Animal biotechnology and its application in agricultural and research. Production of transgenic animals and how this technology has resulted in genetically engineered animal species that have improved qualities or produce novel animal products. Alternative techniques such as culture-induced variation or marker assisted animal breeding that can be used to produce genetically improved animal breeds without use of genetic engineering. The impact of the release of engineered animals: economic, ethical, moral and ecological importance. Introduction of novel genes, Transfection, retrovirus vectors, directed genetic manipulation, unintended genetic side effects, marker genes transposons, directed genetic manipulation, propagation by nuclear transfer, Expression of randomly-inserted genes, necessity for selection.