The production of volatile fatty acids in sheep on different pasture types : a thesis presented in partial fulfilment of the requiremenrts for the degree of Master of Agricultural Science at Massey University

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 Me thod 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 Conoen tr 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

T^able

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 D

_i

e

l

y

is Probe and Intus1on ^Outlet

following page

47

48

Appendix I Appendix II

Appendix III

Append^ix IV

Appendix V

Appendix VI

Appendix VII

Appendix

VIII

Appendix IX

Appendix X Appendix XI

APPENDICES

Live Weight Changes - AD lysis 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

_Rum

en

_VFA

Samples

Measurement ot Spec

i

fic

Activity ot

Rumen

VFA trom

separated Acids - Analysis ot

V

ar_ia

n

_ce

Measurement

^{of Spec1tic}

A

_cti_v

i

_ty ot Total Rumen

VFA

- Analy•is ot Variance Elimination of Spurious Resul

t

^s

Example Calculation ot

_{VFA Pro}

d

_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