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Tài liệu Nghiên cứu khả năng sử dụng protein trong khẩu phần của thỏ californian

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MINISTRY OF EDUCATION AND TRAINING CAN THO UNIVERSITY TRUONG THANH TRUNG A STUDY OF DIETARY PROTEIN FOR GROWING CALIFORNIAN RABBITS IN THE MEKONG DELTA OF VIETNAM DOCTORAL THESIS IN ANIMAL SCIENCE 2017 i MINISTRY OF EDUCATION AND TRAINING CAN THO UNIVERSITY TRUONG THANH TRUNG A STUDY OF DIETARY PROTEIN FOR GROWING CALIFORNIAN RABBITS IN THE MEKONG DELTA OF VIETNAM DOCTORAL THESIS IN ANIMAL SCIENCE SCIENTIFIC SUPERVISOR ASSOCIATE PROFESSOR NGUYEN THI KIM DONG 2017 ii ACKNOWLEDGMENT I would like to thank to lectures at Department of Animal Science, Can Tho University who gave me useful knowledge and encouraged me during the course. I want to express particular appreciation to my supervisors, Association. Professor Dr. Nguyen Thi Kim Dong and Professor Dr. Nguyen Van Thu, Department of Animal Science, Can Tho University, Vietnam, for all your support, advice and explanation throughout the research, also for their reading and correcting my thesis papers. I learnt a lot of useful knowledge and real life experience from them. My thanks are extended to my classmates for sharing knowledge and experience in class. Many thanks to my friends in rabbit farm in Can Tho University for their help and encouragement to me. Last but not least, special thanks to my parents, younger brother, sisters, aunt and my girlfriend for their love and moral support I would like to thank all the people who contributed to this study Truong Thanh Trung iii ABSTRACT This thesis is based on five experiments that were conducted at the experimental farm in Cantho City to evaluate protein utilization of growing Californian rabbits in the Mekong Delta of Vietnam. The first experiment was to identify the nutritional values of some common feedstuffs for feeding rabbits in the Mekong Delta. The second was to determine the optimum level of crude protein in diets of growing Californian rabbits. The third was to compare and choose appropriate protein sources in diets of growing Californian rabbits. The fourth was to find out optimum level of lysine and threonine in diets for growing Californian rabbits. And the last experiment was to determine the optimum ME level in diets of growing Californian rabbits under feeding conditions in the Mekong Delta of Vietnam. The results showed that in the first experiment, almost essential and non-essential amino acid components of water spinach and Psophocarpus scandens were higher than those of Operculina turpethum and para grass. Sweet potato vine and water spinach leaves were good feedstuffs with high CP values and proportional fiber components. Soybean had low values of essential amino acids and non-essential amino acids than those of fish meal, feather meal and blood meal with the exception of methionine, glutamic and arginine concentrations. In the second experiment, the CP intake increased (P<0.05) while the NDF, ADF and EE intakes decrease (P<0.05) among treatments. The daily weight gain were significantly different (P<0.05) among treatments with the higher values (22.4, 23.3 and 23.2 g/day) for the CP19, CP21 and CP23 treatments. The carcass, thigh meat and lean meat weights were significantly higher (P<0.05) for the animals fed the 19, 21 and 23% CP treatments and the highest profit was obtained for the CP21 treatment. In the third experiment, intakes of DM, OM, CP, EE, NDF, ADF and ME of the soybean extraction meal (SEM) and water spinach leaves meal (WLM) treatments were significantly higher (P<0.05) than those the other treatments. The digestible DM, OM, CP, EE, CF, NDF and ADF were significantly higher (P<0.05) for the SEM and WLM treatments as compared to the feather meal (FEM) and blood meal (BM) treatments. Daily weight gain was significantly different (P<0.05) among treatments with the highest value for the SEM treatment (22.8 g/day) and the lowest value for the FEM treatment (14.9 g/day). The carcass weight and carcass percentage of the SEM and WLM treatments were significantly (P<0.05) higher than those of the FEM and BM, while the higher profit was found for the WLM and SEM treatments (3.07 and 2.63 USD/rabbit), respectively. iv In the fourth trial, almost amino acid digestibility of rabbits were significantly higher (P<0.05) for the 0.95-Lys treatment as compared to the 0.85-Lys and 1.05-Lys treatments. In term of threonine treatments, digestibility coefficients of almost amino acids were significantly different (P<0.05) with the higher values for the 0.75-Thr treatment. Daily weight gain of rabbit in the 0.95-Lys and the 0.75-Thr treatments (22.4 and 22.2 g/day, respectively) were significantly higher (P<0.05) than that of the 0.85-Lys and the 1.05-Lys treatments and the 0.65-Thr treatments, respectively. The carcass, lean meat and thigh weights of rabbit in the 0.95-Lys treatments were significantly higher (P<0.05) than others lysine treatments. The carcass, lean meat and thigh weights were also significantly different (P<0.05) between threonine treatments and the higher results were found for the 0.75-Thr treatment. In the fifth experiment, the DM and CP intakes were not significantly different among treatments being from 69.4-74.5 and 13.2-14.2 gDM/rabbit/day, respectively. The digestible DM, OM and CP were not significantly different (P>0.05) among treatments being 39.9-45.4, 35.8-41.3 and 7.65-9.06 g/rabbit/day, respectively. Daily weight gain was significantly different (P<0.05) among treatments with the highest value (24.5 g/day) for the ME11.5 treatment. The carcass, lean meat and thigh meat weights were significantly different (P<0.05) among treatments with the highest values in the ME11.5 treatment (1.374, 1.049 and 412 g, respectively). It was concluded that the combination among locally available feedstuffs in the Mekong Delta of Vietnam could formulate balanced nutrient diets for Californian growing rabbits. The diets contained 19% CP, 0.95% Lysine and 0.75% Threonine and 11.5 MJME/kgDM should be fed on growing Californian rabbits for improving growth performance, nutrient digestibilities, carcass quality and economic returns. Soybean extraction meal should be used in the Californian rabbit diets, as a protein supplement source due to its appetite and high nutrient digestibility. Keywords: carcass quality, income, nitrogen, nutrient digestibility, rodents v DECLARATION I assure that this thesis is a scientific work that was implemented by myself. All the figures and results presented in the thesis are true and not published in any previous theses. Author Truong Thanh Trung vi CONTENT Page Chapter 1. Introduction .................................................................................... 1 1.1 Problem statement...................................................................................... 1 1.2 Research objectives.................................................................................... 3 1.3 Key findings ............................................................................................... 3 1.4 Sciential and practical values ..................................................................... 3 Chapter II. Literature review ........................................................................... 5 2.1 Californian rabbits ..................................................................................... 5 2.1.1 History .................................................................................................... 5 2.1.2 Appearance ............................................................................................. 5 2.1.3 Temperament .......................................................................................... 5 2.1.4 Californian rabbits in Vietnam ............................................................... 6 2.2 The Understanding of Protein digestion on rabbit..................................... 7 2.2.1 Some features of the protein sources using in rabbit diets ..................... 7 2.2.2 Some characteristics of rabbit diets in Mekong Delta Vietnam ............. 9 2.2.3 Balance of protein and amino acid ......................................................... 10 2.2.4 Crude protein and total amino acids ....................................................... 11 2.2.5 Faecal digestibility .................................................................................. 12 2.2.6 Ileal digestibility ..................................................................................... 13 2.2.7 Nitrogen metabolism in the caecum ...................................................... 19 2.2.8 Protein digestion in young rabbits .......................................................... 21 2.3 Soft faeces and protein digestibility .......................................................... 22 2.4 The enhanced objectives for protein nutrition in rabbits ........................... 26 2.4.1 A documented context ............................................................................ 26 2.4.2 The relation between nitrogen and microbial growth ............................. 29 2.4.3 The interaction of nitrogen ileal flow and intestinal health .................... 31 2.4.4 The trend of using protein in rabbit diets................................................ 35 vii Chapter III. Materials and methods ................................................................. 38 3.1 Location and time ...................................................................................... 38 3.2 Animals and housing ................................................................................. 39 3.3 Feed and feeding ........................................................................................ 39 3.4 Experimental design .................................................................................. 45 3.5 Sampling procedure for nutrient digestibility .......................................... 49 3.6 Chemical analyses...................................................................................... 49 3.7 Measurements ............................................................................................ 49 3.8 Statistical analysis ...................................................................................... 50 Chapter IV. Results and discussion ................................................................. 51 4.1 Experiment 1: Nutrient evaluation with emphasis on amino acid values of the common feedstuffs for rabbits in the Mekong delta, Vietnam .................. 51 4.1.1 Nutrient composition of natural plants for feeding rabbits..................... 51 4.1.2 Nutrient composition of agricultural and industrial by-products for feeding rabbits ................................................................................................ 54 4.1.3 Nutrient composition of protein and energy supplemental feed ingredients for feeding rabbits ......................................................................... 58 4.1.4 Summary ................................................................................................. 64 4.2 Experiment 2: Effects of dietary crude protein levels on growth rate, meat production, digestible nutrients and economic return of Californian rabbits in Mekong Delta Vietnam .................................................................................... 65 4.2.1 Feed and nutrient intakes ........................................................................ 65 4.2.2 Daily weight gain and economic returns ................................................ 66 4.2.3 Carcass and meat nutrients ..................................................................... 67 4.2.4 Nutrient digestibility and nitrogen retention........................................... 68 4.2.5 Summary ................................................................................................. 69 4.3 Experiment 3: Effect of different protein sources in the diets on feed intake, nutrient digestibility, growth and carcass value of Californian rabbits in the Mekong Delta Vietnam .............................................................................. 70 4.3.1 Feed and nutrient intakes ........................................................................ 70 viii 4.3.2 Growth performance and economic returns ........................................... 71 4.3.3 Carcass values and meat nutrients .......................................................... 72 4.3.4 Nutrient digestion and nitrogen retention ............................................... 73 4.3.5 Summary ................................................................................................. 75 4.4 Experiment 4: Effect of lysine and threonine levels in the diets on feed intake, nutrient digestibility, growth and carcass value of Californian rabbits in the Mekong Delta, Vietnam ............................................................................. 76 4.4.1 Feed and nutrient intakes ........................................................................ 76 4.4.2 Growth performance and economic returns ........................................... 78 4.4.3 Carcass values and meat quality of experimental rabbits ....................... 80 4.4.4 Nutrient digestion and nitrogen retention ............................................... 81 4.4.5 Summary ................................................................................................. 83 4.5 Experiment 5: A response of feed utilization, nutrient digestibility, growth and carcass value of Californian rabbits to dietary metabolizable energy ..... 84 4.5.1 Feed and nutrient intakes ........................................................................ 84 4.5.2 Growth performance and economic returns ........................................... 85 4.5.3 Carcass values and meat nutrients .......................................................... 86 4.5.4 Nutrient digestion and nitrogen retention ............................................... 87 4.5.5 Summary ................................................................................................. 89 Chapter V. Conclusion and recommendations ................................................ 90 References ........................................................................................................ 92 Appendices..................................................................................................... 109 ix LIST OF FIGURES Page Figure 2.1 Relative value of some protein sources in rabbit diets in relation to soybean meal (100) using different nitrogen units (total versus apparent (app.) faecal digestible . ............................................................................................ 11 Figure 2.2 Apparent (a) and true (b) ileal amino acid digestibility of soybean meal with respect to its crude protein digestibility. ......................................... 15 Figure 2.3 Relationship between faecal crude protein (CP) digestibility and amino acid true ileal digestibility .................................................................... 17 Figure 2.4 Caecal nitrogen metabolism ........................................................... 20 Figure 2.5 Effect of the crude protein (CP) concentration of the caecal contents on the CP of soft faeces ..................................................................... 23 Figure 2.6 Contribution of soft faeces to the total intake of crude protein and some amino acids ............................................................................................ 26 Figure 2.7 Relationship between mortality (%) and the DP/DE ratio in the growing period ...……………………………………………………………31 Figure 2.8 Effect of ileal flux of crude protein on mortality from 25 to 60 days of age ........................................................................................................ 33 Figure 2.9 Relationship between average daily gain (g/d) and the DP/DE ratio in the growing period ...................................................................................... 36 Figure 3.1 Cages were used in the nutrient digestibility experiment .............. 39 Figure 3.2 Operculina turpethum ..................................................................... 43 Figure 3.3 Water spinach ................................................................................. 43 Figure 3.4 Psophocarpus scandens .................................................................. 43 Figure 3.5 Para grass ........................................................................................ 43 Figure 3.6 Sweet potato vines .......................................................................... 43 Figure 3.7 Water spinach leaves ...................................................................... 43 Figure 3.8 Soybean extraction meal ................................................................ 43 Figure 3.9 Soya waste ...................................................................................... 43 Figure 3.10 Soybean meal ............................................................................... 44 Figure 3.11 Fish meal ...................................................................................... 44 10 Figure 3.12 Feather meal ................................................................................. 44 Figure 3.13 Blood meal ................................................................................... 44 Figure 3.14 Maize ............................................................................................ 44 Figure 3.15 Broken rice ................................................................................... 44 Figure 3.16 Sweet potato tuber ........................................................................ 44 Figure 3.17 Amino acids were used in the study ............................................. 45 Figure 3.18 Rabbits for slaughtering ............................................................... 50 Figure 3.19 Experimental rabbit carcass ......................................................... 50 Figure 3.20 Rabbit thigh .................................................................................. 50 Figure 3.21 Rabbit thigh meat ......................................................................... 50 Figure 3.22 Rabbit lean meat ........................................................................... 50 Figure 4.1 DM, CP and ME concentration of para grass, water spinach, Psophocarpus scandens and Operculina turpethum ....................................... 52 Figure 4.2 Lysine, Threonine and Methionine concentration of para grass, water spinach, Psophocarpus scandens and Operculina turpethum ............... 54 Figure 4.3 CP, NDF and ME concentration of sweet potato vines, water spinach leaves, soybean extraction meal and soya waste ................................ 56 Figure 4.4 Lysine, Threonine and Methionine concentration of sweet potato vines, water spinach leaves, soybean extraction meal and soya waste............ 57 Figure 4.5 DM, CP and ME concentration of soybean, fish meal, feather meal and blood meal ................................................................................................. 61 Figure 4.6 Lysine, Threonine and Methionine concentration of soybean, fish meal, feather meal and blood meal .................................................................. 62 Figure 4.7 DM, CP and ME concentration of maize, broken rice and sweet potato tuber ...................................................................................................... 63 Figure 4.8 Lysine, Threonine and Methionine concentration of maize, broken rice and sweet potato tuber .............................................................................. 64 Figure 4.9 Effect of CP intake on daily gain of rabbits in the experiment ...... 67 Figure 4.10 Effect of ME concentration in diets on daily weight gain of rabbits in the experiment ............................................................................................. 86 11 LIST OF TABLES Page Table 2.1 Proportions of the different types of proteins in total protein of cereal and legume grains ................................................................................. 8 Table 2.2 Amino acid composition (g/16 g nitrogen) of wheat proteins ........ 8 Table 2.3 Crude protein (g/kg dry matter) of leaves and stems of lucerne hay and the amino acid composition (as a proportion of total amino acids) of leaf protein from fresh lucerne................................................................................ 9 Table 2.4 Dietary composition of growing rabbit diets in Mekong delta Vietnam ........................................................................................................ 9 Table 2.5 The invitro OMD (%) by using rabbit caecum fluid of some common feeds for rabbit production in the Mekong delta Vietnam................ 10 Table 2.6 Prediction equations for apparent faecal digestible protein (DP, g/kgDM) from chemical composition (g/kgDM) for different groups of feed ingredients ....................................................................................................... 12 Table 2.7 Amino acid composition (g/16 g nitrogen) of endogenous flow at the ileal and faecal levels ....................................................................................... 14 Table 2.8 Total and digestible protein and amino acid content (g/kg dry matter) using different units for the most important sources .......................... 18 Table 2.9 Effect of age on apparent ileal crude protein (CP) digestibility and the distribution of protein apparently digested ............................................... 22 Table 2.10 Protein and amino acid recommendations according to several authors (as-fed basis) ....................................................................................... 27 Table 2.11 Ileal balance in adult rabbits fed alfalfa based diets ..................... 30 Table 2.12 Effect of the level of protein in isofibrous diets (30% NDF) on pathogenic flora and mortality in early (25 d) weaned rabbits...........…........32 Table 2.13 Effect of level and type of dietary CP on intestinal health and ileal CP flow ........................................................................................................................ 34 Table 3.1 Chemical composition and metabolism energy concentration of feeds used in experiment 2 (%DM) ............................................................... 40 Table 3.2 Chemical composition (% DM) and metabolism energy concentration of feeds used in experiment 3 .................................................. 41 Table 3.3 Chemical composition and metabolism energy concentration of feeds used in experiment 4 (% DM, with the exception of DM as fed basic) 42 12 Table 3.4 Chemical composition and metabolism energy concentration of feeds in experiment 5 (%DM) ....................................................................... 42 Table 3.5 Dietary feed ingredients and metabolism energy concentration of the experiment 2 .................................................................................................... 45 Table 3.6 Feed ingredients composition, chemical composition and metabolism energy concentration of diets in the Exp. 3 (% DM) .................. 46 Table 3.7 Feed ingredients composition, dietary chemical composition and metabolism energy concentration in the experiment 4 (% DM) .................... 47 Table 3.8 Feed ingredients composition, dietary chemical composition and metabolism energy concentration in the experiment 5 (% DM) .................... 48 Table 4.1 Nutrient composition of natural grasses for feeding rabbits (Mean ± SD, n=3) .......................................................................................................... 51 Table 4.2 Nutrient composition of agricultural and industrial by-products for feeding rabbits.................................................................................................. 54 Table 4.3 Nutrient composition of protein and energy supplemental feed ingredients for feeding rabbits (Mean ± SD, n=3) .......................................... 58 Table 4.4 The feed, nutrient and metabolizable energy (ME) intakes of rabbits ................................................................................................................. 65 Table 4.5 Daily weight gain, feed conversion ratio and economic returns of experimental rabbits ........................................................................................ 66 Table 4.6 Carcass and meat quality of rabbits in the experiment ................... 67 Table 4.7 Nutrient intakes, digestible nutrients, and nitrogen retention of experimental rabbits ........................................................................................ 68 Table 4.8 The feed, nutrient and metabolizable energy (ME) intakes of rabbits ................................................................................................................. 70 Table 4.9 Final live weight, daily weight gain (DWG) and economic returns of experimental rabbits ........................................................................................ 71 Table 4.10 Carcass values, internal organs and meat quality of rabbits in the experiment ...................................................................................................... 72 Table 4.11 Nutrient intakes, digestible nutrients and nitrogen retention of rabbits in the nutrients digestibility trial ......................................................... 73 Table 4.12 Feed and nutrient intakes of experimental rabbits ........................ 76 Table 4.13 Amino acid intakes of experimental rabbits (g/rabbit/day) .......... 77 13 Table 4.14 Final live weight, daily weight gain (DWG) and economic returns of experimental rabbits ................................................................................... 78 Table 4.15 Carcass values, internal organs and meat quality of rabbits in the experiment ...................................................................................................... 80 Table 4.16 Nutrient intakes, digestible nutrients and nitrogen retention of rabbits in the nutrient digestibility trial .......................................................... 81 Table 4.17 Amino acids intake of rabbits in the nutrient digestibility trial (g/day) ............................................................................................................. 82 Table 4.18 Amino acids digestibility of experimental rabbits (%) ................. 82 Table 4.19 The feed and nutrient intakes of rabbits in the experiment ........... 84 Table 4.20 Body weight, daily weight gain, feed conversion ratio and economic returns of experimental rabbits........................................................ 85 Table 4.21 Carcass values, internal organs and meat quality of rabbits in the experiment ...................................................................................................... 86 Table 4.22 Nutrient intakes, digestible nutrients and nitrogen retention of experimental rabbits ...............................................................................................88 14 LIST OF ABBREVIATION ADF: Acid detergent fiber AID: Apparent ileal CP digestibility AOAC: Association of Official Agricultural Chemists CF: Crude fiber CP: Crude protein CPD: Apparent faecal CP digestibility DM: Dry matter DWG: Daily weight gain EE: Ether extract FCR: Feed conversion ratio FW: Final live weight INRA: National Institute for Agricultural Research of France IW: Initial live weight ME: Metabolizable energy N: Nitrogen NDF: Neutral detergent fiber NI: Nitrogen intake NIAS: National Institute of Animal Science of Vietnam NR: Nitrogen retention NRC: National Research Council Committee on Animal Nutrition OM: Organic matter SD: Standard deviation VFAs: Volatile fatty acids 15 CHAPTER I INTRODUCTION 1.1 Problem statement In recent years, rabbit production has increased considerably in Vietnam because of increasing human consumption. Local rabbits are popularly raised in the Mekong delta due to a good adaptation to the local climate and feeds; however, its productivity is very low. Californian rabbits have been imported into Vietnam to upgrade rabbit production since 1980. In 2000s, rabbit producers in the Mekong delta of Vietnam raised Californian rabbits by feeding locally available feed resources. In initial period, growth and reproductive performances of Californian rabbits were low and unstable. In recent years, Californian rabbits have been adapted to local feeding conditions, thus its productivity has been enhanced. Studies on Californain rabbits was rare, even in the world. In 2000-2012, World Rabbit Science Association published 230 papers including 2 papers research on Pure Californian rabbits, 52 papers for pure New Zealand White rabbits, 35 papers for Californian crossbred rabbits and 141 papers for local rabbits. There were 508 papers that were published in Livestock Research for Rural Development Journal from 1989 to 2016. In which, there was no study on pure Californian rabbits. It had 23 papers for Californian crossbred rabbits, 93 papers for pure New Zealand White rabbits and 392 papers for local rabbits. Shortly, studing on nutritional requirements of pure Californian rabbits has been rarely. It is necessary to study on feed utilization of pure Californin rabbits in local conditions for enhacing rabbit production. Rabbit producers fed natural grasses, wild vegetables and agroindustrial byproducts for both growing and reproductive rabbits. The diets for rabbits usually contain high proportion of fiber and low protein. Protein is needed for growth, reproduction and health of rabbits, and it can be obtained from both plant and animal sources. Protein is an important component for life processes, effects on growth performance, and carcass yield of rabbits. The nutritive value of a protein feed source is determined not only by its amino acid composition, but also by its digestibility of ingested protein. The main factors involved in protein digestibility of rabbits are chemical structure, properties, and accessibility to enzyme activity (McDonald et al., 2010). Rabbits could also utilize more protein resources from microbial activity in caecum by the coprophagy. In recent years, dietary supplementation of protein and amino acids had the major and traditional objective to meet rabbit 16 requirements for production (Carabano et al., 2008). Recent studies in rabbit nutrition have increased the number of criteria included in the nutritional recommendations, especially for fibrous and amino acids components (Gidenne and Fortun, 2003). The most important practical advance was the recommended nutritional needs of growing rabbits for the most frequent limiting amino acids (lysine, methionine and threonine). It is noted that current recommendations are higher for lysine and threonine (Carabano et al., 2008). There is a lot of studies on lysine, methionine and interaction between them on rabbit nutrient requirements, however, researches on interaction between lysine and threonine are rarely. Of all amino acids, lysine is the only one to play a metabolic role almost exclusively to add body protein that is for meat deposition. Lysine is generally related to protein synthesis (Champe and Harvey, 1997). Threonine is an amino acid that is used in the biosynthesis of protein. Threonine also aids in the production of antibodies to strengthen the immune system. Threonine is necessary for creating glycine and serine, two amino acids required to produce collagen, muscle tissue and elastin (Hawwa, 2013). Metabolizable energy (ME) was used by growing rabbits for productive functions as maintenance and growth. Several factors would affect the ME requirement in rabbits including body size, age, gender and breed, vital and productive functions, and feeding environment (De Blas and Wiseman, 2010). Several authors have studied the optimal dietary crude protein, amino acids and metabolizable energy levels for growing rabbits (Carabano et al., 2008) but their studies mainly used commercial pellets for feeding rabbits. Rabbits can be achieved optimum growing performance by supplying a balanced diet of protein, amino acid, fiber and energy. Diet quality has been a major limiting factor of rabbit production in the Mekong Delta of Vietnam, especially Californian rabbit diets. To formulate appropriately rabbit diets, it is necessary to know the nutritional composition of the feedstuffs to be used. However, there is limitary information on the chemical composition of feedstuffs for rabbit diets, especially amino acid components. The researches on suitable protein sources for growing Californian rabbits were not yet implemented. The studies on nutrient requirements, forage feeding and diet digestibility of Californian rabbits under feeding conditions in the Mekong Delta of Vietnam are still limited, especially crude protein levels, lysine and threonine and metabolizable levels in diets. 1.2 Research objectives 17 The objectives of this study were: - To enhance knowledge of the nutritional values of some popular feedstuffs for feeding rabbits in the Mekong Delta of Vietnam. - To identify optimal levels of crude protein in diets for the Californian rabbits - To determine the suitable protein sources in the diets with better uses, growth and benefits of growing Californian rabbits in the Mekong Delta of Vietnam. - To identify optimal levels of lysine and threonine in the Californian rabbit diets - To identify optimal levels of crude protein, lysine and threonine, metabolizable energy in the Californian rabbit diets under feeding conditions in Mekong delta of Vietnam. 1.3 Key findings Key findings of this study were: - Supplying the nutritional values, especially amino acid compostion, of the popular feeds for rabbits in the Mekong Delta of Vietnam - Identifying appropriate protein source in the diets for growing Californian rabbits in the Mekong Delta of Vietnam - Determining optimal levels of crude protein, lysine and threonine, metabolizable energy in the diets for Californian rabbits under feeding conditions in the Mekong delta of Vietnam 1.4 Sciential and practical considerations Sciential consideration This thesis supplies the scientific knowledge about nutrient compositions of some common feedstuffs in the Mekong Delta for feeding Californian rabbits with emphasis to amino acid values. Finding a better protein source in rabbit diets in the Mekong Delta of Vietnam is very informative for scientists who study on rabbits. This thesis researched on the protein utilization of Californian rabbits by systematic method and found the optimal levels of crude protein, lysine and threonine, metabolizable energy in diets. It is profitably scientific information for further studies on Californian rabbits in the Mekong Delta of Vietnam. Practical consideration 18 The findings of this study can be applied in the practice for feeding Californian rabbits to enhance productivity and economic returns for rabbit producers in the Mekong Delta of Vietnam. 19 CHAPTER II LITERATURE REVIEW 2.1 Californian rabbits-introduction The Californian rabbits is a medium to large domestic animals that is the result of a Himalayan crossbred with a Chinchilla, before making kits to a New Zealand white, developed in Southern California in the early years of the 1920s. George West, breeder who are seeking an animal that has good coverage as well as a high quality of meat. At the initial time, Californian failed to arouse the interest of American fanciers and it was not until the 1930s when it became popular. Today, Californian is one of the most common meat production rabbit in the world (Pets4home, 2010). 2.1.1 History The Californian rabbit was originally developed by George West in Southern California such as meat and feather production animal. The country has experienced a boom in rabbit breeding to meet the needs of a hungry population, and Californian was intended to help meet the growing demand for food. By putting together a Himalayan and a standard Chinchilla, West was partway to achieve their goals. By breeding the New Zealand White, he finally realized his ambition of creating a new rabbit that had great muscle cover and lovely body, silky soft fur (Pets4home, 2010). 2.1.2 Appearance Californian's main color is white with dark brown markings on the nose, tail, feet and ears. The average live weight is 3.5 to 4.75 kg for adult. Californian rabbit ears is big, which was held up, and is a moderate to largesized animals. The coat is silky and soft and white, with a dark brown almost ear, tail, nose and feet. This unusual colors make Californian look very similar to its ancestors of the Himalaya. The breed is well rounded and compact, with a short neck. It is muscular, plump and firm. The nose markings continue below the jaw and up towards the eyes, while the leg markings run well up the limbs towards the body and the nails and feet are dark. Ears up from base to tip the tail is also a dark chocolate brown (Pets4home, 2010). 2.1.3 Temperament The California is an animal calm, friendly and kind that makes a great pet. They can sometimes be sensitive, but with the careful handling and encourages, they can learn to adapt in human conditions. It is important to 20
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