View
217
Download
0
Category
Preview:
Citation preview
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.
THE PRODUCTIGN OP VOLATILE FATTY ACIDS
IN SHE!-;}) ON DIFFERENT PASTURE 'l'YPES
A thesis presented 1n partial tultilment ot the
requirements tor tbe degree ot Maeter
ot Agricultural Science in Antmal Science
a·t Maase)' Uu1vers1 t7
J AJJ.ES BRUCE MACKINTOSH
1970
AODOWLEDGEMEirfS
I wlab to �ank my supervisors, Dr. M.J.Ulyatt end
Proteasor D.s.nux, tor tbetr continual Interest, guidance
and asslatance thro�gbout tn1• proJect.
I indebted � the following tor their valuable and
w1111DS aaa1atanoe:
1lr P.Vlleg and tbe tecbn1cal atatt ot the Applied
Btoob let� Dlvialon, D.S.I.R. tor tbe prep ration
101d care ot the anlm8la;
Mr B.A.Tbomaon and Mr A.S.D.KlDg tor technical
aaslatance durlDg the experimot;
Mr J.A.Raven, Kr I.D.Sbelton and Mr N.J.Cbandler tor
aaeistance wltb obemical anal7als ot pasture;
The atatf ot the Herbage Laboraloey, Gr aalmda
Dlvlalon, D.S.I.R. tor tbe botanical anal7aea;
M bera ot the Sheep and Dalr,r Huabandr7 Departmenta
tor belptul dlacu .. lon.
Special tbanka are due to Kre M.D.Bew\b tor t7P1DB tb1a
theala.
PREP ACE
'rhe New Zealand economy depends largely on the
ettlclent conversion ot pasture to exportable animal products.
The current emphasis on higher stocking rates increases the
need tor pastures best suited to animal production.
Pasture species used 1D New Zealand are recognised
as ditter1ng in their ettects on animal production, these
differences being loosely attributed to Yariation 1n�asture
quality". It the level ot oatput ot saleable product la
the accepted measure ot pasture quality, thea the principal
factors governing this are the quantity ot teed consumed
and its subsequent ut111aat1on.
A number of studlea hRve shown that dltterences ln
food intake alone cannot account tor the observed differences
ln antmal performance. It baa thus been considered important
to investigate the factors attectlng the utlliaatlon ot
pasture by the animal.
Volatile tatty acids (VFA) produced ln the rumen
are generally considered to account tor 10 to 80 per cent
ot the net energy requlrementa ot ruminants, and their
production must be a ••Jor dete�lnant ot teed utlllaation.
Dltterences 1D tbe ruminal oonoentrationa and proportloaa ot
VPA have ott.en ben obaerYecl wl'tb pasture teedlDg and have
been otted aa poaalble reaaona tor dltterenoea 1D pasture
qual1t,-.
Tbe lnveat1sat1oa deaor1bed bere waa undertaken a a
prellm1D&r7 atudy ot tbe role ot VPA production lD determining
tbe quall� ot ••• Zealand p sture speolea.
TABLE OF CONTENTS
CHAPTER ONE REVIEW OP LITERATUHE
Introduction 1
1.1. The Quality ot M Jor New Zealand Paature Speolea 2
1.2. The Nutritional Slgn1t1canoe ot Volatile Patty Acid 6
1.3. Teobnlquea tor the �eaeurement ot VPA Production Rete 22
1.4. Sampling trom the : umen ot the Sb ep 36
CHAPTER TWO MAT�:aL\LS AND MF.THODS
2. 1. Animal a 41
2.2. Paatures 42
2.3. Experimental Dealgn 43
2. 4. Peed Organ1aat1on 45
2. 5. Apparent Dtg at1b111ty Determination 46
2.6. Intu ton Techn1qu 47
2. 7. V.A Sampllng Proo dure 48
2.8. ADalyttcal ethoda 51
2.9. St tt tloal AD l7a1a ot Dat 59
CHAPTER THREE
3.2.
CHAPTER FOUR
4.1.
4.2.
4.3.
RESULTS
lxper1mentel Method
Animal
Pastures
Dige tibl Energy Intake
VFA Infusion
VFA Sampling and An lyeia
VFA Production Rotee
The Contribution of VJA ProduotloD to Digestible Energv Intake
DISCUSSION
VFA Produotion RBtee
The Rel tionehlp between V?A Conoentr tion nd VPA Production 1n tb Rumen
The Mea•urement of V?A Production 1n tbe Rumen ot Graslng Sbe p
SUMUARY
REFlm.ENCES
APPJmDICBS
60
66
67
69
71
72
75
n
78
82
84
87
89
Table
1.1.
1.2.
1. 3.
1.4.
1. 5.
2.1.
2.2.
3.1.
3.2.
3. 5.1.
3.6.
3.7.
LIST OF' T.I\BI.ES
Live Weight Gains of Sheep on Different Pasture Species
Rumen Characteristics ot Sheep on Different Pasture Species
Published Estimates of VFA Production in Sheep
Theoretical Ktfic1ency of Utilisation ot Various Subatrates
Interconversion of VFA in the Rumen ot Sheep
General Plan ot the F�periment
Analysts of Total Soluble Sugars
Analysis uf Regression of VFA Proportions in D1alysstcs on Proportions in Prepared Solutions
Molar Proportions ot VFA in Rumen Samples
Analysts ot Regression ot VP.A. Proportions in Dialysates on Proportions in Direct Samples
Recovery of 14c Label after Preparation tor Counting
Live Weights and Live �eight Changes ov er the Experimental Period
Botanical Composition ot Pastures
Chemical Composition and Energy Content ot Herbage
Soluble Carbohydrate Content ot Cut Feeds
following page
2
3
7
page 13
34
43
51
60
61
61
page 62
66
page 67
67
page 68
3.8.
3.10.
3.1 1 .
3.12.
3. 1 3.
3.14.
�. 1 5.
3.1 6.
Mean D lly Intakes and D1geet1b111ty ot Pest�res. Period I
Mean Daily Intakes end D1gest1b111ty ot Paaturee. Period II
Digestible Energy Intakes
Molar Proportion or VFA in D1alyaatea
Percentages ot Total 14c 1n _ oh Hum n Acld
Recovery of Rad1oact1v1ty 1n Rumen VFA during Intrarum1nal Infusion ot Labelled Acetic Acid
Interoonvers1on ot VFA in the Rumen
VPA Production Uetes
Contr1bli tion ot V�A Production to DE Intake
68
68
page 69
72
72
page 73
73
75
77
Figure
1.1.
1. 2.
3.1.
LIST OF FIGURES
Metabolic Pathways ot VFA Production
Metabolic Pathways of VFA Utilisation
Relationship between Channels Retio and Counting Efficiency
following page
6
13
64
Plate I
Plate II
Plate III
LIST OF PLA'l'ES
Infusion and Sampling Apparatus in Operation
Diagrammat1o Representation ot Dialysis Probe
Relative Positions ot Diely is Probe and Intus1on Outlet
following page
47
48
Appendix I
Appendix II
Appendix III
Appendix IV
Appendix V
Appendix VI
Appendix VII
Appendix VIII
Appendix IX
Appendix X
Appendix XI
APPENDICES
Live Weight Changes - AD ly sis ot Variance
Dig stible ergy Intake - Analysis of Ver1anoe
Rate ot Infusion ot 14c-Labelled VFA
Measurement o f Specific Act1v1ty ot Infusion Solutions - Analy 1s of Variance
Specific Aot1v1t1es ot Rumen VFA Samples
Measurement ot Specific Activity ot Rumen VFA trom separated Acids - Analysis ot Variance
Measurement of Spec1tic Activity ot Total Rumen VFA - Analy•is ot Variance
Elimination of Spurious Results
Example Calculation ot VFA Prod uction
Rete and Contribution to DE Intake
Production Rates ot VFA - .Analy la ot Variance
Contribution ot VPA Production to DE Intake - ADaly i or Variance
Recommended