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HUE UNIVERSITY UNIVERSITY OF AGRICULTURE AND FORESTRY LE THI THUY HANG UTILIZATION OF CASSAVA FORAGES FOR GOAT PRODUCTION IN AN GIANG PROVINCE, VIETNAM 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 Supervised by: Assoc Prof Dr Nguyen Xuan Ba Dr Dinh Van Dung 1streviewer: ………………………………… ………………………………… 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, Hue University List of abbreviations, symbols and equivalents ADF Acid detergent fiber ATP Adenosine triphosphate BW Body weight BSP Brewery spent grain CP Crude protein CT Condensed tannins CNP Cyanogenic potential CH4 Methane CO2 Carbon dioxide DM Dry matter EPG Eggs per gram FW Fresh weight GHG Green house gas EPS Self-produced polymeric substance HT Hydrolysable tannins HCN Hydrogen cyanide LW Live weight N Nitrogen NDF Neutral ditergent fiber SCFA Short -chain fatty acid TMR Total mix ration VFA Volatile fatty acid WRC Water retention capacity INTRODUCTION PROBLEM STATEMENT An Giang province in the South of Vietnam, is a watershed province in the Mekong Delta, and one of the largest cultivated areas in the Mekong Delta The total area of agricultural land is more than 282,676 ha, of which paddy land accounts for 85.2% (Statistic yearbook of An Giang, 2018) An Giang is one of the two provinces in the Mekong Delta with hills and mountains, mostly in the northwest of the province, in Tinh Bien and Tri Ton districts This is the last mountain cluster of the Annamites, so the geological features also have similarities with the Southern Truong Son An Giang has a tropical monsoon climate, with two distinct seasons: rainy season and dry season The temperature ranges from 200C to 360C and rainfall from 1400 to 1600 mm The rainy season is the least in February and the highest in September The average humidity is 75-80% (An Giang hydrometeorological Station, 2017) Due to the topography, the land resources are divided into different types: alluvial soil, alkaline soil, mountainous land Total area of hilly land in An Giang is about 29,320 ha, accounting for 8.6% of total land area of the province Agricultural cultivation in this mountainous area is not favorable because of its low productivity, lack of water for irrigation in the dry season, but when the rainy season comes, some districts are affected by floods eg: the flooding in 2018 affected hundreds of hectares of rice and crops in the Mekong Delta As Naqvi and Sejian (2011) showed droughts, flooding and depletion of natural resources, were caused by global climate change Based on the above problems and threats, we hypothesize that utilization of cassava forage for improving goat production and reducing enteric methane emission from goat production in An Giang province, Vietnam This study was designed to test the hypothesis by addressing the following specific aims were to improve nutritive value of cassava stems and stored by urea treatment In addition, using brewers’ grain and biochar supplied to improve growth rate and reduce methane emissions in a basal diet of cassava forage fed to growing goats THE OBJECTIVES The overall aim of this thesis was to improve utilization of cassava forage for increasing performance and reducing enteric methane emission from goat production in An Giang province, Vietnam The present study objectives were: - To evaluate the potential productivity and nutritive value of cassava stems, and cassava forage for goats in An Giang Province - To determine level of urea addition to cassava stems for storage to improve nutritive value, especially its digestibility - To examine the effect of biochar supplementation on feed intake, digestibility, N retention in goats fed urea treated cassava stems - To determine levels of brewery grain that affect feed intake, digestibility and growth in goats fed sweet cassava foliage as basal diet - To determine levels of biochar that would reduce methane production in goats fed a basal diet of fresh cassava foliage and brewery grain SIGNIFICANCE/INNOVATION OF THE DISSERTATION The thesis contributes to the science of: - Using urea to treat cassava stems is one of method to increase nutritive value, reduce HCN content and can be storeed at least weeks - Adding 4% brewery grain and 0.86% biochar (DM based) in Bach Thao goat’s diet, that is basal of fresh cassava foliage has improved growth and reduced enteric methane emission from goat production - The results of the study are of scientific value for managers, researchers, universities, graduate students and agricultural students’ references - The present results of show that adding urea to cassava stems can provide storage to use as feed goat for year around, specially in flooding or rainy season - The study results of the dissertation serve as a scientific basis for businesses and husbandry to use and coordinate goat diets towards reducing methane emissions - Introducing cassava forage as goats feed, reducing the HCN content, improving growth and reducing methane emission with supplementing additive as brewery grain and biochar CHAPTER 1: LITERATURE REVIEW In this chapter, there are main points following (i) Goat and cassava production in An Giang province; (ii) the use of available feed resources for goat production; (iii) introduction to some main local feed resources such as cassava and their byproducts and brewers’ grains and (iv) feed and feeding strategies for methane mitigation from goat production The literature review shows a potential to use local feed resources for goat production for the two purposes of increasing animal performance and reducing methane emission CHAPTER 2: EVALUATION OF THE POTENTIAL OF CASSAVA FORAGE AS FEED FOR GOATS IN AN GIANG PROVINCE, VIETNAM INTRODUCTION An Giang is one of the two provinces in the Mekong Delta with hills and mountains, mostly in the northwest of the province, in Tinh Bien and Tri Ton districts An Giang is in the tropical monsoon climate, with two distinct seasons: rainy season and dry season The rainy season is the least in February and the rainy season is the highest in September The average humidity is 75-80% The basic climate is favorable for agricultural development Due to the topography, the land resources are divided into different types: alluvial soil, alkaline soil, mountainous land Hilly land is mainly distributed in two districts of Tri Ton and Tinh Bien, a small part of Thoai Son district (Ba The area) Total area of hilly land in An Giang is about 29,320 ha, accounting for 8.6% of total land area of the province So, the area of grazing land is limited, the grassland is also limited The cassava was planted in there, it is not so much (representing 0.5% of agricultural land) The production of cassava roots in this area was 28.7 ton/year It is estimated that an amount of cassava foliage is produced 61 thousand tonnes The reason is difficulties in drying the straw or other roughage in the rainy season, but by- production is an underutilized resource for feeding livestock The purpose of planting cassava in this area is to harvest roots, cassava foliage is underutilized, being left to rot in the monsoon season (flooding season) and burned in the dry season Even with a small number of cattle in the province by 98,758 heads in 2017 (Statistic yearbook of An Giang, 2018) a sufficient supply of roughage is not easy to find during the rainy season, and cassava foliage is an underutilized resource for feeding livestock, especially in the hilly land area These areas are suitable for goats raising The design of this thesis responds to tendencies that have been observed in the development of crop and livestock systems in Tinh Bien and Tri Ton districts in An Giang province The survey described in showed that there is an increasing tendency to plant cassava both as a food crop and as a source of starch for industrial processing At the same time there are major trends in ruminant livestock numbers, with the population of goats increasing MATERIALS AND METHODS The following indicators were used in the investigation of the survey From secondary data: - Planting area and cassava productivity in each district in the An Giang province - Number of goats raised in each district in the An Giang province The following indicators were used to select 120 households (60 households have grown cassava; 60 households have raised goats) Data collection and calculation In each district, we chose five households (from 60 selected households) with cassava cultivators at eight months after growing and an area of 1000 m2/plot to collection and calculation of fresh cassava forage productivity Five positions were selected in each plot of land by diagonal method Land area of each position was 4m (Total area was * = 20m2) In each position, all cassava plant was cut and weighed (except root) Cassava plants were the whole plant above the soil Cassava plant was divided into two parts: Cassava forage – which were two thirds of the above ground part of cassava plant; weighed the cassava forage (1); and hard stems (blue line on the right in figure 2.1) - which was one third above soil level, weighted them (2) In this case, cassava forage was divided into two parts: (3) Tenderstems + (4) leaves (including peiole) Tenderstems were called cassava stems (3) Weight of cassva plant = (1) + (2) Weight of cassva forage (1) = (3) + (4) Chemical analysis All samples of cassava forage and stems were analyzed for DM, CP and ash using procedures described by AOAC (1990) ADF and NDF were analyzed according to Van Soest and Robertson (1991) HCN and total tannin were analyzed according to ISO 6703-1:1984 (TCVN 6181:1996), AOAC 955.35 by AOAC (2016) Statistical analysis Data was collected, preliminary calculations performed and stored in the Microsoft Office spreadsheet EXCEL 2010 Data were analysed using General Linear Model (GML); the basic model for analysis of variance (ANOVA); the constants described as averages, the standard deviation was performed on the MINITAB statistical software 16 RESULTS AND DISCUSSION Cassava production Chemical composition of cassava Table 2.1 Chemical composition of cassava parts % DM Variety of cassava DM, % CP NDF Total tannin 4.6 3.1 1.6 1.3 HCN (mg/kg FW) 153 34.5 68.0 30.5 Bitter cassava 26.8 13.4 49.4 Sweet cassava 21.7 13.8 47.0 Bitter cassava 31.5 4.9 66.1 Cassava stems Sweet cassava 24.5 6.1 65.8 Notes: FW: fresh weight DM: Dry matter, CP: crude proetin, NDF: neutral detergent fiber, HCN: Hydrogen cyanide Table 2.2 Yield of cassava proportion with different variety Proporti Sweet cassava Proporti Bitter cassava on (tons/ha) on % (tons/ha) % Fresh cassava plant 13.2 ± 3.6 33.5 17.2 ± 4.5 54.0 Hard stems Cassava forage 26.2 ± 7.2 66.5 14.7 ± 3.8 46.1 Cassava stems 8.7 ± 2.4 22.1 4.9 ± 1.3 15.3 Leaves + petiole 17.5 ± 4.8 44.4 9.8 ± 2.5 30.7 DM cassava plant Hard stems 5.5 ± 1.5 49.1 6.4 ± 1.6 62.1 Cassava forage 5.7 ± 1.6 50.9 3.9 ±1.0 37.9 Cassava stems 2.1 ± 0.5 18.4 1.2 ± 0.3 11.3 Leaves + petiole 3.6 ± 1.0 32.5 2.7 ± 0.76 26.6 CP of cassava forage in 0.79 ± 0.23 0.52 ± 0.15 DM (tons/ha) The fresh and dry weight proportion of cassava plant is shown in Table The cassava forage was differences between two varieties of cassava The proportion of sweet cassava forage was higher than the bitter cassava These results were different due to the differences in variety, farming conditions, regions, soil, and fertilization and cutting time Cassava forage Goat production Table 2.3 Farm size and purpose raising Tri Ton Tinh Bien percentage percentage percentage Total Items % Number Number % % Farm size (Household) 1- 20 head/farm 19 31.7 40 66.7 59 49.2 Purpose raising (Heads) Meat 691 62.9 1,163 95.1 1,854 79.8 Breeding 408 37.1 60 4.9 468 20.2 Total 1,099 1,223 The purpose of raising goats here was mainly to sell meat at 79.8%, in addition to raising goats with the purpose of selecting good ones in the herd to sell goats for local market, or neighbourhood; but account for a smaller percentage (20.6%) In addition, markets for goat production (eg: milk, cheese, ) are in the cities providing farmers with better income and opportunities for further development Table 2.4 Goat production systems in Tri Ton and Tinh Bien district Number of farms in district Percentage, Tri Percentage, Tinh Percentage, Total % Management Ton % Bien % Intensive 31 51.7 35 58.3 66 55.0 Semi-intensive 27 45.0 25 41.7 52 43.3 Extensive 3.33 0.00 1.67 Intensive systems are the main method of goat raising in An Giang, this systems of complete confinement helps the farmers manage each individual, can detect disease or manage oestrus in a timely manner, but feed had to controled actively, while semi- intensive systems help goats have time to graze, develop the right features and reduce the reserve of feed điểm bảo quản (0; 2; 4; tuần), lấy mẫu đánh giá cảm quan qua tiêu nấm mốc, mùi, đo pH, NH3 phân tích thành phần hóa học VCK, đạm thơ, khống tổng số, xơ thơ THÍ NGHIỆM BỐ TRÍ THÍ NGHIỆM Thí nghiệm bố trí theo kiểu hình vuông la – tinh, bốn dê Bách Thảo lai (14 ± kg), bốn nghiệm thức với việc có khơng có bổ sung rau muống than sinh học phần thân sắn xử lý 3% urea sau 21 ngày bảo quản bốn giai đoạn; Cụ thể: Nghiệm thức UCS: Chỉ cho ăn thân sắn xử lý ure Nghiệm thức UCSW: thân sắn xử lý ure + 1% rau muống Nghiệm thức UCSB: thân sắn xử lý ure + 1% than sinh học Nghiệm thức UCSWB: thân sắn xử lý ure + 1% rau muống + 1% than sinh học Mỗi giai đoạn kéo dài 15 ngày (mười ngày cho thích nghi ngày để thu thập phân nước tiểu) Giữa giai đoạn có khoảng thời gian ngày thích nghi cho ăn theo phần giai đoạn thí nghiệm Động vật thí nghiệm cách quản lý thí nghiệm Dê thí nghiệm ni nhốt chuồng cá thể làm từ tre thiết kế để dễ thu phân nước tiểu riêng biệt Dê cân khoảng thời gian cố định 06:30 đến 07:30 trước cho ăn vào lúc bắt đầu kết thúc giai đoạn thí nghiệm Thức ăn cách chăm sóc Than sinh học làm cách đốt trấu bếp Gasifier (TLUD) (Olivier 2010) Lượng bổ sung hàng ngày tính tốn dựa theo trọng lượng mức ăn vào dê Lượng ăn trong chia làm hai lầnMỗi ngày chia hai lần ngày cá cho vào máng ăn riêng biệt với thân sắn rau muống Rau muống cắt nhỏ tay trước đưa vào máng ăn Lượng bổ sung cách cho ăn giống than sinh học Thân sắn (khơng có lá) thu hoạch (bỏ phần thân sứng có độ cao 40-50cm so với mặt đất), lúc sắn trồng 150 ngày, chiều cao 100 - 120 cm Thân sắn cắt nhỏ máy, trộn với urê (3% VCK; không thêm nước) ủ túi nhựa ủ yếm khí Sau ủ 21 ngày, chúng sử dụng làm thức ăn cho dê Lượng thức ăn hàng ngày tính 80% so với tổng số lượng thức ăn tính theo 3% trọng lượng thể Thức ăn chia làm lần ngày cho ăn riêng với loại thức ăn lại Tỷ lệ tiêu hóa nitơ tích lũy Trong giai đoạn, lấy mẫu phân nước tiểu vào năm ngày cuối giai đoạn, ngày cân lấy mẫu hai lần vào lúc 7:00 16:00 Lọ đựng nước tiểu có chứa 100 ml axit sulfuric 10% sẵn, lượng tăng giảm tùy thuộc vào độ pH, giữ pH 4.0 Sau giai đoạn thu thập: (i) mẫu 10% nước tiểu lưu trữ -4o C để phân tích nitơ (AOAC 1990); (ii) phân trộn lại với lấy mẫu (10%) bảo quản đông lạnh -20oC Dịch cỏ lấy trước ăn sau ăn 10 Các tiêu phân tích thí nghiệm Tất mẫu thân sắn, thân sắn xử lý với ure, rau muống than sinh học tính vật chất khơ, khống tổng số, đạm thơ, xơ trung tính xơ acid Phân nước tiểu phân tích VCK, NH3 Dịch cỏ đo pH phân tích NH3 Các tiêu NH3, đạm thơ phân tích theo phương pháp Kjeldahl Xơ trung tính xơ acid phân tích theo Van Soest Robertson (1990) Hàm lượng HCN xác định theo phương pháp tiêu chuẩn AOAC (2016) Tổng hàm lượng tannin xác định theo phương pháp (955,35) AOAC (2016) Năng lượng chuyển hóa thức ăn (MJ / kg) tính từ tỷ lệ tiêu hóa chất hữu (OMD:%) theo công thức Mc Donald cs (2002) Công thức là: ME = 0.160 * OMD Phương pháp thống kê Dữ liệu phân tích chọn theo mơ hình tuyến tính chung ANOVA phần mềm MINITAB (Minitab 2016) KẾT QUẢ VÀ THẢO LUẬN THÍ NGHIỆM Đánh giá cảm quan mẫu thân sắn xử lý ure Đánh giá cảm quan mẫu thân sắn xử lý qua tiêu màu sắc, mùi nấm mốc Kết cho thấy thân sắn xử lý ure điều kiện yếm khí cho chất lượng tốt sau tuần bảo quản: không bị nấm mốc, mùi ammoniac nhiều hay tùy thuộc vào mức ure bổ sung nghiệm thức ngoại trừ nghiệm thức (khơng có urê) Thành phần hóa học thân sắn xử lý với mức độ khác thời gian bảo quản khác Hàm lượng đạm thô thân sắn xử lý thay đổi phụ thuộc vào nhiều yếu tố nguyên liệu, mơi trường q trình xử lý Hơn nữa, gia tăng hàm lượng đạm thơ có liên quan đến mức độ urê xử lý, hàm lượng nước nguyên liệu nhiệt độ Hàm lượng đạm thô thân sắn sau xử lý tăng cao có ý nghĩa so với nguyên liệu cao hàm lượng ure bổ sung cao Bảng 3.1 Ảnh hưởng mức ure thời gian bảo quản đến hàm lượng đạm thô thân sắn Thời gian bảo quản, tuần Hàm lượng ure (%) SEM p-value aE dEF eF dG eH 6.14 6.11 6.06 5.63 5.18 0.014