HUE UNIVERSITY
UNIVERSITY OF AGRICULTURE AND FORESTRY
PHANTHAVONG VONGSAMPHANH
CASSAVA BY-PRODUCT AS POTENTIAL FEED
SOURCE FOR YELLOW CATTLE IN LAO PDR
DOCTOR OF PHILOSOPHY IN ANIMAL SCIENCES
HUE, 2019
HUE UNIVERSITY
UNIVERSITY OF AGRICULTURE AND FORESTRY
PHANTHAVONG VONGSAMPHANH
CASSAVA BY-PRODUCT AS POTENTIAL FEED
SOURCE FOR YELLOW CATTLE IN LAO PDR
SPECIALIZATION: ANIMAL SCIENCES
CODE: 9620105
DOCTOR OF PHILOSOPHY IN ANIMAL SCIENCES
SUPERVISOR 1: ASSOCIATE PROFESSOR. DR. NGUYEN XUAN BA
SUPERVISOR 2: DR. DINH VAN DUNG
HUE, 2019
GUARANTEE
I hereby declare that this dissertation is the result of my work and that is has not
been presented previously as a dissertation at this university or elsewhere. To declare
that all sources to be acknowledged and all to be listed in the reference.
Hue University, 2019
Phanthavong Vongsamphanh, PhD student
i
ACKNOWLEDGEMENTS
I would like to express my sincere gratitude and appreciation to my major
advisor, Associate Professor Dr. Nguyen Xuan Ba, Faculty of Animal Science and
Veterinary Medicine, Hue University of Agriculture and Forestry, Hue University, Hue
City, Vietnam for his invaluable advice, encouragement and generous sharing of
knowledge both scientifically and actually, which has enabled me to complete this
thesis.
I would like also deeply grateful to my co-advisors, Dr. Dinh Van Dung,
Faculty of Animal Science and Veterinary Medicine, Hue University of Agriculture
and Forestry, Hue University, Hue City, Vietnam for his kind not only served as my coadvisor, but has been a friend, encouraging me to explore and experience to the limit.
He has provided so many valuable services beyond just advising, teaching, mentoring
and continuous support in many ways to broaden my perspectives and made this thesis
the final product of my research.
I would like to express my sincere thanks to Professor Dr. T R Preston from
Centro para la Investigación en Sistemas Sostenibles de Producción Agropecuaria
(CIPAV), Carrera 25 No 6-62 Cali, Colombia for his advice, suggestions and guided in
my experiment from the beginning and made correction as needed, include revision of
English in the manuscript. His encouragement, criticism, excellent technical assistance
guided not only my study but also invaluable suggestions for me in the future.
My research and education would not have been possible without Dr
Viengsakoun Napasirth from Faculty of Agriculture, National University of Lao and
the Faculty of Agriculture and Forest Resource, Souphanouvong University and my
friend there’s. Mr. Sangkhom Inthapanya and Mr. Phonevilay Silivong for their
provided valuable help in the laboratory. I also would like to thanks to Mr. Khamla
and Mr. Vakili Vongxay, owners of the Sukanya and Natthanasouck farms where the
experiments were carried out, for providing access to cattle, feed resources and
infrastructure.The Tropical Feed Resources Research and Development Center
(TROFEC) of Khon Kaen University, Thailand is acknowledged for support in
collection of rumen samples and VFA analysis.
ii
Thanks to Department of Livestock and Fisheries, National Agriculture and
Forestry Research Institute, Ministry of Agriculture and Forestry for facilities
supported and permission for me to study. I wish to express my sincere appreciation to
all those people whose names do not appear here-in who helped me to complete this
thesis. I would like to give big thanks to my family for their understanding and moral
support during the study, especially my wife for her encouragement and inspiration.
Finally, I wish to express special thanks to the MEKARN Project II for
generous contribution towards financial support that made this thesis, my education and
career goals possible.
iii
ABSTRACT
The objectives of this study were (i) evaluated the potential of feeding value of
the cassava pulp to local yellow cattle. (ii) to study the effect of brewers' grain and
cassava foliage (Manihot esculenta Cranz) as protein sources for Lao local cattle fed
cassava pulp-urea as basal diet, (iii) to evaluate the effects of source of cassava leaves
(sweet or bitter at 4% DM) and with or without of brewers’ grain at 4% DM in an in
vitro rumen fermentation on gas and methane production using the ensiled cassava pulp
supplemented with urea as basal substrate (iv) to evaluated the basis of the method for
incorporating cassava foliage as the protein-fiber source in a fattening system for local
Yellow cattle based on ensiled cassava pulp (derived from processing of cassava roots
for starch production).
The result of first experiment were the pH was changed with the level of pit
depth the pH was high when collected sample in surface and pH decreased when
collected deeper and DM was between 20 to 25%. Gas production and DM
mineralization values after 24h fermentation in an in vitro incubation showed cassava
pulp was slightly inferior (<10%) to fresh cassava root as an energy feed resource for
ruminants. Local "Yellow" cattle fed ad libitum ensiled cassava pulp, urea, brewers'
grains and rice straw was gain averaged 0.66 kg/day after 4 months of fattening, with a
DM feed conversion of 6.67, confirming that ensiled cassava pulp could be the basal
diet for intensive fattening of cattle in Lao PDR.
For the second experiment found that live weight gains were 517 and 495g/d
and DM feed conversions were similar for the diets in which all the protein came from
brewers’ grains (BG) or when the source of protein was divided equally between
brewers’ grains and bitter cassava foliage (CF-BG) (7.55 and 8.05). DM feed intake
was reduced by 30% and growth rate very poor (160 g/d) when bitter cassava foliage
was the only source of protein. The third experiment the rate of gas production was
higher when leaves of sweet rather than bitter cassava were the source of protein and
when brewers’ grains were added to the substrate. For all incubation intervals the
methane content in the gas was lower for bitter than for sweet cassava leaves and lower
when brewers’ grains were added to the substrate. The proportion of substrate DM that
iv
was digested and the methane produced per unit DM digested were reduced when the
leaves of bitter rather than sweet cassava were the source of protein. The effect of the
brewers’ grains was to increase the proportion of DM digested and to reduce the
methane production per unit of substrate digested. And the last experiment found that
growth rates were 622 and 608 g/day when the diet of ensiled cassava pulp,
supplemented with urea, cassava foliage, brewers’ grains and rice straw, was fed as a
completely mixed ration in fresh form (CMR), or after ensiling for 21 days (ECMR).
Live weight gains were 30% higher (857 g/day) when almost all the protein was in the
form of brewers’ grains, and the ingredients were not mixed (apart from the urea which
was dissolved in the cassava pulp at the time of feeding). Feed conversion rates were
8.85 and 9.14 for the CMR and ECMR systems compared with 6.61 for the control. It
is suggested that excessively high levels of cyanogenic glucosides in the cassava
foliage, which was collected at the end of the dry season from a “bitter” cassava variety
at the time of root harvest, may have contributed to the poorer performance of the cattle
fed the CMR diets. The result indicated that using cassava by-product to cattle fattening
for energy and protein sources promoted weigh gain of cattle.
TABLE OF CONTENTS
v
GUARANTEE..................................................................................................................i
ACKNOWLEDGEMENTS...........................................................................................ii
ABSTRACT...................................................................................................................iv
TABLE OF CONTENTS..............................................................................................vi
LIST OF TABLES..........................................................................................................x
TABLE OF FIGURE....................................................................................................xii
INTRODUCTION..........................................................................................................1
1. Problem statement.........................................................................................................1
2. Aims and objectives of the study..................................................................................4
2.1. Aim of the study....................................................................................................4
2.2. Objectives of the study..........................................................................................4
3. Research Hypothesis.....................................................................................................4
4. Significance / Innovation of the dissertation................................................................5
5. REFFERENCE.............................................................................................................6
CHAPTER 1.....................................................................................................................8
LITERATURE REVIEW.................................................................................................8
1. Cattle production system in Lao PDR..........................................................................8
1.1 The role of cattle production in small households.................................................8
1.2 Cattle population and farm size in Lao PDR.........................................................9
2. Cattle feeds and feeding management........................................................................12
3. Challenge and opportunities for cattle production in Lao PDR..................................17
4. Rumen Microbial Ecosystem......................................................................................20
4.1 The ruminal microorganisms....................................................................................22
5. Manipulated feeding practices....................................................................................26
6. Cassava by-product and brewers’ grains for cattle feeding........................................27
7. Cassava pulp...............................................................................................................31
8. Brewers’ grains...........................................................................................................34
9. References...................................................................................................................38
CHAPTER 2...................................................................................................................47
Abstract...........................................................................................................................47
Introduction.....................................................................................................................48
Materials and methods....................................................................................................49
Testing the pH, dry matter and nutritive value content..............................................49
vi
In vitro gas and methane production..........................................................................49
Feeding trail...............................................................................................................51
Data cOllection, sampling and chemical analysis..........................................................52
Feed sampling............................................................................................................52
Animal test.................................................................................................................52
Statistical analysis......................................................................................................52
Results and discussion....................................................................................................53
pH and chemical composition of cassava pulp..........................................................53
The chemical composition.........................................................................................53
In vitro gas and methane production..........................................................................54
Feed intake and live weight gain of cattle..................................................................56
Conclusions.....................................................................................................................56
Reference........................................................................................................................57
CHAPTER 3...................................................................................................................75
cassava foliage (Manihot esculenta Cranz) and Brewers' grains as protein sources for
local “Yellow” cattle fed cassava pulp as basal diet.......................................................75
Abstract...........................................................................................................................75
Introduction.....................................................................................................................76
Materials and methods....................................................................................................77
Location and duration................................................................................................77
Experimental design...................................................................................................77
Animals and housing..................................................................................................77
Feeding system...........................................................................................................78
Measurements............................................................................................................78
Chemical analysis.......................................................................................................79
Economic analysis......................................................................................................79
Statistical analysis......................................................................................................79
Results and disscusion....................................................................................................79
Chemical composition of the experimental diet.........................................................79
Feed intake, live weight gain and feed conversion....................................................80
Discussion.......................................................................................................................83
Conclusions.....................................................................................................................84
References.......................................................................................................................85
CHAPTER 4...................................................................................................................87
vii
Effect of cassava leaves from different varieties and brewers’ grains on methane
production in an in vitro rumen incubation of cassava pulp...........................................87
Abstract...........................................................................................................................87
Introduction.....................................................................................................................88
Materials and methods....................................................................................................88
Location......................................................................................................................88
Treatments and experimental design..........................................................................89
In vitro rumen fermentation system...........................................................................89
Experimental procedure.............................................................................................90
Data collection and measurements.............................................................................91
Statistical analysis......................................................................................................91
Results and discussion....................................................................................................91
Chemical composition................................................................................................91
Gas and methane production......................................................................................92
Discussion.......................................................................................................................96
Conclusions.....................................................................................................................98
References.......................................................................................................................98
CHAPTER 5.................................................................................................................100
the comparation completely mixed ration and separately feeding on yellow cattle
fattening by using cassava by-product..........................................................................100
Abstract.........................................................................................................................100
Introduction...................................................................................................................101
Materials and methods..................................................................................................102
Location and duration..............................................................................................102
Animals....................................................................................................................103
Feeding system.............................................................................................................104
Measurements..........................................................................................................104
Statistical analysis....................................................................................................105
Results and discussion..................................................................................................105
Chemical composition of the experimental diet.......................................................105
Economic return.......................................................................................................107
Discussion.....................................................................................................................108
Conclusions...................................................................................................................111
References.....................................................................................................................111
viii
CHAPTER 6.................................................................................................................114
GENERAL DISCUSSION AND CONCLUSIONS....................................................114
Implications..................................................................................................................116
Future research..............................................................................................................116
Reference......................................................................................................................118
PUBLICATIONS LIST................................................................................................121
Appendices....................................................................................................................122
LIST OF TABLES
CHAPTER 1.....................................................................................................................8
ix
Table 1. Cattle Number 2011 to 2017 by Province and Region (1,000 head).......9
Table 2. Cattle Herd Sizes as a Percentage of Cattle Holdings...........................11
Table 3. Natural pasture and their typical nutritive value for ruminants in Lao
PDR.....................................................................................................................14
Table 4. Summary of strategic crops, in year 2017.............................................15
Table 5. Physical and chemical characteristics of rumen ecosystem..................21
Table 6. Microbiological characteristics of rumen ecosystem............................23
Table 7 Nutrients and anitinutreints composition of cassava foliage..................28
Table 8 Chemical composition of cassava pulp..................................................31
Table 9 Nutritional composition of brewer’s grains............................................35
CHAPTER 2...................................................................................................................47
Table 1. Proportions of the substrates in the in vitro incubation.........................50
Table 2. Ingredients of the buffer solution..........................................................50
Table 3. Composition of the diet fed to the Yellow cattle...................................51
Table 4. Mean values for gas production, methane in the gas and DM
mineralized in the in vitro incubation of cassava pulp and cassava root
supplemented with urea and cassava leaf meal...................................................54
Table 5. Mean values for the feed intake, growth rate and feed conversion over
the 120 days of the fattening period....................................................................56
CHAPTER 3...................................................................................................................75
Table 1. Approximate amounts of the diet ingredients (DM, kg/day)*..............78
Table 2. Chemical composition of diet ingredients.............................................80
Table 3. Mean values for feed intake according to dietary treatments................81
Table 4. Mean values for DM intake, live weight gain and feed conversion for
“Yellow” cattle fed a basal diet of cassava pulp supplemented with urea and
either brewers’ grains, or bitter cassava foliage or a combination of brewers’
grains and bitter cassava foliage..........................................................................81
Table 5. Economic analysis of value of live weight gain over costs of feed.......83
CHAPTER 4...................................................................................................................87
Table 1. Ingredients in the substrate, g DM........................................................89
Table 2. Ingredients of the buffer solution (g/liter).............................................90
x
Table 3. The chemical composition of substrate ingredients (% in DM, except
DM which is on fresh basis)................................................................................92
Table 4. Mean values for gas production, methane in the gas, DM digestibility
and methane per units substrate...........................................................................93
CHAPTER 5.................................................................................................................100
Table 1. Composition of the experimental diets (% DM basis)........................103
Table 2 Composition of diet ingredients...........................................................103
Table 3. pH of completed mixed feeds prior to and after ensiling, and before
feeding (ECMR) and after mixing and before feeding, for CMR. Fumonisis was
determined in representative samples of feeds mid-way through the experiment
...........................................................................................................................104
Table 4 Chemical composition of experimental diet, % in DM........................105
Table 5. Mean values for DM intake, initial and final live weights, live weight
gain and feed conversion for Yellow cattle fed cassava pulp-urea, cassava
foliage, rice bran and rice straw as complete mixed feed (CMR), as ensiled
mixed feed (ECMR) or with the major feed ingredients offered separately (CTL)
...........................................................................................................................106
Table 6. Mean values for rumen pH and VFA in cattle fed cassava pulp-urea,
cassava foliage and rice straw as complete mixed ration (CMR) or as ensiled
mixed ration (ECMR) or cassava pulp-urea, brewers’ grains and rice straw fed
separately (CTL)................................................................................................107
Table 7. Economic analysis of value of live weight gain over costs of feed.....108
TABLE OF FIGURE
xi
CHAPTER 1.....................................................................................................................8
Figure 1. Age and sex structure of cattle, Lao PDR............................................11
Figure 2. Grazing land area in Lao PDR.............................................................13
Figure 3. Area of improved bred grass species in Lao PDR...............................16
Figure 4 Illustration of rumen swamp buffalo with ruminal bacteria, protozoa,
fungal zoospores, fermentation process and fermentation end-products............22
Figure.5. Model of the interaction of yeast cells with rumen microbes (Jouany,
2006)....................................................................................................................36
CHAPTER 2...................................................................................................................47
Figure.1. cassava pulp sampling point.................................................................49
Figure 2. Changes in dry matter content of the pulp at increasing depth in the pit
.............................................................................................................................53
Figure3. Changes in pH of the pulp at increasing depth in the pit......................53
Figure 4. Gas production from cassava pulp &cassava root supplemented with
urea and cassava leaf meal...................................................................................55
CHAPTER 3...................................................................................................................75
Figures 1-3. DM intake, live weight gain and DM feed conversion of cattle fed
cassava pulp-urea and either brewers' grains (BG), bitter cassava foliage brewers' grains, CF-BG, or bitter cassava foliage (CF).......................................82
Figure 4. Trends in live weight with time on experiment for Yellow cattle fed a
basal diet of cassava pulp supplemented with urea and either brewers’ grains,
(BG) or bitter cassava foliage (CF) or a combination of brewers’ grains and
bitter cassava foliage (CF-BF).............................................................................82
CHAPTER 4...................................................................................................................87
Figure 1. A schematic view of measuring gas production in the in vitro rumen
fermentation.........................................................................................................90
Figure 2. Effect of sweet or bitter cassava leaves with or without brewers’ grains
on gas production 0-6h........................................................................................94
Figure 3. Effect of sweet or bitter cassava leaves with or without brewers’ grains
on gas production 6-12h......................................................................................94
Figure 4. Effect of sweet or bitter cassava leaves with or without brewers’ grains
on gas production 12-18h....................................................................................94
Figure 5. Effect of sweet or bitter cassava leaves with or without brewers’ grains
on gas production 18-24h....................................................................................94
xii
Figure 6. Effect of sweet or bitter cassava leaves with or without brewers’ grains
on percent methane in the gas 0-6h.....................................................................95
Figure 7. Effect of sweet or bitter cassava leaves with or without brewers’ grains
on percent methane in the gas 6-12h...................................................................95
Figure 8. Effect of sweet or bitter cassava leaves with or without brewers’ grains
on percent methane in the gas 12-18h.................................................................95
Figure 9. Effect of sweet or bitter cassava leaves with or without brewers’ grains
on percent methane in the gas 18-24h.................................................................95
Figure 10. Effect of sweet or bitter cassava leaves with or without brewers’
grains on percent DM digested............................................................................96
Figure 11. Effect of sweet or bitter cassava leaves with or without brewers’
grains on methane per unit substrate digested.....................................................96
CHAPTER 5.................................................................................................................100
Figure 1. Comparative growth rates and DM feed conversion of Yellow cattle
fed ensiled cassava pulp-urea, and rice straw supplemented with brewers’ grains
(CTL); or a completely mixed ration (CMR) of 46% ensiled cassava pulp, 26%
fresh cassava foliage and 4% brewers grains (all on DM basis); or the
completely mixed ration ensiled 3 weeks before feeding (ECMR). On all diets,
urea and minerals were added immediately before feeding..............................106
xiii
INTRODUCTION
1. PROBLEM STATEMENT
According to the MAF (2017), there are 1.98 million cattle in Lao PDR mostly
dominated by indigenous "Yellow" cattle (Bos indicus). 95% of the total cattle
population is owned by smallholders. 297,000 of farm households or 38% of the total
farm household have cattle. Approximately 27% of total farm households in the
northern region hold cattle, while in central and southern regions the percentage of
households having cattle were 50% and 32% of total farm households, respectively
(ACO 2012).
Cattle production in Lao PDR is an interplay of human and natural systems
performing critical development functions through its contribution to nutritious diets,
economic growth, livelihoods and environmental sustainability. Cattle production is an
integral part of the smallholder mixed farming systems practiced in the country and can
be characterized by agro-ecological conditions of lowlands, uplands, and highlands,
where farmers utilize various land resources for cattle grazing. The majority of the
cattle production is based on low input integrated with various types of crop production
systems at the household level. Many rural households with cattle are currently best
considered to be “livestock keepers” rather than “livestock producers".
The main problem with cattle production in Lao PDR is nutrient deficiency,
particularly during the long dry season (see figure in appendix 1-4). Fiems et al (2015)
indicating that beef cattle feeding systems that do not meet the energy requirements of
the animals may result in the failure of beef cattle to meet performance expectations.
Poor grazing and dry season management in beef cattle in Lao PDR resulting in low
reproductive performance with calving rate around 51-75% calving interval 14-16
months, time to reach slaughter weight for males 5-8 years and low beef cattle carcass
weights of 65- 84 kg, with dressing percentages well below profitable levels (i.e. less
than 40%) (Nampanya et al., 2013).
Currently, there is an increasing surplus of cassava by-product that is available
year round for animal feed in Lao PDR. Those by-products that have potential to add
1
value as alternative feed resources are cassava pulp, cassava foliage, and rice straw. It
is estimated that the five cassava starch factories have a yearly production of 55,000
tons of pulp and more than 200.000 tone of cassava pulp is stored in open pits
(resulting in local pollution problems). Cassava foliage by-product from cassava
plantation which annually is left in the field after root harvesting (around 1,250 tons
from 63,260 ha of harvested area), the availability of rice straw is 3 million tons per
year (MAF 2017), in addition brewers’ grains the residue of beer processing are around
150,000 tons per year from four brewery factories over the whole country. All these all
resources would be sufficient to fatten some 200,000 beef cattle per year with an added
value to the Lao economy of USD $36 million.
In view of the decrease of natural resources and limitations in access to
conventional feeds (due to competing land use eg rice. maize etc..) is timely to
introduce cassava byproduct which is cheap and less competitive - cattle can convert it
to a higher production yield and end product quality. It has shown that cassava pulp
composes 15.8-23.4% dry matter (DM) with 1.2-2.8% crude protein (CP), 55.0-74.4%
nitrogen-free extract, 0.1-2.4% fat, 17.9-24.0% crude fiber and 1.7-2.8% ash, on DM
basis (Yimmongkol, 2009; Pilajun and Wanapat, 2018), and according to Sriroth et al
(2000) cassava pulp is rich in starch with 69% in DM, Keaokliang O et al (2018)
reported the total digestible nutrients, digestible energy, and ME contents of cassava
pulp were 74.4%, 12.9 MJ/kg DM, and 11.3 MJ/kg DM, respectively, it suitable as the
energy component of an intensive feeding system for fattening cattle it would need to
be supplemented only with urea, a source of roughage and bypass protein and minerals,
as has been demonstrated for other low-protein, carbohydrate-rich tropical feeds such
as molasses (Preston 1971) and sugar cane (Preston et al., 1976; Ffoulkes and Preston
1978).
Cassava foliage can be harvested from 4 months old without any effect on
average total biomass and storage root yields, with non-significant effects on both
height and stem diameter (Munyahali et al 2017) For every tonne of roots that are
harvested there are an additional 600 kg of stems and leaves which also have a high
potential feeding value for cattle (Ffoulkes and Preston 1978; Wanapat et al., 1997),
2
and goats (Ho Quang Do et al., 2002). The protein content in cassava leaves is around
22-25% in dry matter (DM), Cassava foliage also contains anti-nutritional factors
(ANF’s) such as cyanogenic glucosides and tannins. Cyanogenic glucosides can give
rise to toxic hydroxyanic (HCN) by the action of either enzymatic activity in damaged
plant tissue or within the digestive tract of the animal (Van Soest, 1994).
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 (HCN >50mg/kg as fresh), The cassava varieties that are
planted for human consumption are known as “sweet” varieties as they have a lower
content of (HCN < 50mg/kg as as fresh). Much research on evaluating the use of
cassava for livestock feeding has thus concentrated on methods to reduce the HCN
content, such as sun-drying and ensiling (Phuc et al 1995). Development of cassava byproduct to cattle feed sources has been negligible and not been studied previously under
Lao conditions especially cassava pulp storage in open pit.
Therefore the main questions addressed in the various experiments are as follows:
1. Cassava pulp storage in an open pit for more than 4 years in cassava factory can be
potential energy feed sources for beef cattle in Lao PDR ?
2. What is the response of cattle performance on bitter cassava foliage or/and brewers’
grain supplement as protein-fiber source in cassava pulp as basal diet ?
3. What is the effect of supplement of different varieties of cassava leave and 4%
brewers’ grain on gas production, methane in the gas, DM digestibility and methane
per units substrate in an in vitro rumen incubation of cassava pulp?
4. What is the most effective and efficient method to utilize bitter cassava foliage in a
feed mix ration for a fattening system that gives the best economic outcome for the
producer and the Lao economy?
3
2. AIMS AND OBJECTIVES OF THE STUDY
2.1. Aim of the study
The aim of this research study was to improve beef cattle production systems
and reduce methane emissions through the use of cassava pulp stored in open pit for
more than 4 years.
It is hoped that improved utilization of cassava by-products for fattening cattle
will sustainably increase profits to Lao farmers and rural livelihoods in general.
2.2. Objectives of the study
These research studies were divided into 4 consecutive objectives, as follows:
1. To evaluate the potential of feeding value of the storage cassava pulp in an open pit
2. To measure the response of cattle performance on bitter cassava foliage or/and
brewers’ grains as a source of bypass protein and fiber supplements to cassava
pulp-urea basal diet for feeding local yellow cattle
3. To evaluate the effect of different varieties of cassava leaves and supplementation
with brewers' grains (0 or 4%) on methane production in an in vitro production of
cassava pulp – urea as the main substrate
4. To find out the most efficient/economic methodology for incorporating bitter
cassava foliage as the protein-fiber source in the cassava pulp for a cattle fattening
system.
3. RESEARCH HYPOTHESIS
- The characteristics of cassava pulp as stored in an open pit 200m*50m*10m
(around 100,000 tones) would be a suitable basal diet for the intensive fattening of local
yellow cattle in Lao PDR.
- The bitter variety of cassava foliage could be used as the source of bypass
protein and fiber mixed to brewers' grain fed to local yellow cattle fed being on cassava
pulp-urea as basal diets.
4
- The in vitro rumen fermentation of complete mixed ration, the methane
production would be reduced: (i) when the protein source was the foliage of bitter
cassava compared with foliage of sweet cassava; (ii) when small amount brewers’ grain
supplement acts as prebiotic with resultant positive effects on gas methane production
- The different ways of feeding cassava foliage may affect the intake,
digestibility, and solubility of the protein. The proportions of the VFA, and therefore
the production of methane in the rumen fermentation system and a small proportion of
brewers’ grains in the diet (4%) will help control the toxicity of the HCN in bitter
cassava foliage.
4. SIGNIFICANCE / INNOVATION OF THE
DISSERTATION
Utilization of by product from cassava production, significant beef production
gains can be achieved:
- Cassava pulp about 100.000 tones in open pit at cassava starch factory, can be
high potential feed in term of nutrition value and production for fattening cattle in Lao
condition and could be used as basal diet
- The bypass protein and fiber source can be provided in the form of either: (i)
brewers’ grains or: (ii) bitter cassava foliage combines with brewers’ grains (50:50)
will give good performance.
- In vitro rumen incubations of a substrate of cassava pulp showed that: methane
production was decreased by: supplementation with cassava leaves of bitter rather than
sweet varieties; and by the addition of low levels of brewers’ grains (4%)
- Cassava pulp through various methodologies such as separate, fermented and
ensilage feed was shown to have potential for developing intensive fattening of cattle in
feedlot and also in small holders in Lao PDR
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