produc t ion Model
3.4.1 Pasture Producti on Possibilities rvithin the Model
45 46
46 3.4.2 The S t ruc t ure of t he hlodel 51
3 . 4. 3 The Representation of the Grazing
Process by t h e Mod e l 53
3.4.3.1 The Length of Spell Between
Grazings 53
3.4.3.2 The Height t o Which Pa s t ure i s
Grazed 54
3.4.4 Co�ne n t on t he Leng t h of Spel l Op t ions Wi t hin t he Pa s t ure Prod uc t ion Model
3.5 Dl\l Produc t io n A s s o ciated wi t h t he Pas t ure Produc tion Ac tivi t ies
56
58
3.6 Limitations in t he Pa sture Production Model Sl 3.7 Annual DM Production from t he Pasture
Production Mo de l 63
( i V)
3. 8 Summa-ry
CH.AFI'ER .FOUR: ANI MAL PRODUCT I ON
4.1 Introduction 66
4.2 The Intake -of Grazing Beef Animals 66 4.2.1 Factors Affecting the Potential Daily
Intake of Grazing Bee! Animals 69
4.2.2 Factors that Affect the Shape of the Function Relating .\.vailable Pasture
to I ntake 70
4.3 The Representation of Animal IntaRe Within
the .1\�od e 1 7 5
4..4 The Conversion of Feed Intake into Animal Pro duction
4.4.1 The Energy Value of Feed
4.4.2 Systews for Expressing Feed Hequ i re
ments
77 77
80
4.4.2.1 Published Feeding Standards 82 4.5 Feeding Standards Used in this Study 86
1.5.1 Calculat i on of Feed kcquircmcnts 4.5.1.1 The Relati�nship Detwccn
Animal Livewci.ght and nl� \1 1 • n-
86
tenance Requirement 86 4. 5.1.2 The H.elationsl1i1J Bctv.:een
Animal Liveweight Level of Performauce (L .. V. G.)
and Producti on Requirement 87
4.6 Summary
4.5.1.3 The Effect of Pasture (uality on Feeding Standards 91 4.5.1.4 A Consideration of
Compensatory Growth
4.5.1.5 The Significance of Intake (Livewcight Gain) Restrictions in the Feed Requirements
Model
92
93 94
(V)
CHAF'I'ER FI YE: MODEL EXPERH!ENT.\.TION AND RESULTS 5.1 Introduction
5.2 Animals Considered in the Study
5.3 The Stocking Hate Decision 5.3ol BEEF Production Systems
5.3.2 Maximization of Stocking Rates for BEEF Activities
5.3.3 Conditions that Prevent Further Increases in Stocking Rate for BEEF
p��
96 97 97
99
Systems 10 4
I I
I
5 . 3 • 3 • 1 BEJ:;:F 1 5 • 3 . 3 . 2 BESF 2 5 , 3 . 3 , 3 BEEF 3 5.3.3.4 B.SEF 4
5,4 Discussion on Maximum Stocking Rates for D£EF Systems
5.5 Gra�ing 1hnage�ent Plans
5. 5. 1 Comparison of Grazing l\bnagement Plan s 5. 5. 2
for BEEF1 and a.=Er-2
Comparisons of GrazinG lvlanag cmen l Plans that \ r ,,,ax1 nn • • z e Stocking
BEEF2 with l3i:.Eb�3 and BESF4
li � +-r"
J.\.C# '-' ..._. for
5.6 Relating Grazing Manag ement �lans to Farmer Practice
5. 6. 1 Uses of the Model for Grazing J,:anage
ment Studies 5.7 Supplementary Feeding
5.7.1 Hay and Silage Making Activities 5.7.2 Supplementary Feeding Activities 5,7,3 Experimentation with Supplementary
Feeding Possibilities
5.7.4 Discussion on the Increased Stocking Rate Due to Suppleme�tary Feeding
5.7,5 Further Experimentation Possible With the Model Including Supplementary Feeding Possibilities
5.8 Summ�ry
104 104
105 10 5
105 108
120
121
12 5 12 6 12 6 1 2 8
129
131
1 32 133
(vi)
CHAPTER SI X: EVALUATION OF STUDY 6. L Introduction
6. 2 Verifi.cation of the Model
Pag�
134 135
6.2.1 Pasture Production 135
6.2.2 .Animal Production as a Function of
Intake 13 6
6.3 Analysis of Farm 1-:lanagement Problems Using
L.P. Model s 138
6,4 Evaluahon of Study 141
API·ENDIX ONE: THE PASTURE 1-RODUCT I CN MODEL 143
APPEND I X r·.m: BESF r\.CTIVITI2S 140
APPENDIX TIL:�EE: SI-L'�Do.r PRICES 1I.SSOCU1TED \VITH THE
M.-I.XlMUl\f STOCKING R,\Tl.:: .Fl\.0:11 BEJ�F2 150 APPENDIX FOUR: THE SUFPLEl\:ENT:\H.Y FEEDING :VIOD.ZL
I3 I .BL I OGRii.FHY
153
157
Fig:..
1 .1
(v i i)
LIST OF FIGURES
Two A s pec t s of Sy s t em s Analysis in Relation
t o Sy s t em s Synthesis 7
2 . 1 Componen t s of a B e ef Produ ct ion System 1 3 2.2 Int errel a t i o n s h i p s Between Va riable s t hat
Affec t Production i n the t' t h Period of the Year
2 .3 The Evolutionary Deve l opmen t o f Grazing Management Sy s t e m s
3. 1 3.2
3.3
3.4
Generalized Pasture hegrowth Curve
H.epl'e s en tat ion of Hypo t he t i ea 1 )\!a nag emen t Decisions
Pasture Regrowth and DiJ.ily IncreJOents in D:'.·:/hc:..., Afte r i-IIGI-I and Lu,·r Defo l ia t i o n Pasture Production A f t e r Grazing HIGH and LOW in Period ( t )
3.5 Gr<>.z. i ng Pattern for ll!.?.xim,_,m .:�nnual DM
4. 1
Production from t he Jl.!odel
Actual Dai l y Intake/Head a s a Function o f Ava i l ab l e Feed/Head
4.2 A Rel a t i onsh i p Between P a s ture Available/
16
35
37
44
62
64
68
An i mal and Intake/Animal 72
4.3 A Gen e ra l i zed Rep re s en t a t i on of t h e Results
o f Reardon ( 1 9 75) 74
4.4 P a rt i t i on i ng of Feed Ene r g y Wi t h i n t he
Rurni nan t 7 8
4.5 Pa r t i t i on i ng o f Available Energy 79
4 .6 Compar i s o n of the Feeding Standards of Lowe
(1 971), Jagusch (1 9 73), and Tho s e Sho w n in Table 4.1 ; f o r Three Levels o f Livewe ig h t
4.7
Ga i n, and Three L i vewe i g h t s
};.a i n t enance I\e quiremen t as a Func t ion o f L i vewe i gh t
85 88
4.8
(viii)
Maintenance Requirement as a Function of
(L·. lVeWClg . ht)0.75 88
4.9 Livcweight Gain as a Fnnclion of Production
Intake/(Liveweight)0•75 90
5.1 Patterns of Liveweight Achieved by Animals in Beef Production Systems at hlaximum
Stocking ll.ates 5.2
5.3-506
Daily Liveweight Gain Achieved
Period Feed Requirements for BEEF 1, 2, 3 and 4, at Maximum Stocking Rates
5.7-5.10 Grazing Management Plan for BEEF 1, 2, 3 and 4
5. 1 1 The Fate of 27 ha. Grazed LO,'{ in Period
( 1 )
101 102-103 109-112.
11.5-118 124
( ix)
ACKNOiYLEDGSt,!EN fS
The a u thor would like to formally expre s s his gratitude to Professor Robert J. Townsley , Professor of Agricultural
Economics ancl Farm Management, Jl!assey University, for super
vision of the study . The time spent by Professor Townsley
assisti�g the author with interpretation of results and pre
sentation of this thesis i s particularly appreciated.
The author bene fited from discussions with several oth�r s t aff raembers at Massey University, e s pecially Dr. A. '.irigh t
and Dr . A.W.F. Davey .
The staff of the JAassey Universi ly Coroputer Unit have been particularly helpful .
The �� � i n i s t r y o f Ag r i c u 1 t u re and F i she r i e s have b e en tolerant employers throughout the somewhat extended duration of this study. Their financial assistance is gratefully acknowledged.
The author is appreciative of the efficient manner in which Jv:rs. Hildc Godenho typed the bulk of this thesis. Tb2nks
are also due to Miss Cathey Harris for typing parts of the thesis, and �·.ir. Rick Godenho for assistance in presentation of many of the text diagrams and tab 1 es.
The author would <:l.lso like to th<1.nk m.:tny others, friends
and flatmates, who helped make the period of this study a more enjoyable time than it may have otherwise been.
Finally, thanks are due to the author's parents for the interest they have shown, and the encouragement they have
off ered in this and earlier studi�s.
( x)
ABSTR.-iC'f
In the·absence of quantitative data from the practical farJr; situation, Linear Prograrruning (L.P.), was used as a frame
work for collecting research information on an intensive beef grazing system.
Three hundred pasture production activities were defin.;ed so that pasture was available for grazing at two grazing sever
ities i n e ach of 30 per iods throughout the year, after a range
of spelling lengths. Sevellteen supplementary feedmaking act
i vit i es allowed hay or silage to be made over the late spring, early summer period.· Supplementary feed could be fed out 1n
any period o f the year subject to the constraint that per
animal intake of supplementary feed did not exceed maintenance re qui remen t.
Animals considered by the model are Friesian bulls purchased at three months of age, and 100 Kg. livewcight, and grazed within the system for 12 18 months, until they reached a livewcight o f 380 Kg. Animal requirements were calculated as a function of liveweight and level of livcweight gain.
These requirements were expressed in terms of pasture dry matter per animal, and we1·c adjusted for assumed changes in the avz--1.ilable energy O.!.E.) content of pasture throughout the
year.
Although the model could not be verified in relation to the real-life situation, due to lack of quantitative data, the
capability of the model for solving farm management problems was investigated. An i terat i ve procedure for solving the stocking-rate decision was developed, and results presented and analysed. The use of the model for investigation of beef farm management problems was discussed.
. '
'
