The studies presented in this thesis were conducted at the livestock breeding farm of Soctrang province and Department of Animal Husbandry, College of Agriculture and Applied biology, Cantho University, Cantho City, Vietnam, supported by the Swedish International Development Agency/Department for Research Cooperation with Developing countries (SIDA/SAREC).
I would like to express my sincerely gratitude to:
Prof. Dr. Brian Ogle and Prof. Dr. Inger Ledin, Department of Animal Nutrition and Management, SLU for their kind help and encouragement.
Ass. Prof. Dr. Luu Trong Hieu, the former Regional Coordinator, Mr. Nguyen Van Cong and Dr. Duong Nguyen Khang for their valuable support.
Ass. Prof. Dr. Le Quang Minh, the former rector of Cantho University for the permission; Dr. Do Van Xe, vice rector of Cantho University for his help in processing the data.
All the lecturers and instructors from the Swedish University of Agricultural Sciences, Sweden; University of New England, Australia; Center for Livestock and Agriculture Development (CelAgrid), Cambodia; KhonKean University, ChiangMai University, Thailand; An Giang University (AGU), Can Tho University (CTU), Nong Lam University (NLU), Vietnam for transmitting their wide knowledge to our courses.
Mr. Tran Van Tam and the farm crew at the livestock breeding farm of Soctrang province for their permission to use their animals.
My office, Ass. Prof. Dr. Nguyen Van Thu, Mr. Nguyen Minh Thong, Ass. Prof. Dr. Vo Van Son, Dr. Bui Xuan Men, Dr. Ho Quang Do, Mrs. Nguyen Thi Hong Nhan, Mrs. Tran Thi Diep, Dr. Le Thi Men, Mrs. Huynh Thi Thu Loan, Ass. Prof. Dr. Nguyen Nhut Xuan Dung, Ass. Prof. Dr. Luu Huu Manh and the staff crew for creating favourable conditions and sharing their practical experience in scientific research.
My friends Nha, Hiep, Thao, Hue, Ngoc, Khamparn, Malavanh, Daovy, Latsamy, Ammaly, Supharoek, Suphawat, Suchitra, Sath, Buntha, Sokha, Phiny for creating the open atmosphere and their valuable help during the time away home.
To my family, my respectable parents, my older brothers, my older sisters and my intended wife for sharing weal and woe in hard times, their belief in me as well as the encouragement to me during the period of studying.