Utilization of cassava forages for goat production in an giang province viet nam

HUE UNIVERSITY HUE UNIVERSITY OF AGRICULTURE AND FORESTRY LE THI THUY HANG UTILIZATION OF CASSAVA FORAGES FOR GOAT PRODUCTION IN AN GIANG PROVINCE, VIETNAM DOCTOR OF PHILOSOPHY IN ANIMAL SCIENCES HUE, 2020 HUE UNIVERSITY HUE 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 DOCTOR OF PHILOSOPHY IN ANIMAL SCIENCES SUPERVISOR 1: Assoc Prof Nguyen Xuan Ba SUPERVISOR 2: Dr Dinh Van Dung HUE, 2020 DECLARATION I hereby guarantee that scientific work in this thesis is mine All results described in this thesis are righteous and objective They have been published in Journal of Livestock Research for Rural Development (LRRD) http://www.lrrd.org Hue University, 2020 Le Thi Thuy Hang, PhD Student i DEDICATION To my parents who taught me the good things in my life, my loving husband and my sons ii ACKNOWLEDGEMENTS These studies were carried out at An Giang University, Hue University of Agricultural and Forestry, Hue University with financial support from the Mekong Basin Animal Research Network (MEKARN II) Project I am grateful for their support for the thesis research and the scholarship for the PhD study I would like to express my sincere thanks to: Associate Professor Nguyen Xuan Ba, my main supervisor, for all his ideas, knowledge and experience Thanks for unceasing support in research and social activities He has given me invaluable support, encouragement and guidance throughout my study His reading, editing and follow -up of this thesis are gratefully acknowledged Doctor Dinh Van Dung, my second supervisor, who has given me invaluable support, encouragement, criticism, excellent skilled technical assistance and guidance throughout my study Professor Thomas R Preston, who has given me invaluable support, for valuable advice, encouragement, enthusiasm and discussions throughout the study His reading and correcting and follow-up of this thesis from the beginning to the end have enabled me to accomplish this work successfully, especially in correction of my English Associate Professor Nguyen Quang Linh, President of Hue University for giving us the best conditions and encouragement to study Associate Professor Tran Thanh Duc, Rector of Hue University of Agriculture and Forestry for giving us the best conditions, encouragement and support during our studies in Hue Doctor Khieu - Borin, Regional Coordinator of Mekarn II Project “Vietnam – SAREC Sustainable Livestock Production Systems” project, for valuable advice and discussions Professor Duong Nguyen Khang, Consultant of the “Vietnam – SAREC Sustainable Livestock Production Systems”, for valuable advice Professors, Lectures and assistant lecturers in courses which I have attended during my studies for sharing their valuable knowledge Associate Prof Dr Vo Van Thang, Rector of An Giang University for giving me permission to study, facilitation and encouragement iii My Dean, Dr Ho Thanh Binh, Dean of Agriculture and Natural Resources Faculty of An Giang university for giving me permission to study, facilitation and encouragement My colleagues at the Department of Animal Husbandry and Veterinary Medicine of Agriculture and Natural Resources Faculty of An Giang University for performing the chemical analyses and sharing experiences in scientific research and social activities My students, for help me in taking care the experiments To my friends in the PhD course, from Lao, Cambodia and Vietnam for giving me a warm and friendly atmosphere To my big family, for all their support and encouragement throughout my study And special thanks to my husband Tran Xuan Hien, two children’s who understood my work, and shared the happiness and sadness with me, for his loving, unceasing support and patience for my whole- life study iv ABSTRACT The aims of the study were to improve utilization cassava forages for increasing performance and reducing enteric methane emission in goat fed cassava forage restricted level of brewery grain and biochar in An Giang province, Vietnam There were one survey and four experiments in this study The survey of cassava and goat systems in Tinh Bien and Tri Ton districts, An Giang province showed that there is an increasing tendency to plant cassava At the same time, the population of goats was increased However, goat production systems were still extensive with small sizes and low growth rates Feed and feeding for goats were mainly natural grass and by-products, from crop growing, low nutrition It is not enough feed in rainy and flooding season Whole, cassava forage average tons/ha was available, but the farmers did not use them as feed for goats The impact of different levels of urea added to cassava stems (CS) and its chemical properties was investigated (Experiment 1) The urea treated cassava stems (UCS) (3% in DM) made good quality ensilage, with no loss in nutritive value that could be stored up to weeks An additional benefit was that the urea treatment reduced the content of HCN in the ensiled stems Experiment was conducted to determine the effect on feed intake, digestibility and N- retention in goats of supplementing the urea treated cassava stems (UCS) with fresh water spinach and biochar DM intake was increased by 18% by supplementing the UCS with biochar The combined effect of biochar plus water spinach was to increase DM intake by 41% Biochar increased daily N retention by 46% and the biological value of the absorbed N by 12% Experiment describes the addition of increasing levels of brewers’ grains (0 to 6%) in a diet of sweet cassava forage for growing goats The 4% level of brewers’ grains increased the DM intake, the apparent DM digestibility, the N retention and the biological value of the absorbed nitrogenous compounds Twelve growing male goats of the Bach Thao breed were given a basal diet of ad libitum fresh cassava forage supplemented with brewers’ grain (in 4%DM basis) in the experiment The biochar was supplied over the range of to 1.5% in diet DM Responses in feed intake, live weight gain, and feed conversion to biochar followed curvilinear trends with optimum benefits when biochar was added at 1.0% of the diet DM By contrast, the eructed methane production was decreased linearly with the level of biochar Key word: Cassava stems, cassava forage, brewers’ grain, liveweight gain, biochar, methane emission v