Chapter 1: INTRODUCTION 1.1 Necessary of thesis Previous studies showed that ruminants contribute 25% of total methane produced on earth due to microbial fermentation of feeds in rumen to produce volatile fatty acids (VFA), methane and carbonic… These gasses are released by eructation Some researches in Vietnam showed that each cow daily emitted into environment about 170 - 241 litters of methane depended on breed, age and productivity of animals Some scientists reported that cassava leaf (CL) and copra meal (CM) are sources of protein supplement as well as good by-pass feed due to their tannin and lipid Previous studies showed that supplementation of dried CL and CM in cattle diets improved body weight gain but there was few study on methane emission from rumen fermentation Therefore, we conducted the study “Effects of cassava forage (Manihot esculenta Crantz) in diet on growth and methane production in cattle” 1.2 Research objectives To measure in vitro digestibility and methane production of feeds and different mixtures of Napier grass and dried cassava forage in beef cattle diet To measure effects of dried, ensiled and fresh cassava forage in diets based on Napier grass on digestibility, body weight gain and methane production of Sindhi x Yellow cattle To find out the appropriate ration by replacement of copra meal by dried cassava forage in diets based on Napier grass on body weight gain and methane production of Sindhi x Yellow cattle 1.3 Research contents The studies were conducted in following experiements: (1) Study on digestibility and methane production of some feeds and different mixtures of Napier grass and cassava forage by in vitro gas production technique (2) Effects of dried, ensiled and fresh cassava forage in diets on digestibility and methane production of Sindhi x Yellow cattle (3) Effects of dried, ensiled and fresh cassava forage in diets on live weight gain and methane production of Sindhi x Yellow cattle (4) Effects of replacing copra meal by dried cassava forage in diets on live weight gain and methane production of Sindhi x Yellow cattle 1.4 Research subjects Studying methane production of Napier grass, ruzi grass and para grass; dried cassava forage, cotton seed meal and copra meal; mixtures of Napier grass and dried cassava forage in cattle diets using in vitro gas production technique with Sindhi cattle rumen fluid Studying the uses of fresh, dried and ensiled cassava forage after harvesting on digestibility, body weight gain and methane production of Sindhi x Yellow cattle Studying the effects of replacing copra meal by dried cassava forage in diets on body weight gain and methane production of Sindhi x Yellow cattle 1.5 Location and duration The study was conducted from October 2012 to March 2015 The experiment was carried out at laboratory, department of Animal Sciences, college of Agriculture and Applied Biology, Can Tho university Experiment 2, and were carried out at Center for Research and Technology Transfer, Nong Lam University of Ho Chi Minh city 1.6 Findings of dissertation Para grass, dried cassava forage and a mixture of 20% dried cassava forage and Napier grass decreased in vitro methane production Replacement of 20% dried, ensiled and fresh cassava forage for Napier grass in diets decreased methane emission of Sindhi x Yellow cattle Replacement of 10% copra meal by 10% dried cassava forage in cattle diets improved body weight gain and tended to reduce methane production 1.7 Outline of dissertation There are pages of introduction, 32 pages of literature review, 19 pages of materials and methods, 52 pages of results and discussion, page of conclusion and recommendation, references and index The dissertation has 46 tables, 20 figures and 188 references Chapter 2: LITERATURE REVIEW 2.1 Rumen digestibility Approximate 85% of feeds are digested in rumen by microbial fermentation Microbial fermentation of feeds produces VFA, NH3, amino acids and fatty acids… These products are absorbed through rumen wall, whereas carbonic and methane are released into environment by eructation Undigestibility feeds move and digest at abomasum and small intestine to supply nutrients for animals However, studies showed that 10% of energy intake are lost by rumen methane production An balance ration will improve performance and decrease methane production in cattle Cassava leaf contains 18.3–24.5% crude protein, full of essential amino acids and minerals Cassava leaf also contain quite high toxic compounds such as condensed tannin (2.7– 4.4%) and hydrogen cyanide (325–399 mg/kg in dried and ensiled cassava leaf and 911–1,426 mg/kg in fresh cassava leaf) If feeding at high amount of fresh cassava leaf, it will affect animal health By recommendation, the appropriate level of additional cassava leaf in ruminant diet is 20% The researches in cattle showed that supplementation of cassava leaf and copra meal has improved dry matter intake, feed digestion and body weight gain, but reduces protozoa population and methane production 2.2 Effect of diets on rumen methane production Studies showed that supplemental diets of cassava leaf or copra meal reduce methane emission because condensed tannin and lipid content in diet reduce amount of protozoa and decrease rumen methane production Tannin: Addition of 20% cassava leaf or 0.4% condensed tannin in diet often reduces ruminal protozoa population of cattle and buffaloes, which relates to decrease methane emission Ruminal protozoa involve in rumen methane production, and protozoa may produce hydrogen and provide this gas for activity of rumen methanogen bacteria Methanogen bacteria and protozoa live symbiotically in rumen, and therefore, reducing of protozoa population may affect activity of rumen methanogen bacteria Lipid: Supplementing lipid in diet often decreases methane emission, which depends on kinds of lipid However, supplementation of lipid at - 8% in diet will cause negative effects on dry matter intake and digestibility of carbohydrates On the other hand, lipid reduces rumen protozoa population, and some fatty acids are toxic to methanogen bacteria or hydrogenation of unsaturated fatty acids leads to decline methane production Chapter 3: MATERIALS AND METHODS 3.1 Research methods 3.1.1 Experiment 1: Study on digestibility and methane production of feeds and mixtures of Napier grass and cassava forage by in vitro gas production technique The objectives of this experiment were to determine in vitro digestibility and methane production of some feeds such as Napier grass, ruzi grass, guinea grass, para grass, cassava forage, cotton seed meal, copra meal, and mixtures of Napier grasss grass and cassava forage in cattle diet The experiment was carried out from October 2012 to March 2013 Table 3.1: Nutrient composition of feeds used in experiment Feed DM, % % DM basis OM CP NDF Ash Para grass 17.6 88.2 8.40 57.7 11.8 Ruzi grass 20.0 91.2 8.65 58.0 8.82 Guinea grass 20.5 88.4 8.93 69.0 11.6 Napier grass 18.3 88.0 10.7 62.2 12.0 Cassava forage 87.9 86.1 21.2 44.0 13.9 Coconut meal 93.6 92.4 17.5 56.3 7.59 Cotton seed meal 87.8 92.6 35.6 41.4 7.37 DM: dry matter, OM: organic matter, CP: crude protein, NDF: neutral detergent fiber, Ash: total minerals In vitro gas production technique was followed the method of Menke and Steingass (1988) Preparation of media solution for in vitro gas production was a mixture of solutions: macro-mineral solution, micro-mineral solution, buffer solution, resazurin solution and reducing solution The media solution was incubated at 39°C, stirred and gassed carbonic until solution turns blue to pink pH value of media solution before incubation ranges from 7.0 to 7.3 Rumen fluid was used from 03 fistulated cattle fed the same diet based on natural grass and rice straw Rumen fluid was collected before morning feeding and kept in thermos flasks It was then transported to laboratory, filtered through muslin fabric into pre-warmed thermos flasks and incubated at 39°C Rumen fluid was gassed further with carbonic to make anaerobic condition, tighly closed and incubated for experiments The experiment was conducted as a completely randomized design with replicates The treatments included (1) forages such as para grass, ruzi grass, guinea grass and Napier grass; (2) protein-supplemented feeds such as cassava forage, cotton seed meal and copra meal; (3) mixtures of replacing Napier grass for cassava forage at 0, 10, 20 and 30% in diet (DM basis) Two replicates of blank solution were also included in this study The blank solution contained only rumen fluid and media solution without substrates Measured gas from blank solution was used to correct the exact calculation of gas production Parameters: Digestibility of DM and OM, total gas volume, methane and carbonic concentrations, methane and carbonic volumes at 48 h post incubation 3.1.2 Experiment 2: Effects of dried, ensiled and fresh cassava forage in diet on digestibility and methane production of Sindhi x Yellow cattle The objective of this experiment was to determine effect of dried, ensiled and fresh cassava forage in Napier grass diet on DM intake, nutrient digestibility, nitrogen retention, rumen fluid parameters and methane production of Sindhi x Yellow cattle The experiment was carried out from March to June 2013 Nutrient composition of feeds and diets are presented in Table 3.2 and 3.3 Table 3.2: Nutrient composition of feeds used in experiment % DM basis DM, % CP Ash NDF Tannin1 HCN,mg/kg ME,MJ/kg NG 18.4 10.2 9.63 53.3 - - 8.45 DCF 88.7 18.6 7.28 41.6 3.04 294 9.82 ECF 30.3 17.3 7.64 42.8 2.96 282 9.62 FCF 18.1 18.3 7.04 47.9 3.09 816 9.81 Feed NG: Napier grass, DCF: dried cassava forage; ECF: ensiled cassava forage; FCF: fresh cassava forage, DM: dry matter, OM: organic matter, CP: crude protein, NDF: neutral detergent fiber, Ash: total minerals, HCN: hydrogen cyanide, ME: metabolizable energy (Abate and Mayer, 1997), 1condensed tannin determination followed Butanol-HCl method of Terrill et al (1992) The experiment was conducted as a x Latin square design Four treatments were control without replacing of Napier grass by cassava forage (CF-0), replacing of Napier grass by 20% dried cassava forage (DCF-20), replacing of Napier grass by 20% ensiled cassava forage (ECF-20) and replacing of Napier grass by 20% fresh cassava forage (FCF-20) Each experimental period lasted for 21 days including the first 14-day for adaptation to experimental diets Animals were then kept in cage floor for 7-day to collect the data of feed intake, feces and urine At the end of days of each experimental period, cattle were located into respiration chambers to determine volume of methane emission Table 3.3: Diet formulation and nutrients of experiment (% DM) Ingredient, % DM Treatment CF-0 DCF-20 ECF-20 FCF-20 100 80 80 80 Cassava forage, % 20 20 20 NaCl, g 20 20 20 20 Crude protein, % 10.2 11.4 11.2 11.1 Neutral detergent fiber, % 53.3 51.0 51.2 51.4 Condensed tannin , % 00.0 0.60 0.59 0.53 ME, MJ/kgDM 8.45 8.60 8.58 8.59 Napier grass, % CF-0: control without replacing cassava forage for Napier grass, DCF-20, ECF-20, FCF-20: replacing 20% dried, ensiled, fresh cassava forage for Napier grass in diet; ME: metabolizable energy Cattle methane production was determined by using improved respiration chambers: the amount of cattle methane emission was measured through measuring systems of air flow and methane concentration which were connected to improved respiration chambers The air circulation in improved respiration chambers was control in one direction depending on the vacuum pump which was connected to the air vent out This system drawn air through the measuring device of air flow to determine total amount of air which was sucked out of respiratory chambers The air inside improved respiration chambers was sucked out by Air Blower equiment (Model GF180, Resun Group Co., Ltd., China) at air flow 18 m3/h Air flow in chambers was measured by Gas Meter equipment (Model G16, Hangzhou Beta Gas Meter Co., Ltd., China) which could determine air flow from 16 to 25 m3/h Air samples inside respiratory chambers were collected for every 30 minutes At every sapling time points, air samples were collected for one minute and kept in m3 gas collecting bags When bags were full of air, it would be measured for methane concentration using Gasmet equiment (Model DX 4030, Gasmet Techologies Inc., Finland) Similarly, this process was repeated during each sampling period Parameters: feed and nutrient intakes, nutrient digestibility, pH, N-NH3, numbers of rumen bacteria and protozoa, daily volume of cattle methane emission 3.1.3 Experiment 3: Effects of dried, ensiled and fresh cassava in diet on body weight gain and methane production of Sindhi x Yellow cattle The objective of experiment was to determine effect of dried, ensiled and fresh cassava forage in Napier grass diet on body weight gain, feed conversion ratio, economic effect and methane production of Sindhi x Yellow cattle The experiment was carried out from July 2012 to December 2013 Chemical composition of feeds are presented in Table 3.4 and 3.5 Table 3.4: Nutrient composition of feeds used in experiment % DM basis DM, % CP Ash NDF Tannin1 HCN,mg/kg ME, MJ/kg NG 18.2 10.1 10.2 49.1 - - 8.37 DCF 85.2 17.5 8.27 36.7 2.87 279.5 9.57 ECF 36.6 17.1 8.81 38.2 2.71 298.3 9.46 FCF 19.4 17.7 7.94 39.7 2.95 851.2 9.64 Feed NG: Napier grass, DCF: dried cassava forage; ECF: ensiled cassava forage; FCF: fresh cassava forage, DM: dry matter, OM: organic matter, CP: crude protein, NDF: neutral detergent fiber, Ash: total minerals, HCN: hydrogen cyanide, ME: metabolizable energy (Abate and Mayer, 1997), 1condensed tannin determination followed Butanol-HCl method of Terrill et al (1992) The experiment was conducted as a completely randomized design with treatments and replicates Four treatments were control without replacing of Napier grass by cassava forage (CF-0), replacing of Napier grass by 20% dried cassava forage (DCF-20), replacing of Napier grass by 20% ensiled cassava forage (ECF-20) and replacing of Napier grass by 20% fresh cassava forage (FCF-20) Table 3.5: Diet formulation and nutrients of experiment (% DM) Item Treatment CF-0 DCF-20 ECF-20 FCF-20 100 80 80 80 Cassava forage, % 20 20 20 NaCl, g 20 20 20 20 Crude protein, % 10.1 11.2 11.0 11.1 Neutral detergent fiber, % 49.1 46.6 46.9 47.4 ME, MJ/kgDM 8.37 8.58 8.57 8.56 Napier grass, % CF-0: control without replacing cassava forage for Napier grass, DCF-20, ECF-20, FCF-20: replacing 20% dried, ensiled, fresh cassava forage for Napier grass in diet; ME: metabolizable energy Parameters: Feed and nutrient intakes, feed conversion ratio, weight gain, economic effect and methane emission 3.1.4 Experiment 4: Effect of replacing copra meal by dried cassava forage in diet on body weight gain and methane production of beef cattle The objective of experiment was to determine effect of replacing copra meal by dried cassava forage in diet on body weight gain, feed conversion ratio, economic effect and methane production of Sindhi x Yellow cattle The experiment was carried out from March 2014 to March 2015 Chemical composition of feeds and diets are presented in Table 3.6 and 3.7 Table 3.6: Nutrient composition of feeds used in experiment % DM basis DM,% CP EE NDF Ash Tannin1 ME, MJ/kg NG 17.9 10.3 2.69 59.3 10.1 - 8.69 DCF 87.2 17.1 3.45 42.6 7.95 2.13 9.92 CM 87.8 17.9 7.02 50.1 7.28 0.21 11.0 RB 88.2 12.2 11.8 28.3 8.13 - 11.2 Feed NG: Napier grass, DCF: dried cassava forage, CM: copra meal, RB: rice bran, DM: dry matter, EE: ether extract, CP: crude protein, NDF: neutral detergent fiber, Ash: total minerals, HCN: hydrogen cyanide ME: metabolizable energy (Viện Chăn nuôi, 2001), tannin1: condensed tannin Table 3.7: Diet formulation and nutrients of experiment Item Treatment CM-20 CM-15 CM-10 CM-5 CM-0 Napier grass, % 70 70 70 70 70 Concentrate, % 30 30 30 30 30 NaCl, g 20 20 20 20 20 Crude protein, % 11,9 11,9 11,9 11,8 11,8 Ether extract, % 4,28 4,15 3,76 3,73 3,61 ME, MJ/kgDM 9,39 9,34 9,29 9,24 9,19 CM-20, CM-15, CM-10,CM-5 CM-0: replacing copra meal by dried cassava forage at 0, 5, 10, 15 and 20% in diet based on Napier grass; ME: metabolizable energy The ratio of concentrate:roughage was 30:70 The levels of replacing copra meal by dried cassava forage were at 0, 5, 10, 15 and 20% while rice bran was kept at 10% in diets The formulation of concentrate is presented in Table 3.8 Table 3.8: Formulation and nutritional values of concentrate (% DM) Item Feed ingredients of concentrate (%) CM-20 CM-15 CM-10 CM-5 CM-0 Coconut meal, % 68 51 34 17 Dried cassava forage, % 17 34 51 68 Rice bran, % 32 32 32 32 32 Crude protein, % 15,8 15,7 15,7 15,5 15,4 ME, MJ/kgDM 11,0 10,8 10,7 10,5 10,3 CM-20, CM-15, CM-10,CM-5 CM-0: replacing copra meal by dried cassava forage at 0, 5, 10, 15 and 20% in diet based on Napier grass; ME: metabolizable energy The experiment was conducted as a completely randomized design with treatments and replicates Five treatments were 0, 5, 10, 15 and 20% copra meal replaced by dried cassava forage in Napier grass basal diets All parameters in this experiment were similar to those in experiment 3.2 Statistical analysis Experimental data were analyzed variance by ANOVA procedure of General Linear Model and regression of Minitab 16.0 Significant differences among treatment means were assessed by Tukey's multiple comparison tests after a significant F-test Overall differences between treatment means were considered to be significant at P[...]... digestibility while reducing number of protozoa and methane emission in Sindhi x Yellow cattle Replacing of 20% dried and ensiled cassava forages in Napier grass diets improves dry matter intake, weight gain, economic effectiveness in terms of feed and reduction of methane emission on Sindhi x Yellow cattle It is not recommended to replace of 20% fresh cassava forage in diet of cattle because it may lead... diets Therefore, replacing of 20% dried and ensiled and fresh cassava forage in Napier grass diets improved weight gain Table 4.10 showed that feed intake and weight gain increased in diet of replacing cassava forage leaded to feed conversion ratio reducing with replacing of dried, ensiled and fresh cassva forage, significantly (P