Forage quality of some Kalahari browse species and its ability to reduce methane emission

102 Pages·2015·1.91 MB·English

Forage quality of some Kalahari browse species and its ability to reduce
methane emission

by

Jacobus Johannes Francois Theart

Submitted in partial fulfilment of the requirements of the degree
MSc (Agric) Animal Science: Animal Nutrition

In the Faculty of Natural and Agricultural Sciences
University of Pretoria
May 2015

Promotor: Dr Abubeker Hassen
Co-promotor: Prof Willem Adriaan van Niekerk
Table of contents
Table of content I
List of figures IV
List of tables IV
List of abbreviations VI
Declaration VIII
Acknowledgements IX
Summary X
General introduction 1
Chapter 1 Literature review 4
1.1.1 Plant bioactive compounds 4
1.1.2 Tannins (condensed and hydrolysed) 6
1.1.3 Other secondary plant components 8
1.1.3.1 Saponins 8
1.1.3.2 Essential oils 9
1.1.4 Plant species with the potential to be used as a feed supplement during
times of drought 10
1.1.5 Plant species with potential to decrease methane 11
1.1.6 Conclusion 12
1.1.7 Study objectives 13
1.1.8 Hypothesis 13
Chapter 2 Chemical compositions of some Kalahari browse forage species 14
2.1 Abstract 14
2.2 Introduction 15
2.3 Materials and methods 16
2.3.1 Sample collection and preparation 16
2.3.2 Determination of chemical composition of forage sample 16
2.3.3 Statistical analysis 17
2.4 Results and discussion 17
2.4.1 Chemical composition of the browse leaves 17
2.4.2 Secondary plant compound composition of browse species 18
2.4.3 Mineral composition of browse species 20
2.5 Conclusion 21
Chapter 3 Potential reduction of in vitro gas and methane production associated
with the tannin composition of browse foliage from the Kalahari region 26
3.1 Abstract 26
I
3.2 Introduction 26
3.3 Materials and methods 28
3.3.1 Sample collection and preparation 28
3.3.2 Determination of chemical composition of forage sample 28
3.3.3 In vitro gas production measurement 28
3.3.3.1 Collection of rumen fluid from donor sheep 28
3.3.3.2 Buffer media preparation, sample incubation and gas measurement 29
3.3.4 Short chain volatile fatty acids and ammonia-nitrogen analysis 29
3.3.5 Determination of in vitro digestible organic matter 30
3.3.6 Methane production measurements 30
3.3.7 Statistical 31
3.4 Results and discussion 31
3.4.1 In vitro gas production and tannin bioactivity 31
3.4.2 In vitro CH production 31
4
3.4.3 Volatile fatty acid and rumen ammonia-N production 32
3.4.4 Loss of energy as CH 34
4
3.4.5 Correlations between chemical composition, secondary compounds
and in vitro digestibility, gas and methane production 35
3.5 Conclusion 36
Chapter 4 In vitro methane and gas production characteristics of Eragrostis trichopophora
substrate supplemented with different browse foliage 42
4.1 Abstract 42
4.2 Introduction 42
4.3 Materials and methods 43
4.3.1 Selection of browse foliage 43
4.3.2 In vitro gas production measurement 44
4.3.2.1 Collection of rumen fluid from donor sheep 44
4.3.2.2 Buffer media preparation, sample incubation and gas measurement 44
4.3.3 Short chain volatile fatty acids and ammonia-nitrogen analysis 45
4.3.4 Determination of in vitro digestible organic matter 45
4.3.5 Methane production measurements 46
4.3.6 Statistical analysis 46
4.4 Results and discussion 46
4.4.1 Chemical composition 46
4.4.2 In vitro enteric methane production 47
4.4.3 In vitro gas production and in vitro organic matter digestibility 48
4.4.4 VFA concentration 50
II
4.4.5 Loss of energy as CH 50
4
4.5 Conclusion 51
Chapter 5 Dissertation conclusion 57
Chapter 6 Critical evaluation 59
6.1 Collection of browse species and chemical composition 59
6.2 Quantifying tannins 59
6.3 Poly ethanol glycol 60
6.4 Continuous reduction in methane production 60
6.5 Feeding trail 60
References 61

III
List of figures
1. Methane formation during fermentation 5
5.1 Methane production from browse with low tannin concentration during 48 hour incubation 48
5.2 Methane production from browse with low tannin concentration during 48 hour incubation 48
5.3 Gas production from browse with high tannin concentration during 48 hours incubation 49
5.4 Gas production from browse with low tannin concentration during 48 hours incubation 49

List of tables
1.1 Table 1 Effect of tannins on fermentation 12
2.1 List of browse species included in the study 22
2.2 Chemical composition and gross energy content of browse species used in the study 23
2.3 Phenolic composition of browse species selected form the Kalahari region in g/kg DM 24
2.4 Mineral composition of trees and shrubs 25
3.1 Correlation between fermentation products, different nutritional and phenolic components 36
3.2 Volumes (mL/g DM) of gas production from the studied browse and shrubs 38
3.3 Volumes (mL/g DM) of methane production from the studied browse and shrubs 39
3.4 Total and individual volatile fatty acid (mmol/L) concentration, in the supernatant after 72h
incubation of 400mg DM of browses with or without poly ethylene glycol 40
3.5 Loss of energy from the browse sample as methane expressed as (MJ/g DM) 41
4.1 Chemical composition of Eragrostis trichopophora (g/kg) 46
4.2 Volumes (mL/g DM) of gas production from the studied browse and shrubs supplemented to grass
hay at a ratio of 30:70 with or without polyethylene glycol 52
4.3 Volumes (mL/g DM) of methane production from the studied browse and shrubs supplemented to
grass hay at a ratio of 30:70 with or without polyethylene glycol 53
IV
4.4 Total and individual volatile fatty acid (mmol/L) concentration, in the supernatant after 72h
incubation of 400mg DM of browses with or without poly ethylene glycol 54
4.5 Loss of energy as methane (MJ/g DM) browse sample supplemented to grass hay at a ratio
of 30:70 55

4.6 Ratio of methane to some fermentation parameters (1:1) on a DM basis 56

V
List of abbreviations
ADF acid detergent fiber
ADL acid detergent lignin
CH methane
4
CO carbon dioxide
2
CP crud protein
CT condensed tannins
EE ether extract
GE gross energy
Gg Giga gram
GP gas production
IVDMD in vitro dry matter digestibility
IVOMD in vitro organic matter digestibility
Kg kilograms
ME metabolizable energy
mg milligrams
MJ mega joules
mL milliliters
MSE mean standard error
MW molecular weights
NDF neutral detergent fiber
NDFN neutral detergent fiber nitrogen
NFC non fiber carbohydrates
NTP non-tannin phenols
VI
OM organic matter
PEG polyethylene glycol
PVPP polyvinyl-polypyrrolidone
SCVFA short chain volatile fatty acid
TP total phenols
TT total tannins
VFA volatile fatty acid

VII
Declaration
I Jacobus Johannes Francois Theart declare that this dissertation, which I hereby submit for the degree
MSc (Agric) Animal Science: Animal Nutrition at the University of Pretoria, is my own work and has
not been previously submitted by me for a degree at this or any other tertiary institution.

Signature:……………………
May 2015

VIII
Acknowledgements
Sincere thanks to all the people and organizations that made this study possible. I would like to
express my sincerest gratitude to the following:
 Dr A. Hassen for his academic support and guidance throughout my post graduate studies
as well as his knowledge and patience during this study.
 Gemeda B.S. for his guidance, friendship and moral support during this study.
 Prof. W. A. Van Niekerk for his academic support and guidance throughout my undergrad
and post graduate studies.
 The European Union and Department of Science and Technology in South Africa for
funding the research as part of the AnimalChange project.
 My father Jan Theart and mother Marelise Theart for the help with the collection of the
browse material and their continuous support, love and encouragement throughout my
under graduate and post graduate studies.

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