Cassava by-Product as potential feed source for yellow cattle in lao pdr

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
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 co-advisor, 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. 
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. 
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 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 
LIST OF TABLES
CHAPTER 1	8
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
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
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
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
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) indic ... ned by the negative effect of the HCN precursors (which was ameliorated by the addition of 5% of brewers’ grains to the diet). Further confirmation for the role of brewers’ grains as a prebiotic was the research of Binh et al (2017), which demonstrated a direct relationship between feeding brewers’ grains, growth enhancement of cattle and reduced excretion in the urine of thiocyanate - the product of the detoxification of HCN. Based on these findings, experiments were subsequently  carried out in which the brewers’ grains were reduced to even lower levels (4% of the diet DM) as the supplement to fattening diets for cattle based on cassava pulp-urea and sweet cassava foliage (Inthapanya et al., 2016).
In an in vitro incubation of cassava root pulp the rate of gas production was higher, when leaves of sweet rather than bitter cassava were the source of protein and when 4% of brewers’ grains were added to the substrate (in experiment iii), There aremany confirming the reduction in methane production when leaves from bitter cassava replace leaves from the sweet variety in in vitro rumen incubations of molasses (Phuong et al 2012), cassava root pulp (Phanthavong et al., 2015; Binh et al., 2018) and Bauhinia acuminata (Silivong et al., 2018). This effect in reducing methane production would seem to be the direct consequence of the higher concentrations in bitter versus sweet cassava leaves of a range of anti-nutritional compounds (cyanogenic glycosides, trypsin inhibitors, oxalates, phytate and tannin) reported by Sarkiyayi and Agar (2010). The research of Smith et al (1985) supports the concept that cyanide is toxic to methanogens, and/or reduces their potential growth by lowering the availability of sulphur by formation of thiocyanates (Majak and Cheng 1984). Additions of 5, 10, and 25 mg 1itre-l cyanide (from KCN or linamarin) temporarily inhibited methanogenesis in biodigesters charged with cassava root waste, but when the concentration of cyanide returned to lower levels (as it was before KCN or linamarin addition), methane production recovered (Cuzin and Labat, 1992). It was concluded that the biodigester methanogenic microflora were sensitive to the added cyanide.
From the fourth experiment there was a major difference between the CMR and CTL diets in the sources of protein with cassava foliage (26%) and brewers’ grains (4%) in the CMR diets replaced by 30% brewers’ grains in the control diet. This is not thought to be the reason for the differences in performance as in a feeding trial with the same basal diets and breed of animals (but with feeds that were not mixed), there were no differences in live weight gain between treatments in which brewers’ grains were the sole source of protein (ADG 563g/d) compared with only fresh cassava foliage as protein source (ADG 528g/d) (Keopaseuth and Preston, 2017). When cassava foliage was the sole source of protein in a cattle-fattening diet based on molasses-urea, there were no benefits from replacing 50% of the cassava foliage with soybean meal (Ffoulkes and Preston, 1978).
 	The results of the present experiment confirm that local "Yellow" cattle can be fattened on the byproduct pulp from cassava-starch factories using urea as source of rumen ammonia and cassava foliage as the main source of bypass protein, derived by recovering the leaves, petioles and fine stems available at the time of root harvest. These findings complement those of Keopaseuth and Preston (2017) using cassava foliage grown specifically as a forage crop to balance the cassava pulp-urea, but with these feeds offered separately. Growth rates (650g/d) were similar to those obtained in the present experiment with the cassava foliage collected at the time of root harvest and used in the CMR and ECMR systems. 
IMPLICATIONS 
The cassava pulp produced by the five cassava starch factories in Lao PDR about 55,000 tones per year, together with the cassava foliage available at root harvest could be the basis for supporting the intensive fattening of more than 100,000 head of local yellow cattle annually producing 7,000 tonnes of beef of high quality for export. Additional protein needs are more than covered by the brewers’ grains from the 5 beer factories. Farmers who presently produce the cassava roots, the raw material for the starch manufacture, should be encouraged to establish the cattle fattening systems on their farms, as this would generate as a byproduct the organic manure urgently needed to offset the loss of soil nutrients and organic matter which results when cassava is cropped continuously on the same land area. 
FUTURE RESEARCH 
There appears to be an unlimited market for beef in neighboring countries, especially China. Quality will be an increasingly important factor in order to secure highest prices for the product, either in carcass form or as live animals. Beef quality is achieved by ensuring fast rates of growth which increases growth of lean tissue and the content of the fat (marbling) in the meat, which ensures tenderness of the meat. Growth rates should be of the order of 600 to 700 g/day for local Yellow cattle, and 800 to 900 g/day for crossbred animals to achieve these standards. This in turn requires a diet of high nutritional value; high digestibility and adequate content of “metabolizable” protein. Grasses in tropical latitudes are much less digestible fiber than those in temperate latitudes; they are also lower in total protein, and the protein is “soluble” and rapidly fermented to ammonia in the rumen. Thus, in order to produce beef of high quality (and high price) it is essential to provide feeds that are: (i) highly digestible and have low fiber; and (ii) are rich in by-pass protein. 
Cassava roots fulfill the requirements as being the main source of digestible energy, either as whole roots or as the by-product (cassava pulp) from starch manufacture. The existing cassava factories cover a restricted area of the country. Future developments for the areas of Lao PDR not served by cassava starch factories could be based on ensiled cassava root as replacement for cassava pulp. Research is in progress to develop such a system. Brewers’ grains are one of the best sources of “by-pass” protein but, as in the case of the cassava pulp, access is restricted to the approximately 100 km radius from the breweries. Cassava foliage (leaves and thin stems) have been successfully used as the only protein supplement in diets for cattle based on urea-treated rice straw (Sath et al 2008) or molasses-urea (Ffoulkes et al 1978). Initial attempts to use cassava foliage as the sole protein supplement in cassava pulp-urea diets have successful as ensilage form and 4% replacement of the brewers’ grains with fresh cassava foliage appears to be feasible, and 100% replacement can probably be achieved in the future, through ongoing research. 
To further justify the emphasis on the cassava crop as the basis for intensive livestock production, it is relevant to emphasize the conclusions of a recent study in Africa which indicated that cassava would be least affected, or even benefitted, by global warming, whereas staple carbohydrate crops such as rice and maize would experience reduced yields (Jarvis et al 2012). 
Moreover, research conducted in this thesis, and elsewhere in Lao PDR (Leng et al ., 2012; Sivilong et al., 2018) and Vietnam (Thuy Hang et al., 2018; Binh et al., 2018, in press) indicates there are immediate animal growth and health benefits to be gained from supplementing livestock diets with biochar, the byproduct from the carbonization at high temperature of carbon-rich biomass (Preston, 2015). The stems of cassava are an excellent source of biomass for this purpose (Phalla, 2006) while the simple technology to produce the biochar is widely available in the form of updraft gasifier cook-stoves (Olivier, 2018) and downdraft gasifiers (Orosco et al., 2017). There is also the strong likelihood that the recycled excreta from biochar-supplemented livestock will retain the environmental benefits that biochar confers on soils in the form of increased retention of plant nutrients, reduced emissions of greenhouse gases (methane and nitrous oxides) and sequestration of carbon (Lehman 2007: Preston, 2015; Bouravong et al., 2017). Research to corroborate this use of cassava stems that are superfluous to the needs of subsequent plantings is of high priority.
REFERENCE 
Binh P L T, Preston T R, Duong K N & Leng R A (2017). A low concentration (4% in diet dry matter) of brewers’ grains improves the growth rate and reduces thiocyanate excretion of cattle fed cassava pulp-urea and “bitter” cassava foliage. Livestock Research for Rural Development. Volume 29, Article #104. 
Bouaravong B, Dung N N X & Preston T R (2017). Effect of biochar and biodigester effluent on yield of Taro (Colocasia esculenta) foliage. Livestock Research for Rural Development. Volume 29, Article #69.
Cuzin N & Labat M (1992). Reduction of cyanide levels during anaerobic digestion of cassava. International Journal of Food Science 27 329-326
Ffoulkes D & Preston T R (1978). Cassava or sweet potato forage as combined sources of protein and roughage in molasses based diets: effect of supplementation with soybean meal. Tropical Animal Production, Volume 3, Number 3 pp186-192  
Inthapanya S, Preston T R & Leng R A (2016). Ensiled brewers’ grains increased feed intake, digestibility and N retention in cattle fed ensiled cassava root, urea and rice straw with fresh cassava foliage or water spinach as main source of protein. Livestock Research for Rural Development. Volume 28, Article #20  28020.htm 
Jarvis A, Ramirez-Villegas J, Herrera Campo B V & Navarro-Racines C (2012). Is Cassava the Answer to African Climate Change Adaptation? Tropical Plant Biology.5 (1) 9-29. 
Keopaseuth T & Preston T R (2017). Cassava (Manihot esculenta Cranz) foliage replacing brewer’s grains as protein supplement for Yellow cattle fed cassava pulp-urea and rice straw; effects on growth, feed conversion and methane emissions. Livestock Research for Rural Development. Volume 29, Article #35. 
Leng R A, Preston T R & Inthapanya S (2012). Biochar reduces enteric methane and improves growth and feed conversion in local “Yellow” cattle fed cassava root chips and fresh cassava foliage. Livestock Research for Rural Development. Volume 24, Article #199. 
Majak W & Cheng K J (1984). Cyanogrnesis in bovine rumen contents and pure cultures of rumen bacteria Journal Animal Science 59, 784-790 
Phanthavong V, Viengsakoun N, Sangkhom I & Preston T R (2015). Effect of biochar and leaves from sweet or bitter cassava on gas and methane production in an in vitro rumen incubation using cassava root pulp as source of energy. Livestock Research for Rural Development. Volume 27, Article #72. 
Phanthavong V, Khamla S & Preston T R (2016a). Fattening cattle in Lao PDR with cassava pulp. Livestock Research for Rural Development. Volume 28, Article #10 
Phuong L T B, Preston T R & Leng R A (2016). Effect of foliage from “sweet” and “bitter” cassava varieties on methane production in an in vitro incubation with molasses supplemented with potassium nitrate or urea. Livestock Research for Rural Development. Volume 24, Article #189. Retrieved April 2, 2014, from  
Phuong L T B, Preston T R & Leng R A (2012). Effect of foliage from “sweet” and “bitter” cassava varieties on methane production in in vitro incubation with molasses supplemented with potassium nitrate or urea. Livestock Research for Rural Development. Volume 24, Article #189.
Preston T R (1971). Quantitative aspects of animal protein production from NPN in ruminants Source:FAO/IAEA. Tracer studies on non-protein nitrogen for ruminants. publications\Preston1971(IAEA).pdf
Preston T R, Carcaño C, Alvarez F J & Gutierrez D G (1976). Rice polishings as a supplement in a sugar cane diet effect of level of rice polishings and of processing the sugar cane by derinding or chopping. Tropical Animal Production. Volume 1, Number 3 pp 1-14 
Preston T R (2015). the role of biochar in farming systems producing food and energy from biomass. In: Geotherapy: Innovative Methods of Soil Fertility Restoration, Carbon Sequestration and Reversing CO2 Increase (Editor: Thomas J Goreau) CRC Press, Tayler and Francis Group, Boca Raton, Florida USA
Sath K, Borin K & Preston T R (2008). Effect of levels of sun-dried cassava foliage on growth performance of cattle fed rice straw. Livestock Research for Rural Development. Volume 20, supplement. 
Silivong P, Preston T R, Van N H & Hai D T (2018). 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). Livestock Research for Rural Development. Volume 30, Article #163. 
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Suksombat W, Lounglawan P & Noosen P (2007). Energy and protein evaluation of five feedstuffs used in diet in which cassava pulp as main energy source for lactating dairy cows. Suranaree Journal of Science and Technology Volume 14, Number 1, pp 99-107
PUBLICATIONS LIST
Phanthavong V, Sangkhom I, Preston T R, Dung D V & Ba N X (2018): Effect of leaves from sweet or bitter cassava and brewers’ grains on methane production in an in vitro rumen incubation of cassava root pulp-urea. Livestock Research for Rural Development. Volume 30, Article #167. Retrieved March 19, 2019, from 
Phanthavong V, Preston T R, Vorlaphim T, Dung D V & Ba N X (2018): Fattening “Yellow” cattle on cassava root pulp, urea and rice straw: completely mixed ration system with cassava foliage as protein supplement compared with feeds not mixed and brewers’ grains as protein source. Livestock Research for Rural Development. Volume 30, Article #169. Retrieved March 19, 2019, from 
APPENDICES
Figure 1-4 : Lao yellow cattle condition in long dry season in Vientiane Capital 
Figure 5. The pit holding an estimated 100,000 tones of cassava pulp in the Lao-indochina Cassava Factory in Vientiane
 Figure 6. Inserting the PVC tube 
 to reach the bottom of the pit for 
 sample taking in the pipe 
Figure 7. Separating the samples from the core taken from the PVC tube and pH and chemical analysis in Laboratory 
Figure8.  Stages in the fattening of local cattle on ensiled cassava pulp, urea, brewers' grains and rice straw of 1st group
Figure 9. Local Yellow cattle fattened for 90 days on cassava pulp-urea, brewers’ grains and rice straw
Figure 10. The cassava field ready for root harvest
 Figure 11. Harvesting the foliage
Figure 12. The branch (tender stem, petioles and leaves) to be used as animal feed