Animal somatic cloning: state of the art in cattle and small ruminants

Among the recent reproductive biotechnologies for domestic mammals, somatic cell nuclear transfer is a new step forward, since the birth of Dolly the sheep. This article reports the current results obtained worldwide in cattle, sheep and goats, the limits of the technique and some potential applications. The overall efficiency (nb of young born/nb of reconstructed embryos) remains low (<= 7 %), but has been progressing. Embryonic mortality and important foetal physiopathologies are limiting factors. A research programme on bovine clones at INRA is aimed at the evaluation of the clone's health, their zootechnical performances as well as potential risks related to cloning. Despite some uncontrolled biological barriers, several applications of somatic cloning are being developed such as animal models for diseases, new tools for genetic selection, reproduction of rare genotypes or association with transgenesis for biomedical use. Current research takes into account the ethical aspects and societal concerns about animal cloning.