Transgenic animals ? worms, flies, fishes, rodents and livestock are the invaluable models that have allowed the scientific and medical community to study in depth the mechanisms of gene and genome function and complex disease phenotypes, to discover current and potential therapeutic approaches. Transgenic animals are routinely used in the laboratory as models in biomedical research. They are important tools for researching human disease, being used to understand gene function in the context of disease susceptibility, progression and to determine responses to a therapeutic intervention. The optimized techniques such as somatic cell nuclear transfer and cytoplasmic injection of exogenous DNA into zygotes are also the promising tools to generate transgenic livestock with special traits. This book elucidates new techniques and the applications in this field in a multidisciplinary approach. It elaborates on the different theories and concepts related to this area. It focuses on stem cells and animal transgenesis, senile systemic amyloidosis, transgenic animal technology, transboundary animal diseases, repetitive DNA and reproductive technologies. It also presents function measurements and recombineering of BAC DNA. The possible future directions and unresolved challenges are outlined. The topics included in this book are of utmost significance and are bound to provide incredible insights to the readers. It will serve as a valuable source of reference for those interested in this field and related branches.