Role of reproductive biotechnologies: global perspective, current methods and success rates.

Artificial Insemination (AI), the first generation of Reproductive Biotechnologies (RB), is widely used in cattle with more than 110 million females, accounting for 20% of the total global population of breeding females, inseminated annually. There is still great potential for expansion, but further increases will depend on improved conception rates on commercial premises. AI is also used in sheep and goats but to a much lesser extent. AI in pigs has become increasing popular in recent years (close to 50%) with further expansion (around 10% or more) expected in the next decade. The major challenge for AI in the years to come is to reduce the cost of the offspring that are produced. Irrespective of the species, the key element determining this cost is the percentage of inseminations that result in viable offspring. In vivo collected embryo transfer has also been widely used across the world but to a much lesser extent than AI. In cattle around 500,000 embryos are transferred annually, generating an active international exchange of germplasm. Technical limitations associated with variability in superovulatory responses between individuals will limit further uptake of this technology. In contrast, in vitro embryo production, particularly in the bovine, has greater potential for expansion due to its ability to (1) generate a large number of offspring, (2) reduce costs of embryo production, (3) facilitate adoption of nuclear transfer and transgenesis and (4) regulate and minimise potential hazards associated with disease transmission. A remaining factor limiting uptake of this technology is the achievement of satisfactory pregnancy rates following the transfer of cryopreserved embryos, although recent developments suggest these problems can be overcome. Nuclear transfer and transgenesis present numerous opportunities for genetic conservation, but are still very much at the experimental stage. Genetically modified animals may only be tolerated by society if they lead to benefits in human health or to the environment. Emphasis should be directed to disease resistance in relation to both animal and zoonotic diseases.