A person's accomplishments are not only achieved through one person, but the many people that are there for support, motivation and encouragement. While there are countless helpful hands that deserve my appreciation, I can mention a few individuals that have been supportive in my program. First, and foremost, I would like to thank my first supervisor Prof. Dr. Wolfgang Holtz (Doktorvater), for his invaluable advice and discussions during my study. He has been able to pass some of his experiences to me and this has allowed me to expand my knowledge in semen processing, estrus synchronisation, superovulation and manipulation of embryos. I would also like to express my appreciation for Prof. Dr. Dr. M Gauly who has given me the opportunity to work within his group. I express my deepest thanks to Prof. Dr. Christoph Knorr for scientific advice in molecular biology. Thanks also goes to Prof. Dr. Soleiman Salhab for reviewing this dissertation and his precious advice during may study. It is a pleasure to thank Mr Abdoulaye Gonde and Mrs E. Stüwe for expert technical assistance in ultrasonography and hormone analysis by ELISA, respectively. I owe my truthful thanks to the Animal Assistants Mr. Jochen Köhler and his team for their assistance. I hereby thank my colleagues at the department of Animal Sciences for various support especially Mr. Shahin, Mr Ahmad Idris and Mr Azzam Al Yacoub. I sincerely thank my parents and family for their endless love and support. This dissertation was prepared with financial support from Damascus University to whom I hereby show my deepest appreciation. II Dedication To My beloved mother and adored father My wife and sons Ali, Bilal and Husam III Chapter II Superovulation of ovsynch-synchronized Boer goats induced to ovulate with GnRH or hCG.