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

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 SUMMARY OF DISERTATION IN ANIMAL SCIENCES HUE, 2020 This dissertation is completed at University of Agriculture and Forestry, Hue University Suppervised by: Associate Professor Dr Nguyen Huu Van Dr Dương Thanh Hai 1st reviewer:…………………………………………………………………………………………………………… 2nd reviewer: …………………………………………………………………………………………………………… 3rd reviewer: …………………………………………………………………………………………………………… The dissertation will be defended at the Council of dissertation assessment of Hue University, 04 Le Loi Street, Hue city, at………….on …… /……… /2020 Dissertation can be further referred at: National Library Center for Information and Library of Hue University of Agriculture and Forestry INTRODUCTION 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 Laos 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) 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 fully-commercial 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 2,000-3,000 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 goat-raising 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 Laos 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 anti-nutritional 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 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 al., 2009; Woodward et al., 2004), apparently through a direct toxic effect on methanogens Brewers’ grains is a byproduct derived from the industrial brewing of beer Research with goats (Sina et al; 2017) highlighted a major interaction between the effect of the supplementary brewers’ grains and the nature of the basal diet The improvement in growth rate due to addition of brewers’ grains was 130% when the basal diet was fresh cassava foliage but only 30% when the basal diet was water spinach (Sina et al., 2017) A positive approach to the problem of how to reduce methane emissions from live stock has been to incorporate a low level (1%) of biochar in the diet (Sangkhom et al., 2012; Leng et al., 2012a,b,c) Biochar is the product of incomplete carbonization of fibrous biomass at high temperatures (Lehmann and Joseph, 2009) It is a highly porous material which gives it valuable properties as a support mechanism for biofilms that facilitate the adsorption of consortia of micro-organisms and nutrients that may prioritize incorporation of hydrogen into volatile acids rather than methane (Leng, 2018 personal communication) THE OBJECTIVES The study aimed at the utilization of locally available feed resources for increasing growth performance and reducing enteric methane emissions from goats in Lao PDR The specific objectives were following: (i) To evaluate the of water spinach as a source of high soluble protein and biochar on methane production in an in vitro system with substrate of Bauhinia acuminata or Guazuma ulmifolia leaves; (ii) To evaluate the effect of water spinach as a source of high soluble protein and biochar on feed intake, digestibility, N retention, methane emission and growth performance of goats fed Bauhinia acuminata foliages plus molasses or dried cassava root chip as the basal diets; (iii) To examine the effect of replacing water spinach by cassava foliage and/or brewer’s grain on feed intake, digestibility, N retention and growth performance of goat fed Bauhinia acuminata plus dried cassava root chip as the basal diets; (iv) To compare the sweet or bitter of cassava leaves and biochar on gas production, methane content of the gas and methane ml/g DM digested in an in vitro incubation THE HYPOTHESIS (i) Water spinach, with its high content of soluble protein, would increase the rate of fermentation and production of methane when added to forage rich in insoluble protein such as Bauhinia acuminata or Guazuma ulmifolia leaves; (ii) The performance of growing goats fed Bauhinia acuminata as the basal diet would be improved by supplementation with water spinach as a rapidly fermentable protein source Enteric methane production would be reduced by adding a low level (1%) of biochar; (iii) Goats fed foliage of the legume tree Bauhinia acuminata would respond positively in growth rate and feed conversion to a low-level supplement of brewers’ grains, and that the degree of response would be greater when cassava foliage, rather than water spinach, was the complementary source of protein; (iv) The methane content of the gas produced in an in vitro fermentation would be reduced when leaves of bitter cassava replaced leaves of sweet cassava as supplementary protein source and when 1% of biochar was added to the substrate SIGNIFICANT/INNOVATION OF THE DISSERTATION This is the first series of study and the first sciencetific information on improving the utilization of Bauhinia acuminata for goat production in Laos The results presented in this dissertation indicate that: (1) Goats fed Bauhinia acuminata responded with improved diet digestibility, N retention and growth rate when the Bauhinia acuminata was supplemented with water spinach; (2) But an important negative effect was that the improvement in diet digestibility by supplementation with water spinach led to increases in methane production per unit diet DM digested; (3) Supplementing Bauhinia acuminata foliage with leaves from a bitter variety of cassava reduced the in vitro production of methane when compared with supplementation by leaves from a sweet variety of cassava; (4) Ensiled brewers’ grains fed as an additive (5% as DM) to a diet of Bauhinia acuminata improved the digestibility, N retention and growth rate of goats The degree of improvement was greater when the Bauhinia acuminata was supplemented with cassava foliage instead of water spinach; (5) Biochar fed at 1% of a diet of Bauhinia acuminata and cassava foliage was as effective as brewers’ grains in improving the growth rate of the goats CHAPTER 1: LITERATURE REVIEW There are main points following (i) Goat production in Laos; (ii) Role of goat production in Laos; (iii) Goat nutrient and methane emission; (iv) Local available feed resources for goat in Laos 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 INTRODUCTION The greenhouse gases (GHG) emissions from the agriculture sector account for about 25.5% of total global radiative forcing and over 60% of anthropogenic sources (FAO 2009) Animal husbandry accounts for 18% of GHG emissions Emission of methane (CH4) is responsible for nearly as much radiative forcing as all other non-CO2 GHG gases combined (Beauchemin and McGinn 2005) While atmospheric concentrations of GHGs have risen by about 39% since preindustrial era, CH4 concentration has more than doubled during this period (WHO, 2009) Reducing GHG emissions from agriculture, especially from livestock, should therefore be a top priority since it could curb global warming fairly rapidly (Sejian et al., 2010) Ruminants, such as cattle, buffalo, sheep and goats, are the major contributors of total methane agricultural emissions (Leng, 1993; Lassey, 2007; Chhabra et al., 2009) In ruminants, the H2 produced in rumen fermentation is normally removed by the reduction of CO2 to methane There is a need to develop feeding systems for ruminants that will result in reduced emissions of methane gas from the enteric fermentation in these animals Previous research showed that methane production was less when fish meal rather than groundnut meal was the substrate (Preston et al., 2013) The differences in methane production appeared to be related to the solubility of the protein which was 16% in fish meal compared with 70% in groundnut meal A similar finding was reported by Silivong and Preston (2015) who showed that addition of water spinach to the substrate in an in vitro rumen fermentation increased the rate of gas production and methane content in the gas The protein in the water spinach was highly soluble (66%) The hypothesis that underlined the present study was that water spinach, with its high content of soluble protein, would increase the rate of fermentation and production of methane when added to forages-rich in insoluble protein MATERIALS AND METHODS Treatments and experimental design The experimental design was a × factorial arrangement of treatments with four replications The factors were: - Foliage source: Bauhinia acuminata and Guazuma ulmifolia (BA and GU) - Level of water spinach: 0, 5, 15 and 25% in substrate DM Preparation of substrate and the in vitro system The in vitro system used recycled “PET” plastic bottles as flasks for the incubation and gas collection A simple in vitro system was used with recycled plastic bottles as flasks for the incubation and gas collection (Diagram 1) a b c d Water bath Fermentation bottle (1.5liters) Water storage reservoir (3liters) Gas collection bottle (1.5liters) Plastic tube (id: 4mm) Diagram A schematic view of the in vitro system to measure gas production in an in vitro incubation - B and D bottles (1.5 liters capacity)., C bottle (3liters capacity) The B bottle containing the substrate for fermentation was connected to the D bottle by a plastic tube (4 mm diameter) The D bottle was marked at 50ml intervals before being suspended in the C bottle containing water Clay was used to cover the stoppers of the plastic bottle and junction of stopper and plastic tube to prevent leakage of gas The leaves from Bauhinia and Quazuma, and leaves plus stems of water spinach, were chopped into small pieces (3-5mm) and dried at 65°C for 48h then ground with a coffee grinder, and mixed according to the proportions shown in Table The mixtures (12g DM) were put in the incubation bottle with 960 ml of buffer solution (Table 2) and 240 ml of rumen fluid The rumen fluid was taken at 3.00-4.00am from the slaughter house from a buffalo immediately after the animal was killed A representative sample of the rumen contents (including feed residues) was put in a vacuum flask and taken to the laboratory, and stored until 5.00am, when the contents were filtered through a layer of cloth before being added to the incubation bottle The remaining air in the flask was flushed out with carbon dioxide The bottles were incubated at 38°C in a water bath for 24 h Table Composition of diets (% DM basis) BA#GU BA#GU-WS BA#GU-WS 15 BA#GU-WS 25 Leaf meal# 80 75 65 55 Water spinach 15 25 Molasses 20 20 20 20 Total 100 100 100 100 # Bauhinia or Guazuma leaf meals Table Ingredients of the buffer solution (g/liter) CaCl2 NaHPO4.12H2O NaCl Cl MgSO4.7H2O NaHCO3 Cysteine 0.04 9.30 0.47 0.57 0.12 9.80 0.25 Source: Tilly and Terry (1963) Data collection and measurements Gas production was measured at intervals for 6, 12, 18 and 24h by water displacement (a calibrated recycled water bottle with the bottom removed) and at the end of each incubation, the methane concentration in the gas was measured with a Crowcon infra-red analyser (Crowcon Instruments Ltd, UK) Residual DM in the incubation bottle was determined by filtering the incubation residues through cloth to estimate DM loss during incubation and drying the residue (65°C for 72h) Chemical analyses The samples of foliage, water spinach and residual substrate were analysed for DM, ash and N according to AOAC (1990) methods Solubility of the protein in the leaves was determined by shaking 3g of dry leaf meal in 100 ml of M NaCl for 3h then filtering through Whatman No.4 filter paper, and determining the N content of the filtrate (Whitelaw et al., 1963) Statiscal analysis The data were analyzed by the general linear model option of the ANOVA program in the Minitab software (Minitab, 2014) In the model the sources of variation were: treatments, replicates and error The statistical model was: Yijk = μ + Pi + Aj + Pi*Aj+ eijk Where: Yijk is dependent variables., μ is overall mean., Pi is the effect of foliage source Aj is the effect of level of water spinach., (P*A) ij is the interaction between source of foliage and source of level of water spinach and eijk is random error RESULTS Chemical composition Percentages of crude protein, ash and protein solubility were higher in water spinach than in Bauhinia acuminata and Guazuma ulmifolia leaves, but DM was lower The protein content and solubility in the leaves of Guazuma ulmifolia were higher than in Bauhinia acuminata, but ash was lower (Table 3) Table The chemical composition of feed (% in DM, except DM which is on fresh basis) DM N*6.25 Ash Protein solubility Tannin NDF ADF Bauhinia leaves 40.0 15.0 21.2 23.7 1.1 43.7 32.4 Bauhinia stem 38.1 12.3 4.29 - 42.7 31.5 Guazuma ulmifolia 36.0 18.4 3.9 33.3 Water spinach 10.6 18.5 9.7 66.4 42.3 33.3 Molasses 80.4 5.4 10.5 - Source: Silivong et al., 2018 Values for the gas production, percent methane in the gas and methane produced per unit substrate solubilized increased with length of incubation time (Table 4) Gas production and percent substrate solubilized were increased by increasing the level of water spinach in the substrate, and were higher for Guazuma ulmifolia than Bauhinia acuminata at each incubation interval Table 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 Foliage source BA Level of water spinach (%) p GU Interaction p WS-0 WS-5 WS-15 WS-25 SEM SEM P 0-6 hr Gas production, ml 363 483