This book provides a comprehensive review of in ovo techniques and treatments in poultry eggs, which are aimed at improving embryonic development and decreasing economic losses in poultry farms. The book is divided into five chapters, which address the basics of in ovo techniques and sites of in ovo injection, nutrient utilisation for the development of the chick embryo, the role of early in ovo feeding for the chick embryo, and applications of in ovo technology for various nutrients and biological supplements in poultry.