Transgenic livestock technologies

Recombinant DNA technology and gene transfer were set about forty years ago and since then have provided powerful tools for the production of biological molecules, the development of new varieties of crop and for generating key animal models in biomedical research. Following the synthesis of recombinant insulin, many other pharmacological proteins have been produced by expressing heterologous genes in micro-organisms, plants and animals. The application of gene transfer or “transgenesis” to animals has been developed mainly in mouse, while its use for generating transgenic livestock has encountered unanticipated resistances originated by social, economical and technical consideration. Apart from public concern and social consideration about the release of Genetically Engineered products on the market and GE-animals into the environment, that will not be discussed in this chapter, the development of transgenic livestock has been slow due to the technical difficulties faced in transferring this technology from mouse to large domestic animals and by the initial discouraging results, outlining the difficulties in obtaining the expected effect upon a genetic modification. This review will survey the scientific advancement making the generation of GE swine and ruminants more accessible in the last few years, positively influencing the technical and, as a consequence, the economical issues related to their development.