State-of-the-art production, conservation and transfer of in-vitro-produced embryos in small ruminants

Abstract

Today, although not efficient enough to replace multiple ovulation and embryo transfer, in vitro embryo production for small ruminants is a platform for new reproductive technologies, such as embryo sexing, transgenesis and cloning. The in vitro embryo-production system developed for sheep and goats is more efficient now than 15 years ago, but could still be improved. Laparoscopic collection of oocytes in live animals treated with gonadotrophin indicates a promising future for the application of this technology to genetic improvement programmes. Oocyte maturation in defined medium with epidermal growth factor and cysteamine appears as efficient as oocyte maturation in follicular fluid-supplemented medium and allows future study of the effect of other factors involved in the cytoplasmic maturation of oocytes from these species. Further efforts have to be made to standardise the semen-capacitating process and to improve the quality and freezability of in-vitro-produced (IVP) embryos. The optimisation of IVP procedures for deer species has required the study of the seasonal variation of oocyte competence and the development of a specific methodology to allow the culture of embryos up to the blastocyst stage.