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Nâng cao hiệu quả sử dụng bauhinia acuminate trong chăn nuôi dê ở lào

HUE UNIVERSITY
UNIVERSITY OF AGRICULTURE AND FORESTRY

PHONEVILAY SILIVONG

IMPROVED UTILISATION OF BAUHINIA ACUMINATA
FOR GOAT PRODUCTION IN LAO PDR

DOCTOR OF PHILOSOPHY IN ANIMAL SCIENCES

HUE, 2020


HUE UNIVERSITY
UNIVERSITY OF AGRICULTURE AND FORESTRY

PHONEVILAY SILIVONG

IMPROVED UTILISATION OF BAUHINIA ACUMINATA
FOR GOAT PRODUCTION IN LAO PDR


SPECIALIZATION: ANIMAL SCIENCES
CODE: 9620105

DOCTOR OF PHILOSOPHY IN ANIMAL SCIENCES

SUPERVISOR 1: ASSOC.PROF. NGUYEN HUU VAN
SUPERVISOR 2: DR. DUONG THANH HAI

HUE, 2020


GUARANTEE

I hereby guarantee that scientific work in this thesis is mine. All results
described in this thesis are righteous and objective. They have been published in
Journal of Livestock Research for Rural Development (LRRD) http://www.lrrd.org

Hue University, 2020

Phonevilay Silivong, PhD student

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ACKNOWLEDGEMENTS

The research in this PhD thesis was conducted at the farm and laboratory of
Department of Animal Science, Faculty of Agriculture and Forest Resource,
Souphanouvong University, in Luangprabang Province, Lao PDR with supported from
Mekong Basin Animal Research Network (MEKARN II) project for funding this
theses research and the scholarship for the PhD degree. I am grateful for the support
from all of those people and institutions.
I am greatly indebted to my main supervisor, Associate Professor Nguyen Huu
Van and co-supervisor, Dr. Duong Thanh Hai for his mentoring and constructive
advice during my studies. He made me much more confident as a scientist and
researcher. His patience and encouragement during my illness and positive criticism
made it possible to accomplish this work.
My special thanks to Professor Thomas Reg Preston and Professor Dr. Ron Leng,
my teacher and adviser, for all your valuable guidance and support during the study.
I would also like to extend sincere thanks to Professor Dr. Ewadle, International


Coordinator MEKARN II project; Dr. Vanthong Phengvichith, National Agriculture
and Forestry Researcher Institute (NAFRI), Lao PDR; Dr. Kieu Borin, MEKARN II
regional coordinator for their facilitation, help and support to the whole course.
Professors, lecturers and assistant lecturers in Hue University of Agriculture and
Forestry and MEKARN II program, for giving me care and useful knowledge.
Warm thanks are extended to my father, Mr. Souk Silivong for his great help
and support. My mother, Ms. Khampoun Silivong for her assistance and
encouragement, my older brothers and sister Mrs. Kesone Silivong, Mr. Vone
Silivong, Mr. Sonexay Silivong and younger sister Mrs. Bounmee Silivong for their
supported and encouragement; to my wife, Mrs. Souksadar Vongyalud and my son
Phetsamone Silivong and my daughter Souphaphone Silivong for their love.
I would like to warmly thank Mr. Khamlek and Mr. Phonesavath, and Mr.
Siphone, my analysis assistants and my colleagues in the Department of Animal
Science, Faculty of Agriculture and Forest Resource, Souphanouvong University. All
of my friends in the PhD program 2017-2020 from the three countries: Laos, Vietnam
and Cambodia, for sharing the culture, friendship and creating a warm atmosphere
throughout the time of the course.
I would like to thanks all the people who contributed to this study.

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ABSTRACTS
This study was aimed at the utilization of locally available feed resources for
increasing growth performance and reducing enteric methane emissions from goats in
Lao PDR. Five experiments (two in vitro and three in vivo) were carried out and
presented in four chapters of this dissertation. Experiment 1 evaluated the effect on
methane production from leaves of Bauhinia acuminata and Guazuma ulmifolia of an
increasing level of water spinach as source of soluble protein. Experiment 2 and 3
were studied the effects of water spinach and biochar on enteric methane emissions
and growth performance in local goats fed Bauhinia acuminata and molasses, or
cassava root chip, as the basal diet. Experiment 4 aimed to determine the effect of
different protein sources (cassava foliage or water spinach) with or without of brewers’
grain (5% of diet DM)) on feed intake, digestibility, N balance and growth
performance of local goats. Experiment 5 was to determine the effect of biochar and
leaf meal from sweet and bitter cassava leaves, on methane production in an in vitro
incubation of Bauhinia acuminata and water spinach as basal substrate.
The main findings of the study were that: (1) Goats fed Bauhinia acuminata
responded with improved diet digestibility, N retention and growth rate when the
Bauhinia acuminata was supplemented with water spinach; (2) However an important
negative effect was that the improvement in diet digestibility by supplementation with
water spinach led to increases in methane production per unit diet DM digested; (3)
Supplementing Bauhinia acuminata foliage with leaves from a bitter variety of
cassava reduced the in vitro production of methane when compared with
supplementation by leaves from a sweet variety of cassava; (4) Ensiled brewers’ grains
fed as an additive (5% as DM) to a diet of Bauhinia acuminata improved the
digestibility, N retention and growth rate of goats. The degree of improvement was
greater when the Bauhinia acuminata was supplemented with cassava foliage instead
of water spinach; (5) Biochar fed at 1% of a diet of Bauhinia acuminata and cassava
foliage was as effective as brewers’ grains in improving the growth rate of the goats.
The results of this study indicated that supplementation of foliage from water
spinach or cassava improved growth of local goats fed Bauhinia acuminata as basal
diet. HCN present in the leaves of cassava could be the reason for the reduction in
methane emission. Ensiled brewers’ grains and biochar fed to goats as additives
probably act as “prebiotics” to improve growth performance and assist in
detoxification in the animal.
Key words: N-balance, protein solubility, bauhinia, water spinach, solubility Nbalance, rumen ammonia, biochar, prebiotics, HCN
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DEDICATION

To my parents, my wife Souksadar Vongyalud, my son (Phetsamone Silivong)
and daughter (Souphaphone Silivong)
To:
My country (Lao PDR)

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TABLE OF CONTENT

GUARANTEE...............................................................................................................I
ACKNOWLEDGEMENTS..........................................................................................II
ABSTRACTS.............................................................................................................. III
DEDICATION............................................................................................................IV
TABLE OF CONTENT..............................................................................................IV
LIST OF FIGURES...................................................................................................VII
LIST OF TABLES.......................................................................................................X
LIST OF ABBREVIATIONS, SYMBOLS AND EQUIVALENTS........................XIV
INTRODUCTION.........................................................................................................I
1. PROBLEM STATEMENT...............................................................................1
2. THE OBJECTIVES..........................................................................................4
3. THE HYPOTHESIS.........................................................................................5
4. SIGNIFICANT/INNOVATION OF THE DISSERTATION...........................5
REFERENCES.....................................................................................................5
CHAPTER 1. LITERATURE REVIEW.....................................................................10
1. GOAT PRODUCTION IN LAO PDR............................................................10
2. ROLE OF GOAT PRODUCTION IN LAOS.................................................12
2.1. GOAT POPULATION AND DISTRIBUTION........................................12
2.2. GOAT PRODUCTION SYSTEMS IN SMALLHOLDER FARMS.........15
2.3. GOAT BREED AND BREEDING............................................................17
2.4. CONSTRAINTS OF GOAT PRODUCTION IN LAO.............................19
2.5. POTENTIAL OF GOAT PRODUCTION DEVELOPMENT IN LAO....19
3. GOAT NUTRITION AND METHANE EMISSION.....................................21
3.1. NUTRIENT REQUIREMENT FOR GOAT.............................................21
3.2. METHANE EMISSION............................................................................25
4. LOCAL AVAILABLE FEES RESOURCES FOR GOAT IN LAO...............29
4.1. FEEDING SYSTEM.................................................................................35
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REFERENCES...................................................................................................43
CHAPTER 2. EFFECT OF WATER SPINACH ON METHANE PRODUCTION IN
AN IN VITRO INCUBATION WITH SUBSTRATES OF BAUHINIA
ACUMINATA OR GUAZUMA ULMIFOLIA LEAVES AND MOLASSES...........59
ABSTRACT.......................................................................................................59
INTRODUCTION..............................................................................................59
MATERIALS AND METHODS........................................................................60
RESULTS...........................................................................................................63
DISCUSSION.....................................................................................................67
CONCLUSIONS................................................................................................68
REFERENCES...................................................................................................68
CHAPTER 3. EFFECTS OF WATER SPINACH AND BIOCHAR ON METHANE
EMISSIONS AND GROWTH PERFORMANCE OF GOAT FED BAUHINIA
ACUMINATA AND MOLASSES OR CASSAVA ROOT CHIPS AS......................71
ABSTRACT.......................................................................................................71
INTRODUCTION..............................................................................................71
MATERIALS AND METHODS........................................................................73
RESULTS...........................................................................................................78
DISCUSSION.....................................................................................................90
CONCLUSIONS................................................................................................91
REFERENCES...................................................................................................91
CHAPTER 4. EFFECT OF REPLACING WATER SPINACH (IPOMOEA
AQUATICA) BY CASSAVA (MANIHOT ESCULENTA CRANTZ) FOLIAGE
AND/OR BREWERS’ GRAINS ON FEED INTAKE, DIGESTIBILITY, N
RETENTION AND GROWTH PERFORMANCE IN GOAT FED BAUHINIA
ACUMINATA PLUS CASSAVA ROOT CHIPS AS THE BASAL DIET................95
ABSTRACT.......................................................................................................95
INTRODUCTION..............................................................................................95
MATERIALS AND METHODS........................................................................96
RESULTS.........................................................................................................100
DISCUSSION...................................................................................................105
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CONCLUSIONS..............................................................................................105
REFERENCES.................................................................................................105
CHARPTER 5. EFFECT OF SWEET OR BITTER CASSAVA LEAVES AND
BIOCHAR ON METHANE PRODUCTION IN AN IN VITRO INCUBATION WITH
SUBSTRATES OF BAUHINIA ACUMINATA AND WATER SPINACH (IPOMOEA
AQUATICA)..............................................................................................................107
ABSTRACT.....................................................................................................107
INTRODUCTION............................................................................................107
MATERIALS AND METHODS......................................................................108
RESULTS.........................................................................................................111
DISCUSSION...................................................................................................116
CONCLUSIONS..............................................................................................116
REFERENCES.................................................................................................117
GENERAL DISCUSSION AND CONCLUSIONS..................................................120
GENERAL DISCUSSION...............................................................................120
GENERAL CONCLUSIONS...........................................................................123
IMPLICATIONS..............................................................................................123
FURTHER RESEARCH..................................................................................124
REFERENCES.................................................................................................124
PUBLISHCATION LIST..........................................................................................127

vii


LIST OF TABLES

CHAPTER 1. LITERATURE REVIE

Table 1. The number of goat in Lao PDR...........................................................13
Table 2. Estimated of animals requirement (2017-2020)...................................20
Table 3. Daily Nutrient Requirements for Meat Producing Goats.......................22
Table 4. Nutrient Requirements of Mature Does.................................................24
Table 5. Important fodder tree and shrubs in the Lao PDR.................................30
Table 6. Chemical composition of fodder trees and shrubs leaves......................31
CHAPTER 2. EFFECT OF WATER SPINACH ON METHANE PRODUCTION IN
AN IN VITRO INCUBATION WITH SUBSTRATES OF BAUHINIA
ACUMINATA OR GUAZUMA ULMIFOLIA LEAVES AND MOLASSES
Table 1. Composition of diets (% DM basis).......................................................62
Table 2. Ingredients of the buffer solution (g/liter)..............................................62
Table 3. The chemical composition of feed (% in DM, except DM which is on
fresh basis)..........................................................................................................64
Table 4. Mean values for gas production, percentage of methane in the gas,
methane production (ml), DM solubilized and methane production per unit DM
solubilized according to leaf source (Bauhinia and Guazuma) and level of water
spinach................................................................................................................65
CHAPTER 3. EFFECTS OF WATER SPINACH AND BIOCHAR ON METHANE
EMISSIONS AND GROWTH PERFORMANCE OF GOAT FED BAUHINIA
ACUMINATA AND MOLASSES OR CASSAVA ROOT CHIPS AS THE BASAL DIET
Table 1. Chemical composition of dietary ingredients (% in DM, except DM
which is on fresh basis).......................................................................................78
Table 2. Mean values of feed intake by goats fed Bauhinia acuminata
supplemented with water spinach (WS) or biochar (BC) or not supplemented...79
Table 3. Mean values for live weight, live weight change, feed DM intake and
DM feed conversion for goats fed a basal diet of Bauhinia acuminata foliage and
molasses..............................................................................................................79

viii


Table 4. Mean values of apparent digestibility and N balance in goats fed
Bauhinia acuminata and molasses supplemented with water spinach (WS) and
biochar (BC) or not supplemented (No-WS; No-BC).........................................81
Table 5. Mean values of rumen pH and ammonia, and ratio of methane to carbon
dioxide in eructed breath of goats fed Bauhinia acuminata and molasses
supplemented with water spinach (WS) and biochar (BC) or not supplemented
(No-WS; No-BC)................................................................................................82
Table 6. Mean values of feed intake by goats fed Bauhinia acuminata and cassava
root chips supplemented with water spinach (WS) or biochar (BC) or not
supplemented......................................................................................................84
Table 7. Mean values for live weight, live weight change, feed DM intake and
DM feed conversion for goats fed a basal diet of Bauhinia acuminata foliage and
Cassava root chips...............................................................................................85
Table 8. Mean values of apparent digestibility and N balance in goats fed
Bauhinia acuminata and cassava root chips supplemented with water spinach
(WS) and biochar (BC)or not supplemented (No-WS; No-BC)..........................87
Table 9. Mean values of rumen pH and ammonia in goats fed Bauhinia
acuminata and cassava root chips supplemented with water spinach (WS) and
biochar (BC) or not supplemented (No-WS; No-BC).........................................89
CHAPTER 4. EFFECT OF REPLACING WATER SPINACH (IPOMOEA
AQUATICA) BY CASSAVA (MANIHOT ESCULENTA CRANTZ) FOLIAGE
AND/OR BREWERS’ GRAINS ON FEED INTAKE, DIGESTIBILITY, N
RETENTION AND GROWTH PERFORMANCE IN GOAT FED BAUHINIA
ACUMINATA PLUS CASSAVA ROOT CHIPS AS THE BASAL DIET
Table 1. Layout of the digestibility/N retention study.........................................97
Table 2. Chemical composition of dietary ingredients (% in DM, except DM
which is on fresh basis).....................................................................................100
Table 3. Mean values of apparent digestibility and N balance in goats fed
Bauhinia acuminata supplemented with water spinach or cassava foliage, with
(BG) and without (No-BG) brewers’ grains.....................................................101
Table 4. Mean values of feed intake by goats fed Bauhinia acuminata plus
cassava root.......................................................................................................102
Table 5. Mean values for live weight, live weight change, DM intake and DM
feed conversion for goats fed Bauhinia acuminata supplemented with cassava or
water spinach foliage, with or without brewers’ grains (interaction effects).....103
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Table 6. Molar VFA proportions in rumen fluid from goats fed Bauhinia
acuminata supplemented with water spinach or cassava foliage, with and without
brewers’ grains..................................................................................................104
CHARPTER 5. EFFECT OF SWEET OR BITTER CASSAVA LEAVES AND
BIOCHAR ON METHANE PRODUCTION IN AN IN VITRO INCUBATION
WITH SUBSTRATES OF BAUHINIA ACUMINATA AND WATER SPINACH
(IPOMOEA AQUATICA)
Table 1. Composition of substrate (% DM basis)..............................................110
Table 2. Ingredients of the buffer solution (g/liter)...........................................110

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LIST OF FIGURES

CHAPTER 1. LITERATURE REVIEW
Figure 1. Fermentation pathways in the rumen...................................................27
CHAPTER 2. EFFECT OF WATER SPINACH ON METHANE PRODUCTION IN
AN IN VITRO INCUBATION WITH SUBSTRATES OF BAUHINIA ACUMINATA
OR GUAZUMA ULMIFOLIA LEAVES AND MOLASSES
Diagram 1. A schematic view of the in vitro system to measure gas production in
an in vitro incubation...........................................................................................60
Photo 1: Bauhinia acuminata...............................................................................61
Photo 2: Guazuma ulmifolia................................................................................61
Photo 3. The in vitro system made from recycled "pep" water bottles................63
Photo 4. The substrate residue filtered though cloth............................................63
Figure 1. Effect of Bauhinia (BA) and Guazuma (GU) leaf meals on gas
production at increasing incubation intervals......................................................66
Figure 2. Effect of increasing level of water spinach on gas production at
increasing incubation intervals............................................................................66
Figure 3. Effect of foliages from Bauhinia (BA) and Guazuma (GU) on methane
content in the gas at increasing incubation intervals............................................66
Figure 4. Effect of increasing level of water spinach on methane content in the
gas at increasing incubation intervals..................................................................66
Figure 5. Effect of leaf meals from Bauhinia (BA) and Guazuma (GU) on
substrate DM solubilized at increasing incubation interval.................................67
Figure 6. Effect of level of water spinach on substrate DM solubilized at
increasing incubation intervals............................................................................67
Figure 7. Effect of leaf meals from Bauhinia (BA) and Guazuma (GU) on
methane per unit DM solubilized at different incubation intervals......................67
Figure 8. Effect of increasing level of water spinach in the substrate on methane
per unit DM solubilized at increasing incubation intervals..................................67
CHAPTER 3. EFFECTS OF WATER SPINACH AND BIOCHAR ON METHANE
EMISSIONS AND GROWTH PERFORMANCE OF GOAT FED BAUHINIA

xi


ACUMINATA AND MOLASSES OR CASSAVA ROOT CHIPS AS THE BASAL
DIET
Photo 1. Goats confined in the metabolism pens.................................................74
Photo 2. Bauhinia acuminata foliage as presented to the goats...........................75
Photo 3. Goats were confined in a plastic-lined cage for the measurement of the
eructed gases with the Gasmet meter...................................................................76
Photo 4. Taking rumen fluid by...........................................................................76
stomach tube.......................................................................................................76
Figure 1. Effect of biochar on live weight gain of goats fed Bauhinia acuminate
and molasses with and without water spinach.....................................................80
Figure 2. Effect of supplementation with water spinach and biochar, separately or
together, on the growth rate of goats fed a basal diet of foliage from Bauhinia
acuminata and molasses.......................................................................................80
Figure 3. Effect of biochar compared with water spinach on feed conversion of
goats fed Bauhinia acuminata and molasses as....................................................80
basal diet.............................................................................................................80
Figure 4. Relationship between live weight gain and feed conversion in goats fed
Bauhinia acuminata foliage and molasses supplemented or not with water spinach
and biochar..........................................................................................................80
Figure 5. Effect of biochar on N retention as % N intake of goats fed Bauhinia
acuminata and molasses as basal diet with or without water spinach..................82
Figure 6. Effect of biochar on N retention as % N digested of goats fed Bauhinia
acuminata and molasses as basal diet with or without water spinach..................82
Figure 7. Effect of supplementation with water spinach and biochar, separately or
together, on rumen ammonia of goats fed a basal diet of foliage from Bauhinia
acuminate and molasses.......................................................................................83
Figure 8. Effect of water spinach on ratio of methane to carbon dioxide in eructed
gas from goats fed either Bauhinia acuminata and molasses as basal diet...........83
Figure 9. Effect of biochar on ratio of methane to carbon dioxide in eructed gas
from goats fed either Bauhinia acuminata and molasses as basal diet.................83
Figure 10. Supplements of water spinach and biochar increased the live weight
gain of goats fed Bauhinia acuminata and cassava root chips..............................85

xii


Figure 11. Supplements of water spinach and biochar improved the DM feed
conversion of goats fed Bauhinia acuminata and cassava root chips...................86
Figure 12. Relationship between live weight gain and feed conversion in goats
fed Bauhinia acuminata foliage and cassava root chips supplemented or not with
water spinach and biochar...................................................................................86
Figure 13. Supplements of water spinach and biochar increased the N retention
by goats fed Bauhinia acuminata and cassava root chips.....................................88
Figure 14. Supplements of water spinach and biochar improved the N retention
as % of N intake by goats fed Bauhinia acuminata and cassava root chips.........88
Figure 15. Supplements of water spinach and biochar improved the N retention
as % of N digested by goats fed Bauhinia acuminata and cassava root chips......89
Figure 16. A supplement of water spinach increased rumen ammonia in goats fed
Bauhinia acuminata and cassava root chips as basal diet.....................................90
Figure 17. Relationship between live weight gain and rumen ammonia in goats
fed Bauhinia acuminata foliage and cassava root chips supplemented or not with
water spinach and biochar...................................................................................90
CHAPTER 4. EFFECT OF REPLACING WATER SPINACH (IPOMOEA
AQUATICA) BY CASSAVA (MANIHOT ESCULENTA CRANTZ) FOLIAGE AND/
OR BREWERS’ GRAINS ON FEED INTAKE, DIGESTIBILITY, N RETENTION
AND GROWTH PERFORMANCE IN GOAT FED BAUHINIA ACUMINATA PLUS
CASSAVA ROOT CHIPS AS THE BASAL DIET
Photo 1. Cassava foliage hanging above the feed trough........................................98
Photo 2. Water spinach hanging above the feed trough..........................................98
Photo 3. Bauhinia acuminata hanging above the feed trough.................................98
Photo 4. Goats were presented in the metabolism pen...........................................98
Figure 1. Effect of brewer’s grain on N retention in goats fed water spinach or
cassava foliage as supplementary protein source..................................................102
Figure 2. Effect of brewer’s grain on N retention as % of digested N in goats fed
Bauhinia acuminata and water spinach or cassava foliage as supplementary protein
source................................................................................................................. 102
Figure 3. Proportions of dietary components in each treatment............................103
Figure 4. Effect of a supplement of brewers’ grains on live weight gain of goats fed
Bauhinia acuminata in combination with cassava foliage (CF) or water spinach
(WS)..................................................................................................................104
xiii


Figure 5. Effect of a supplement of brewers’ grains on DM feed conversion of goats
fed Bauhinia acuminata in combination with cassava foliage or water spinach.....104
CHARPTER 5. EFFECT OF SWEET OR BITTER CASSAVA LEAVES AND
BIOCHAR ON METHANE PRODUCTION IN AN IN VITRO INCUBATION WITH
SUBSTRATES OF BAUHINIA ACUMINATA AND WATER SPINACH (IPOMOEA
AQUATICA)
Diagram 1. A schematic view of the in vitro system to measure gas production in
an in vitro incubation (Inthapanya et al., 2017)....................................................109
Photos 1-3. Rice husks, gasifier stove and biochar derived from the rice husks....109
Figure 1. Effect of sweet or bitter cassava leaves on % methane in the gas...........114
Figure 2. Effect of biochar on % methane in the gas............................................114
Figure 3. Effect of supplementation with biochar on proportion of substrate digested
........................................................................................................................... 114
Figure 4. Effect of bitter versus sweet cassava on proportion of substrate digested
........................................................................................................................... 115
Figure 5. Effect of supplementation with biochar on production of methane per unit
substrate digested................................................................................................115
Figure 6. Effect of bitter versus sweet cassava on production of methane per unit
substrate digested...............................................................................................116

xiv


LIST OF ABBREVIATIONS, SYMBOLS AND EQUIVALENTS

ADF

Acid detergent fibre

ANOVA

Analysis of variance

AOAC

Association of Official Analytical Chemists

BW

Body weight

BG

Brewers’ grains

BC

Biochar

CF

Cassava foliage

CR

Cassava root

CF

Crude fibre

CH4

Methane

CO2

Carbon dioxide

CP

Crude protein

CT

Condensed tannins

CLM

Cassava leaf meal

DM

Dry matter

DMI

Dry matter intake

FCR

Feed conversion ratio

FMD

Foot and Mouth Disease

GDP

Gross Domestic Product

GHG

Green House Gas

ha

Hectare

Kg

Kilogram

HCN

Hydrogen cyanide

HS

Hemorrhagic Septicemia

LW

Live weight

Mekarn

Mekong basin animal research network

N

Nitrogen
xv


NDF

Neutral detergent fibre

NH3

Ammonia

NPN

None protein nitrogen

OM

Organic matter

pH

Percentage of Hydrogen Ion

Prob/P

Probability

PPM

Part per million

RCBD

Randomized complete block design

SE Asia

South East Asia

SEM

Standard error of the mean

Sida-SAREC Swedish international development cooperation
agency Department for research cooperation
TDN

Total Digestible Nutrition

VFA

Volatile Fatty Acid

WS

Water spinach

xvi


INTRODUCTION
1. PROBLEM STATEMENT
Laos is located in the central part of the Indochinese Peninsula. It is an inland
state surrounded by China, Vietnam, Cambodia, Thailand and Myanmar. Lao PDR has
a total land area of 236,800 km2. The agricultural land is limited to around 4% of total,
consisting of 18 provinces/cities comprising 148 districts.
Laos population has 7,028,094 people and is equivalent to 0.09% of the total
world population. Laos has a distinct rainy season from May to November, followed
by a dry season from December to April. Local tradition holds that there are three
seasons (rainy, cold and hot) as the latter two months of the climatologically defined
dry season are noticeably hotter than the earlier four months.
Goats are increasingly important for subsistence food production with over 90%
of the global goat population found in developing countries (Glimp, 1995; FAO, 2005;
World Bank, 2013). As goats produce several livestock products with lower inputs
than cattle and buffalo, smallholder goat farmers in developing countries, particularly
in Asia and Africa, have increasingly been recruited to goat raising, with goats
described as an ‘entry point’ on the ‘pathway from poverty’. Goats are considered
more easily managed than cattle, especially by resource poor farmers, including
women. Goat raising offers households nutritional benefits as meat protein for hunger
alleviation, enhanced livelihoods from animal trading income, more effective
utilisation of family labour, and increased livelihood stability and resilience in rural
communities due to more self-reliance (FAO, 2005; World Bank, 2013). In Southeast
Asia, goats have been of increasing importance, particularly in countries with large
Islamic populations, including Indonesia, Malaysia, and parts of the Philippines and
Thailand. However, in recent years, increasing demand for consumption of goat meat
in Vietnam and China has created opportunities for increasing production in the Lao
People’s Democratic Republic (Laos, henceforth). Currently, the government of Laos
is attempting to obtain an average meat supply for local consumption of
60kg/capita/year, plus increased meat exports to a value of USD 50 million by 2020
(FAO, 2005).
In Laos, goat production is traditionally extensive with low inputs, and
subsequently low outputs (Kounnavongsa et al., 2010). Four major goat management
systems have been described, including: free range; semi-free range; semi-rotational
grazing; and permanent grazing with or without tethering. Free range is the most
commonly observed system, although semi-free range can be found in areas where
cropping predominates (Kounnavongsa et al., 2010; Phengvichith and Preston, 2011).
1


In most systems, goats are herded back to the village and kept in small hutches
overnight for protection, although housing is only considered beneficial if it is kept
clean (Phengsavanh, 2003). The system used by an individual farmer will depend upon
feed and labour availability plus local community agreements, particularly related to
cropping and use of common grazing areas (Kounnavongsa et al., 2010; Phengvichith
and Preston, 2011). Typically, Lao goat herds consist of 3-10 animals (Kounnavongsa
et al., 2010; Phengvichith and Preston, 2011), although there are some recent examples
of developing herds with as many as 200 animals raised on semi- and fullycommercial farms. Approximately 551,153 goats were recorded in Laos in the 2016
agricultural census (DLF, 2016). This number is likely to be underestimated, as it is
widely considered to have been increasing rapidly due to recent expanding regional
demand for goat meat, particularly from Vietnam, with estimates that between 2,0003,000 goats per month are being exported. Increasing demand for consumption of goat
meat in Laos and neighbouring Vietnam and China, is providing opportunities for
smallholder farmers to increase productivity and has led to the development of semi to
full commercial production systems to capitalise on the growth in this emerging
livestock sector, particularly if biosecure transboundary trade can be enhanced (Stur et
al., 2002; Windsor, 2011; Nampanya et al., 2015). However, introducing goats and
expanding small goat herds where smallholders and potential commercial operators
have limited experience of small ruminants can be exceedingly challenging. In recent
years, many international development agencies have promoted smallholder goatraising programs with distribution of goats to untrained farmers, often accompanied by
severe mortality and morbidity problems (Windsor et al., 2017).
In developing improved systems for feeding livestock, account must also be
taken of the impacts on the environment. It is estimated that livestock presently
account for some 18% of greenhouses gases which cause global warming (Steinfeld et
al., 2006). Enteric methane from fermentative rumen digestion is the main source of
these emissions. There is an urgent need to develop ways of reducing methane
emissions from ruminants in order to meet future targets for mitigating global
warming.
The legume tree Bauhinia acuminata is widely distributed in many parts of Lao
specially in Luang Prabang, and it has been observed that the foliage is readily
consumed by goats. The leaves of Bauhinia acuminata have 14.5% of protein of low
solubility (22%). As is the case with foliage from most legume trees, it contains many
secondary plant compounds including tannins (Silivong and Preston, 2015)
Water spinach (Ipomoea aquatica) is cultivated for human food and also is fed
to animals such as goats, pigs, ducks and rabbits. It does not appear to contain antinutritional compounds and has been used successfully for goats as the only source of
2


supplementary protein (Phongpanith et al; 2013). It grows equally well in water or in
soil. It responds dramatically in biomass yield and protein content when fertilized.
(Preston et al., 2013) reported that the leaves contain 24% protein in dry matter (DM)
and that the protein is highly soluble (71%) and therefore easily fermentable as a
source of nutrients for rumen microorganisms. These qualities make water spinach an
ideal supplement for tree foliages of low nutritive value. Thus, (Kongmanila et al.,
2007) reported that water spinach supplementation of foliages from Fig, Jujube and
Mango trees increased the DM and crude protein intake of goats, and improved the
apparent digestibility and N retention. According to Thu Hong et al., 2011, the live
weight gain of goats fed Mimosa foliage was increased 27% by supplementing with
fresh water spinach. Goats fed a sole diet of cassava foliage also responded with
increased DM digestibility and N retention when fresh water spinach was provided as
a supplement (Patshoummalangsy and Preston, 2006).
Cassava (Manihot esculenta Crantz) is an annual crop grown widely in the
tropical and subtropical regions. Roots of cassava are rich in energy (75 to 85% of
soluble carbohydrate) but with minimal levels of crude protein (2 to 3% in DM). The
development of the starch industry in Lao for export to China and other neighboring
countries has increased the market for cassava roots. As a result, cassava is currently
the third most important crop in Laos, after rice and maize.
The varieties used for industrial starch production are known as “bitter”
varieties due to the high content of cyanogenic glucosides that are converted into the
highly toxic hydrocyanic acid when consumed by animals and people. The cassava
varieties that are planted for human consumption are known as “sweet” varieties as
they have a lower content of cyanogenic glucosides.
For every tonne of roots that are harvested there are an additional 600kg of
stems and leaves. However, the farmers in the cassava factory area have no experience
in the utilization of cassava leaves as the protein supplement to feed to animals,
especially cattle.
The foliage of cassava has been shown to be an effective source of bypass
protein for fattening steers (Ffoulkes and Preston, 1978; Keo Sath et al., 2008;
Wanapat et al., 1997). It is thus a logical forage to provide the additional protein
required in diets rich in carbohydrate but low in protein. Cassava leaves are known to
contain variable levels of condensed tannins; about 3% in DM according to Netpana et
al., 2001 and Bui Phan Thu Hang and Ledin, 2005. Condensed tannins are reported to
decrease rumen methane production and increase the efficiency of microbial protein
synthesis (Makkar et al., 1995; Grainger et al., 2009). Reductions of CH 4 production of
13 to 16% have been reported (Carulla et al., 2005; Waghorn et al., 2002, Grainger et
3


al., 2009; Woodward et al., 2004), apparently through a direct toxic effect on
methanogens.
Brewers’ grains is a byproduct derived from the industrial brewing of beer.
Research with goats (Sina et al; 2017) highlighted a major interaction between the
effect of the supplementary brewers’ grains and the nature of the basal diet. The
improvement in growth rate due to addition of brewers’ grains was 130% when the
basal diet was fresh cassava foliage but only 30% when the basal diet was water
spinach (Sina et al., 2017).
A positive approach to the problem of how to reduce methane emissions from
live stock has been to incorporate a low level (1%) of biochar in the diet (Sangkhom et
al., 2012; Leng et al., 2012a,b,c). Biochar is the product of incomplete carbonization of
fibrous biomass at high temperatures (Lehmann and Joseph, 2009). It is a highly
porous material which gives it valuable properties as a support mechanism for biofilms
that facilitate the adsorption of consortia of micro-organisms and nutrients that may
prioritize incorporation of hydrogen into volatile acids rather than methane (Leng,
2018 personal communication).
2. THE OBJECTIVES
The study aimed at the utilization of locally available feed resources for
increasing growth performance and reducing enteric methane emissions from goats in
Lao PDR. The specific objectives were following:
- To evaluate the of water spinach as a source of high soluble protein and
biochar on methane production in an in vitro system with substrate of Bauhinia
acuminata or Guazuma ulmifolia leaves
- To evaluate the effect of water spinach as a source of high soluble protein and
biochar on feed intake, digestibility, N retention, methane emission and growth
performance of goats fed Bauhinia acuminata foliages plus molasses or dried cassava
root chip as the basal diets.
- To examine the effect of replacing water spinach by cassava foliage and/or
brewer’s grain on feed intake, digestibility, N retention and growth performance of
goat fed Bauhinia acuminata plus dried cassava root chip as the basal diets.
- To compare the sweet or bitter of cassava leaves and biochar on gas
production, methane content of the gas and methane ml/g DM digested in an in vitro
incubation.

4


3. THE HYPOTHESIS
- Water spinach, with its high content of soluble protein, would increase the rate
of fermentation and production of methane when added to forage rich in insoluble
protein such as Bauhinia acuminata or Guazuma ulmifolia leaves.
- The performance of growing goats fed Bauhinia acuminata as the basal diet
would be improved by supplementation with water spinach as a rapidly fermentable
protein source. Enteric methane production would be reduced by adding a low level
(1%) of biochar.
- Goats fed foliage of the legume tree Bauhinia acuminata would respond
positively in growth rate and feed conversion to a low-level supplement of brewers’
grains, and that the degree of response would be greater when cassava foliage, rather
than water spinach, was the complementary source of protein.
- The methane content of the gas produced in an in vitro fermentation would be
reduced when leaves of bitter cassava replaced leaves of sweet cassava as
supplementary protein source and when 1% of biochar was added to the substrate.
4. SIGNIFICANT/INNOVATION OF THE DISSERTATION
This is the first series of study and the first sciencetific information on
improving the utilization of Bauhinia acuminata for goat production in Laos. The
results presented in this dissertation indicate that: (1) Goats fed Bauhinia acuminata
responded with improved diet digestibility, N retention and growth rate when the
Bauhinia acuminata was supplemented with water spinach; (2) But an important
negative effect was that the improvement in diet digestibility by supplementation with
water spinach led to increases in methane production per unit diet DM digested; (3)
Supplementing Bauhinia acuminata foliage with leaves from a bitter variety of
cassava reduced the in vitro production of methane when compared with
supplementation by leaves from a sweet variety of cassava; (4) Ensiled brewers’ grains
fed as an additive (5% as DM) to a diet of Bauhinia acuminata improved the
digestibility, N retention and growth rate of goats. The degree of improvement was
greater when the Bauhinia acuminata was supplemented with cassava foliage instead
of water spinach; (5) Biochar fed at 1% of a diet of Bauhinia acuminata and cassava
foliage was as effective as brewers’ grains in improving the growth rate of the goats.
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2005.http://www.mekarn.org/procsr/hangctu.pdf

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