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

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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 i 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. ii 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 iii DEDICATION To my parents, my wife Souksadar Vongyalud, my son (Phetsamone Silivong) and daughter (Souphaphone Silivong) To: My country (Lao PDR) iv 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 v 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 vi 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 REVIEW 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 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 viii 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 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 ix 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 x 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 ACUMINATA AND MOLASSES OR CASSAVA ROOT CHIPS AS THE BASAL DIET xi 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 Figure 11. Supplements of water spinach and biochar improved the DM feed conversion of goats fed Bauhinia acuminata and cassava root chips ...................86 xii 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 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 xiii 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 supplementary protein (Phongpanith et al; 2013). It grows equally well in water or in 2 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 CH4 production of 13 to 16% have been reported (Carulla et al., 2005; Waghorn et al., 2002, Grainger et 3
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